[PATCH 00/19] x86, mpx updates for 4.2 (take 9)

[PATCH 00/19] x86, mpx updates for 4.2 (take 9)

[Dave Hansen]

Changes from take 8 / v23:
 * Respond to some of Ingo's comments about get_xsave_field_ptr():
   1. add const in return type, and fix up the cascading need for
      'const' in other parts of the MPX code and tracepoints.
   2. add a local 'fpu' var
   3. Update patch description

Changes from take 7 / v22:
 * Add Thomas's reviewed-by
 * merge with tip/x86/fpu changes
 * Fix tiny spelling nit

Changes from take 6 / v21:
 * Address a bunch of Thomas's review comments.

Changes from take 5 / v20:

 * Fix get_xsave_addr() to consult xstate_bv in anticipation
   of fixes to xsave code.
 * Bug fix for when an VMA being unmapped has neighbors which
   are bounds tables.
 * Rewrite unmapping code.  I didn't do this lightly. It was
   not originally my own code, and I resisted changing it
   because it worked.  But, I started bug chasing and decided
   it was unmaintainable.  The rewrite ended up removing
   about 20% of the unmapping code and made it much simpler.

Changes from take 4 / v19:

 * Do not pass a task_struct around when we are
   really just going to operate on current

Changes from take 3 / v18 (all minor):

 * use DECLARE_EVENT_CLASS()/DEFINE_EVENT() for
   the ranged tracepoints to save 10 lines of code.

Changes from take 2 / v17 (all minor):

 * fix a couple of whitespace borkages caught by checkpatch,
   and a spelling error or two.
 * replace printk with pr_info() for boot disable
 * change trace print format for address intervals
 * fix up variable name in tsk_get_xsave_addr() comment
 * remove tsk_get_xsave_field() GPL export
 * fix up Qiaowei's From:

--

Hi x86 maintainers,

There are a few basic things going on here:
1. Make FPU/xsave code cleaner and less error-prone
2. Add trace points to make kernel and app debugging easier
3. Add a boot-time disable for mpx
4. Rewrite the unmapping code.
5. Support 32-bit binaries to run on 64-bit kernels

This set is also available against tip/x86/fpu (8c05f05edb) in git:

  git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx.git mpx-v24

Dave Hansen (19):
      x86, mpx, xsave: Fix up bad get_xsave_addr() assumptions
      x86, fpu: Wrap get_xsave_addr() to make it safer
      x86, mpx: Use new get_xsave_field_ptr()
      x86, mpx: Cleanup: Do not pass task around when unnecessary
      x86, mpx: remove redundant MPX_BNDCFG_ADDR_MASK
      x86, mpx: Restrict mmap size check to bounds tables
      x86, mpx: boot-time disable
      x86, mpx: trace #BR exceptions
      x86, mpx: trace entry to bounds exception paths
      x86, mpx: Trace the attempts to find bounds tables
      x86, mpx: trace allocation of new bounds tables
      x86: make is_64bit_mm() widely available
      x86, mpx: Add temporary variable to reduce masking
      x86, mpx: new directory entry to addr helper
      x86, mpx: do 32-bit-only cmpxchg for 32-bit apps
      x86, mpx: support 32-bit binaries on 64-bit kernel
      x86, mpx: rewrite unmap code
      x86, mpx: do not count MPX VMAs as neighbors when unmapping
      x86, mpx: allow mixed binaries again

 Documentation/kernel-parameters.txt |   4 +
 arch/x86/include/asm/fpu/xstate.h   |   1 +
 arch/x86/include/asm/mmu_context.h  |  13 +
 arch/x86/include/asm/mpx.h          |  74 ++--
 arch/x86/include/asm/processor.h    |  12 +-
 arch/x86/include/asm/trace/mpx.h    | 132 +++++++
 arch/x86/kernel/cpu/common.c        |  16 +
 arch/x86/kernel/fpu/xstate.c        |  77 ++++-
 arch/x86/kernel/traps.c             |  20 +-
 arch/x86/kernel/uprobes.c           |  10 +-
 arch/x86/mm/mpx.c                   | 514 +++++++++++++++++-----------
 kernel/sys.c                        |   8 +-
 12 files changed, 610 insertions(+), 271 deletions(-)

[PATCH 01/19] x86, mpx, xsave: Fix up bad get_xsave_addr() assumptions

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

get_xsave_addr() assumes that if an xsave bit is present in the
hardware (pcntxt_mask) that it is present in a given xsave
buffer.  Due to an bug in the xsave code on all of the systems
that have MPX (and thus all the users of this code), that has
been a true assumption.

But, the bug is getting fixed, so our assumption is not going
to hold any more.

It's quite possible (and normal) for an enabled state to be
present on 'pcntxt_mask', but *not* in 'xstate_bv'.  We need
to consult 'xstate_bv'.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/kernel/fpu/xstate.c |   45 +++++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff -puN arch/x86/kernel/fpu/xstate.c~consullt-xstate_bv arch/x86/kernel/fpu/xstate.c
--- a/arch/x86/kernel/fpu/xstate.c~consullt-xstate_bv	2015-06-01 10:24:03.025676699 -0700
+++ b/arch/x86/kernel/fpu/xstate.c	2015-06-01 10:24:03.029676880 -0700
@@ -382,19 +382,48 @@ void fpu__resume_cpu(void)
  * This is the API that is called to get xstate address in either
  * standard format or compacted format of xsave area.
  *
+ * Note that if there is no data for the field in the xsave buffer
+ * this will return NULL.
+ *
  * Inputs:
- *	xsave: base address of the xsave area;
- *	xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE,
- *	etc.)
+ *	xstate: the thread's storage area for all FPU data
+ *	xstate_feature: state which is defined in xsave.h (e.g.
+ *	XSTATE_FP, XSTATE_SSE, etc...)
  * Output:
- *	address of the state in the xsave area.
+ *	address of the state in the xsave area, or NULL if the
+ *	field is not present in the xsave buffer.
  */
-void *get_xsave_addr(struct xregs_state *xsave, int xstate)
+void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature)
 {
-	int feature = fls64(xstate) - 1;
-	if (!test_bit(feature, (unsigned long *)&xfeatures_mask))
+	int feature_nr = fls64(xstate_feature) - 1;
+	/*
+	 * Do we even *have* xsave state?
+	 */
+	if (!boot_cpu_has(X86_FEATURE_XSAVE))
+		return NULL;
+
+	xsave = &current->thread.fpu.state.xsave;
+	/*
+	 * We should not ever be requesting features that we
+	 * have not enabled.  Remember that pcntxt_mask is
+	 * what we write to the XCR0 register.
+	 */
+	WARN_ONCE(!(xfeatures_mask & xstate_feature),
+		  "get of unsupported state");
+	/*
+	 * This assumes the last 'xsave*' instruction to
+	 * have requested that 'xstate_feature' be saved.
+	 * If it did not, we might be seeing and old value
+	 * of the field in the buffer.
+	 *
+	 * This can happen because the last 'xsave' did not
+	 * request that this feature be saved (unlikely)
+	 * or because the "init optimization" caused it
+	 * to not be saved.
+	 */
+	if (!(xsave->header.xfeatures & xstate_feature))
 		return NULL;
 
-	return (void *)xsave + xstate_comp_offsets[feature];
+	return (void *)xsave + xstate_comp_offsets[feature_nr];
 }
 EXPORT_SYMBOL_GPL(get_xsave_addr);
_

[tip:x86/fpu] x86/fpu/xstate: Fix up bad get_xsave_addr() assumptions

[tip-bot for Dave Hansen]

Commit-ID:  0c4109bec0a6cde471bef3a21cd6f8384a614469
Gitweb:     http://git.kernel.org/tip/0c4109bec0a6cde471bef3a21cd6f8384a614469
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:00 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:29 +0200

x86/fpu/xstate: Fix up bad get_xsave_addr() assumptions

get_xsave_addr() assumes that if an xsave bit is present in the
hardware (pcntxt_mask) that it is present in a given xsave
buffer.  Due to an bug in the xsave code on all of the systems
that have MPX (and thus all the users of this code), that has
been a true assumption.

But, the bug is getting fixed, so our assumption is not going
to hold any more.

It's quite possible (and normal) for an enabled state to be
present on 'pcntxt_mask', but *not* in 'xstate_bv'.  We need
to consult 'xstate_bv'.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183700.1E739B34@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/fpu/xstate.c | 45 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index a580eb5..af3700e 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -382,19 +382,48 @@ void fpu__resume_cpu(void)
  * This is the API that is called to get xstate address in either
  * standard format or compacted format of xsave area.
  *
+ * Note that if there is no data for the field in the xsave buffer
+ * this will return NULL.
+ *
  * Inputs:
- *	xsave: base address of the xsave area;
- *	xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE,
- *	etc.)
+ *	xstate: the thread's storage area for all FPU data
+ *	xstate_feature: state which is defined in xsave.h (e.g.
+ *	XSTATE_FP, XSTATE_SSE, etc...)
  * Output:
- *	address of the state in the xsave area.
+ *	address of the state in the xsave area, or NULL if the
+ *	field is not present in the xsave buffer.
  */
-void *get_xsave_addr(struct xregs_state *xsave, int xstate)
+void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature)
 {
-	int feature = fls64(xstate) - 1;
-	if (!test_bit(feature, (unsigned long *)&xfeatures_mask))
+	int feature_nr = fls64(xstate_feature) - 1;
+	/*
+	 * Do we even *have* xsave state?
+	 */
+	if (!boot_cpu_has(X86_FEATURE_XSAVE))
+		return NULL;
+
+	xsave = &current->thread.fpu.state.xsave;
+	/*
+	 * We should not ever be requesting features that we
+	 * have not enabled.  Remember that pcntxt_mask is
+	 * what we write to the XCR0 register.
+	 */
+	WARN_ONCE(!(xfeatures_mask & xstate_feature),
+		  "get of unsupported state");
+	/*
+	 * This assumes the last 'xsave*' instruction to
+	 * have requested that 'xstate_feature' be saved.
+	 * If it did not, we might be seeing and old value
+	 * of the field in the buffer.
+	 *
+	 * This can happen because the last 'xsave' did not
+	 * request that this feature be saved (unlikely)
+	 * or because the "init optimization" caused it
+	 * to not be saved.
+	 */
+	if (!(xsave->header.xfeatures & xstate_feature))
 		return NULL;
 
-	return (void *)xsave + xstate_comp_offsets[feature];
+	return (void *)xsave + xstate_comp_offsets[feature_nr];
 }
 EXPORT_SYMBOL_GPL(get_xsave_addr);

[PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The MPX code appears is calling a low-level FPU function
(copy_fpregs_to_fpstate()).  This function is not able to
be called in all contexts, although it is safe to call
directly in some cases.

Although probably correct, the current code is ugly and
potentially error-prone.  So, add a wrapper that calls
the (slightly) higher-level fpu__save() (which is preempt-
safe) and also ensures that we even *have* an FPU context
(in the case that this was called when in lazy FPU mode).

Ingo had this to say about the details about when we need
preemption disabled:

> it's indeed generally unsafe to access/copy FPU registers with preemption enabled,
> for two reasons:
>
>   - on older systems that use FSAVE the instruction destroys FPU register
>     contents, which has to be handled carefully
>
>   - even on newer systems if we copy to FPU registers (which this code doesn't)
>     then we don't want a context switch to occur in the middle of it, because a
>     context switch will write to the fpstate, potentially overwriting our new data
>     with old FPU state.
>
> But it's safe to access FPU registers with preemption enabled in a couple of
> special cases:
>
>   - potentially destructively saving FPU registers: the signal handling code does
>     this in copy_fpstate_to_sigframe(), because it can rely on the signal restore
>     side to restore the original FPU state.
>
>   - reading FPU registers on modern systems: we don't do this anywhere at the
>     moment, mostly to keep symmetry with older systems where FSAVE is
>     destructive.
>
>   - initializing FPU registers on modern systems: fpu__clear() does this. Here
>     it's safe because we don't copy from the fpstate.
>
>   - directly writing FPU registers from user-space memory (!). We do this in
>     fpu__restore_sig(), and it's safe because neither context switches nor
>     irq-handler FPU use can corrupt the source context of the copy (which is
>     user-space memory).
>
> Note that the MPX code's current use of copy_fpregs_to_fpstate() was safe I think,
> because:
>
>  - MPX is predicated on eagerfpu, so the destructive F[N]SAVE instruction won't be
>    used.
>
>  - the code was only reading FPU registers, and was doing it only in places that
>    guaranteed that an FPU state was already active (i.e. didn't do it in
>    kthreads)

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: bp@alien8.de
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: the arch/x86 maintainers <x86@kernel.org>

---

Changes from take 8 / v23:
 * Add const specifier for get_xsave_field_ptr() return type
 * Add temporary 'fpu' variable to shorten up the code and
   make it look more consistent with the other FPU code.

Changes from v21:
 * add comments about preemption
 * rename helper to get_xsave_field_ptr()

Changes from "v19":
 * remove 'tsk' argument to get_xsave_addr() since the code
   can only realistically work on 'current', and fix up the
   comment a bit to match.

Changes from "v17":
 * fix s/xstate/xsave_field/ in the function comment
 * remove EXPORT_SYMBOL_GPL()

---

 b/arch/x86/include/asm/fpu/xstate.h |    1 +
 b/arch/x86/kernel/fpu/xstate.c      |   32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff -puN arch/x86/include/asm/fpu/xstate.h~tsk_get_xsave_addr arch/x86/include/asm/fpu/xstate.h
--- a/arch/x86/include/asm/fpu/xstate.h~tsk_get_xsave_addr	2015-06-01 10:24:03.427694831 -0700
+++ b/arch/x86/include/asm/fpu/xstate.h	2015-06-01 10:24:03.432695056 -0700
@@ -41,5 +41,6 @@ extern u64 xstate_fx_sw_bytes[USER_XSTAT
 extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
 
 void *get_xsave_addr(struct xregs_state *xsave, int xstate);
+const void *get_xsave_field_ptr(int xstate_field);
 
 #endif
diff -puN arch/x86/kernel/fpu/xstate.c~tsk_get_xsave_addr arch/x86/kernel/fpu/xstate.c
--- a/arch/x86/kernel/fpu/xstate.c~tsk_get_xsave_addr	2015-06-01 10:24:03.429694921 -0700
+++ b/arch/x86/kernel/fpu/xstate.c	2015-06-01 10:24:03.433695102 -0700
@@ -427,3 +427,35 @@ void *get_xsave_addr(struct xregs_state
 	return (void *)xsave + xstate_comp_offsets[feature_nr];
 }
 EXPORT_SYMBOL_GPL(get_xsave_addr);
+
+/*
+ * This wraps up the common operations that need to occur when retrieving
+ * data from xsave state.  It first ensures that the current task was
+ * using the FPU and retrieves the data in to a buffer.  It then calculates
+ * the offset of the requested field in the buffer.
+ *
+ * This function is safe to call whether the FPU is in use or not.
+ *
+ * Note that this only works on the current task.
+ *
+ * Inputs:
+ *	@xsave_state: state which is defined in xsave.h (e.g. XSTATE_FP,
+ *	XSTATE_SSE, etc...)
+ * Output:
+ *	address of the state in the xsave area or NULL if the state
+ *	is not present or is in its 'init state'.
+ */
+const void *get_xsave_field_ptr(int xsave_state)
+{
+	struct fpu *fpu = &current->thread.fpu;
+
+	if (!fpu->fpstate_active)
+		return NULL;
+	/*
+	 * fpu__save() takes the CPU's xstate registers
+	 * and saves them off to the 'fpu memory buffer.
+	 */
+	fpu__save(fpu);
+
+	return get_xsave_addr(&fpu->state.xsave, xsave_state);
+}
_

[tip:x86/fpu] x86/fpu/xstate: Wrap get_xsave_addr() to make it safer

[tip-bot for Dave Hansen]

Commit-ID:  04cd027bcba1ead7bfe39e7f1c6f4d993c4c3323
Gitweb:     http://git.kernel.org/tip/04cd027bcba1ead7bfe39e7f1c6f4d993c4c3323
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:00 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:29 +0200

x86/fpu/xstate: Wrap get_xsave_addr() to make it safer

The MPX code appears is calling a low-level FPU function
(copy_fpregs_to_fpstate()).  This function is not able to
be called in all contexts, although it is safe to call
directly in some cases.

Although probably correct, the current code is ugly and
potentially error-prone.  So, add a wrapper that calls
the (slightly) higher-level fpu__save() (which is preempt-
safe) and also ensures that we even *have* an FPU context
(in the case that this was called when in lazy FPU mode).

Ingo had this to say about the details about when we need
preemption disabled:

> it's indeed generally unsafe to access/copy FPU registers with preemption enabled,
> for two reasons:
>
>   - on older systems that use FSAVE the instruction destroys FPU register
>     contents, which has to be handled carefully
>
>   - even on newer systems if we copy to FPU registers (which this code doesn't)
>     then we don't want a context switch to occur in the middle of it, because a
>     context switch will write to the fpstate, potentially overwriting our new data
>     with old FPU state.
>
> But it's safe to access FPU registers with preemption enabled in a couple of
> special cases:
>
>   - potentially destructively saving FPU registers: the signal handling code does
>     this in copy_fpstate_to_sigframe(), because it can rely on the signal restore
>     side to restore the original FPU state.
>
>   - reading FPU registers on modern systems: we don't do this anywhere at the
>     moment, mostly to keep symmetry with older systems where FSAVE is
>     destructive.
>
>   - initializing FPU registers on modern systems: fpu__clear() does this. Here
>     it's safe because we don't copy from the fpstate.
>
>   - directly writing FPU registers from user-space memory (!). We do this in
>     fpu__restore_sig(), and it's safe because neither context switches nor
>     irq-handler FPU use can corrupt the source context of the copy (which is
>     user-space memory).
>
> Note that the MPX code's current use of copy_fpregs_to_fpstate() was safe I think,
> because:
>
>  - MPX is predicated on eagerfpu, so the destructive F[N]SAVE instruction won't be
>    used.
>
>  - the code was only reading FPU registers, and was doing it only in places that
>    guaranteed that an FPU state was already active (i.e. didn't do it in
>    kthreads)

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave@sr71.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183700.AA881696@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/fpu/xstate.h |  1 +
 arch/x86/kernel/fpu/xstate.c      | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 3398946..4656b25 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -41,5 +41,6 @@ extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
 extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
 
 void *get_xsave_addr(struct xregs_state *xsave, int xstate);
+const void *get_xsave_field_ptr(int xstate_field);
 
 #endif
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index af3700e..49d0d9b 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -427,3 +427,35 @@ void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature)
 	return (void *)xsave + xstate_comp_offsets[feature_nr];
 }
 EXPORT_SYMBOL_GPL(get_xsave_addr);
+
+/*
+ * This wraps up the common operations that need to occur when retrieving
+ * data from xsave state.  It first ensures that the current task was
+ * using the FPU and retrieves the data in to a buffer.  It then calculates
+ * the offset of the requested field in the buffer.
+ *
+ * This function is safe to call whether the FPU is in use or not.
+ *
+ * Note that this only works on the current task.
+ *
+ * Inputs:
+ *	@xsave_state: state which is defined in xsave.h (e.g. XSTATE_FP,
+ *	XSTATE_SSE, etc...)
+ * Output:
+ *	address of the state in the xsave area or NULL if the state
+ *	is not present or is in its 'init state'.
+ */
+const void *get_xsave_field_ptr(int xsave_state)
+{
+	struct fpu *fpu = &current->thread.fpu;
+
+	if (!fpu->fpstate_active)
+		return NULL;
+	/*
+	 * fpu__save() takes the CPU's xstate registers
+	 * and saves them off to the 'fpu memory buffer.
+	 */
+	fpu__save(fpu);
+
+	return get_xsave_addr(&fpu->state.xsave, xsave_state);
+}

[PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr()

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The MPX registers (bndcsr/bndcfgu/bndstatus) are not directly
accessible via normal instructions.  They essentially act as
if they were floating point registers and are saved/restored
along with those registers.

There are two main paths in the MPX code where we care about
the contents of these registers:
	1. #BR (bounds) faults
	2. the prctl() code where we are setting MPX up

Both of those paths _might_ be called without the FPU having
been used.  That means that 'tsk->thread.fpu.state' might
never be allocated.

Also, fpu_save_init() is not preempt-safe.  It was a bug to
call it without disabling preemption.  The new
get_xsave_addr() calls unlazy_fpu() instead and properly
disables preemption.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: bp@alien8.de
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>

---

Changes from v21:
 * rename get_xsave_field() to get_xsave_field_ptr()
---

 b/arch/x86/include/asm/mpx.h |    8 ++++----
 b/arch/x86/kernel/traps.c    |   17 ++++++++---------
 b/arch/x86/mm/mpx.c          |   30 +++++++++++++++---------------
 3 files changed, 27 insertions(+), 28 deletions(-)

diff -puN arch/x86/include/asm/mpx.h~use-new-tsk_get_xsave_addr arch/x86/include/asm/mpx.h
--- a/arch/x86/include/asm/mpx.h~use-new-tsk_get_xsave_addr	2015-06-01 10:24:03.804711835 -0700
+++ b/arch/x86/include/asm/mpx.h	2015-06-01 10:24:03.810712106 -0700
@@ -60,8 +60,8 @@
 
 #ifdef CONFIG_X86_INTEL_MPX
 siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct xregs_state *xsave_buf);
-int mpx_handle_bd_fault(struct xregs_state *xsave_buf);
+				struct task_struct *tsk);
+int mpx_handle_bd_fault(struct task_struct *tsk);
 static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
 {
 	return (mm->bd_addr != MPX_INVALID_BOUNDS_DIR);
@@ -78,11 +78,11 @@ void mpx_notify_unmap(struct mm_struct *
 		      unsigned long start, unsigned long end);
 #else
 static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-					      struct xregs_state *xsave_buf)
+					      struct task_struct *tsk)
 {
 	return NULL;
 }
-static inline int mpx_handle_bd_fault(struct xregs_state *xsave_buf)
+static inline int mpx_handle_bd_fault(struct task_struct *tsk)
 {
 	return -EINVAL;
 }
diff -puN arch/x86/kernel/traps.c~use-new-tsk_get_xsave_addr arch/x86/kernel/traps.c
--- a/arch/x86/kernel/traps.c~use-new-tsk_get_xsave_addr	2015-06-01 10:24:03.805711880 -0700
+++ b/arch/x86/kernel/traps.c	2015-06-01 10:24:03.810712106 -0700
@@ -59,6 +59,7 @@
 #include <asm/fixmap.h>
 #include <asm/mach_traps.h>
 #include <asm/alternative.h>
+#include <asm/fpu/xstate.h>
 #include <asm/mpx.h>
 
 #ifdef CONFIG_X86_64
@@ -371,9 +372,8 @@ dotraplinkage void do_double_fault(struc
 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 {
 	struct task_struct *tsk = current;
-	struct xregs_state *xsave_buf;
 	enum ctx_state prev_state;
-	struct bndcsr *bndcsr;
+	const struct bndcsr *bndcsr;
 	siginfo_t *info;
 
 	prev_state = exception_enter();
@@ -392,12 +392,11 @@ dotraplinkage void do_bounds(struct pt_r
 
 	/*
 	 * We need to look at BNDSTATUS to resolve this exception.
-	 * It is not directly accessible, though, so we need to
-	 * do an xsave and then pull it out of the xsave buffer.
+	 * A NULL here might mean that it is in its 'init state',
+	 * which is all zeros which indicates MPX was not
+	 * responsible for the exception.
 	 */
-	copy_fpregs_to_fpstate(&tsk->thread.fpu);
-	xsave_buf = &(tsk->thread.fpu.state.xsave);
-	bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR);
+	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
 		goto exit_trap;
 
