[PATCH 09/17] x86: make is_64bit_mm() widely available

Dave Hansen
2015-03-26T18:33:39Z

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) beacuse
it makes it explicit where the context is coming from. It will also
make it easier if we ever need to access the MPX structures from
another process.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
---

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 2015-03-26 11:27:31.685419698 -0700
+++ b/arch/x86/include/asm/mmu_context.h 2015-03-26 11:27:31.690419923 -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 2015-03-26 11:27:31.687419788 -0700
+++ b/arch/x86/kernel/uprobes.c 2015-03-26 11:27:31.690419923 -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
*/
_