@@ -408,11 +407,11 @@ dotraplinkage void do_bounds(struct pt_r
 	 */
 	switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
 	case 2:	/* Bound directory has invalid entry. */
-		if (mpx_handle_bd_fault(xsave_buf))
+		if (mpx_handle_bd_fault(tsk))
 			goto exit_trap;
 		break; /* Success, it was handled */
 	case 1: /* Bound violation. */
-		info = mpx_generate_siginfo(regs, xsave_buf);
+		info = mpx_generate_siginfo(regs, tsk);
 		if (IS_ERR(info)) {
 			/*
 			 * We failed to decode the MPX instruction.  Act as if
diff -puN arch/x86/mm/mpx.c~use-new-tsk_get_xsave_addr arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~use-new-tsk_get_xsave_addr	2015-06-01 10:24:03.807711971 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:03.811712151 -0700
@@ -272,9 +272,9 @@ bad_opcode:
  * The caller is expected to kfree() the returned siginfo_t.
  */
 siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct xregs_state *xsave_buf)
+				struct task_struct *tsk)
 {
-	struct bndreg *bndregs, *bndreg;
+	const struct bndreg *bndregs, *bndreg;
 	siginfo_t *info = NULL;
 	struct insn insn;
 	uint8_t bndregno;
@@ -294,8 +294,8 @@ siginfo_t *mpx_generate_siginfo(struct p
 		err = -EINVAL;
 		goto err_out;
 	}
-	/* get the bndregs _area_ of the xsave structure */
-	bndregs = get_xsave_addr(xsave_buf, XSTATE_BNDREGS);
+	/* get bndregs field from current task's xsave area */
+	bndregs = get_xsave_field_ptr(XSTATE_BNDREGS);
 	if (!bndregs) {
 		err = -EINVAL;
 		goto err_out;
@@ -342,7 +342,7 @@ err_out:
 
 static __user void *task_get_bounds_dir(struct task_struct *tsk)
 {
-	struct bndcsr *bndcsr;
+	const struct bndcsr *bndcsr;
 
 	if (!cpu_feature_enabled(X86_FEATURE_MPX))
 		return MPX_INVALID_BOUNDS_DIR;
@@ -357,8 +357,7 @@ static __user void *task_get_bounds_dir(
 	 * The bounds directory pointer is stored in a register
 	 * only accessible if we first do an xsave.
 	 */
-	copy_fpregs_to_fpstate(&tsk->thread.fpu);
-	bndcsr = get_xsave_addr(&tsk->thread.fpu.state.xsave, XSTATE_BNDCSR);
+	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
 		return MPX_INVALID_BOUNDS_DIR;
 
@@ -389,9 +388,10 @@ int mpx_enable_management(struct task_st
 	 * directory into XSAVE/XRSTOR Save Area and enable MPX through
 	 * XRSTOR instruction.
 	 *
-	 * copy_xregs_to_kernel() is expected to be very expensive. Storing the bounds
-	 * directory here means that we do not have to do xsave in the unmap
-	 * path; we can just use mm->bd_addr instead.
+	 * The copy_xregs_to_kernel() beneath get_xsave_field_ptr() is
+	 * expected to be relatively expensive. Storing the bounds
+	 * directory here means that we do not have to do xsave in the
+	 * unmap path; we can just use mm->bd_addr instead.
 	 */
 	bd_base = task_get_bounds_dir(tsk);
 	down_write(&mm->mmap_sem);
@@ -497,12 +497,12 @@ out_unmap:
  * bound table is 16KB. With 64-bit mode, the size of BD is 2GB,
  * and the size of each bound table is 4MB.
  */
-static int do_mpx_bt_fault(struct xregs_state *xsave_buf)
+static int do_mpx_bt_fault(struct task_struct *tsk)
 {
 	unsigned long bd_entry, bd_base;
-	struct bndcsr *bndcsr;
+	const struct bndcsr *bndcsr;
 
-	bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR);
+	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
 		return -EINVAL;
 	/*
@@ -525,7 +525,7 @@ static int do_mpx_bt_fault(struct xregs_
 	return allocate_bt((long __user *)bd_entry);
 }
 
-int mpx_handle_bd_fault(struct xregs_state *xsave_buf)
+int mpx_handle_bd_fault(struct task_struct *tsk)
 {
 	/*
 	 * Userspace never asked us to manage the bounds tables,
@@ -534,7 +534,7 @@ int mpx_handle_bd_fault(struct xregs_sta
 	if (!kernel_managing_mpx_tables(current->mm))
 		return -EINVAL;
 
-	if (do_mpx_bt_fault(xsave_buf)) {
+	if (do_mpx_bt_fault(tsk)) {
 		force_sig(SIGSEGV, current);
 		/*
 		 * The force_sig() is essentially "handling" this
_

[tip:x86/fpu] x86/mpx: Use the new get_xsave_field_ptr()API

[tip-bot for Dave Hansen]

Commit-ID:  a84eeaa96b36a03188e1423349669c108d3a4bd7
Gitweb:     http://git.kernel.org/tip/a84eeaa96b36a03188e1423349669c108d3a4bd7
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:01 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:30 +0200

x86/mpx: Use the new get_xsave_field_ptr()API

The MPX registers (bndcsr/bndcfgu/bndstatus) are not directly
accessible via normal instructions.  They essentially act as
if they were floating point registers and are saved/restored
along with those registers.

There are two main paths in the MPX code where we care about
the contents of these registers:

	1. #BR (bounds) faults
	2. the prctl() code where we are setting MPX up

Both of those paths _might_ be called without the FPU having
been used.  That means that 'tsk->thread.fpu.state' might
never be allocated.

Also, fpu_save_init() is not preempt-safe.  It was a bug to
call it without disabling preemption.  The new
get_xsave_addr() calls unlazy_fpu() instead and properly
disables preemption.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave@sr71.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183701.BC0D37CF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/mpx.h |  8 ++++----
 arch/x86/kernel/traps.c    | 17 ++++++++---------
 arch/x86/mm/mpx.c          | 30 +++++++++++++++---------------
 3 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index f3c1b71..39f2d0f 100644
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -60,8 +60,8 @@
 
 #ifdef CONFIG_X86_INTEL_MPX
 siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct xregs_state *xsave_buf);
-int mpx_handle_bd_fault(struct xregs_state *xsave_buf);
+				struct task_struct *tsk);
+int mpx_handle_bd_fault(struct task_struct *tsk);
 static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
 {
 	return (mm->bd_addr != MPX_INVALID_BOUNDS_DIR);
@@ -78,11 +78,11 @@ void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long start, unsigned long end);
 #else
 static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-					      struct xregs_state *xsave_buf)
+					      struct task_struct *tsk)
 {
 	return NULL;
 }
-static inline int mpx_handle_bd_fault(struct xregs_state *xsave_buf)
+static inline int mpx_handle_bd_fault(struct task_struct *tsk)
 {
 	return -EINVAL;
 }
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index a2510f2..42f1531 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -59,6 +59,7 @@
 #include <asm/fixmap.h>
 #include <asm/mach_traps.h>
 #include <asm/alternative.h>
+#include <asm/fpu/xstate.h>
 #include <asm/mpx.h>
 
 #ifdef CONFIG_X86_64
@@ -371,9 +372,8 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 {
 	struct task_struct *tsk = current;
-	struct xregs_state *xsave_buf;
 	enum ctx_state prev_state;
-	struct bndcsr *bndcsr;
+	const struct bndcsr *bndcsr;
 	siginfo_t *info;
 
 	prev_state = exception_enter();
@@ -392,12 +392,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 
 	/*
 	 * We need to look at BNDSTATUS to resolve this exception.
-	 * It is not directly accessible, though, so we need to
-	 * do an xsave and then pull it out of the xsave buffer.
+	 * A NULL here might mean that it is in its 'init state',
+	 * which is all zeros which indicates MPX was not
+	 * responsible for the exception.
 	 */
-	copy_fpregs_to_fpstate(&tsk->thread.fpu);
-	xsave_buf = &(tsk->thread.fpu.state.xsave);
-	bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR);
+	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
 		goto exit_trap;
 
@@ -408,11 +407,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 	 */
 	switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
 	case 2:	/* Bound directory has invalid entry. */
-		if (mpx_handle_bd_fault(xsave_buf))
+		if (mpx_handle_bd_fault(tsk))
 			goto exit_trap;
 		break; /* Success, it was handled */
 	case 1: /* Bound violation. */
-		info = mpx_generate_siginfo(regs, xsave_buf);
+		info = mpx_generate_siginfo(regs, tsk);
 		if (IS_ERR(info)) {
 			/*
 			 * We failed to decode the MPX instruction.  Act as if
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 2e0dfd3..9d67e23 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -272,9 +272,9 @@ bad_opcode:
  * The caller is expected to kfree() the returned siginfo_t.
  */
 siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct xregs_state *xsave_buf)
+				struct task_struct *tsk)
 {
-	struct bndreg *bndregs, *bndreg;
+	const struct bndreg *bndregs, *bndreg;
 	siginfo_t *info = NULL;
 	struct insn insn;
 	uint8_t bndregno;
@@ -294,8 +294,8 @@ siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
 		err = -EINVAL;
 		goto err_out;
 	}
-	/* get the bndregs _area_ of the xsave structure */
-	bndregs = get_xsave_addr(xsave_buf, XSTATE_BNDREGS);
+	/* get bndregs field from current task's xsave area */
+	bndregs = get_xsave_field_ptr(XSTATE_BNDREGS);
 	if (!bndregs) {
 		err = -EINVAL;
 		goto err_out;
@@ -342,7 +342,7 @@ err_out:
 
 static __user void *task_get_bounds_dir(struct task_struct *tsk)
 {
-	struct bndcsr *bndcsr;
+	const struct bndcsr *bndcsr;
 
 	if (!cpu_feature_enabled(X86_FEATURE_MPX))
 		return MPX_INVALID_BOUNDS_DIR;
@@ -357,8 +357,7 @@ static __user void *task_get_bounds_dir(struct task_struct *tsk)
 	 * The bounds directory pointer is stored in a register
 	 * only accessible if we first do an xsave.
 	 */
-	copy_fpregs_to_fpstate(&tsk->thread.fpu);
-	bndcsr = get_xsave_addr(&tsk->thread.fpu.state.xsave, XSTATE_BNDCSR);
+	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
 		return MPX_INVALID_BOUNDS_DIR;
 
@@ -389,9 +388,10 @@ int mpx_enable_management(struct task_struct *tsk)
 	 * directory into XSAVE/XRSTOR Save Area and enable MPX through
 	 * XRSTOR instruction.
 	 *
-	 * copy_xregs_to_kernel() is expected to be very expensive. Storing the bounds
-	 * directory here means that we do not have to do xsave in the unmap
-	 * path; we can just use mm->bd_addr instead.
+	 * The copy_xregs_to_kernel() beneath get_xsave_field_ptr() is
+	 * expected to be relatively expensive. Storing the bounds
+	 * directory here means that we do not have to do xsave in the
+	 * unmap path; we can just use mm->bd_addr instead.
 	 */
 	bd_base = task_get_bounds_dir(tsk);
 	down_write(&mm->mmap_sem);
@@ -497,12 +497,12 @@ out_unmap:
  * bound table is 16KB. With 64-bit mode, the size of BD is 2GB,
  * and the size of each bound table is 4MB.
  */
-static int do_mpx_bt_fault(struct xregs_state *xsave_buf)
+static int do_mpx_bt_fault(struct task_struct *tsk)
 {
 	unsigned long bd_entry, bd_base;
-	struct bndcsr *bndcsr;
+	const struct bndcsr *bndcsr;
 
-	bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR);
+	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
 		return -EINVAL;
 	/*
@@ -525,7 +525,7 @@ static int do_mpx_bt_fault(struct xregs_state *xsave_buf)
 	return allocate_bt((long __user *)bd_entry);
 }
 
-int mpx_handle_bd_fault(struct xregs_state *xsave_buf)
+int mpx_handle_bd_fault(struct task_struct *tsk)
 {
 	/*
 	 * Userspace never asked us to manage the bounds tables,
@@ -534,7 +534,7 @@ int mpx_handle_bd_fault(struct xregs_state *xsave_buf)
 	if (!kernel_managing_mpx_tables(current->mm))
 		return -EINVAL;
 
-	if (do_mpx_bt_fault(xsave_buf)) {
+	if (do_mpx_bt_fault(tsk)) {
 		force_sig(SIGSEGV, current);
 		/*
 		 * The force_sig() is essentially "handling" this

[PATCH 05/19] x86, mpx: remove redundant MPX_BNDCFG_ADDR_MASK

[Dave Hansen]

From: Qiaowei Ren <qiaowei.ren@intel.com>

MPX_BNDCFG_ADDR_MASK is defined two times, so this patch removes
redundant one.

Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/include/asm/mpx.h |    1 -
 1 file changed, 1 deletion(-)

diff -puN arch/x86/include/asm/mpx.h~0001-x86-mpx-remove-redundant-MPX_BNDCFG_ADDR_MASK arch/x86/include/asm/mpx.h
--- a/arch/x86/include/asm/mpx.h~0001-x86-mpx-remove-redundant-MPX_BNDCFG_ADDR_MASK	2015-06-01 10:24:04.792756398 -0700
+++ b/arch/x86/include/asm/mpx.h	2015-06-01 10:24:04.795756533 -0700
@@ -45,7 +45,6 @@
 #define MPX_BNDSTA_TAIL		2
 #define MPX_BNDCFG_TAIL		12
 #define MPX_BNDSTA_ADDR_MASK	(~((1UL<<MPX_BNDSTA_TAIL)-1))
-#define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
 #define MPX_BT_ADDR_MASK	(~((1UL<<MPX_BD_ENTRY_TAIL)-1))
 
 #define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
_

[tip:x86/fpu] x86/mpx: Remove redundant MPX_BNDCFG_ADDR_MASK

[tip-bot for Qiaowei Ren]

Commit-ID:  3c1d32300920a446c67d697cd6b80f012ad06028
Gitweb:     http://git.kernel.org/tip/3c1d32300920a446c67d697cd6b80f012ad06028
Author:     Qiaowei Ren <qiaowei.ren@intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:02 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:30 +0200

x86/mpx: Remove redundant MPX_BNDCFG_ADDR_MASK

MPX_BNDCFG_ADDR_MASK is defined two times, so this patch removes
redundant one.

Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183702.5F129376@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/mpx.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index 0cdd16a..871e5e5 100644
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -45,7 +45,6 @@
 #define MPX_BNDSTA_TAIL		2
 #define MPX_BNDCFG_TAIL		12
 #define MPX_BNDSTA_ADDR_MASK	(~((1UL<<MPX_BNDSTA_TAIL)-1))
-#define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
 #define MPX_BT_ADDR_MASK	(~((1UL<<MPX_BD_ENTRY_TAIL)-1))
 
 #define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))

[PATCH 06/19] x86, mpx: Restrict mmap size check to bounds tables

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The comment and code here are confusing.  We do not currently
allocate the bounds directory in the kernel.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/mm/mpx.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN arch/x86/mm/mpx.c~x86-mpx-we-do-not-allocate-the-bounds-directory arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~x86-mpx-we-do-not-allocate-the-bounds-directory	2015-06-01 10:24:05.203774935 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:05.207775116 -0700
@@ -46,8 +46,8 @@ static unsigned long mpx_mmap(unsigned l
 	vm_flags_t vm_flags;
 	struct vm_area_struct *vma;
 
-	/* Only bounds table and bounds directory can be allocated here */
-	if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES)
+	/* Only bounds table can be allocated here */
+	if (len != MPX_BT_SIZE_BYTES)
 		return -EINVAL;
 
 	down_write(&mm->mmap_sem);
_

[tip:x86/fpu] x86/mpx: Restrict the mmap() size check to bounds tables

[tip-bot for Dave Hansen]

Commit-ID:  eb099e5bc5457c42043e57cf0f4ce574669b9697
Gitweb:     http://git.kernel.org/tip/eb099e5bc5457c42043e57cf0f4ce574669b9697
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:02 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:31 +0200

x86/mpx: Restrict the mmap() size check to bounds tables

The comment and code here are confusing.  We do not currently
allocate the bounds directory in the kernel.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183702.222CEC2A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/mpx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 47e4a856..d6e02f3 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -46,8 +46,8 @@ static unsigned long mpx_mmap(unsigned long len)
 	vm_flags_t vm_flags;
 	struct vm_area_struct *vma;
 
-	/* Only bounds table and bounds directory can be allocated here */
-	if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES)
+	/* Only bounds table can be allocated here */
+	if (len != MPX_BT_SIZE_BYTES)
 		return -EINVAL;
 
 	down_write(&mm->mmap_sem);

[PATCH 04/19] x86, mpx: Cleanup: Do not pass task around when unnecessary

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The MPX code can only work on the current task.  You can not, for
instance, enable MPX management in another process or thread.
You can also not handle a fault for another process or thread.

Despite this, we pass a task_struct around prolifically.  This
patch removes all of the task struct passing for code paths where
the code can not deal with another task (which turns out to be
all of them).

This has no functional changes.  It's just a cleanup.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: bp@alien8.de
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
---

 b/arch/x86/include/asm/mpx.h       |   10 ++++------
 b/arch/x86/include/asm/processor.h |   12 ++++++------
 b/arch/x86/kernel/traps.c          |    5 ++---
 b/arch/x86/mm/mpx.c                |   19 +++++++++----------
 b/kernel/sys.c                     |    8 ++++----
 5 files changed, 25 insertions(+), 29 deletions(-)

diff -puN arch/x86/include/asm/mpx.h~x86-mpx-dont-pass-current-around arch/x86/include/asm/mpx.h
--- a/arch/x86/include/asm/mpx.h~x86-mpx-dont-pass-current-around	2015-06-01 10:24:04.227730914 -0700
+++ b/arch/x86/include/asm/mpx.h	2015-06-01 10:24:04.238731410 -0700
@@ -59,9 +59,8 @@
 		MPX_BT_ENTRY_MASK) << MPX_BT_ENTRY_SHIFT)
 
 #ifdef CONFIG_X86_INTEL_MPX
-siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct task_struct *tsk);
-int mpx_handle_bd_fault(struct task_struct *tsk);
+siginfo_t *mpx_generate_siginfo(struct pt_regs *regs);
+int mpx_handle_bd_fault(void);
 static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
 {
 	return (mm->bd_addr != MPX_INVALID_BOUNDS_DIR);
@@ -77,12 +76,11 @@ static inline void mpx_mm_init(struct mm
 void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long start, unsigned long end);
 #else
-static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-					      struct task_struct *tsk)
+static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)
 {
 	return NULL;
 }
-static inline int mpx_handle_bd_fault(struct task_struct *tsk)
+static inline int mpx_handle_bd_fault(void)
 {
 	return -EINVAL;
 }
diff -puN arch/x86/include/asm/processor.h~x86-mpx-dont-pass-current-around arch/x86/include/asm/processor.h
--- a/arch/x86/include/asm/processor.h~x86-mpx-dont-pass-current-around	2015-06-01 10:24:04.229731004 -0700
+++ b/arch/x86/include/asm/processor.h	2015-06-01 10:24:04.239731455 -0700
@@ -802,18 +802,18 @@ extern int get_tsc_mode(unsigned long ad
 extern int set_tsc_mode(unsigned int val);
 
 /* Register/unregister a process' MPX related resource */
-#define MPX_ENABLE_MANAGEMENT(tsk)	mpx_enable_management((tsk))
-#define MPX_DISABLE_MANAGEMENT(tsk)	mpx_disable_management((tsk))
+#define MPX_ENABLE_MANAGEMENT()	mpx_enable_management()
+#define MPX_DISABLE_MANAGEMENT()	mpx_disable_management()
 
 #ifdef CONFIG_X86_INTEL_MPX
-extern int mpx_enable_management(struct task_struct *tsk);
-extern int mpx_disable_management(struct task_struct *tsk);
+extern int mpx_enable_management(void);
+extern int mpx_disable_management(void);
 #else
-static inline int mpx_enable_management(struct task_struct *tsk)
+static inline int mpx_enable_management(void)
 {
 	return -EINVAL;
 }
-static inline int mpx_disable_management(struct task_struct *tsk)
+static inline int mpx_disable_management(void)
 {
 	return -EINVAL;
 }
diff -puN arch/x86/kernel/traps.c~x86-mpx-dont-pass-current-around arch/x86/kernel/traps.c
--- a/arch/x86/kernel/traps.c~x86-mpx-dont-pass-current-around	2015-06-01 10:24:04.231731095 -0700
+++ b/arch/x86/kernel/traps.c	2015-06-01 10:24:04.239731455 -0700
@@ -371,7 +371,6 @@ dotraplinkage void do_double_fault(struc
 
 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 {
-	struct task_struct *tsk = current;
 	enum ctx_state prev_state;
 	const struct bndcsr *bndcsr;
 	siginfo_t *info;
@@ -407,11 +406,11 @@ dotraplinkage void do_bounds(struct pt_r
 	 */
 	switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
 	case 2:	/* Bound directory has invalid entry. */
-		if (mpx_handle_bd_fault(tsk))
+		if (mpx_handle_bd_fault())
 			goto exit_trap;
 		break; /* Success, it was handled */
 	case 1: /* Bound violation. */
-		info = mpx_generate_siginfo(regs, tsk);
+		info = mpx_generate_siginfo(regs);
 		if (IS_ERR(info)) {
 			/*
 			 * We failed to decode the MPX instruction.  Act as if
diff -puN arch/x86/mm/mpx.c~x86-mpx-dont-pass-current-around arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~x86-mpx-dont-pass-current-around	2015-06-01 10:24:04.233731185 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:04.240731501 -0700
@@ -271,8 +271,7 @@ bad_opcode:
  *
  * The caller is expected to kfree() the returned siginfo_t.
  */
-siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct task_struct *tsk)
+siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)
 {
 	const struct bndreg *bndregs, *bndreg;
 	siginfo_t *info = NULL;
@@ -340,7 +339,7 @@ err_out:
 	return ERR_PTR(err);
 }
 
-static __user void *task_get_bounds_dir(struct task_struct *tsk)
+static __user void *mpx_get_bounds_dir(void)
 {
 	const struct bndcsr *bndcsr;
 
@@ -376,10 +375,10 @@ static __user void *task_get_bounds_dir(
 		(bndcsr->bndcfgu & MPX_BNDCFG_ADDR_MASK);
 }
 
-int mpx_enable_management(struct task_struct *tsk)
+int mpx_enable_management(void)
 {
 	void __user *bd_base = MPX_INVALID_BOUNDS_DIR;
-	struct mm_struct *mm = tsk->mm;
+	struct mm_struct *mm = current->mm;
 	int ret = 0;
 
 	/*
@@ -393,7 +392,7 @@ int mpx_enable_management(struct task_st
 	 * directory here means that we do not have to do xsave in the
 	 * unmap path; we can just use mm->bd_addr instead.
 	 */
-	bd_base = task_get_bounds_dir(tsk);
+	bd_base = mpx_get_bounds_dir();
 	down_write(&mm->mmap_sem);
 	mm->bd_addr = bd_base;
 	if (mm->bd_addr == MPX_INVALID_BOUNDS_DIR)
@@ -403,7 +402,7 @@ int mpx_enable_management(struct task_st
 	return ret;
 }
 
-int mpx_disable_management(struct task_struct *tsk)
+int mpx_disable_management(void)
 {
 	struct mm_struct *mm = current->mm;
 
@@ -497,7 +496,7 @@ out_unmap:
  * bound table is 16KB. With 64-bit mode, the size of BD is 2GB,
  * and the size of each bound table is 4MB.
  */
-static int do_mpx_bt_fault(struct task_struct *tsk)
+static int do_mpx_bt_fault(void)
 {
 	unsigned long bd_entry, bd_base;
 	const struct bndcsr *bndcsr;
@@ -525,7 +524,7 @@ static int do_mpx_bt_fault(struct task_s
 	return allocate_bt((long __user *)bd_entry);
 }
 
-int mpx_handle_bd_fault(struct task_struct *tsk)
+int mpx_handle_bd_fault(void)
 {
 	/*
 	 * Userspace never asked us to manage the bounds tables,
@@ -534,7 +533,7 @@ int mpx_handle_bd_fault(struct task_stru
 	if (!kernel_managing_mpx_tables(current->mm))
 		return -EINVAL;
 
-	if (do_mpx_bt_fault(tsk)) {
+	if (do_mpx_bt_fault()) {
 		force_sig(SIGSEGV, current);
 		/*
 		 * The force_sig() is essentially "handling" this
diff -puN kernel/sys.c~x86-mpx-dont-pass-current-around kernel/sys.c
--- a/kernel/sys.c~x86-mpx-dont-pass-current-around	2015-06-01 10:24:04.235731275 -0700
+++ b/kernel/sys.c	2015-06-01 10:24:04.241731546 -0700
@@ -92,10 +92,10 @@
 # define SET_TSC_CTL(a)		(-EINVAL)
 #endif
 #ifndef MPX_ENABLE_MANAGEMENT
-# define MPX_ENABLE_MANAGEMENT(a)	(-EINVAL)
+# define MPX_ENABLE_MANAGEMENT()	(-EINVAL)
 #endif
 #ifndef MPX_DISABLE_MANAGEMENT
-# define MPX_DISABLE_MANAGEMENT(a)	(-EINVAL)
+# define MPX_DISABLE_MANAGEMENT()	(-EINVAL)
 #endif
 #ifndef GET_FP_MODE
 # define GET_FP_MODE(a)		(-EINVAL)
@@ -2230,12 +2230,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
 	case PR_MPX_ENABLE_MANAGEMENT:
 		if (arg2 || arg3 || arg4 || arg5)
 			return -EINVAL;
-		error = MPX_ENABLE_MANAGEMENT(me);
+		error = MPX_ENABLE_MANAGEMENT();
 		break;
 	case PR_MPX_DISABLE_MANAGEMENT:
 		if (arg2 || arg3 || arg4 || arg5)
 			return -EINVAL;
-		error = MPX_DISABLE_MANAGEMENT(me);
+		error = MPX_DISABLE_MANAGEMENT();
 		break;
 	case PR_SET_FP_MODE:
 		error = SET_FP_MODE(me, arg2);
_

[tip:x86/fpu] x86/mpx: Clean up the code by not passing a task pointer around when unnecessary

[tip-bot for Dave Hansen]

Commit-ID:  46a6e0cf1c6665a8e867d8f7798d7a3538633f03
Gitweb:     http://git.kernel.org/tip/46a6e0cf1c6665a8e867d8f7798d7a3538633f03
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:02 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:30 +0200

x86/mpx: Clean up the code by not passing a task pointer around when unnecessary

The MPX code can only work on the current task.  You can not,
for instance, enable MPX management in another process or
thread. You can also not handle a fault for another process or
thread.

Despite this, we pass a task_struct around prolifically.  This
patch removes all of the task struct passing for code paths
where the code can not deal with another task (which turns out
to be all of them).

This has no functional changes.  It's just a cleanup.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183702.6A81DA2C@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/mpx.h       | 10 ++++------
 arch/x86/include/asm/processor.h | 12 ++++++------
 arch/x86/kernel/traps.c          |  5 ++---
 arch/x86/mm/mpx.c                | 19 +++++++++----------
 kernel/sys.c                     |  8 ++++----
 5 files changed, 25 insertions(+), 29 deletions(-)

diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index 39f2d0f..0cdd16a 100644
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -59,9 +59,8 @@
 		MPX_BT_ENTRY_MASK) << MPX_BT_ENTRY_SHIFT)
 
 #ifdef CONFIG_X86_INTEL_MPX
-siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct task_struct *tsk);
-int mpx_handle_bd_fault(struct task_struct *tsk);
+siginfo_t *mpx_generate_siginfo(struct pt_regs *regs);
+int mpx_handle_bd_fault(void);
 static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
 {
 	return (mm->bd_addr != MPX_INVALID_BOUNDS_DIR);
@@ -77,12 +76,11 @@ static inline void mpx_mm_init(struct mm_struct *mm)
 void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long start, unsigned long end);
 #else
-static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-					      struct task_struct *tsk)
+static inline siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)
 {
 	return NULL;
 }
-static inline int mpx_handle_bd_fault(struct task_struct *tsk)
+static inline int mpx_handle_bd_fault(void)
 {
 	return -EINVAL;
 }
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 8e04f51..53dbd2b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -802,18 +802,18 @@ extern int get_tsc_mode(unsigned long adr);
 extern int set_tsc_mode(unsigned int val);
 
 /* Register/unregister a process' MPX related resource */
-#define MPX_ENABLE_MANAGEMENT(tsk)	mpx_enable_management((tsk))
-#define MPX_DISABLE_MANAGEMENT(tsk)	mpx_disable_management((tsk))
+#define MPX_ENABLE_MANAGEMENT()	mpx_enable_management()
+#define MPX_DISABLE_MANAGEMENT()	mpx_disable_management()
 
 #ifdef CONFIG_X86_INTEL_MPX
-extern int mpx_enable_management(struct task_struct *tsk);
-extern int mpx_disable_management(struct task_struct *tsk);
+extern int mpx_enable_management(void);
+extern int mpx_disable_management(void);
 #else
-static inline int mpx_enable_management(struct task_struct *tsk)
+static inline int mpx_enable_management(void)
 {
 	return -EINVAL;
 }
-static inline int mpx_disable_management(struct task_struct *tsk)
+static inline int mpx_disable_management(void)
 {
 	return -EINVAL;
 }
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 42f1531..cffff66 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -371,7 +371,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 
 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 {
-	struct task_struct *tsk = current;
 	enum ctx_state prev_state;
 	const struct bndcsr *bndcsr;
 	siginfo_t *info;
@@ -407,11 +406,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 	 */
 	switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) {
 	case 2:	/* Bound directory has invalid entry. */
-		if (mpx_handle_bd_fault(tsk))
+		if (mpx_handle_bd_fault())
 			goto exit_trap;
 		break; /* Success, it was handled */
 	case 1: /* Bound violation. */
-		info = mpx_generate_siginfo(regs, tsk);
+		info = mpx_generate_siginfo(regs);
 		if (IS_ERR(info)) {
 			/*
 			 * We failed to decode the MPX instruction.  Act as if
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 9d67e23..47e4a856 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -271,8 +271,7 @@ bad_opcode:
  *
  * The caller is expected to kfree() the returned siginfo_t.
  */
-siginfo_t *mpx_generate_siginfo(struct pt_regs *regs,
-				struct task_struct *tsk)
+siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)
 {
 	const struct bndreg *bndregs, *bndreg;
 	siginfo_t *info = NULL;
@@ -340,7 +339,7 @@ err_out:
 	return ERR_PTR(err);
 }
 
-static __user void *task_get_bounds_dir(struct task_struct *tsk)
+static __user void *mpx_get_bounds_dir(void)
 {
 	const struct bndcsr *bndcsr;
 
@@ -376,10 +375,10 @@ static __user void *task_get_bounds_dir(struct task_struct *tsk)
 		(bndcsr->bndcfgu & MPX_BNDCFG_ADDR_MASK);
 }
 
-int mpx_enable_management(struct task_struct *tsk)
+int mpx_enable_management(void)
 {
 	void __user *bd_base = MPX_INVALID_BOUNDS_DIR;
-	struct mm_struct *mm = tsk->mm;
+	struct mm_struct *mm = current->mm;
 	int ret = 0;
 
 	/*
@@ -393,7 +392,7 @@ int mpx_enable_management(struct task_struct *tsk)
 	 * directory here means that we do not have to do xsave in the
 	 * unmap path; we can just use mm->bd_addr instead.
 	 */
-	bd_base = task_get_bounds_dir(tsk);
+	bd_base = mpx_get_bounds_dir();
 	down_write(&mm->mmap_sem);
 	mm->bd_addr = bd_base;
 	if (mm->bd_addr == MPX_INVALID_BOUNDS_DIR)
@@ -403,7 +402,7 @@ int mpx_enable_management(struct task_struct *tsk)
 	return ret;
 }
 
-int mpx_disable_management(struct task_struct *tsk)
+int mpx_disable_management(void)
 {
 	struct mm_struct *mm = current->mm;
 
@@ -497,7 +496,7 @@ out_unmap:
  * bound table is 16KB. With 64-bit mode, the size of BD is 2GB,
  * and the size of each bound table is 4MB.
  */
-static int do_mpx_bt_fault(struct task_struct *tsk)
+static int do_mpx_bt_fault(void)
 {
 	unsigned long bd_entry, bd_base;
 	const struct bndcsr *bndcsr;
@@ -525,7 +524,7 @@ static int do_mpx_bt_fault(struct task_struct *tsk)
 	return allocate_bt((long __user *)bd_entry);
 }
 
-int mpx_handle_bd_fault(struct task_struct *tsk)
+int mpx_handle_bd_fault(void)
 {
 	/*
 	 * Userspace never asked us to manage the bounds tables,
@@ -534,7 +533,7 @@ int mpx_handle_bd_fault(struct task_struct *tsk)
 	if (!kernel_managing_mpx_tables(current->mm))
 		return -EINVAL;
 
-	if (do_mpx_bt_fault(tsk)) {
+	if (do_mpx_bt_fault()) {
 		force_sig(SIGSEGV, current);
 		/*
 		 * The force_sig() is essentially "handling" this
diff --git a/kernel/sys.c b/kernel/sys.c
index a4e372b..8571296 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -92,10 +92,10 @@
 # define SET_TSC_CTL(a)		(-EINVAL)
 #endif
 #ifndef MPX_ENABLE_MANAGEMENT
-# define MPX_ENABLE_MANAGEMENT(a)	(-EINVAL)
+# define MPX_ENABLE_MANAGEMENT()	(-EINVAL)
 #endif
 #ifndef MPX_DISABLE_MANAGEMENT
-# define MPX_DISABLE_MANAGEMENT(a)	(-EINVAL)
+# define MPX_DISABLE_MANAGEMENT()	(-EINVAL)
 #endif
 #ifndef GET_FP_MODE
 # define GET_FP_MODE(a)		(-EINVAL)
@@ -2230,12 +2230,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 	case PR_MPX_ENABLE_MANAGEMENT:
 		if (arg2 || arg3 || arg4 || arg5)
 			return -EINVAL;
-		error = MPX_ENABLE_MANAGEMENT(me);
+		error = MPX_ENABLE_MANAGEMENT();
 		break;
 	case PR_MPX_DISABLE_MANAGEMENT:
 		if (arg2 || arg3 || arg4 || arg5)
 			return -EINVAL;
-		error = MPX_DISABLE_MANAGEMENT(me);
+		error = MPX_DISABLE_MANAGEMENT();
 		break;
 	case PR_SET_FP_MODE:
 		error = SET_FP_MODE(me, arg2);

[PATCH 07/19] x86, mpx: boot-time disable

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

MPX has the _potential_ to cause some issues.  Say part of your init
system tried to protect one of its components from buffer overflows
with MPX.  If there were a false positive, it's possible that MPX
could keep a system from booting.

MPX could also potentially cause performance issues since it is
present in hot paths like the unmap path.

Allow it to be disabled at boot time.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de
---

 b/Documentation/kernel-parameters.txt |    4 ++++
 b/arch/x86/kernel/cpu/common.c        |   16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff -puN arch/x86/kernel/cpu/common.c~x86-mpx-disable-boot-time arch/x86/kernel/cpu/common.c
--- a/arch/x86/kernel/cpu/common.c~x86-mpx-disable-boot-time	2015-06-01 10:24:05.614793473 -0700
+++ b/arch/x86/kernel/cpu/common.c	2015-06-01 10:24:05.620793744 -0700
@@ -144,6 +144,22 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_p
 } };
 EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
 
+static int __init x86_mpx_setup(char *s)
+{
+	/* require an exact match without trailing characters */
+	if (strlen(s))
+		return 0;
+
+	/* do not emit a message if the feature is not present */
+	if (!boot_cpu_has(X86_FEATURE_MPX))
+		return 1;
+
+	setup_clear_cpu_cap(X86_FEATURE_MPX);
+	pr_info("nompx: Intel Memory Protection Extensions (MPX) disabled\n");
+	return 1;
+}
+__setup("nompx", x86_mpx_setup);
+
 #ifdef CONFIG_X86_32
 static int cachesize_override = -1;
 static int disable_x86_serial_nr = 1;
diff -puN Documentation/kernel-parameters.txt~x86-mpx-disable-boot-time Documentation/kernel-parameters.txt
--- a/Documentation/kernel-parameters.txt~x86-mpx-disable-boot-time	2015-06-01 10:24:05.616793563 -0700
+++ b/Documentation/kernel-parameters.txt	2015-06-01 10:24:05.621793789 -0700
@@ -937,6 +937,10 @@ bytes respectively. Such letter suffixes
 			Enable debug messages at boot time.  See
 			Documentation/dynamic-debug-howto.txt for details.
 
+	nompx		[X86] Disables Intel Memory Protection Extensions.
+			See Documentation/x86/intel_mpx.txt for more
+			information about the feature.
+
 	eagerfpu=	[X86]
 			on	enable eager fpu restore
 			off	disable eager fpu restore
_

[tip:x86/fpu] x86/mpx: Introduce a boot-time disable flag

[tip-bot for Dave Hansen]

Commit-ID:  8c3641e957a948f41f0174290096ed7a3b95e703
Gitweb:     http://git.kernel.org/tip/8c3641e957a948f41f0174290096ed7a3b95e703
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:02 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:31 +0200

x86/mpx: Introduce a boot-time disable flag

MPX has the _potential_ to cause some issues.  Say part of your
init system tried to protect one of its components from buffer
overflows with MPX.  If there were a false positive, it's
possible that MPX could keep a system from booting.

MPX could also potentially cause performance issues since it is
present in hot paths like the unmap path.

Allow it to be disabled at boot time.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150607183702.2E8B77AB@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 Documentation/kernel-parameters.txt |  4 ++++
 arch/x86/kernel/cpu/common.c        | 16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 61ab162..8b7e5c3 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -937,6 +937,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Enable debug messages at boot time.  See
 			Documentation/dynamic-debug-howto.txt for details.
 
+	nompx		[X86] Disables Intel Memory Protection Extensions.
+			See Documentation/x86/intel_mpx.txt for more
+			information about the feature.
+
 	eagerfpu=	[X86]
 			on	enable eager fpu restore
 			off	disable eager fpu restore
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 401ccb03..3956858 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -144,6 +144,22 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
 } };
 EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
 
+static int __init x86_mpx_setup(char *s)
+{
+	/* require an exact match without trailing characters */
+	if (strlen(s))
+		return 0;
+
+	/* do not emit a message if the feature is not present */
+	if (!boot_cpu_has(X86_FEATURE_MPX))
+		return 1;
+
+	setup_clear_cpu_cap(X86_FEATURE_MPX);
+	pr_info("nompx: Intel Memory Protection Extensions (MPX) disabled\n");
+	return 1;
+}
+__setup("nompx", x86_mpx_setup);
+
 #ifdef CONFIG_X86_32
 static int cachesize_override = -1;
 static int disable_x86_serial_nr = 1;

[PATCH 10/19] x86, mpx: Trace the attempts to find bounds tables

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

There are two different events being traced here.  They are
doing similar things so share a trace "EVENT_CLASS" and are
presented together.

1. Trace when MPX is zapping pages "mpx_unmap_zap":

	When MPX can not free an entire bounds table, it will
	instead try to zap unused parts of a bounds table to free
	the backing memory.  This decreases RSS (resident set
	size) without decreasing the virtual space allocated
	for bounds tables.

2. Trace attempts to find bounds tables "mpx_unmap_search":

	This event traces any time we go looking to unmap a
	bounds table for a given virtual address range.  This is
	useful to ensure that the kernel actually "tried" to free
	a bounds table versus times it succeeded in finding one.

	It might try and fail if it realized that a table was
	shared with an adjacent VMA which is not being unmapped.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/include/asm/trace/mpx.h |   32 ++++++++++++++++++++++++++++++++
 b/arch/x86/mm/mpx.c                |    2 ++
 2 files changed, 34 insertions(+)

diff -puN arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_zap arch/x86/include/asm/trace/mpx.h
--- a/arch/x86/include/asm/trace/mpx.h~mpx-trace_unmap_zap	2015-06-01 10:24:06.928852740 -0700
+++ b/arch/x86/include/asm/trace/mpx.h	2015-06-01 10:24:06.934853011 -0700
@@ -63,6 +63,38 @@ TRACE_EVENT(bounds_exception_mpx,
 		__entry->bndstatus)
 );
 
+DECLARE_EVENT_CLASS(mpx_range_trace,
+
+	TP_PROTO(unsigned long start,
+		 unsigned long end),
+	TP_ARGS(start, end),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, start)
+		__field(unsigned long, end)
+	),
+
+	TP_fast_assign(
+		__entry->start = start;
+		__entry->end   = end;
+	),
+
+	TP_printk("[0x%p:0x%p]",
+		(void *)__entry->start,
+		(void *)__entry->end
+	)
+);
+
+DEFINE_EVENT(mpx_range_trace, mpx_unmap_zap,
+	TP_PROTO(unsigned long start, unsigned long end),
+	TP_ARGS(start, end)
+);
+
+DEFINE_EVENT(mpx_range_trace, mpx_unmap_search,
+	TP_PROTO(unsigned long start, unsigned long end),
+	TP_ARGS(start, end)
+);
+
 #else
 
 /*
diff -puN arch/x86/mm/mpx.c~mpx-trace_unmap_zap arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-trace_unmap_zap	2015-06-01 10:24:06.930852830 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:06.934853011 -0700
@@ -668,6 +668,7 @@ static int zap_bt_entries(struct mm_stru
 
 		len = min(vma->vm_end, end) - addr;
 		zap_page_range(vma, addr, len, NULL);
+		trace_mpx_unmap_zap(addr, addr+len);
 
 		vma = vma->vm_next;
 		addr = vma->vm_start;
@@ -840,6 +841,7 @@ static int mpx_unmap_tables(struct mm_st
 	long __user *bd_entry, *bde_start, *bde_end;
 	unsigned long bt_addr;
 
+	trace_mpx_unmap_search(start, end);
 	/*
 	 * "Edge" bounds tables are those which are being used by the region
 	 * (start -> end), but that may be shared with adjacent areas.  If they
_

[tip:x86/fpu] x86/mpx: Trace the attempts to find bounds tables

[tip-bot for Dave Hansen]

Commit-ID:  2a1dcb1f796ad37028df37d96fc7c5b6b1705a43
Gitweb:     http://git.kernel.org/tip/2a1dcb1f796ad37028df37d96fc7c5b6b1705a43
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:03 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:32 +0200

x86/mpx: Trace the attempts to find bounds tables

There are two different events being traced here.  They are
doing similar things so share a trace "EVENT_CLASS" and are
presented together.

1. Trace when MPX is zapping pages "mpx_unmap_zap":

	When MPX can not free an entire bounds table, it will
	instead try to zap unused parts of a bounds table to free
	the backing memory.  This decreases RSS (resident set
	size) without decreasing the virtual space allocated
	for bounds tables.

2. Trace attempts to find bounds tables "mpx_unmap_search":

	This event traces any time we go looking to unmap a
	bounds table for a given virtual address range.  This is
	useful to ensure that the kernel actually "tried" to free
	a bounds table versus times it succeeded in finding one.

	It might try and fail if it realized that a table was
	shared with an adjacent VMA which is not being unmapped.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.B9D2468B@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/trace/mpx.h | 32 ++++++++++++++++++++++++++++++++
 arch/x86/mm/mpx.c                |  2 ++
 2 files changed, 34 insertions(+)

diff --git a/arch/x86/include/asm/trace/mpx.h b/arch/x86/include/asm/trace/mpx.h
index 5c3af06..c13c6fa 100644
--- a/arch/x86/include/asm/trace/mpx.h
+++ b/arch/x86/include/asm/trace/mpx.h
@@ -63,6 +63,38 @@ TRACE_EVENT(bounds_exception_mpx,
 		__entry->bndstatus)
 );
 
+DECLARE_EVENT_CLASS(mpx_range_trace,
+
+	TP_PROTO(unsigned long start,
+		 unsigned long end),
+	TP_ARGS(start, end),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, start)
+		__field(unsigned long, end)
+	),
+
+	TP_fast_assign(
+		__entry->start = start;
+		__entry->end   = end;
+	),
+
+	TP_printk("[0x%p:0x%p]",
+		(void *)__entry->start,
+		(void *)__entry->end
+	)
+);
+
+DEFINE_EVENT(mpx_range_trace, mpx_unmap_zap,
+	TP_PROTO(unsigned long start, unsigned long end),
+	TP_ARGS(start, end)
+);
+
+DEFINE_EVENT(mpx_range_trace, mpx_unmap_search,
+	TP_PROTO(unsigned long start, unsigned long end),
+	TP_ARGS(start, end)
+);
+
 #else
 
 /*
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 75e5d70..55729ee 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -668,6 +668,7 @@ static int zap_bt_entries(struct mm_struct *mm,
 
 		len = min(vma->vm_end, end) - addr;
 		zap_page_range(vma, addr, len, NULL);
+		trace_mpx_unmap_zap(addr, addr+len);
 
 		vma = vma->vm_next;
 		addr = vma->vm_start;
@@ -840,6 +841,7 @@ static int mpx_unmap_tables(struct mm_struct *mm,
 	long __user *bd_entry, *bde_start, *bde_end;
 	unsigned long bt_addr;
 
+	trace_mpx_unmap_search(start, end);
 	/*
 	 * "Edge" bounds tables are those which are being used by the region
 	 * (start -> end), but that may be shared with adjacent areas.  If they

[PATCH 08/19] x86, mpx: trace #BR exceptions

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

This is the first in a series of MPX tracing patches.
I've found these extremely useful in the process of
debugging applications and the kernel code itself.

This exception hooks in to the bounds (#BR) exception
very early and allows capturing the key registers which
would influence how the exception is handled.

Note that bndcfgu/bndstatus are technically still
64-bit registers even in 32-bit mode.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/include/asm/trace/mpx.h |   50 +++++++++++++++++++++++++++++++++++++
 b/arch/x86/kernel/traps.c          |    2 +
 b/arch/x86/mm/mpx.c                |    3 ++
 3 files changed, 55 insertions(+)

diff -puN /dev/null arch/x86/include/asm/trace/mpx.h
--- /dev/null	2015-05-29 14:41:09.563023787 -0700
+++ b/arch/x86/include/asm/trace/mpx.h	2015-06-01 10:24:06.063813725 -0700
@@ -0,0 +1,50 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mpx
+
+#if !defined(_TRACE_MPX_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MPX_H
+
+#include <linux/tracepoint.h>
+
+#ifdef CONFIG_X86_INTEL_MPX
+
+TRACE_EVENT(bounds_exception_mpx,
+
+	TP_PROTO(const struct bndcsr *bndcsr),
+	TP_ARGS(bndcsr),
+
+	TP_STRUCT__entry(
+		__field(u64, bndcfgu)
+		__field(u64, bndstatus)
+	),
+
+	TP_fast_assign(
+		/* need to get rid of the 'const' on bndcsr */
+		__entry->bndcfgu   = (u64)bndcsr->bndcfgu;
+		__entry->bndstatus = (u64)bndcsr->bndstatus;
+	),
+
+	TP_printk("bndcfgu:0x%llx bndstatus:0x%llx",
+		__entry->bndcfgu,
+		__entry->bndstatus)
+);
+
+#else
+
+/*
+ * This gets used outside of MPX-specific code, so we need a stub.
+ */
+static inline void trace_bounds_exception_mpx(const struct bndcsr *bndcsr)
+{
+}
+
+#endif /* CONFIG_X86_INTEL_MPX */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH asm/trace/
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE mpx
+#endif /* _TRACE_MPX_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff -puN arch/x86/kernel/traps.c~x86-br-exception-trace arch/x86/kernel/traps.c
--- a/arch/x86/kernel/traps.c~x86-br-exception-trace	2015-06-01 10:24:06.058813499 -0700
+++ b/arch/x86/kernel/traps.c	2015-06-01 10:24:06.064813770 -0700
@@ -60,6 +60,7 @@
 #include <asm/mach_traps.h>
 #include <asm/alternative.h>
 #include <asm/fpu/xstate.h>
+#include <asm/trace/mpx.h>
 #include <asm/mpx.h>
 
 #ifdef CONFIG_X86_64
@@ -399,6 +400,7 @@ dotraplinkage void do_bounds(struct pt_r
 	if (!bndcsr)
 		goto exit_trap;
 
+	trace_bounds_exception_mpx(bndcsr);
 	/*
 	 * The error code field of the BNDSTATUS register communicates status
 	 * information of a bound range exception #BR or operation involving
diff -puN arch/x86/mm/mpx.c~x86-br-exception-trace arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~x86-br-exception-trace	2015-06-01 10:24:06.060813590 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:06.064813770 -0700
@@ -17,6 +17,9 @@
 #include <asm/processor.h>
 #include <asm/fpu/internal.h>
 
+#define CREATE_TRACE_POINTS
+#include <asm/trace/mpx.h>
+
 static const char *mpx_mapping_name(struct vm_area_struct *vma)
 {
 	return "[mpx]";
_

[tip:x86/fpu] x86/mpx: Trace #BR exceptions

[tip-bot for Dave Hansen]

Commit-ID:  e7126cf5f10aef1555cb99eddb7efff41bdf9566
Gitweb:     http://git.kernel.org/tip/e7126cf5f10aef1555cb99eddb7efff41bdf9566
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:03 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:31 +0200

x86/mpx: Trace #BR exceptions

This is the first in a series of MPX tracing patches.
I've found these extremely useful in the process of
debugging applications and the kernel code itself.

This exception hooks in to the bounds (#BR) exception
very early and allows capturing the key registers which
would influence how the exception is handled.

Note that bndcfgu/bndstatus are technically still
64-bit registers even in 32-bit mode.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.5FE2619A@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/trace/mpx.h | 50 ++++++++++++++++++++++++++++++++++++++++
 arch/x86/kernel/traps.c          |  2 ++
 arch/x86/mm/mpx.c                |  3 +++
 3 files changed, 55 insertions(+)

diff --git a/arch/x86/include/asm/trace/mpx.h b/arch/x86/include/asm/trace/mpx.h
new file mode 100644
index 0000000..5c03ec8
--- /dev/null
+++ b/arch/x86/include/asm/trace/mpx.h
@@ -0,0 +1,50 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mpx
+
+#if !defined(_TRACE_MPX_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MPX_H
+
+#include <linux/tracepoint.h>
+
+#ifdef CONFIG_X86_INTEL_MPX
+
+TRACE_EVENT(bounds_exception_mpx,
+
+	TP_PROTO(const struct bndcsr *bndcsr),
+	TP_ARGS(bndcsr),
+
+	TP_STRUCT__entry(
+		__field(u64, bndcfgu)
+		__field(u64, bndstatus)
+	),
+
+	TP_fast_assign(
+		/* need to get rid of the 'const' on bndcsr */
+		__entry->bndcfgu   = (u64)bndcsr->bndcfgu;
+		__entry->bndstatus = (u64)bndcsr->bndstatus;
+	),
+
+	TP_printk("bndcfgu:0x%llx bndstatus:0x%llx",
+		__entry->bndcfgu,
+		__entry->bndstatus)
+);
+
+#else
+
+/*
+ * This gets used outside of MPX-specific code, so we need a stub.
+ */
+static inline void trace_bounds_exception_mpx(const struct bndcsr *bndcsr)
+{
+}
+
+#endif /* CONFIG_X86_INTEL_MPX */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH asm/trace/
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE mpx
+#endif /* _TRACE_MPX_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index cffff66..36cb15b 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -60,6 +60,7 @@
 #include <asm/mach_traps.h>
 #include <asm/alternative.h>
 #include <asm/fpu/xstate.h>
+#include <asm/trace/mpx.h>
 #include <asm/mpx.h>
 
 #ifdef CONFIG_X86_64
@@ -399,6 +400,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 	if (!bndcsr)
 		goto exit_trap;
 
+	trace_bounds_exception_mpx(bndcsr);
 	/*
 	 * The error code field of the BNDSTATUS register communicates status
 	 * information of a bound range exception #BR or operation involving
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index d6e02f3..1fef52c 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -17,6 +17,9 @@
 #include <asm/processor.h>
 #include <asm/fpu/internal.h>
 
+#define CREATE_TRACE_POINTS
+#include <asm/trace/mpx.h>
+
 static const char *mpx_mapping_name(struct vm_area_struct *vma)
 {
 	return "[mpx]";

[PATCH 09/19] x86, mpx: trace entry to bounds exception paths

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

There are two basic things that can happen as the result of
a bounds exception (#BR):

	1. We allocate a new bounds table
	2. We pass up a bounds exception to userspace.

This patch adds a trace point for the case where we are
passing the exception up to userspace with a signal.

We are also explicit that we're printing out the inverse of
the 'upper' that we encounter.  If you want to filter, for
instance, you need to ~ the value first.  The reason we do
this is because of how 'upper' is stored in the bounds table.
If a pointer's range is:

	0x1000 -> 0x2000

it is stored in the bounds table as (32-bits here for brevity):

	lower: 0x00001000
	upper: 0xffffdfff

That is so that an all 0's entry:

	lower: 0x00000000
	upper: 0x00000000

corresponds to the "init" bounds which store a *range* of:

	0x00000000 -> 0xffffffff

That is, by far, the common case, and that lets us use the
zero page, or deduplicate the memory, etc... The 'upper'
stored in the table is gibberish to print by itself, so we
print ~upper to get the *actual*, logical, human-readable
value printed out.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/include/asm/trace/mpx.h |   34 ++++++++++++++++++++++++++++++++++
 b/arch/x86/mm/mpx.c                |    1 +
 2 files changed, 35 insertions(+)

diff -puN arch/x86/include/asm/trace/mpx.h~x86-mpx-trace-1 arch/x86/include/asm/trace/mpx.h
--- a/arch/x86/include/asm/trace/mpx.h~x86-mpx-trace-1	2015-06-01 10:24:06.504833616 -0700
+++ b/arch/x86/include/asm/trace/mpx.h	2015-06-01 10:24:06.509833841 -0700
@@ -8,6 +8,40 @@
 
 #ifdef CONFIG_X86_INTEL_MPX
 
+TRACE_EVENT(mpx_bounds_register_exception,
+
+	TP_PROTO(void *addr_referenced,
+		 const struct bndreg *bndreg),
+	TP_ARGS(addr_referenced, bndreg),
+
+	TP_STRUCT__entry(
+		__field(void *, addr_referenced)
+		__field(u64, lower_bound)
+		__field(u64, upper_bound)
+	),
+
+	TP_fast_assign(
+		__entry->addr_referenced = addr_referenced;
+		__entry->lower_bound = bndreg->lower_bound;
+		__entry->upper_bound = bndreg->upper_bound;
+	),
+	/*
+	 * Note that we are printing out the '~' of the upper
+	 * bounds register here.  It is actually stored in its
+	 * one's complement form so that its 'init' state
+	 * corresponds to all 0's.  But, that looks like
+	 * gibberish when printed out, so print out the 1's
+	 * complement instead of the actual value here.  Note
+	 * though that you still need to specify filters for the
+	 * actual value, not the displayed one.
+	 */
+	TP_printk("address referenced: 0x%p bounds: lower: 0x%llx ~upper: 0x%llx",
+		__entry->addr_referenced,
+		__entry->lower_bound,
+		~__entry->upper_bound
+	)
+);
+
 TRACE_EVENT(bounds_exception_mpx,
 
 	TP_PROTO(const struct bndcsr *bndcsr),
diff -puN arch/x86/mm/mpx.c~x86-mpx-trace-1 arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~x86-mpx-trace-1	2015-06-01 10:24:06.506833706 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:06.510833886 -0700
@@ -335,6 +335,7 @@ siginfo_t *mpx_generate_siginfo(struct p
 		err = -EINVAL;
 		goto err_out;
 	}
+	trace_mpx_bounds_register_exception(info->si_addr, bndreg);
 	return info;
 err_out:
 	/* info might be NULL, but kfree() handles that */
_

[tip:x86/fpu] x86/mpx: Trace entry to bounds exception paths

[tip-bot for Dave Hansen]

Commit-ID:  97efebf1bc30a80122af3295ebdb726dbc040ca6
Gitweb:     http://git.kernel.org/tip/97efebf1bc30a80122af3295ebdb726dbc040ca6
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:03 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:32 +0200

x86/mpx: Trace entry to bounds exception paths

There are two basic things that can happen as the result of
a bounds exception (#BR):

	1. We allocate a new bounds table
	2. We pass up a bounds exception to userspace.

This patch adds a trace point for the case where we are
passing the exception up to userspace with a signal.

We are also explicit that we're printing out the inverse of
the 'upper' that we encounter.  If you want to filter, for
instance, you need to ~ the value first.  The reason we do
this is because of how 'upper' is stored in the bounds table.

If a pointer's range is:

	0x1000 -> 0x2000

it is stored in the bounds table as (32-bits here for brevity):

	lower: 0x00001000
	upper: 0xffffdfff

That is so that an all 0's entry:

	lower: 0x00000000
	upper: 0x00000000

corresponds to the "init" bounds which store a *range* of:

	0x00000000 -> 0xffffffff

That is, by far, the common case, and that lets us use the
zero page, or deduplicate the memory, etc... The 'upper'
stored in the table is gibberish to print by itself, so we
print ~upper to get the *actual*, logical, human-readable
value printed out.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183703.027BB9B0@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/trace/mpx.h | 34 ++++++++++++++++++++++++++++++++++
 arch/x86/mm/mpx.c                |  1 +
 2 files changed, 35 insertions(+)

diff --git a/arch/x86/include/asm/trace/mpx.h b/arch/x86/include/asm/trace/mpx.h
index 5c03ec8..5c3af06 100644
--- a/arch/x86/include/asm/trace/mpx.h
+++ b/arch/x86/include/asm/trace/mpx.h
@@ -8,6 +8,40 @@
 
 #ifdef CONFIG_X86_INTEL_MPX
 
+TRACE_EVENT(mpx_bounds_register_exception,
+
+	TP_PROTO(void *addr_referenced,
+		 const struct bndreg *bndreg),
+	TP_ARGS(addr_referenced, bndreg),
+
+	TP_STRUCT__entry(
+		__field(void *, addr_referenced)
+		__field(u64, lower_bound)
+		__field(u64, upper_bound)
+	),
+
+	TP_fast_assign(
+		__entry->addr_referenced = addr_referenced;
+		__entry->lower_bound = bndreg->lower_bound;
+		__entry->upper_bound = bndreg->upper_bound;
+	),
+	/*
+	 * Note that we are printing out the '~' of the upper
+	 * bounds register here.  It is actually stored in its
+	 * one's complement form so that its 'init' state
+	 * corresponds to all 0's.  But, that looks like
+	 * gibberish when printed out, so print out the 1's
+	 * complement instead of the actual value here.  Note
+	 * though that you still need to specify filters for the
+	 * actual value, not the displayed one.
+	 */
+	TP_printk("address referenced: 0x%p bounds: lower: 0x%llx ~upper: 0x%llx",
+		__entry->addr_referenced,
+		__entry->lower_bound,
+		~__entry->upper_bound
+	)
+);
+
 TRACE_EVENT(bounds_exception_mpx,
 
 	TP_PROTO(const struct bndcsr *bndcsr),
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 1fef52c..75e5d70 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -335,6 +335,7 @@ siginfo_t *mpx_generate_siginfo(struct pt_regs *regs)
 		err = -EINVAL;
 		goto err_out;
 	}
+	trace_mpx_bounds_register_exception(info->si_addr, bndreg);
 	return info;
 err_out:
 	/* info might be NULL, but kfree() handles that */

[PATCH 14/19] x86, mpx: new directory entry to addr helper

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

Currently, to get from a bounds directory entry to the virtual
address of a bounds table, we simply mask off a few low bits.
However, the set of bits we mask off is different for 32 and
64-bit binaries.

This breaks the operation out in to a helper function and also
adds a temporary variable to store the result until we are
sure we are returning one.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

---

 b/arch/x86/include/asm/mpx.h |    1 -
 b/arch/x86/mm/mpx.c          |   41 ++++++++++++++++++++++++++++++++++-------
 2 files changed, 34 insertions(+), 8 deletions(-)

diff -puN arch/x86/include/asm/mpx.h~mpx-new-entry-to-addr-helper arch/x86/include/asm/mpx.h
--- a/arch/x86/include/asm/mpx.h~mpx-new-entry-to-addr-helper	2015-06-01 10:24:08.603928289 -0700
+++ b/arch/x86/include/asm/mpx.h	2015-06-01 10:24:08.608928515 -0700
@@ -45,7 +45,6 @@
 #define MPX_BNDSTA_TAIL		2
 #define MPX_BNDCFG_TAIL		12
 #define MPX_BNDSTA_ADDR_MASK	(~((1UL<<MPX_BNDSTA_TAIL)-1))
-#define MPX_BT_ADDR_MASK	(~((1UL<<MPX_BD_ENTRY_TAIL)-1))
 
 #define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
 #define MPX_BNDSTA_ERROR_CODE	0x3
diff -puN arch/x86/mm/mpx.c~mpx-new-entry-to-addr-helper arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-new-entry-to-addr-helper	2015-06-01 10:24:08.604928334 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:08.609928560 -0700
@@ -576,29 +576,55 @@ static int mpx_resolve_fault(long __user
 	return 0;
 }
 
+static unsigned long mpx_bd_entry_to_bt_addr(struct mm_struct *mm,
+					     unsigned long bd_entry)
+{
+	unsigned long bt_addr = bd_entry;
+	int align_to_bytes;
+	/*
+	 * Bit 0 in a bt_entry is always the valid bit.
+	 */
+	bt_addr &= ~MPX_BD_ENTRY_VALID_FLAG;
+	/*
+	 * Tables are naturally aligned at 8-byte boundaries
+	 * on 64-bit and 4-byte boundaries on 32-bit.  The
+	 * documentation makes it appear that the low bits
+	 * are ignored by the hardware, so we do the same.
+	 */
+	if (is_64bit_mm(mm))
+		align_to_bytes = 8;
+	else
+		align_to_bytes = 4;
+	bt_addr &= ~(align_to_bytes-1);
+	return bt_addr;
+}
+
 /*
  * Get the base of bounds tables pointed by specific bounds
  * directory entry.
  */
 static int get_bt_addr(struct mm_struct *mm,
-			long __user *bd_entry, unsigned long *bt_addr)
+			long __user *bd_entry_ptr,
+			unsigned long *bt_addr_result)
 {
 	int ret;
 	int valid_bit;
+	unsigned long bd_entry;
+	unsigned long bt_addr;
 
-	if (!access_ok(VERIFY_READ, (bd_entry), sizeof(*bd_entry)))
+	if (!access_ok(VERIFY_READ, (bd_entry_ptr), sizeof(*bd_entry_ptr)))
 		return -EFAULT;
 
 	while (1) {
 		int need_write = 0;
 
 		pagefault_disable();
-		ret = get_user(*bt_addr, bd_entry);
+		ret = get_user(bd_entry, bd_entry_ptr);
 		pagefault_enable();
 		if (!ret)
 			break;
 		if (ret == -EFAULT)
-			ret = mpx_resolve_fault(bd_entry, need_write);
+			ret = mpx_resolve_fault(bd_entry_ptr, need_write);
 		/*
 		 * If we could not resolve the fault, consider it
 		 * userspace's fault and error out.
@@ -607,8 +633,8 @@ static int get_bt_addr(struct mm_struct
 			return ret;
 	}
 
-	valid_bit = *bt_addr & MPX_BD_ENTRY_VALID_FLAG;
-	*bt_addr &= MPX_BT_ADDR_MASK;
+	valid_bit = bd_entry & MPX_BD_ENTRY_VALID_FLAG;
+	bt_addr = mpx_bd_entry_to_bt_addr(mm, bd_entry);
 
 	/*
 	 * When the kernel is managing bounds tables, a bounds directory
@@ -617,7 +643,7 @@ static int get_bt_addr(struct mm_struct
 	 * data in the address field, we know something is wrong. This
 	 * -EINVAL return will cause a SIGSEGV.
 	 */
-	if (!valid_bit && *bt_addr)
+	if (!valid_bit && bt_addr)
 		return -EINVAL;
 	/*
 	 * Do we have an completely zeroed bt entry?  That is OK.  It
@@ -628,6 +654,7 @@ static int get_bt_addr(struct mm_struct
 	if (!valid_bit)
 		return -ENOENT;
 
+	*bt_addr_result = bt_addr;
 	return 0;
 }
 
_

[tip:x86/fpu] x86/mpx: Introduce new 'directory entry' to 'addr' helper function

[tip-bot for Dave Hansen]

Commit-ID:  54587653904c552c56b9dec153d7a89063394b09
Gitweb:     http://git.kernel.org/tip/54587653904c552c56b9dec153d7a89063394b09
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:04 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:33 +0200

x86/mpx: Introduce new 'directory entry' to 'addr' helper function

Currently, to get from a bounds directory entry to the virtual
address of a bounds table, we simply mask off a few low bits.
However, the set of bits we mask off is different for 32-bit and
64-bit binaries.

This breaks the operation out in to a helper function and also
adds a temporary variable to store the result until we are
sure we are returning one.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183704.007686CE@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/mpx.h |  1 -
 arch/x86/mm/mpx.c          | 41 ++++++++++++++++++++++++++++++++++-------
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index 871e5e5..99d374e 100644
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -45,7 +45,6 @@
 #define MPX_BNDSTA_TAIL		2
 #define MPX_BNDCFG_TAIL		12
 #define MPX_BNDSTA_ADDR_MASK	(~((1UL<<MPX_BNDSTA_TAIL)-1))
-#define MPX_BT_ADDR_MASK	(~((1UL<<MPX_BD_ENTRY_TAIL)-1))
 
 #define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
 #define MPX_BNDSTA_ERROR_CODE	0x3
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 4f7fb7c..8cc7934 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -576,29 +576,55 @@ static int mpx_resolve_fault(long __user *addr, int write)
 	return 0;
 }
 
+static unsigned long mpx_bd_entry_to_bt_addr(struct mm_struct *mm,
+					     unsigned long bd_entry)
+{
+	unsigned long bt_addr = bd_entry;
+	int align_to_bytes;
+	/*
+	 * Bit 0 in a bt_entry is always the valid bit.
+	 */
+	bt_addr &= ~MPX_BD_ENTRY_VALID_FLAG;
+	/*
+	 * Tables are naturally aligned at 8-byte boundaries
+	 * on 64-bit and 4-byte boundaries on 32-bit.  The
+	 * documentation makes it appear that the low bits
+	 * are ignored by the hardware, so we do the same.
+	 */
+	if (is_64bit_mm(mm))
+		align_to_bytes = 8;
+	else
+		align_to_bytes = 4;
+	bt_addr &= ~(align_to_bytes-1);
+	return bt_addr;
+}
+
 /*
  * Get the base of bounds tables pointed by specific bounds
  * directory entry.
  */
 static int get_bt_addr(struct mm_struct *mm,
-			long __user *bd_entry, unsigned long *bt_addr)
+			long __user *bd_entry_ptr,
+			unsigned long *bt_addr_result)
 {
 	int ret;
 	int valid_bit;
+	unsigned long bd_entry;
+	unsigned long bt_addr;
 
-	if (!access_ok(VERIFY_READ, (bd_entry), sizeof(*bd_entry)))
+	if (!access_ok(VERIFY_READ, (bd_entry_ptr), sizeof(*bd_entry_ptr)))
 		return -EFAULT;
 
 	while (1) {
 		int need_write = 0;
 
 		pagefault_disable();
-		ret = get_user(*bt_addr, bd_entry);
+		ret = get_user(bd_entry, bd_entry_ptr);
 		pagefault_enable();
 		if (!ret)
 			break;
 		if (ret == -EFAULT)
-			ret = mpx_resolve_fault(bd_entry, need_write);
+			ret = mpx_resolve_fault(bd_entry_ptr, need_write);
 		/*
 		 * If we could not resolve the fault, consider it
 		 * userspace's fault and error out.
@@ -607,8 +633,8 @@ static int get_bt_addr(struct mm_struct *mm,
 			return ret;
 	}
 
-	valid_bit = *bt_addr & MPX_BD_ENTRY_VALID_FLAG;
-	*bt_addr &= MPX_BT_ADDR_MASK;
+	valid_bit = bd_entry & MPX_BD_ENTRY_VALID_FLAG;
+	bt_addr = mpx_bd_entry_to_bt_addr(mm, bd_entry);
 
 	/*
 	 * When the kernel is managing bounds tables, a bounds directory
@@ -617,7 +643,7 @@ static int get_bt_addr(struct mm_struct *mm,
 	 * data in the address field, we know something is wrong. This
 	 * -EINVAL return will cause a SIGSEGV.
 	 */
-	if (!valid_bit && *bt_addr)
+	if (!valid_bit && bt_addr)
 		return -EINVAL;
 	/*
 	 * Do we have an completely zeroed bt entry?  That is OK.  It
@@ -628,6 +654,7 @@ static int get_bt_addr(struct mm_struct *mm,
 	if (!valid_bit)
 		return -ENOENT;
 
+	*bt_addr_result = bt_addr;
 	return 0;
 }
 

[PATCH 13/19] x86, mpx: Add temporary variable to reduce masking

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

When we allocate a bounds table, we call mmap(), then add a
"valid" bit to the value before storing it in to the bounds
directory.

If we fail along the way, we go and mask that valid bit
_back_ out.  That seems a little silly, and this makes it
much more clear when we have a plain address versus an
actual table _entry_.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/mm/mpx.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff -puN arch/x86/mm/mpx.c~mpx-remove-unnecessary-masking arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-remove-unnecessary-masking	2015-06-01 10:24:08.222911104 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:08.227911330 -0700
@@ -429,6 +429,7 @@ static int allocate_bt(long __user *bd_e
 	unsigned long expected_old_val = 0;
 	unsigned long actual_old_val = 0;
 	unsigned long bt_addr;
+	unsigned long bd_new_entry;
 	int ret = 0;
 
 	/*
@@ -441,7 +442,7 @@ static int allocate_bt(long __user *bd_e
 	/*
 	 * Set the valid flag (kinda like _PAGE_PRESENT in a pte)
 	 */
-	bt_addr = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
+	bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
 
 	/*
 	 * Go poke the address of the new bounds table in to the
@@ -455,7 +456,7 @@ static int allocate_bt(long __user *bd_e
 	 * of the MPX code that have to pagefault_disable().
 	 */
 	ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
-					   expected_old_val, bt_addr);
+					   expected_old_val, bd_new_entry);
 	if (ret)
 		goto out_unmap;
 
@@ -486,7 +487,7 @@ static int allocate_bt(long __user *bd_e
 	trace_mpx_new_bounds_table(bt_addr);
 	return 0;
 out_unmap:
-	vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES);
+	vm_munmap(bt_addr, MPX_BT_SIZE_BYTES);
 	return ret;
 }
 
_

[tip:x86/fpu] x86/mpx: Add temporary variable to reduce masking

[tip-bot for Dave Hansen]

Commit-ID:  a1149fc83a1f97612e72ec24a0bdbabff7b85e77
Gitweb:     http://git.kernel.org/tip/a1149fc83a1f97612e72ec24a0bdbabff7b85e77
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:04 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:33 +0200

x86/mpx: Add temporary variable to reduce masking

When we allocate a bounds table, we call mmap(), then add a
"valid" bit to the value before storing it in to the bounds
directory.

If we fail along the way, we go and mask that valid bit
_back_ out.  That seems a little silly, and this makes it
much more clear when we have a plain address versus an
actual table _entry_.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183704.3D69D5F4@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/mpx.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index c17fd27..4f7fb7c 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -429,6 +429,7 @@ static int allocate_bt(long __user *bd_entry)
 	unsigned long expected_old_val = 0;
 	unsigned long actual_old_val = 0;
 	unsigned long bt_addr;
+	unsigned long bd_new_entry;
 	int ret = 0;
 
 	/*
@@ -441,7 +442,7 @@ static int allocate_bt(long __user *bd_entry)
 	/*
 	 * Set the valid flag (kinda like _PAGE_PRESENT in a pte)
 	 */
-	bt_addr = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
+	bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
 
 	/*
 	 * Go poke the address of the new bounds table in to the
@@ -455,7 +456,7 @@ static int allocate_bt(long __user *bd_entry)
 	 * of the MPX code that have to pagefault_disable().
 	 */
 	ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
-					   expected_old_val, bt_addr);
+					   expected_old_val, bd_new_entry);
 	if (ret)
 		goto out_unmap;
 
@@ -486,7 +487,7 @@ static int allocate_bt(long __user *bd_entry)
 	trace_mpx_new_bounds_table(bt_addr);
 	return 0;
 out_unmap:
-	vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES);
+	vm_munmap(bt_addr, MPX_BT_SIZE_BYTES);
 	return ret;
 }
 

[PATCH 12/19] x86: make is_64bit_mm() widely available

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The uprobes code has a nice helper, is_64bit_mm(), that consults both
the runtime and compile-time flags for 32-bit support.  Instead of
reinventing the wheel, pull it in to an x86 header so we can use it
for MPX.

I prefer passing the mm around to test_thread_flag(TIF_IA32) because
it makes it explicit where the context is coming from.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/include/asm/mmu_context.h |   13 +++++++++++++
 b/arch/x86/kernel/uprobes.c          |   10 +---------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff -puN arch/x86/include/asm/mmu_context.h~x86-make-is_64bit_mm-available arch/x86/include/asm/mmu_context.h
--- a/arch/x86/include/asm/mmu_context.h~x86-make-is_64bit_mm-available	2015-06-01 10:24:07.787891484 -0700
+++ b/arch/x86/include/asm/mmu_context.h	2015-06-01 10:24:07.793891755 -0700
@@ -142,6 +142,19 @@ static inline void arch_exit_mmap(struct
 	paravirt_arch_exit_mmap(mm);
 }
 
+#ifdef CONFIG_X86_64
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+	return	!config_enabled(CONFIG_IA32_EMULATION) ||
+		!(mm->context.ia32_compat == TIF_IA32);
+}
+#else
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+	return false;
+}
+#endif
+
 static inline void arch_bprm_mm_init(struct mm_struct *mm,
 		struct vm_area_struct *vma)
 {
diff -puN arch/x86/kernel/uprobes.c~x86-make-is_64bit_mm-available arch/x86/kernel/uprobes.c
--- a/arch/x86/kernel/uprobes.c~x86-make-is_64bit_mm-available	2015-06-01 10:24:07.789891574 -0700
+++ b/arch/x86/kernel/uprobes.c	2015-06-01 10:24:07.793891755 -0700
@@ -29,6 +29,7 @@
 #include <linux/kdebug.h>
 #include <asm/processor.h>
 #include <asm/insn.h>
+#include <asm/mmu_context.h>
 
 /* Post-execution fixups. */
 
@@ -312,11 +313,6 @@ static int uprobe_init_insn(struct arch_
 }
 
 #ifdef CONFIG_X86_64
-static inline bool is_64bit_mm(struct mm_struct *mm)
-{
-	return	!config_enabled(CONFIG_IA32_EMULATION) ||
-		!(mm->context.ia32_compat == TIF_IA32);
-}
 /*
  * If arch_uprobe->insn doesn't use rip-relative addressing, return
  * immediately.  Otherwise, rewrite the instruction so that it accesses
@@ -497,10 +493,6 @@ static void riprel_post_xol(struct arch_
 	}
 }
 #else /* 32-bit: */
-static inline bool is_64bit_mm(struct mm_struct *mm)
-{
-	return false;
-}
 /*
  * No RIP-relative addressing on 32-bit
  */
_

[tip:x86/fpu] x86: Make is_64bit_mm() widely available

[tip-bot for Dave Hansen]

Commit-ID:  b0e9b09b3bd64e67bba862e238d3757b2482b6de
Gitweb:     http://git.kernel.org/tip/b0e9b09b3bd64e67bba862e238d3757b2482b6de
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:04 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:32 +0200

x86: Make is_64bit_mm() widely available

The uprobes code has a nice helper, is_64bit_mm(), that consults
both the runtime and compile-time flags for 32-bit support.
Instead of reinventing the wheel, pull it in to an x86 header so
we can use it for MPX.

I prefer passing the 'mm' around to test_thread_flag(TIF_IA32)
because it makes it explicit where the context is coming from.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183704.F0209999@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/mmu_context.h | 13 +++++++++++++
 arch/x86/kernel/uprobes.c          | 10 +---------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 883f6b9..5e8daee 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -142,6 +142,19 @@ static inline void arch_exit_mmap(struct mm_struct *mm)
 	paravirt_arch_exit_mmap(mm);
 }
 
+#ifdef CONFIG_X86_64
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+	return	!config_enabled(CONFIG_IA32_EMULATION) ||
+		!(mm->context.ia32_compat == TIF_IA32);
+}
+#else
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+	return false;
+}
+#endif
+
 static inline void arch_bprm_mm_init(struct mm_struct *mm,
 		struct vm_area_struct *vma)
 {
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 0b81ad6..6647624 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -29,6 +29,7 @@
 #include <linux/kdebug.h>
 #include <asm/processor.h>
 #include <asm/insn.h>
+#include <asm/mmu_context.h>
 
 /* Post-execution fixups. */
 
@@ -312,11 +313,6 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool
 }
 
 #ifdef CONFIG_X86_64
-static inline bool is_64bit_mm(struct mm_struct *mm)
-{
-	return	!config_enabled(CONFIG_IA32_EMULATION) ||
-		!(mm->context.ia32_compat == TIF_IA32);
-}
 /*
  * If arch_uprobe->insn doesn't use rip-relative addressing, return
  * immediately.  Otherwise, rewrite the instruction so that it accesses
@@ -497,10 +493,6 @@ static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 	}
 }
 #else /* 32-bit: */
-static inline bool is_64bit_mm(struct mm_struct *mm)
-{
-	return false;
-}
 /*
  * No RIP-relative addressing on 32-bit
  */

[PATCH 11/19] x86, mpx: trace allocation of new bounds tables

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

Bounds tables are a significant consumer of memory.  It is important
to know when they are being allocated.  Add a trace point to trace
whenever an allocation occurs and also its virtual address.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

---

 b/arch/x86/include/asm/trace/mpx.h |   16 ++++++++++++++++
 b/arch/x86/mm/mpx.c                |    1 +
 2 files changed, 17 insertions(+)

diff -puN arch/x86/include/asm/trace/mpx.h~trace_mpx_new_bounds_table arch/x86/include/asm/trace/mpx.h
--- a/arch/x86/include/asm/trace/mpx.h~trace_mpx_new_bounds_table	2015-06-01 10:24:07.357872090 -0700
+++ b/arch/x86/include/asm/trace/mpx.h	2015-06-01 10:24:07.362872315 -0700
@@ -95,6 +95,22 @@ DEFINE_EVENT(mpx_range_trace, mpx_unmap_
 	TP_ARGS(start, end)
 );
 
+TRACE_EVENT(mpx_new_bounds_table,
+
+	TP_PROTO(unsigned long table_vaddr),
+	TP_ARGS(table_vaddr),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, table_vaddr)
+	),
+
+	TP_fast_assign(
+		__entry->table_vaddr = table_vaddr;
+	),
+
+	TP_printk("table vaddr:%p", (void *)__entry->table_vaddr)
+);
+
 #else
 
 /*
diff -puN arch/x86/mm/mpx.c~trace_mpx_new_bounds_table arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~trace_mpx_new_bounds_table	2015-06-01 10:24:07.359872180 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:07.363872360 -0700
@@ -483,6 +483,7 @@ static int allocate_bt(long __user *bd_e
 		ret = -EINVAL;
 		goto out_unmap;
 	}
+	trace_mpx_new_bounds_table(bt_addr);
 	return 0;
 out_unmap:
 	vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES);
_

[tip:x86/fpu] x86/mpx: Trace allocation of new bounds tables

[tip-bot for Dave Hansen]

Commit-ID:  cd4996dce18b619bd7b3acf75c91f49c77f05a97
Gitweb:     http://git.kernel.org/tip/cd4996dce18b619bd7b3acf75c91f49c77f05a97
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:04 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:32 +0200

x86/mpx: Trace allocation of new bounds tables

Bounds tables are a significant consumer of memory.  It is
important to know when they are being allocated.  Add a trace
point to trace whenever an allocation occurs and also its
virtual address.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183704.EC23A93E@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/trace/mpx.h | 16 ++++++++++++++++
 arch/x86/mm/mpx.c                |  1 +
 2 files changed, 17 insertions(+)

diff --git a/arch/x86/include/asm/trace/mpx.h b/arch/x86/include/asm/trace/mpx.h
index c13c6fa..173dd3b 100644
--- a/arch/x86/include/asm/trace/mpx.h
+++ b/arch/x86/include/asm/trace/mpx.h
@@ -95,6 +95,22 @@ DEFINE_EVENT(mpx_range_trace, mpx_unmap_search,
 	TP_ARGS(start, end)
 );
 
+TRACE_EVENT(mpx_new_bounds_table,
+
+	TP_PROTO(unsigned long table_vaddr),
+	TP_ARGS(table_vaddr),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, table_vaddr)
+	),
+
+	TP_fast_assign(
+		__entry->table_vaddr = table_vaddr;
+	),
+
+	TP_printk("table vaddr:%p", (void *)__entry->table_vaddr)
+);
+
 #else
 
 /*
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 55729ee..c17fd27 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -483,6 +483,7 @@ static int allocate_bt(long __user *bd_entry)
 		ret = -EINVAL;
 		goto out_unmap;
 	}
+	trace_mpx_new_bounds_table(bt_addr);
 	return 0;
 out_unmap:
 	vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES);

[PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

user_atomic_cmpxchg_inatomic() actually looks at sizeof(*ptr) to
figure out how many bytes to copy.  If we run it on a 64-bit
kernel with a 64-bit pointer, it will copy a 64-bit bounds
directory entry.  That's fine, except when we have 32-bit
programs with 32-bit bounds directory entries and we only *want*
32-bits.

This patch breaks the cmpxchg operation out in to its own
function and performs the 32-bit type swizzling in there.

Note, the "64-bit" version of this code _would_ work on a
32-bit-only kernel.  The issue this patch addresses is only for
when the kernel's 'long' is mismatched from the size of the
bounds directory entry of the process we are working on.

The new helper modifies 'actual_old_val' or returns an error.
But gcc doesn't know this, so it warns about 'actual_old_val'
being unused.  Shut it up with an uninitialized_var().

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

---

Changes from v21:
 * correct type of bd_entry_addr from long -> unsigned long
 * shorten variable names
 * add whitespace after variables
 * unconditionally do assignment
---

 b/arch/x86/mm/mpx.c |   41 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 5 deletions(-)

diff -puN arch/x86/mm/mpx.c~mpx-variable-sized-userspace-pokes arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-variable-sized-userspace-pokes	2015-06-01 10:24:08.926942858 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:08.928942948 -0700
@@ -419,6 +419,35 @@ int mpx_disable_management(void)
 	return 0;
 }
 
+static int mpx_cmpxchg_bd_entry(struct mm_struct *mm,
+		unsigned long *curval,
+		unsigned long __user *addr,
+		unsigned long old_val, unsigned long new_val)
+{
+	int ret;
+	/*
+	 * user_atomic_cmpxchg_inatomic() actually uses sizeof()
+	 * the pointer that we pass to it to figure out how much
+	 * data to cmpxchg.  We have to be careful here not to
+	 * pass a pointer to a 64-bit data type when we only want
+	 * a 32-bit copy.
+	 */
+	if (is_64bit_mm(mm)) {
+		ret = user_atomic_cmpxchg_inatomic(curval,
+				addr, old_val, new_val);
+	} else {
+		u32 uninitialized_var(curval_32);
+		u32 old_val_32 = old_val;
+		u32 new_val_32 = new_val;
+		u32 __user *addr_32 = (u32 __user *)addr;
+
+		ret = user_atomic_cmpxchg_inatomic(&curval_32,
+				addr_32, old_val_32, new_val_32);
+		*curval = curval_32;
+	}
+	return ret;
+}
+
 /*
  * With 32-bit mode, MPX_BT_SIZE_BYTES is 4MB, and the size of each
  * bounds table is 16KB. With 64-bit mode, MPX_BT_SIZE_BYTES is 2GB,
@@ -426,6 +455,7 @@ int mpx_disable_management(void)
  */
 static int allocate_bt(long __user *bd_entry)
 {
+	struct mm_struct *mm = current->mm;
 	unsigned long expected_old_val = 0;
 	unsigned long actual_old_val = 0;
 	unsigned long bt_addr;
@@ -455,8 +485,8 @@ static int allocate_bt(long __user *bd_e
 	 * mmap_sem at this point, unlike some of the other part
 	 * of the MPX code that have to pagefault_disable().
 	 */
-	ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
-					   expected_old_val, bd_new_entry);
+	ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,	bd_entry,
+				   expected_old_val, bd_new_entry);
 	if (ret)
 		goto out_unmap;
 
@@ -710,15 +740,16 @@ static int unmap_single_bt(struct mm_str
 		long __user *bd_entry, unsigned long bt_addr)
 {
 	unsigned long expected_old_val = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
-	unsigned long actual_old_val = 0;
+	unsigned long uninitialized_var(actual_old_val);
 	int ret;
 
 	while (1) {
 		int need_write = 1;
+		unsigned long cleared_bd_entry = 0;
 
 		pagefault_disable();
-		ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
-						   expected_old_val, 0);
+		ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,
+				bd_entry, expected_old_val, cleared_bd_entry);
 		pagefault_enable();
 		if (!ret)
 			break;
_

[tip:x86/fpu] x86/mpx: Use 32-bit-only cmpxchg() for 32-bit apps

[tip-bot for Dave Hansen]

Commit-ID:  6ac52bb4913eadfa327138b91aab5d37234a2c3b
Gitweb:     http://git.kernel.org/tip/6ac52bb4913eadfa327138b91aab5d37234a2c3b
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:05 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:33 +0200

x86/mpx: Use 32-bit-only cmpxchg() for 32-bit apps

user_atomic_cmpxchg_inatomic() actually looks at sizeof(*ptr) to
figure out how many bytes to copy.  If we run it on a 64-bit
kernel with a 64-bit pointer, it will copy a 64-bit bounds
directory entry.  That's fine, except when we have 32-bit
programs with 32-bit bounds directory entries and we only *want*
32-bits.

This patch breaks the cmpxchg() operation out in to its own
function and performs the 32-bit type swizzling in there.

Note, the "64-bit" version of this code _would_ work on a
32-bit-only kernel.  The issue this patch addresses is only for
when the kernel's 'long' is mismatched from the size of the
bounds directory entry of the process we are working on.

The new helper modifies 'actual_old_val' or returns an error.
But gcc doesn't know this, so it warns about 'actual_old_val'
being unused.  Shut it up with an uninitialized_var().

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183705.672B115E@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/mpx.c | 41 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 8cc7934..294ea20 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -419,6 +419,35 @@ int mpx_disable_management(void)
 	return 0;
 }
 
+static int mpx_cmpxchg_bd_entry(struct mm_struct *mm,
+		unsigned long *curval,
+		unsigned long __user *addr,
+		unsigned long old_val, unsigned long new_val)
+{
+	int ret;
+	/*
+	 * user_atomic_cmpxchg_inatomic() actually uses sizeof()
+	 * the pointer that we pass to it to figure out how much
+	 * data to cmpxchg.  We have to be careful here not to
+	 * pass a pointer to a 64-bit data type when we only want
+	 * a 32-bit copy.
+	 */
+	if (is_64bit_mm(mm)) {
+		ret = user_atomic_cmpxchg_inatomic(curval,
+				addr, old_val, new_val);
+	} else {
+		u32 uninitialized_var(curval_32);
+		u32 old_val_32 = old_val;
+		u32 new_val_32 = new_val;
+		u32 __user *addr_32 = (u32 __user *)addr;
+
+		ret = user_atomic_cmpxchg_inatomic(&curval_32,
+				addr_32, old_val_32, new_val_32);
+		*curval = curval_32;
+	}
+	return ret;
+}
+
 /*
  * With 32-bit mode, MPX_BT_SIZE_BYTES is 4MB, and the size of each
  * bounds table is 16KB. With 64-bit mode, MPX_BT_SIZE_BYTES is 2GB,
@@ -426,6 +455,7 @@ int mpx_disable_management(void)
  */
 static int allocate_bt(long __user *bd_entry)
 {
+	struct mm_struct *mm = current->mm;
 	unsigned long expected_old_val = 0;
 	unsigned long actual_old_val = 0;
 	unsigned long bt_addr;
@@ -455,8 +485,8 @@ static int allocate_bt(long __user *bd_entry)
 	 * mmap_sem at this point, unlike some of the other part
 	 * of the MPX code that have to pagefault_disable().
 	 */
-	ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
-					   expected_old_val, bd_new_entry);
+	ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,	bd_entry,
+				   expected_old_val, bd_new_entry);
 	if (ret)
 		goto out_unmap;
 
@@ -710,15 +740,16 @@ static int unmap_single_bt(struct mm_struct *mm,
 		long __user *bd_entry, unsigned long bt_addr)
 {
 	unsigned long expected_old_val = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
-	unsigned long actual_old_val = 0;
+	unsigned long uninitialized_var(actual_old_val);
 	int ret;
 
 	while (1) {
 		int need_write = 1;
+		unsigned long cleared_bd_entry = 0;
 
 		pagefault_disable();
-		ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
-						   expected_old_val, 0);
+		ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,
+				bd_entry, expected_old_val, cleared_bd_entry);
 		pagefault_enable();
 		if (!ret)
 			break;

[PATCH 16/19] x86, mpx: support 32-bit binaries on 64-bit kernel

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

Right now, the kernel can only switch between 64-bit and 32-bit
binaries at compile time. This patch adds support for 32-bit
binaries on 64-bit kernels when we support ia32 emulation.

We essentially choose which set of table sizes to use when doing
arithmetic for the bounds table calculations.

This also uses a different approach for calculating the table
indexes than before.  I think the new one makes it much more
clear what is going on, and allows us to share more code between
the 32 and 64-bit cases.

Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

--

Changes from v22:
 * fix spelling nit

Changes from v21:
 * remove old comment
 * add a comment about why the masks are OK
 * use cpu_info->x86_virt_bits
 * add comment about lack of 32-bit hole

Changes from v20:

 * Fix macro confusion between BD and BT
 * Add accessor for bt_entry_size_bytes()

---

 b/arch/x86/include/asm/mpx.h |   66 ++++++++--------
 b/arch/x86/mm/mpx.c          |  170 +++++++++++++++++++++++++++++++++++++------
 2 files changed, 181 insertions(+), 55 deletions(-)

diff -puN arch/x86/include/asm/mpx.h~0002-x86-mpx-support-32bit-binaries-on-64bit-kernel arch/x86/include/asm/mpx.h
--- a/arch/x86/include/asm/mpx.h~0002-x86-mpx-support-32bit-binaries-on-64bit-kernel	2015-06-01 10:24:09.323960764 -0700
+++ b/arch/x86/include/asm/mpx.h	2015-06-01 10:24:09.329961034 -0700
@@ -13,49 +13,47 @@
 #define MPX_BNDCFG_ENABLE_FLAG	0x1
 #define MPX_BD_ENTRY_VALID_FLAG	0x1
 
-#ifdef CONFIG_X86_64
-
-/* upper 28 bits [47:20] of the virtual address in 64-bit used to
- * index into bounds directory (BD).
+/*
+ * The upper 28 bits [47:20] of the virtual address in 64-bit
+ * are used to index into bounds directory (BD).
+ *
+ * The directory is 2G (2^31) in size, and with 8-byte entries
+ * it has 2^28 entries.
  */
-#define MPX_BD_ENTRY_OFFSET	28
-#define MPX_BD_ENTRY_SHIFT	3
-/* bits [19:3] of the virtual address in 64-bit used to index into
- * bounds table (BT).
+#define MPX_BD_SIZE_BYTES_64	(1UL<<31)
+#define MPX_BD_ENTRY_BYTES_64	8
+#define MPX_BD_NR_ENTRIES_64	(MPX_BD_SIZE_BYTES_64/MPX_BD_ENTRY_BYTES_64)
+
+/*
+ * The 32-bit directory is 4MB (2^22) in size, and with 4-byte
+ * entries it has 2^20 entries.
  */
-#define MPX_BT_ENTRY_OFFSET	17
-#define MPX_BT_ENTRY_SHIFT	5
-#define MPX_IGN_BITS		3
-#define MPX_BD_ENTRY_TAIL	3
-
-#else
-
-#define MPX_BD_ENTRY_OFFSET	20
-#define MPX_BD_ENTRY_SHIFT	2
-#define MPX_BT_ENTRY_OFFSET	10
-#define MPX_BT_ENTRY_SHIFT	4
-#define MPX_IGN_BITS		2
-#define MPX_BD_ENTRY_TAIL	2
-
-#endif
-
-#define MPX_BD_SIZE_BYTES (1UL<<(MPX_BD_ENTRY_OFFSET+MPX_BD_ENTRY_SHIFT))
-#define MPX_BT_SIZE_BYTES (1UL<<(MPX_BT_ENTRY_OFFSET+MPX_BT_ENTRY_SHIFT))
+#define MPX_BD_SIZE_BYTES_32	(1UL<<22)
+#define MPX_BD_ENTRY_BYTES_32	4
+#define MPX_BD_NR_ENTRIES_32	(MPX_BD_SIZE_BYTES_32/MPX_BD_ENTRY_BYTES_32)
+
+/*
+ * A 64-bit table is 4MB total in size, and an entry is
+ * 4 64-bit pointers in size.
+ */
+#define MPX_BT_SIZE_BYTES_64	(1UL<<22)
+#define MPX_BT_ENTRY_BYTES_64	32
+#define MPX_BT_NR_ENTRIES_64	(MPX_BT_SIZE_BYTES_64/MPX_BT_ENTRY_BYTES_64)
+
+/*
+ * A 32-bit table is 16kB total in size, and an entry is
+ * 4 32-bit pointers in size.
+ */
+#define MPX_BT_SIZE_BYTES_32	(1UL<<14)
+#define MPX_BT_ENTRY_BYTES_32	16
+#define MPX_BT_NR_ENTRIES_32	(MPX_BT_SIZE_BYTES_32/MPX_BT_ENTRY_BYTES_32)
 
 #define MPX_BNDSTA_TAIL		2
 #define MPX_BNDCFG_TAIL		12
 #define MPX_BNDSTA_ADDR_MASK	(~((1UL<<MPX_BNDSTA_TAIL)-1))
-
 #define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
 #define MPX_BNDSTA_ERROR_CODE	0x3
 
-#define MPX_BD_ENTRY_MASK	((1<<MPX_BD_ENTRY_OFFSET)-1)
-#define MPX_BT_ENTRY_MASK	((1<<MPX_BT_ENTRY_OFFSET)-1)
-#define MPX_GET_BD_ENTRY_OFFSET(addr)	((((addr)>>(MPX_BT_ENTRY_OFFSET+ \
-		MPX_IGN_BITS)) & MPX_BD_ENTRY_MASK) << MPX_BD_ENTRY_SHIFT)
-#define MPX_GET_BT_ENTRY_OFFSET(addr)	((((addr)>>MPX_IGN_BITS) & \
-		MPX_BT_ENTRY_MASK) << MPX_BT_ENTRY_SHIFT)
-
 #ifdef CONFIG_X86_INTEL_MPX
 siginfo_t *mpx_generate_siginfo(struct pt_regs *regs);
 int mpx_handle_bd_fault(void);
diff -puN arch/x86/mm/mpx.c~0002-x86-mpx-support-32bit-binaries-on-64bit-kernel arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~0002-x86-mpx-support-32bit-binaries-on-64bit-kernel	2015-06-01 10:24:09.325960854 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:09.330961080 -0700
@@ -34,6 +34,22 @@ static int is_mpx_vma(struct vm_area_str
 	return (vma->vm_ops == &mpx_vma_ops);
 }
 
+static inline unsigned long mpx_bd_size_bytes(struct mm_struct *mm)
+{
+	if (is_64bit_mm(mm))
+		return MPX_BD_SIZE_BYTES_64;
+	else
+		return MPX_BD_SIZE_BYTES_32;
+}
+
+static inline unsigned long mpx_bt_size_bytes(struct mm_struct *mm)
+{
+	if (is_64bit_mm(mm))
+		return MPX_BT_SIZE_BYTES_64;
+	else
+		return MPX_BT_SIZE_BYTES_32;
+}
+
 /*
  * This is really a simplified "vm_mmap". it only handles MPX
  * bounds tables (the bounds directory is user-allocated).
@@ -50,7 +66,7 @@ static unsigned long mpx_mmap(unsigned l
 	struct vm_area_struct *vma;
 
 	/* Only bounds table can be allocated here */
-	if (len != MPX_BT_SIZE_BYTES)
+	if (len != mpx_bt_size_bytes(mm))
 		return -EINVAL;
 
 	down_write(&mm->mmap_sem);
@@ -449,13 +465,12 @@ static int mpx_cmpxchg_bd_entry(struct m
 }
 
 /*
- * With 32-bit mode, MPX_BT_SIZE_BYTES is 4MB, and the size of each
- * bounds table is 16KB. With 64-bit mode, MPX_BT_SIZE_BYTES is 2GB,
+ * With 32-bit mode, a bounds directory is 4MB, and the size of each
+ * bounds table is 16KB. With 64-bit mode, a bounds directory is 2GB,
  * and the size of each bounds table is 4MB.
  */
-static int allocate_bt(long __user *bd_entry)
+static int allocate_bt(struct mm_struct *mm, long __user *bd_entry)
 {
-	struct mm_struct *mm = current->mm;
 	unsigned long expected_old_val = 0;
 	unsigned long actual_old_val = 0;
 	unsigned long bt_addr;
@@ -466,7 +481,7 @@ static int allocate_bt(long __user *bd_e
 	 * Carve the virtual space out of userspace for the new
 	 * bounds table:
 	 */
-	bt_addr = mpx_mmap(MPX_BT_SIZE_BYTES);
+	bt_addr = mpx_mmap(mpx_bt_size_bytes(mm));
 	if (IS_ERR((void *)bt_addr))
 		return PTR_ERR((void *)bt_addr);
 	/*
@@ -517,7 +532,7 @@ static int allocate_bt(long __user *bd_e
 	trace_mpx_new_bounds_table(bt_addr);
 	return 0;
 out_unmap:
-	vm_munmap(bt_addr, MPX_BT_SIZE_BYTES);
+	vm_munmap(bt_addr, mpx_bt_size_bytes(mm));
 	return ret;
 }
 
@@ -536,6 +551,7 @@ static int do_mpx_bt_fault(void)
 {
 	unsigned long bd_entry, bd_base;
 	const struct bndcsr *bndcsr;
+	struct mm_struct *mm = current->mm;
 
 	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
@@ -554,10 +570,10 @@ static int do_mpx_bt_fault(void)
 	 * the directory is.
 	 */
 	if ((bd_entry < bd_base) ||
-	    (bd_entry >= bd_base + MPX_BD_SIZE_BYTES))
+	    (bd_entry >= bd_base + mpx_bd_size_bytes(mm)))
 		return -EINVAL;
 
-	return allocate_bt((long __user *)bd_entry);
+	return allocate_bt(mm, (long __user *)bd_entry);
 }
 
 int mpx_handle_bd_fault(void)
@@ -789,7 +805,115 @@ static int unmap_single_bt(struct mm_str
 	 * avoid recursion, do_munmap() will check whether it comes
 	 * from one bounds table through VM_MPX flag.
 	 */
-	return do_munmap(mm, bt_addr, MPX_BT_SIZE_BYTES);
+	return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
+}
+
+static inline int bt_entry_size_bytes(struct mm_struct *mm)
+{
+	if (is_64bit_mm(mm))
+		return MPX_BT_ENTRY_BYTES_64;
+	else
+		return MPX_BT_ENTRY_BYTES_32;
+}
+
+/*
+ * Take a virtual address and turns it in to the offset in bytes
+ * inside of the bounds table where the bounds table entry
+ * controlling 'addr' can be found.
+ */
+static unsigned long mpx_get_bt_entry_offset_bytes(struct mm_struct *mm,
+		unsigned long addr)
+{
+	unsigned long bt_table_nr_entries;
+	unsigned long offset = addr;
+
+	if (is_64bit_mm(mm)) {
+		/* Bottom 3 bits are ignored on 64-bit */
+		offset >>= 3;
+		bt_table_nr_entries = MPX_BT_NR_ENTRIES_64;
+	} else {
+		/* Bottom 2 bits are ignored on 32-bit */
+		offset >>= 2;
+		bt_table_nr_entries = MPX_BT_NR_ENTRIES_32;
+	}
+	/*
+	 * We know the size of the table in to which we are
+	 * indexing, and we have eliminated all the low bits
+	 * which are ignored for indexing.
+	 *
+	 * Mask out all the high bits which we do not need
+	 * to index in to the table.  Note that the tables
+	 * are always powers of two so this gives us a proper
+	 * mask.
+	 */
+	offset &= (bt_table_nr_entries-1);
+	/*
+	 * We now have an entry offset in terms of *entries* in
+	 * the table.  We need to scale it back up to bytes.
+	 */
+	offset *= bt_entry_size_bytes(mm);
+	return offset;
+}
+
+/*
+ * How much virtual address space does a single bounds
+ * directory entry cover?
+ *
+ * Note, we need a long long because 4GB doesn't fit in
+ * to a long on 32-bit.
+ */
+static inline unsigned long bd_entry_virt_space(struct mm_struct *mm)
+{
+	unsigned long long virt_space = (1ULL << boot_cpu_data.x86_virt_bits);
+	if (is_64bit_mm(mm))
+		return virt_space / MPX_BD_NR_ENTRIES_64;
+	else
+		return virt_space / MPX_BD_NR_ENTRIES_32;
+}
+
+/*
+ * Return an offset in terms of bytes in to the bounds
+ * directory where the bounds directory entry for a given
+ * virtual address resides.
+ *
+ * This has to be in bytes because the directory entries
+ * are different sizes on 64/32 bit.
+ */
+static unsigned long mpx_get_bd_entry_offset(struct mm_struct *mm,
+		unsigned long addr)
+{
+	/*
+	 * There are several ways to derive the bd offsets.  We
+	 * use the following approach here:
+	 * 1. We know the size of the virtual address space
+	 * 2. We know the number of entries in a bounds table
+	 * 3. We know that each entry covers a fixed amount of
+	 *    virtual address space.
+	 * So, we can just divide the virtual address by the
+	 * virtual space used by one entry to determine which
+	 * entry "controls" the given virtual address.
+	 */
+	if (is_64bit_mm(mm)) {
+		int bd_entry_size = 8; /* 64-bit pointer */
+		/*
+		 * Take the 64-bit addressing hole in to account.
+		 */
+		addr &= ((1UL << boot_cpu_data.x86_virt_bits) - 1);
+		return (addr / bd_entry_virt_space(mm)) * bd_entry_size;
+	} else {
+		int bd_entry_size = 4; /* 32-bit pointer */
+		/*
+		 * 32-bit has no hole so this case needs no mask
+		 */
+		return (addr / bd_entry_virt_space(mm)) * bd_entry_size;
+	}
+	/*
+	 * The two return calls above are exact copies.  If we
+	 * pull out a single copy and put it in here, gcc won't
+	 * realize that we're doing a power-of-2 divide and use
+	 * shifts.  It uses a real divide.  If we put them up
+	 * there, it manages to figure it out (gcc 4.8.3).
+	 */
 }
 
 /*
@@ -803,6 +927,7 @@ static int unmap_shared_bt(struct mm_str
 		unsigned long end, bool prev_shared, bool next_shared)
 {
 	unsigned long bt_addr;
+	unsigned long start_off, end_off;
 	int ret;
 
 	ret = get_bt_addr(mm, bd_entry, &bt_addr);
@@ -814,17 +939,20 @@ static int unmap_shared_bt(struct mm_str
 	if (ret)
 		return ret;
 
+	start_off = mpx_get_bt_entry_offset_bytes(mm, start);
+	end_off   = mpx_get_bt_entry_offset_bytes(mm, end);
+
 	if (prev_shared && next_shared)
 		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(start),
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(end));
+				bt_addr + start_off,
+				bt_addr + end_off);
 	else if (prev_shared)
 		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(start),
-				bt_addr+MPX_BT_SIZE_BYTES);
+				bt_addr + start_off,
+				bt_addr + mpx_bt_size_bytes(mm));
 	else if (next_shared)
 		ret = zap_bt_entries(mm, bt_addr, bt_addr,
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(end));
+				bt_addr + end_off);
 	else
 		ret = unmap_single_bt(mm, bd_entry, bt_addr);
 
@@ -845,8 +973,8 @@ static int unmap_edge_bts(struct mm_stru
 	struct vm_area_struct *prev, *next;
 	bool prev_shared = false, next_shared = false;
 
-	bde_start = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(start);
-	bde_end = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(end-1);
+	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
 
 	/*
 	 * Check whether bde_start and bde_end are shared with adjacent
@@ -858,10 +986,10 @@ static int unmap_edge_bts(struct mm_stru
 	 * in to 'next'.
 	 */
 	next = find_vma_prev(mm, start, &prev);
-	if (prev && (mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(prev->vm_end-1))
+	if (prev && (mm->bd_addr + mpx_get_bd_entry_offset(mm, prev->vm_end-1))
 			== bde_start)
 		prev_shared = true;
-	if (next && (mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(next->vm_start))
+	if (next && (mm->bd_addr + mpx_get_bd_entry_offset(mm, next->vm_start))
 			== bde_end)
 		next_shared = true;
 
@@ -927,8 +1055,8 @@ static int mpx_unmap_tables(struct mm_st
 	 *   1. fully covered
 	 *   2. not at the edges of the mapping, even if full aligned
 	 */
-	bde_start = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(start);
-	bde_end = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(end-1);
+	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
 	for (bd_entry = bde_start + 1; bd_entry < bde_end; bd_entry++) {
 		ret = get_bt_addr(mm, bd_entry, &bt_addr);
 		switch (ret) {
_

[tip:x86/fpu] x86/mpx: Support 32-bit binaries on 64-bit kernels

[tip-bot for Dave Hansen]

Commit-ID:  613fcb7d3c79ec25b5913a6aa974c9047c31e68c
Gitweb:     http://git.kernel.org/tip/613fcb7d3c79ec25b5913a6aa974c9047c31e68c
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:05 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:34 +0200

x86/mpx: Support 32-bit binaries on 64-bit kernels

Right now, the kernel can only switch between 64-bit and 32-bit
binaries at compile time. This patch adds support for 32-bit
binaries on 64-bit kernels when we support ia32 emulation.

We essentially choose which set of table sizes to use when doing
arithmetic for the bounds table calculations.

This also uses a different approach for calculating the table
indexes than before.  I think the new one makes it much more
clear what is going on, and allows us to share more code between
the 32-bit and 64-bit cases.

Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183705.E01F21E2@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/mpx.h |  62 ++++++++---------
 arch/x86/mm/mpx.c          | 170 +++++++++++++++++++++++++++++++++++++++------
 2 files changed, 179 insertions(+), 53 deletions(-)

diff --git a/arch/x86/include/asm/mpx.h b/arch/x86/include/asm/mpx.h
index 99d374e..7a35495 100644
--- a/arch/x86/include/asm/mpx.h
+++ b/arch/x86/include/asm/mpx.h
@@ -13,49 +13,47 @@
 #define MPX_BNDCFG_ENABLE_FLAG	0x1
 #define MPX_BD_ENTRY_VALID_FLAG	0x1
 
-#ifdef CONFIG_X86_64
-
-/* upper 28 bits [47:20] of the virtual address in 64-bit used to
- * index into bounds directory (BD).
- */
-#define MPX_BD_ENTRY_OFFSET	28
-#define MPX_BD_ENTRY_SHIFT	3
-/* bits [19:3] of the virtual address in 64-bit used to index into
- * bounds table (BT).
+/*
+ * The upper 28 bits [47:20] of the virtual address in 64-bit
+ * are used to index into bounds directory (BD).
+ *
+ * The directory is 2G (2^31) in size, and with 8-byte entries
+ * it has 2^28 entries.
  */
-#define MPX_BT_ENTRY_OFFSET	17
-#define MPX_BT_ENTRY_SHIFT	5
-#define MPX_IGN_BITS		3
-#define MPX_BD_ENTRY_TAIL	3
+#define MPX_BD_SIZE_BYTES_64	(1UL<<31)
+#define MPX_BD_ENTRY_BYTES_64	8
+#define MPX_BD_NR_ENTRIES_64	(MPX_BD_SIZE_BYTES_64/MPX_BD_ENTRY_BYTES_64)
 
-#else
-
-#define MPX_BD_ENTRY_OFFSET	20
-#define MPX_BD_ENTRY_SHIFT	2
-#define MPX_BT_ENTRY_OFFSET	10
-#define MPX_BT_ENTRY_SHIFT	4
-#define MPX_IGN_BITS		2
-#define MPX_BD_ENTRY_TAIL	2
+/*
+ * The 32-bit directory is 4MB (2^22) in size, and with 4-byte
+ * entries it has 2^20 entries.
+ */
+#define MPX_BD_SIZE_BYTES_32	(1UL<<22)
+#define MPX_BD_ENTRY_BYTES_32	4
+#define MPX_BD_NR_ENTRIES_32	(MPX_BD_SIZE_BYTES_32/MPX_BD_ENTRY_BYTES_32)
 
-#endif
+/*
+ * A 64-bit table is 4MB total in size, and an entry is
+ * 4 64-bit pointers in size.
+ */
+#define MPX_BT_SIZE_BYTES_64	(1UL<<22)
+#define MPX_BT_ENTRY_BYTES_64	32
+#define MPX_BT_NR_ENTRIES_64	(MPX_BT_SIZE_BYTES_64/MPX_BT_ENTRY_BYTES_64)
 
-#define MPX_BD_SIZE_BYTES (1UL<<(MPX_BD_ENTRY_OFFSET+MPX_BD_ENTRY_SHIFT))
-#define MPX_BT_SIZE_BYTES (1UL<<(MPX_BT_ENTRY_OFFSET+MPX_BT_ENTRY_SHIFT))
+/*
+ * A 32-bit table is 16kB total in size, and an entry is
+ * 4 32-bit pointers in size.
+ */
+#define MPX_BT_SIZE_BYTES_32	(1UL<<14)
+#define MPX_BT_ENTRY_BYTES_32	16
+#define MPX_BT_NR_ENTRIES_32	(MPX_BT_SIZE_BYTES_32/MPX_BT_ENTRY_BYTES_32)
 
 #define MPX_BNDSTA_TAIL		2
 #define MPX_BNDCFG_TAIL		12
 #define MPX_BNDSTA_ADDR_MASK	(~((1UL<<MPX_BNDSTA_TAIL)-1))
-
 #define MPX_BNDCFG_ADDR_MASK	(~((1UL<<MPX_BNDCFG_TAIL)-1))
 #define MPX_BNDSTA_ERROR_CODE	0x3
 
-#define MPX_BD_ENTRY_MASK	((1<<MPX_BD_ENTRY_OFFSET)-1)
-#define MPX_BT_ENTRY_MASK	((1<<MPX_BT_ENTRY_OFFSET)-1)
-#define MPX_GET_BD_ENTRY_OFFSET(addr)	((((addr)>>(MPX_BT_ENTRY_OFFSET+ \
-		MPX_IGN_BITS)) & MPX_BD_ENTRY_MASK) << MPX_BD_ENTRY_SHIFT)
-#define MPX_GET_BT_ENTRY_OFFSET(addr)	((((addr)>>MPX_IGN_BITS) & \
-		MPX_BT_ENTRY_MASK) << MPX_BT_ENTRY_SHIFT)
-
 #ifdef CONFIG_X86_INTEL_MPX
 siginfo_t *mpx_generate_siginfo(struct pt_regs *regs);
 int mpx_handle_bd_fault(void);
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 294ea20..e323ef6 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -34,6 +34,22 @@ static int is_mpx_vma(struct vm_area_struct *vma)
 	return (vma->vm_ops == &mpx_vma_ops);
 }
 
+static inline unsigned long mpx_bd_size_bytes(struct mm_struct *mm)
+{
+	if (is_64bit_mm(mm))
+		return MPX_BD_SIZE_BYTES_64;
+	else
+		return MPX_BD_SIZE_BYTES_32;
+}
+
+static inline unsigned long mpx_bt_size_bytes(struct mm_struct *mm)
+{
+	if (is_64bit_mm(mm))
+		return MPX_BT_SIZE_BYTES_64;
+	else
+		return MPX_BT_SIZE_BYTES_32;
+}
+
 /*
  * This is really a simplified "vm_mmap". it only handles MPX
  * bounds tables (the bounds directory is user-allocated).
@@ -50,7 +66,7 @@ static unsigned long mpx_mmap(unsigned long len)
 	struct vm_area_struct *vma;
 
 	/* Only bounds table can be allocated here */
-	if (len != MPX_BT_SIZE_BYTES)
+	if (len != mpx_bt_size_bytes(mm))
 		return -EINVAL;
 
 	down_write(&mm->mmap_sem);
@@ -449,13 +465,12 @@ static int mpx_cmpxchg_bd_entry(struct mm_struct *mm,
 }
 
 /*
- * With 32-bit mode, MPX_BT_SIZE_BYTES is 4MB, and the size of each
- * bounds table is 16KB. With 64-bit mode, MPX_BT_SIZE_BYTES is 2GB,
+ * With 32-bit mode, a bounds directory is 4MB, and the size of each
+ * bounds table is 16KB. With 64-bit mode, a bounds directory is 2GB,
  * and the size of each bounds table is 4MB.
  */
-static int allocate_bt(long __user *bd_entry)
+static int allocate_bt(struct mm_struct *mm, long __user *bd_entry)
 {
-	struct mm_struct *mm = current->mm;
 	unsigned long expected_old_val = 0;
 	unsigned long actual_old_val = 0;
 	unsigned long bt_addr;
@@ -466,7 +481,7 @@ static int allocate_bt(long __user *bd_entry)
 	 * Carve the virtual space out of userspace for the new
 	 * bounds table:
 	 */
-	bt_addr = mpx_mmap(MPX_BT_SIZE_BYTES);
+	bt_addr = mpx_mmap(mpx_bt_size_bytes(mm));
 	if (IS_ERR((void *)bt_addr))
 		return PTR_ERR((void *)bt_addr);
 	/*
@@ -517,7 +532,7 @@ static int allocate_bt(long __user *bd_entry)
 	trace_mpx_new_bounds_table(bt_addr);
 	return 0;
 out_unmap:
-	vm_munmap(bt_addr, MPX_BT_SIZE_BYTES);
+	vm_munmap(bt_addr, mpx_bt_size_bytes(mm));
 	return ret;
 }
 
@@ -536,6 +551,7 @@ static int do_mpx_bt_fault(void)
 {
 	unsigned long bd_entry, bd_base;
 	const struct bndcsr *bndcsr;
+	struct mm_struct *mm = current->mm;
 
 	bndcsr = get_xsave_field_ptr(XSTATE_BNDCSR);
 	if (!bndcsr)
@@ -554,10 +570,10 @@ static int do_mpx_bt_fault(void)
 	 * the directory is.
 	 */
 	if ((bd_entry < bd_base) ||
-	    (bd_entry >= bd_base + MPX_BD_SIZE_BYTES))
+	    (bd_entry >= bd_base + mpx_bd_size_bytes(mm)))
 		return -EINVAL;
 
-	return allocate_bt((long __user *)bd_entry);
+	return allocate_bt(mm, (long __user *)bd_entry);
 }
 
 int mpx_handle_bd_fault(void)
@@ -789,7 +805,115 @@ static int unmap_single_bt(struct mm_struct *mm,
 	 * avoid recursion, do_munmap() will check whether it comes
 	 * from one bounds table through VM_MPX flag.
 	 */
-	return do_munmap(mm, bt_addr, MPX_BT_SIZE_BYTES);
+	return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
+}
+
+static inline int bt_entry_size_bytes(struct mm_struct *mm)
+{
+	if (is_64bit_mm(mm))
+		return MPX_BT_ENTRY_BYTES_64;
+	else
+		return MPX_BT_ENTRY_BYTES_32;
+}
+
+/*
+ * Take a virtual address and turns it in to the offset in bytes
+ * inside of the bounds table where the bounds table entry
+ * controlling 'addr' can be found.
+ */
+static unsigned long mpx_get_bt_entry_offset_bytes(struct mm_struct *mm,
+		unsigned long addr)
+{
+	unsigned long bt_table_nr_entries;
+	unsigned long offset = addr;
+
+	if (is_64bit_mm(mm)) {
+		/* Bottom 3 bits are ignored on 64-bit */
+		offset >>= 3;
+		bt_table_nr_entries = MPX_BT_NR_ENTRIES_64;
+	} else {
+		/* Bottom 2 bits are ignored on 32-bit */
+		offset >>= 2;
+		bt_table_nr_entries = MPX_BT_NR_ENTRIES_32;
+	}
+	/*
+	 * We know the size of the table in to which we are
+	 * indexing, and we have eliminated all the low bits
+	 * which are ignored for indexing.
+	 *
+	 * Mask out all the high bits which we do not need
+	 * to index in to the table.  Note that the tables
+	 * are always powers of two so this gives us a proper
+	 * mask.
+	 */
+	offset &= (bt_table_nr_entries-1);
+	/*
+	 * We now have an entry offset in terms of *entries* in
+	 * the table.  We need to scale it back up to bytes.
+	 */
+	offset *= bt_entry_size_bytes(mm);
+	return offset;
+}
+
+/*
+ * How much virtual address space does a single bounds
+ * directory entry cover?
+ *
+ * Note, we need a long long because 4GB doesn't fit in
+ * to a long on 32-bit.
+ */
+static inline unsigned long bd_entry_virt_space(struct mm_struct *mm)
+{
+	unsigned long long virt_space = (1ULL << boot_cpu_data.x86_virt_bits);
+	if (is_64bit_mm(mm))
+		return virt_space / MPX_BD_NR_ENTRIES_64;
+	else
+		return virt_space / MPX_BD_NR_ENTRIES_32;
+}
+
+/*
+ * Return an offset in terms of bytes in to the bounds
+ * directory where the bounds directory entry for a given
+ * virtual address resides.
+ *
+ * This has to be in bytes because the directory entries
+ * are different sizes on 64/32 bit.
+ */
+static unsigned long mpx_get_bd_entry_offset(struct mm_struct *mm,
+		unsigned long addr)
+{
+	/*
+	 * There are several ways to derive the bd offsets.  We
+	 * use the following approach here:
+	 * 1. We know the size of the virtual address space
+	 * 2. We know the number of entries in a bounds table
+	 * 3. We know that each entry covers a fixed amount of
+	 *    virtual address space.
+	 * So, we can just divide the virtual address by the
+	 * virtual space used by one entry to determine which
+	 * entry "controls" the given virtual address.
+	 */
+	if (is_64bit_mm(mm)) {
+		int bd_entry_size = 8; /* 64-bit pointer */
+		/*
+		 * Take the 64-bit addressing hole in to account.
+		 */
+		addr &= ((1UL << boot_cpu_data.x86_virt_bits) - 1);
+		return (addr / bd_entry_virt_space(mm)) * bd_entry_size;
+	} else {
+		int bd_entry_size = 4; /* 32-bit pointer */
+		/*
+		 * 32-bit has no hole so this case needs no mask
+		 */
+		return (addr / bd_entry_virt_space(mm)) * bd_entry_size;
+	}
+	/*
+	 * The two return calls above are exact copies.  If we
+	 * pull out a single copy and put it in here, gcc won't
+	 * realize that we're doing a power-of-2 divide and use
+	 * shifts.  It uses a real divide.  If we put them up
+	 * there, it manages to figure it out (gcc 4.8.3).
+	 */
 }
 
 /*
@@ -803,6 +927,7 @@ static int unmap_shared_bt(struct mm_struct *mm,
 		unsigned long end, bool prev_shared, bool next_shared)
 {
 	unsigned long bt_addr;
+	unsigned long start_off, end_off;
 	int ret;
 
 	ret = get_bt_addr(mm, bd_entry, &bt_addr);
@@ -814,17 +939,20 @@ static int unmap_shared_bt(struct mm_struct *mm,
 	if (ret)
 		return ret;
 
+	start_off = mpx_get_bt_entry_offset_bytes(mm, start);
+	end_off   = mpx_get_bt_entry_offset_bytes(mm, end);
+
 	if (prev_shared && next_shared)
 		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(start),
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(end));
+				bt_addr + start_off,
+				bt_addr + end_off);
 	else if (prev_shared)
 		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(start),
-				bt_addr+MPX_BT_SIZE_BYTES);
+				bt_addr + start_off,
+				bt_addr + mpx_bt_size_bytes(mm));
 	else if (next_shared)
 		ret = zap_bt_entries(mm, bt_addr, bt_addr,
-				bt_addr+MPX_GET_BT_ENTRY_OFFSET(end));
+				bt_addr + end_off);
 	else
 		ret = unmap_single_bt(mm, bd_entry, bt_addr);
 
@@ -845,8 +973,8 @@ static int unmap_edge_bts(struct mm_struct *mm,
 	struct vm_area_struct *prev, *next;
 	bool prev_shared = false, next_shared = false;
 
-	bde_start = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(start);
-	bde_end = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(end-1);
+	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
 
 	/*
 	 * Check whether bde_start and bde_end are shared with adjacent
@@ -858,10 +986,10 @@ static int unmap_edge_bts(struct mm_struct *mm,
 	 * in to 'next'.
 	 */
 	next = find_vma_prev(mm, start, &prev);
-	if (prev && (mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(prev->vm_end-1))
+	if (prev && (mm->bd_addr + mpx_get_bd_entry_offset(mm, prev->vm_end-1))
 			== bde_start)
 		prev_shared = true;
-	if (next && (mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(next->vm_start))
+	if (next && (mm->bd_addr + mpx_get_bd_entry_offset(mm, next->vm_start))
 			== bde_end)
 		next_shared = true;
 
@@ -927,8 +1055,8 @@ static int mpx_unmap_tables(struct mm_struct *mm,
 	 *   1. fully covered
 	 *   2. not at the edges of the mapping, even if full aligned
 	 */
-	bde_start = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(start);
-	bde_end = mm->bd_addr + MPX_GET_BD_ENTRY_OFFSET(end-1);
+	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
 	for (bd_entry = bde_start + 1; bd_entry < bde_end; bd_entry++) {
 		ret = get_bt_addr(mm, bd_entry, &bt_addr);
 		switch (ret) {

[PATCH 17/19] x86, mpx: rewrite unmap code

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The MPX code needs to clear out bounds tables for memory which
is no longer in use.  We do this when a userspace mapping is
torn down (unmapped).

There are two modes:
1. An entire bounds table becomes unused, and can be freed
   and its pointer removed from the bounds directory.  This
   happens either when a large mapping is torn down, or when
   a small mapping is torn down and it is the last mapping
   "covered" by a bounds table.
2. Only part of a bounds table becomes unused, in which case
   we free the backing memory as if MADV_DONTNEED was called.

The old code was a spaghetti mess of "edge" bounds tables
where the edges were handled specially, even if we were
unmapping an entire one.  Non-edge bounds tables are always
fully unmapped, but share a different code path from the edge
ones.  The old code had a bug where it was unmapping too much
memory.  I worked on fixing it for two days and gave up.

I didn't write the original code.  I didn't particularly like
it, but it worked, so I left it.  After my debug session, I
realized it was undebuggagle *and* buggy, so out it went.

I also wrote a new unmapping test program which uncovers bugs
pretty nicely.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/mm/mpx.c |  411 +++++++++++++++++++++-------------------------------
 1 file changed, 168 insertions(+), 243 deletions(-)

diff -puN arch/x86/mm/mpx.c~rewrite-unmap-code arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~rewrite-unmap-code	2015-06-01 10:24:09.726978941 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:09.729979076 -0700
@@ -704,110 +704,6 @@ static int get_bt_addr(struct mm_struct
 	return 0;
 }
 
-/*
- * Free the backing physical pages of bounds table 'bt_addr'.
- * Assume start...end is within that bounds table.
- */
-static int zap_bt_entries(struct mm_struct *mm,
-		unsigned long bt_addr,
-		unsigned long start, unsigned long end)
-{
-	struct vm_area_struct *vma;
-	unsigned long addr, len;
-
-	/*
-	 * Find the first overlapping vma. If vma->vm_start > start, there
-	 * will be a hole in the bounds table. This -EINVAL return will
-	 * cause a SIGSEGV.
-	 */
-	vma = find_vma(mm, start);
-	if (!vma || vma->vm_start > start)
-		return -EINVAL;
-
-	/*
-	 * A NUMA policy on a VM_MPX VMA could cause this bouds table to
-	 * be split. So we need to look across the entire 'start -> end'
-	 * range of this bounds table, find all of the VM_MPX VMAs, and
-	 * zap only those.
-	 */
-	addr = start;
-	while (vma && vma->vm_start < end) {
-		/*
-		 * We followed a bounds directory entry down
-		 * here.  If we find a non-MPX VMA, that's bad,
-		 * so stop immediately and return an error.  This
-		 * probably results in a SIGSEGV.
-		 */
-		if (!is_mpx_vma(vma))
-			return -EINVAL;
-
-		len = min(vma->vm_end, end) - addr;
-		zap_page_range(vma, addr, len, NULL);
-		trace_mpx_unmap_zap(addr, addr+len);
-
-		vma = vma->vm_next;
-		addr = vma->vm_start;
-	}
-
-	return 0;
-}
-
-static int unmap_single_bt(struct mm_struct *mm,
-		long __user *bd_entry, unsigned long bt_addr)
-{
-	unsigned long expected_old_val = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
-	unsigned long uninitialized_var(actual_old_val);
-	int ret;
-
-	while (1) {
-		int need_write = 1;
-		unsigned long cleared_bd_entry = 0;
-
-		pagefault_disable();
-		ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,
-				bd_entry, expected_old_val, cleared_bd_entry);
-		pagefault_enable();
-		if (!ret)
-			break;
-		if (ret == -EFAULT)
-			ret = mpx_resolve_fault(bd_entry, need_write);
-		/*
-		 * If we could not resolve the fault, consider it
-		 * userspace's fault and error out.
-		 */
-		if (ret)
-			return ret;
-	}
-	/*
-	 * The cmpxchg was performed, check the results.
-	 */
-	if (actual_old_val != expected_old_val) {
-		/*
-		 * Someone else raced with us to unmap the table.
-		 * There was no bounds table pointed to by the
-		 * directory, so declare success.  Somebody freed
-		 * it.
-		 */
-		if (!actual_old_val)
-			return 0;
-		/*
-		 * Something messed with the bounds directory
-		 * entry.  We hold mmap_sem for read or write
-		 * here, so it could not be a _new_ bounds table
-		 * that someone just allocated.  Something is
-		 * wrong, so pass up the error and SIGSEGV.
-		 */
-		return -EINVAL;
-	}
-
-	/*
-	 * Note, we are likely being called under do_munmap() already. To
-	 * avoid recursion, do_munmap() will check whether it comes
-	 * from one bounds table through VM_MPX flag.
-	 */
-	return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
-}
-
 static inline int bt_entry_size_bytes(struct mm_struct *mm)
 {
 	if (is_64bit_mm(mm))
@@ -872,13 +768,69 @@ static inline unsigned long bd_entry_vir
 }
 
 /*
- * Return an offset in terms of bytes in to the bounds
- * directory where the bounds directory entry for a given
- * virtual address resides.
- *
- * This has to be in bytes because the directory entries
- * are different sizes on 64/32 bit.
+ * Free the backing physical pages of bounds table 'bt_addr'.
+ * Assume start...end is within that bounds table.
  */
+static noinline int zap_bt_entries_mapping(struct mm_struct *mm,
+		unsigned long bt_addr,
+		unsigned long start_mapping, unsigned long end_mapping)
+{
+	struct vm_area_struct *vma;
+	unsigned long addr, len;
+	unsigned long start;
+	unsigned long end;
+
+	/*
+	 * if we 'end' on a boundary, the offset will be 0 which
+	 * is not what we want.  Back it up a byte to get the
+	 * last bt entry.  Then once we have the entry itself,
+	 * move 'end' back up by the table entry size.
+	 */
+	start = bt_addr + mpx_get_bt_entry_offset_bytes(mm, start_mapping);
+	end   = bt_addr + mpx_get_bt_entry_offset_bytes(mm, end_mapping - 1);
+	/*
+	 * Move end back up by one entry.  Among other things
+	 * this ensures that it remains page-aligned and does
+	 * not screw up zap_page_range()
+	 */
+	end += bt_entry_size_bytes(mm);
+
+	/*
+	 * Find the first overlapping vma. If vma->vm_start > start, there
+	 * will be a hole in the bounds table. This -EINVAL return will
+	 * cause a SIGSEGV.
+	 */
+	vma = find_vma(mm, start);
+	if (!vma || vma->vm_start > start)
+		return -EINVAL;
+
+	/*
+	 * A NUMA policy on a VM_MPX VMA could cause this bounds table to
+	 * be split. So we need to look across the entire 'start -> end'
+	 * range of this bounds table, find all of the VM_MPX VMAs, and
+	 * zap only those.
+	 */
+	addr = start;
+	while (vma && vma->vm_start < end) {
+		/*
+		 * We followed a bounds directory entry down
+		 * here.  If we find a non-MPX VMA, that's bad,
+		 * so stop immediately and return an error.  This
+		 * probably results in a SIGSEGV.
+		 */
+		if (!is_mpx_vma(vma))
+			return -EINVAL;
+
+		len = min(vma->vm_end, end) - addr;
+		zap_page_range(vma, addr, len, NULL);
+		trace_mpx_unmap_zap(addr, addr+len);
+
+		vma = vma->vm_next;
+		addr = vma->vm_start;
+	}
+	return 0;
+}
+
 static unsigned long mpx_get_bd_entry_offset(struct mm_struct *mm,
 		unsigned long addr)
 {
@@ -916,69 +868,80 @@ static unsigned long mpx_get_bd_entry_of
 	 */
 }
 
-/*
- * If the bounds table pointed by bounds directory 'bd_entry' is
- * not shared, unmap this whole bounds table. Otherwise, only free
- * those backing physical pages of bounds table entries covered
- * in this virtual address region start...end.
- */
-static int unmap_shared_bt(struct mm_struct *mm,
-		long __user *bd_entry, unsigned long start,
-		unsigned long end, bool prev_shared, bool next_shared)
+static int unmap_entire_bt(struct mm_struct *mm,
+		long __user *bd_entry, unsigned long bt_addr)
 {
-	unsigned long bt_addr;
-	unsigned long start_off, end_off;
+	unsigned long expected_old_val = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
+	unsigned long uninitialized_var(actual_old_val);
 	int ret;
 
-	ret = get_bt_addr(mm, bd_entry, &bt_addr);
+	while (1) {
+		int need_write = 1;
+		unsigned long cleared_bd_entry = 0;
+
+		pagefault_disable();
+		ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,
+				bd_entry, expected_old_val, cleared_bd_entry);
+		pagefault_enable();
+		if (!ret)
+			break;
+		if (ret == -EFAULT)
+			ret = mpx_resolve_fault(bd_entry, need_write);
+		/*
+		 * If we could not resolve the fault, consider it
+		 * userspace's fault and error out.
+		 */
+		if (ret)
+			return ret;
+	}
+	/*
+	 * The cmpxchg was performed, check the results.
+	 */
+	if (actual_old_val != expected_old_val) {
+		/*
+		 * Someone else raced with us to unmap the table.
+		 * That is OK, since we were both trying to do
+		 * the same thing.  Declare success.
+		 */
+		if (!actual_old_val)
+			return 0;
+		/*
+		 * Something messed with the bounds directory
+		 * entry.  We hold mmap_sem for read or write
+		 * here, so it could not be a _new_ bounds table
+		 * that someone just allocated.  Something is
+		 * wrong, so pass up the error and SIGSEGV.
+		 */
+		return -EINVAL;
+	}
 	/*
-	 * We could see an "error" ret for not-present bounds
-	 * tables (not really an error), or actual errors, but
-	 * stop unmapping either way.
+	 * Note, we are likely being called under do_munmap() already. To
+	 * avoid recursion, do_munmap() will check whether it comes
+	 * from one bounds table through VM_MPX flag.
 	 */
-	if (ret)
-		return ret;
-
-	start_off = mpx_get_bt_entry_offset_bytes(mm, start);
-	end_off   = mpx_get_bt_entry_offset_bytes(mm, end);
-
-	if (prev_shared && next_shared)
-		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr + start_off,
-				bt_addr + end_off);
-	else if (prev_shared)
-		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr + start_off,
-				bt_addr + mpx_bt_size_bytes(mm));
-	else if (next_shared)
-		ret = zap_bt_entries(mm, bt_addr, bt_addr,
-				bt_addr + end_off);
-	else
-		ret = unmap_single_bt(mm, bd_entry, bt_addr);
-
-	return ret;
+	return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
 }
 
-/*
- * A virtual address region being munmap()ed might share bounds table
- * with adjacent VMAs. We only need to free the backing physical
- * memory of these shared bounds tables entries covered in this virtual
- * address region.
- */
-static int unmap_edge_bts(struct mm_struct *mm,
-		unsigned long start, unsigned long end)
+static int try_unmap_single_bt(struct mm_struct *mm,
+	       unsigned long start, unsigned long end)
 {
+	struct vm_area_struct *next;
+	struct vm_area_struct *prev;
+	/*
+	 * "bta" == Bounds Table Area: the area controlled by the
+	 * bounds table that we are unmapping.
+	 */
+	unsigned long bta_start_vaddr = start & ~(bd_entry_virt_space(mm)-1);
+	unsigned long bta_end_vaddr = bta_start_vaddr + bd_entry_virt_space(mm);
+	unsigned long uninitialized_var(bt_addr);
+	void __user *bde_vaddr;
 	int ret;
-	long __user *bde_start, *bde_end;
-	struct vm_area_struct *prev, *next;
-	bool prev_shared = false, next_shared = false;
-
-	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
-	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
-
 	/*
-	 * Check whether bde_start and bde_end are shared with adjacent
-	 * VMAs.
+	 * We know 'start' and 'end' lie within an area controlled
+	 * by a single bounds table.  See if there are any other
+	 * VMAs controlled by that bounds table.  If there are not
+	 * then we can "expand" the are we are unmapping to possibly
+	 * cover the entire table.
 	 *
 	 * We already unliked the VMAs from the mm's rbtree so 'start'
 	 * is guaranteed to be in a hole. This gets us the first VMA
@@ -986,102 +949,64 @@ static int unmap_edge_bts(struct mm_stru
 	 * in to 'next'.
 	 */
 	next = find_vma_prev(mm, start, &prev);
-	if (prev && (mm->bd_addr + mpx_get_bd_entry_offset(mm, prev->vm_end-1))
-			== bde_start)
-		prev_shared = true;
-	if (next && (mm->bd_addr + mpx_get_bd_entry_offset(mm, next->vm_start))
-			== bde_end)
-		next_shared = true;
-
-	/*
-	 * This virtual address region being munmap()ed is only
-	 * covered by one bounds table.
-	 *
-	 * In this case, if this table is also shared with adjacent
-	 * VMAs, only part of the backing physical memory of the bounds
-	 * table need be freeed. Otherwise the whole bounds table need
-	 * be unmapped.
-	 */
-	if (bde_start == bde_end) {
-		return unmap_shared_bt(mm, bde_start, start, end,
-				prev_shared, next_shared);
+	if ((!prev || prev->vm_end <= bta_start_vaddr) &&
+	    (!next || next->vm_start >= bta_end_vaddr)) {
+		/*
+		 * No neighbor VMAs controlled by same bounds
+		 * table.  Try to unmap the whole thing
+		 */
+		start = bta_start_vaddr;
+		end = bta_end_vaddr;
 	}
 
+	bde_vaddr = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	ret = get_bt_addr(mm, bde_vaddr, &bt_addr);
 	/*
-	 * If more than one bounds tables are covered in this virtual
-	 * address region being munmap()ed, we need to separately check
-	 * whether bde_start and bde_end are shared with adjacent VMAs.
+	 * No bounds table there, so nothing to unmap.
 	 */
-	ret = unmap_shared_bt(mm, bde_start, start, end, prev_shared, false);
-	if (ret)
-		return ret;
-	ret = unmap_shared_bt(mm, bde_end, start, end, false, next_shared);
+	if (ret == -ENOENT) {
+		ret = 0;
+		return 0;
+	}
 	if (ret)
 		return ret;
-
-	return 0;
+	/*
+	 * We are unmapping an entire table.  Either because the
+	 * unmap that started this whole process was large enough
+	 * to cover an entire table, or that the unmap was small
+	 * but was the area covered by a bounds table.
+	 */
+	if ((start == bta_start_vaddr) &&
+	    (end == bta_end_vaddr))
+		return unmap_entire_bt(mm, bde_vaddr, bt_addr);
+	return zap_bt_entries_mapping(mm, bt_addr, start, end);
 }
 
 static int mpx_unmap_tables(struct mm_struct *mm,
 		unsigned long start, unsigned long end)
 {
-	int ret;
-	long __user *bd_entry, *bde_start, *bde_end;
-	unsigned long bt_addr;
-
+	unsigned long one_unmap_start;
 	trace_mpx_unmap_search(start, end);
-	/*
-	 * "Edge" bounds tables are those which are being used by the region
-	 * (start -> end), but that may be shared with adjacent areas.  If they
-	 * turn out to be completely unshared, they will be freed.  If they are
-	 * shared, we will free the backing store (like an MADV_DONTNEED) for
-	 * areas used by this region.
-	 */
-	ret = unmap_edge_bts(mm, start, end);
-	switch (ret) {
-		/* non-present tables are OK */
-		case 0:
-		case -ENOENT:
-			/* Success, or no tables to unmap */
-			break;
-		case -EINVAL:
-		case -EFAULT:
-		default:
-			return ret;
-	}
-
-	/*
-	 * Only unmap the bounds table that are
-	 *   1. fully covered
-	 *   2. not at the edges of the mapping, even if full aligned
-	 */
-	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
-	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
-	for (bd_entry = bde_start + 1; bd_entry < bde_end; bd_entry++) {
-		ret = get_bt_addr(mm, bd_entry, &bt_addr);
-		switch (ret) {
-			case 0:
-				break;
-			case -ENOENT:
-				/* No table here, try the next one */
-				continue;
-			case -EINVAL:
-			case -EFAULT:
-			default:
-				/*
-				 * Note: we are being strict here.
-				 * Any time we run in to an issue
-				 * unmapping tables, we stop and
-				 * SIGSEGV.
-				 */
-				return ret;
-		}
 
-		ret = unmap_single_bt(mm, bd_entry, bt_addr);
+	one_unmap_start = start;
+	while (one_unmap_start < end) {
+		int ret;
+		unsigned long next_unmap_start = ALIGN(one_unmap_start+1,
+						       bd_entry_virt_space(mm));
+		unsigned long one_unmap_end = end;
+		/*
+		 * if the end is beyond the current bounds table,
+		 * move it back so we only deal with a single one
+		 * at a time
+		 */
+		if (one_unmap_end > next_unmap_start)
+			one_unmap_end = next_unmap_start;
+		ret = try_unmap_single_bt(mm, one_unmap_start, one_unmap_end);
 		if (ret)
 			return ret;
-	}
 
+		one_unmap_start = next_unmap_start;
+	}
 	return 0;
 }
 
_

[tip:x86/fpu] x86/mpx: Rewrite the unmap code

[tip-bot for Dave Hansen]

Commit-ID:  3ceaccdf92073d193f0bfbe24280dd736e3fed86
Gitweb:     http://git.kernel.org/tip/3ceaccdf92073d193f0bfbe24280dd736e3fed86
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:06 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:34 +0200

x86/mpx: Rewrite the unmap code

The MPX code needs to clear out bounds tables for memory which
is no longer in use.  We do this when a userspace mapping is
torn down (unmapped).

There are two modes:

  1. An entire bounds table becomes unused, and can be freed
     and its pointer removed from the bounds directory.  This
     happens either when a large mapping is torn down, or when
     a small mapping is torn down and it is the last mapping
     "covered" by a bounds table.

  2. Only part of a bounds table becomes unused, in which case
     we free the backing memory as if MADV_DONTNEED was called.

The old code was a spaghetti mess of "edge" bounds tables
where the edges were handled specially, even if we were
unmapping an entire one.  Non-edge bounds tables are always
fully unmapped, but share a different code path from the edge
ones.  The old code had a bug where it was unmapping too much
memory.  I worked on fixing it for two days and gave up.

I didn't write the original code.  I didn't particularly like
it, but it worked, so I left it.  After my debug session, I
realized it was undebuggagle *and* buggy, so out it went.

I also wrote a new unmapping test program which uncovers bugs
pretty nicely.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183706.DCAEC67D@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/mpx.c | 411 ++++++++++++++++++++++--------------------------------
 1 file changed, 168 insertions(+), 243 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index e323ef6..18fcf73 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -704,110 +704,6 @@ static int get_bt_addr(struct mm_struct *mm,
 	return 0;
 }
 
-/*
- * Free the backing physical pages of bounds table 'bt_addr'.
- * Assume start...end is within that bounds table.
- */
-static int zap_bt_entries(struct mm_struct *mm,
-		unsigned long bt_addr,
-		unsigned long start, unsigned long end)
-{
-	struct vm_area_struct *vma;
-	unsigned long addr, len;
-
-	/*
-	 * Find the first overlapping vma. If vma->vm_start > start, there
-	 * will be a hole in the bounds table. This -EINVAL return will
-	 * cause a SIGSEGV.
-	 */
-	vma = find_vma(mm, start);
-	if (!vma || vma->vm_start > start)
-		return -EINVAL;
-
-	/*
-	 * A NUMA policy on a VM_MPX VMA could cause this bouds table to
-	 * be split. So we need to look across the entire 'start -> end'
-	 * range of this bounds table, find all of the VM_MPX VMAs, and
-	 * zap only those.
-	 */
-	addr = start;
-	while (vma && vma->vm_start < end) {
-		/*
-		 * We followed a bounds directory entry down
-		 * here.  If we find a non-MPX VMA, that's bad,
-		 * so stop immediately and return an error.  This
-		 * probably results in a SIGSEGV.
-		 */
-		if (!is_mpx_vma(vma))
-			return -EINVAL;
-
-		len = min(vma->vm_end, end) - addr;
-		zap_page_range(vma, addr, len, NULL);
-		trace_mpx_unmap_zap(addr, addr+len);
-
-		vma = vma->vm_next;
-		addr = vma->vm_start;
-	}
-
-	return 0;
-}
-
-static int unmap_single_bt(struct mm_struct *mm,
-		long __user *bd_entry, unsigned long bt_addr)
-{
-	unsigned long expected_old_val = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
-	unsigned long uninitialized_var(actual_old_val);
-	int ret;
-
-	while (1) {
-		int need_write = 1;
-		unsigned long cleared_bd_entry = 0;
-
-		pagefault_disable();
-		ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,
-				bd_entry, expected_old_val, cleared_bd_entry);
-		pagefault_enable();
-		if (!ret)
-			break;
-		if (ret == -EFAULT)
-			ret = mpx_resolve_fault(bd_entry, need_write);
-		/*
-		 * If we could not resolve the fault, consider it
-		 * userspace's fault and error out.
-		 */
-		if (ret)
-			return ret;
-	}
-	/*
-	 * The cmpxchg was performed, check the results.
-	 */
-	if (actual_old_val != expected_old_val) {
-		/*
-		 * Someone else raced with us to unmap the table.
-		 * There was no bounds table pointed to by the
-		 * directory, so declare success.  Somebody freed
-		 * it.
-		 */
-		if (!actual_old_val)
-			return 0;
-		/*
-		 * Something messed with the bounds directory
-		 * entry.  We hold mmap_sem for read or write
-		 * here, so it could not be a _new_ bounds table
-		 * that someone just allocated.  Something is
-		 * wrong, so pass up the error and SIGSEGV.
-		 */
-		return -EINVAL;
-	}
-
-	/*
-	 * Note, we are likely being called under do_munmap() already. To
-	 * avoid recursion, do_munmap() will check whether it comes
-	 * from one bounds table through VM_MPX flag.
-	 */
-	return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
-}
-
 static inline int bt_entry_size_bytes(struct mm_struct *mm)
 {
 	if (is_64bit_mm(mm))
@@ -872,13 +768,69 @@ static inline unsigned long bd_entry_virt_space(struct mm_struct *mm)
 }
 
 /*
- * Return an offset in terms of bytes in to the bounds
- * directory where the bounds directory entry for a given
- * virtual address resides.
- *
- * This has to be in bytes because the directory entries
- * are different sizes on 64/32 bit.
+ * Free the backing physical pages of bounds table 'bt_addr'.
+ * Assume start...end is within that bounds table.
  */
+static noinline int zap_bt_entries_mapping(struct mm_struct *mm,
+		unsigned long bt_addr,
+		unsigned long start_mapping, unsigned long end_mapping)
+{
+	struct vm_area_struct *vma;
+	unsigned long addr, len;
+	unsigned long start;
+	unsigned long end;
+
+	/*
+	 * if we 'end' on a boundary, the offset will be 0 which
+	 * is not what we want.  Back it up a byte to get the
+	 * last bt entry.  Then once we have the entry itself,
+	 * move 'end' back up by the table entry size.
+	 */
+	start = bt_addr + mpx_get_bt_entry_offset_bytes(mm, start_mapping);
+	end   = bt_addr + mpx_get_bt_entry_offset_bytes(mm, end_mapping - 1);
+	/*
+	 * Move end back up by one entry.  Among other things
+	 * this ensures that it remains page-aligned and does
+	 * not screw up zap_page_range()
+	 */
+	end += bt_entry_size_bytes(mm);
+
+	/*
+	 * Find the first overlapping vma. If vma->vm_start > start, there
+	 * will be a hole in the bounds table. This -EINVAL return will
+	 * cause a SIGSEGV.
+	 */
+	vma = find_vma(mm, start);
+	if (!vma || vma->vm_start > start)
+		return -EINVAL;
+
+	/*
+	 * A NUMA policy on a VM_MPX VMA could cause this bounds table to
+	 * be split. So we need to look across the entire 'start -> end'
+	 * range of this bounds table, find all of the VM_MPX VMAs, and
+	 * zap only those.
+	 */
+	addr = start;
+	while (vma && vma->vm_start < end) {
+		/*
+		 * We followed a bounds directory entry down
+		 * here.  If we find a non-MPX VMA, that's bad,
+		 * so stop immediately and return an error.  This
+		 * probably results in a SIGSEGV.
+		 */
+		if (!is_mpx_vma(vma))
+			return -EINVAL;
+
+		len = min(vma->vm_end, end) - addr;
+		zap_page_range(vma, addr, len, NULL);
+		trace_mpx_unmap_zap(addr, addr+len);
+
+		vma = vma->vm_next;
+		addr = vma->vm_start;
+	}
+	return 0;
+}
+
 static unsigned long mpx_get_bd_entry_offset(struct mm_struct *mm,
 		unsigned long addr)
 {
@@ -916,69 +868,80 @@ static unsigned long mpx_get_bd_entry_offset(struct mm_struct *mm,
 	 */
 }
 
-/*
- * If the bounds table pointed by bounds directory 'bd_entry' is
- * not shared, unmap this whole bounds table. Otherwise, only free
- * those backing physical pages of bounds table entries covered
- * in this virtual address region start...end.
- */
-static int unmap_shared_bt(struct mm_struct *mm,
-		long __user *bd_entry, unsigned long start,
-		unsigned long end, bool prev_shared, bool next_shared)
+static int unmap_entire_bt(struct mm_struct *mm,
+		long __user *bd_entry, unsigned long bt_addr)
 {
-	unsigned long bt_addr;
-	unsigned long start_off, end_off;
+	unsigned long expected_old_val = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
+	unsigned long uninitialized_var(actual_old_val);
 	int ret;
 
-	ret = get_bt_addr(mm, bd_entry, &bt_addr);
+	while (1) {
+		int need_write = 1;
+		unsigned long cleared_bd_entry = 0;
+
+		pagefault_disable();
+		ret = mpx_cmpxchg_bd_entry(mm, &actual_old_val,
+				bd_entry, expected_old_val, cleared_bd_entry);
+		pagefault_enable();
+		if (!ret)
+			break;
+		if (ret == -EFAULT)
+			ret = mpx_resolve_fault(bd_entry, need_write);
+		/*
+		 * If we could not resolve the fault, consider it
+		 * userspace's fault and error out.
+		 */
+		if (ret)
+			return ret;
+	}
 	/*
-	 * We could see an "error" ret for not-present bounds
-	 * tables (not really an error), or actual errors, but
-	 * stop unmapping either way.
+	 * The cmpxchg was performed, check the results.
 	 */
-	if (ret)
-		return ret;
-
-	start_off = mpx_get_bt_entry_offset_bytes(mm, start);
-	end_off   = mpx_get_bt_entry_offset_bytes(mm, end);
-
-	if (prev_shared && next_shared)
-		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr + start_off,
-				bt_addr + end_off);
-	else if (prev_shared)
-		ret = zap_bt_entries(mm, bt_addr,
-				bt_addr + start_off,
-				bt_addr + mpx_bt_size_bytes(mm));
-	else if (next_shared)
-		ret = zap_bt_entries(mm, bt_addr, bt_addr,
-				bt_addr + end_off);
-	else
-		ret = unmap_single_bt(mm, bd_entry, bt_addr);
-
-	return ret;
+	if (actual_old_val != expected_old_val) {
+		/*
+		 * Someone else raced with us to unmap the table.
+		 * That is OK, since we were both trying to do
+		 * the same thing.  Declare success.
+		 */
+		if (!actual_old_val)
+			return 0;
+		/*
+		 * Something messed with the bounds directory
+		 * entry.  We hold mmap_sem for read or write
+		 * here, so it could not be a _new_ bounds table
+		 * that someone just allocated.  Something is
+		 * wrong, so pass up the error and SIGSEGV.
+		 */
+		return -EINVAL;
+	}
+	/*
+	 * Note, we are likely being called under do_munmap() already. To
+	 * avoid recursion, do_munmap() will check whether it comes
+	 * from one bounds table through VM_MPX flag.
+	 */
+	return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
 }
 
-/*
- * A virtual address region being munmap()ed might share bounds table
- * with adjacent VMAs. We only need to free the backing physical
- * memory of these shared bounds tables entries covered in this virtual
- * address region.
- */
-static int unmap_edge_bts(struct mm_struct *mm,
-		unsigned long start, unsigned long end)
+static int try_unmap_single_bt(struct mm_struct *mm,
+	       unsigned long start, unsigned long end)
 {
+	struct vm_area_struct *next;
+	struct vm_area_struct *prev;
+	/*
+	 * "bta" == Bounds Table Area: the area controlled by the
+	 * bounds table that we are unmapping.
+	 */
+	unsigned long bta_start_vaddr = start & ~(bd_entry_virt_space(mm)-1);
+	unsigned long bta_end_vaddr = bta_start_vaddr + bd_entry_virt_space(mm);
+	unsigned long uninitialized_var(bt_addr);
+	void __user *bde_vaddr;
 	int ret;
-	long __user *bde_start, *bde_end;
-	struct vm_area_struct *prev, *next;
-	bool prev_shared = false, next_shared = false;
-
-	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
-	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
-
 	/*
-	 * Check whether bde_start and bde_end are shared with adjacent
-	 * VMAs.
+	 * We know 'start' and 'end' lie within an area controlled
+	 * by a single bounds table.  See if there are any other
+	 * VMAs controlled by that bounds table.  If there are not
+	 * then we can "expand" the are we are unmapping to possibly
+	 * cover the entire table.
 	 *
 	 * We already unliked the VMAs from the mm's rbtree so 'start'
 	 * is guaranteed to be in a hole. This gets us the first VMA
@@ -986,102 +949,64 @@ static int unmap_edge_bts(struct mm_struct *mm,
 	 * in to 'next'.
 	 */
 	next = find_vma_prev(mm, start, &prev);
-	if (prev && (mm->bd_addr + mpx_get_bd_entry_offset(mm, prev->vm_end-1))
-			== bde_start)
-		prev_shared = true;
-	if (next && (mm->bd_addr + mpx_get_bd_entry_offset(mm, next->vm_start))
-			== bde_end)
-		next_shared = true;
-
-	/*
-	 * This virtual address region being munmap()ed is only
-	 * covered by one bounds table.
-	 *
-	 * In this case, if this table is also shared with adjacent
-	 * VMAs, only part of the backing physical memory of the bounds
-	 * table need be freeed. Otherwise the whole bounds table need
-	 * be unmapped.
-	 */
-	if (bde_start == bde_end) {
-		return unmap_shared_bt(mm, bde_start, start, end,
-				prev_shared, next_shared);
+	if ((!prev || prev->vm_end <= bta_start_vaddr) &&
+	    (!next || next->vm_start >= bta_end_vaddr)) {
+		/*
+		 * No neighbor VMAs controlled by same bounds
+		 * table.  Try to unmap the whole thing
+		 */
+		start = bta_start_vaddr;
+		end = bta_end_vaddr;
 	}
 
+	bde_vaddr = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
+	ret = get_bt_addr(mm, bde_vaddr, &bt_addr);
 	/*
-	 * If more than one bounds tables are covered in this virtual
-	 * address region being munmap()ed, we need to separately check
-	 * whether bde_start and bde_end are shared with adjacent VMAs.
+	 * No bounds table there, so nothing to unmap.
 	 */
-	ret = unmap_shared_bt(mm, bde_start, start, end, prev_shared, false);
-	if (ret)
-		return ret;
-	ret = unmap_shared_bt(mm, bde_end, start, end, false, next_shared);
+	if (ret == -ENOENT) {
+		ret = 0;
+		return 0;
+	}
 	if (ret)
 		return ret;
-
-	return 0;
+	/*
+	 * We are unmapping an entire table.  Either because the
+	 * unmap that started this whole process was large enough
+	 * to cover an entire table, or that the unmap was small
+	 * but was the area covered by a bounds table.
+	 */
+	if ((start == bta_start_vaddr) &&
+	    (end == bta_end_vaddr))
+		return unmap_entire_bt(mm, bde_vaddr, bt_addr);
+	return zap_bt_entries_mapping(mm, bt_addr, start, end);
 }
 
 static int mpx_unmap_tables(struct mm_struct *mm,
 		unsigned long start, unsigned long end)
 {
-	int ret;
-	long __user *bd_entry, *bde_start, *bde_end;
-	unsigned long bt_addr;
-
+	unsigned long one_unmap_start;
 	trace_mpx_unmap_search(start, end);
-	/*
-	 * "Edge" bounds tables are those which are being used by the region
-	 * (start -> end), but that may be shared with adjacent areas.  If they
-	 * turn out to be completely unshared, they will be freed.  If they are
-	 * shared, we will free the backing store (like an MADV_DONTNEED) for
-	 * areas used by this region.
-	 */
-	ret = unmap_edge_bts(mm, start, end);
-	switch (ret) {
-		/* non-present tables are OK */
-		case 0:
-		case -ENOENT:
-			/* Success, or no tables to unmap */
-			break;
-		case -EINVAL:
-		case -EFAULT:
-		default:
-			return ret;
-	}
-
-	/*
-	 * Only unmap the bounds table that are
-	 *   1. fully covered
-	 *   2. not at the edges of the mapping, even if full aligned
-	 */
-	bde_start = mm->bd_addr + mpx_get_bd_entry_offset(mm, start);
-	bde_end   = mm->bd_addr + mpx_get_bd_entry_offset(mm, end-1);
-	for (bd_entry = bde_start + 1; bd_entry < bde_end; bd_entry++) {
-		ret = get_bt_addr(mm, bd_entry, &bt_addr);
-		switch (ret) {
-			case 0:
-				break;
-			case -ENOENT:
-				/* No table here, try the next one */
-				continue;
-			case -EINVAL:
-			case -EFAULT:
-			default:
-				/*
-				 * Note: we are being strict here.
-				 * Any time we run in to an issue
-				 * unmapping tables, we stop and
-				 * SIGSEGV.
-				 */
-				return ret;
-		}
 
-		ret = unmap_single_bt(mm, bd_entry, bt_addr);
+	one_unmap_start = start;
+	while (one_unmap_start < end) {
+		int ret;
+		unsigned long next_unmap_start = ALIGN(one_unmap_start+1,
+						       bd_entry_virt_space(mm));
+		unsigned long one_unmap_end = end;
+		/*
+		 * if the end is beyond the current bounds table,
+		 * move it back so we only deal with a single one
+		 * at a time
+		 */
+		if (one_unmap_end > next_unmap_start)
+			one_unmap_end = next_unmap_start;
+		ret = try_unmap_single_bt(mm, one_unmap_start, one_unmap_end);
 		if (ret)
 			return ret;
-	}
 
+		one_unmap_start = next_unmap_start;
+	}
 	return 0;
 }
 

[PATCH 19/19] x86, mpx: allow mixed binaries again

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

We explicitly disable allowing 32-bit binaries to enable
MPX on 64-bit kernels.  Re-allow that.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/mm/mpx.c |    6 ------
 1 file changed, 6 deletions(-)

diff -puN arch/x86/mm/mpx.c~x86-mpx-allow-mixed-binaries-again arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~x86-mpx-allow-mixed-binaries-again	2015-06-01 10:24:26.813749587 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:26.816749722 -0700
@@ -367,12 +367,6 @@ static __user void *mpx_get_bounds_dir(v
 		return MPX_INVALID_BOUNDS_DIR;
 
 	/*
-	 * 32-bit binaries on 64-bit kernels are currently
-	 * unsupported.
-	 */
-	if (IS_ENABLED(CONFIG_X86_64) && test_thread_flag(TIF_IA32))
-		return MPX_INVALID_BOUNDS_DIR;
-	/*
 	 * The bounds directory pointer is stored in a register
 	 * only accessible if we first do an xsave.
 	 */
_

[tip:x86/fpu] x86/mpx: Allow 32-bit binaries on 64-bit kernels again

[tip-bot for Dave Hansen]

Commit-ID:  97ac46a5087eaf87fd76ff7bb31ec9c896010442
Gitweb:     http://git.kernel.org/tip/97ac46a5087eaf87fd76ff7bb31ec9c896010442
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:06 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:34 +0200

x86/mpx: Allow 32-bit binaries on 64-bit kernels again

Now that the bugs in mixed mode MPX handling are fixed, re-allow
32-bit binaries on 64-bit kernels again.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183706.70277DAD@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/mpx.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 6233d51..7a657f5 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -367,12 +367,6 @@ static __user void *mpx_get_bounds_dir(void)
 		return MPX_INVALID_BOUNDS_DIR;
 
 	/*
-	 * 32-bit binaries on 64-bit kernels are currently
-	 * unsupported.
-	 */
-	if (IS_ENABLED(CONFIG_X86_64) && test_thread_flag(TIF_IA32))
-		return MPX_INVALID_BOUNDS_DIR;
-	/*
 	 * The bounds directory pointer is stored in a register
 	 * only accessible if we first do an xsave.
 	 */

[PATCH 18/19] x86, mpx: do not count MPX VMAs as neighbors when unmapping

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

The comment pretty much says it all.

I wrote a test program that does lots of random allocations
and forces bounds tables to be created.  It came up with a
layout like this:

  ....   | BOUNDS DIRECTORY ENTRY COVERS |  ....
         |    BOUNDS TABLE COVERS        |
|  BOUNDS TABLE |  REAL ALLOC | BOUNDS TABLE |

Unmapping "REAL ALLOC" should have been able to free the
bounds table "covering" the "REAL ALLOC" because it was the
last real user.  But, the neighboring VMA bounds tables were
found, considered as real neighbors, and we declined to free
the bounds table covering the area.

Doing this over and over left a small but significant number
of these orphans.  Handling them is fairly straighforward.
All we have to do is walk the VMAs and skip all of the MPX
ones when looking for neighbors.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---

 b/arch/x86/mm/mpx.c |   24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff -puN arch/x86/mm/mpx.c~mpx-dont-count-mpx-vmas-as-neighbors arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-dont-count-mpx-vmas-as-neighbors	2015-06-01 10:24:10.037992968 -0700
+++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:10.040993104 -0700
@@ -937,16 +937,30 @@ static int try_unmap_single_bt(struct mm
 	void __user *bde_vaddr;
 	int ret;
 	/*
+	 * We already unliked the VMAs from the mm's rbtree so 'start'
+	 * is guaranteed to be in a hole. This gets us the first VMA
+	 * before the hole in to 'prev' and the next VMA after the hole
+	 * in to 'next'.
+	 */
+	next = find_vma_prev(mm, start, &prev);
+	/*
+	 * Do not count other MPX bounds table VMAs as neighbors.
+	 * Although theoretically possible, we do not allow bounds
+	 * tables for bounds tables so our heads do not explode.
+	 * If we count them as neighbors here, we may end up with
+	 * lots of tables even though we have no actual table
+	 * entries in use.
+	 */
+	while (next && is_mpx_vma(next))
+		next = next->vm_next;
+	while (prev && is_mpx_vma(prev))
+		prev = prev->vm_prev;
+	/*
 	 * We know 'start' and 'end' lie within an area controlled
 	 * by a single bounds table.  See if there are any other
 	 * VMAs controlled by that bounds table.  If there are not
 	 * then we can "expand" the are we are unmapping to possibly
 	 * cover the entire table.
-	 *
-	 * We already unliked the VMAs from the mm's rbtree so 'start'
-	 * is guaranteed to be in a hole. This gets us the first VMA
-	 * before the hole in to 'prev' and the next VMA after the hole
-	 * in to 'next'.
 	 */
 	next = find_vma_prev(mm, start, &prev);
 	if ((!prev || prev->vm_end <= bta_start_vaddr) &&
_

Re: [PATCH 18/19] x86, mpx: do not count MPX VMAs as neighbors when unmapping

[Ingo Molnar]

* Dave Hansen <dave@sr71.net> wrote:

> diff -puN arch/x86/mm/mpx.c~mpx-dont-count-mpx-vmas-as-neighbors arch/x86/mm/mpx.c
> --- a/arch/x86/mm/mpx.c~mpx-dont-count-mpx-vmas-as-neighbors	2015-06-01 10:24:10.037992968 -0700
> +++ b/arch/x86/mm/mpx.c	2015-06-01 10:24:10.040993104 -0700
> @@ -937,16 +937,30 @@ static int try_unmap_single_bt(struct mm
>  	void __user *bde_vaddr;
>  	int ret;
>  	/*
> +	 * We already unliked the VMAs from the mm's rbtree so 'start'
> +	 * is guaranteed to be in a hole. This gets us the first VMA
> +	 * before the hole in to 'prev' and the next VMA after the hole
> +	 * in to 'next'.

Hey, I didn't know VMAs were on Facebook ;-)

I fixed it up to 'unlinked'.

Thanks,

	Ingo

[tip:x86/fpu] x86/mpx: Do not count MPX VMAs as neighbors when unmapping

[tip-bot for Dave Hansen]

Commit-ID:  bea03c50b871a2fa922f31ad7c9993bb4fc7b192
Gitweb:     http://git.kernel.org/tip/bea03c50b871a2fa922f31ad7c9993bb4fc7b192
Author:     Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Sun, 7 Jun 2015 11:37:06 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 9 Jun 2015 12:24:34 +0200

x86/mpx: Do not count MPX VMAs as neighbors when unmapping

The comment pretty much says it all.

I wrote a test program that does lots of random allocations
and forces bounds tables to be created.  It came up with a
layout like this:

  ....   | BOUNDS DIRECTORY ENTRY COVERS |  ....
         |    BOUNDS TABLE COVERS        |
|  BOUNDS TABLE |  REAL ALLOC | BOUNDS TABLE |

Unmapping "REAL ALLOC" should have been able to free the
bounds table "covering" the "REAL ALLOC" because it was the
last real user.  But, the neighboring VMA bounds tables were
found, considered as real neighbors, and we declined to free
the bounds table covering the area.

Doing this over and over left a small but significant number
of these orphans.  Handling them is fairly straighforward.
All we have to do is walk the VMAs and skip all of the MPX
ones when looking for neighbors.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150607183706.A6BD90BF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/mpx.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 18fcf73..6233d51 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -937,16 +937,30 @@ static int try_unmap_single_bt(struct mm_struct *mm,
 	void __user *bde_vaddr;
 	int ret;
 	/*
+	 * We already unlinked the VMAs from the mm's rbtree so 'start'
+	 * is guaranteed to be in a hole. This gets us the first VMA
+	 * before the hole in to 'prev' and the next VMA after the hole
+	 * in to 'next'.
+	 */
+	next = find_vma_prev(mm, start, &prev);
+	/*
+	 * Do not count other MPX bounds table VMAs as neighbors.
+	 * Although theoretically possible, we do not allow bounds
+	 * tables for bounds tables so our heads do not explode.
+	 * If we count them as neighbors here, we may end up with
+	 * lots of tables even though we have no actual table
+	 * entries in use.
+	 */
+	while (next && is_mpx_vma(next))
+		next = next->vm_next;
+	while (prev && is_mpx_vma(prev))
+		prev = prev->vm_prev;
+	/*
 	 * We know 'start' and 'end' lie within an area controlled
 	 * by a single bounds table.  See if there are any other
 	 * VMAs controlled by that bounds table.  If there are not
 	 * then we can "expand" the are we are unmapping to possibly
 	 * cover the entire table.
-	 *
-	 * We already unliked the VMAs from the mm's rbtree so 'start'
-	 * is guaranteed to be in a hole. This gets us the first VMA
-	 * before the hole in to 'prev' and the next VMA after the hole
-	 * in to 'next'.
 	 */
 	next = find_vma_prev(mm, start, &prev);
 	if ((!prev || prev->vm_end <= bta_start_vaddr) &&