[patch 00/11] Text Edit Lock / text poke

[patch 00/11] Text Edit Lock / text poke

[Mathieu Desnoyers]

Hi Andrew,

This new version includes a rewrite of the i386 and x86_64 text edit lock using
text poke. I clear and set the WP cr0 bit instead of changing the page
attributes when patching RO code.

It applies to 2.6.23-rc2-mm2 in this order:

kprobes-use-mutex-for-insn-pages.patch
kprobes-dont-use-kprobes-mutex-in-arch-code.patch
kprobes-declare-kprobes-mutex-static.patch
text-edit-lock-architecture-independent-code.patch
text-edit-lock-alternative-i386-and-x86_64.patch
text-edit-lock-kprobes-architecture-independent.patch
text-edit-lock-kprobes-i386.patch
text-edit-lock-kprobes-x86_64.patch
text-edit-lock-i386-standardize-debug-rodata.patch
text-edit-lock-x86_64-standardize-debug-rodata.patch

Mathieu

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 01/11] Fall back on interrupt disable in cmpxchg8b on 80386 and 80486

[Mathieu Desnoyers]

[-- Attachment #1: i386-cmpxchg64-80386-80486-fallback.patch --]
[-- Type: text/plain, Size: 7517 bytes --]

Actually, on 386, cmpxchg and cmpxchg_local fall back on
cmpxchg_386_u8/16/32: it disables interruptions around non atomic
updates to mimic the cmpxchg behavior.

The comment:
/* Poor man's cmpxchg for 386. Unsuitable for SMP */

already present in cmpxchg_386_u32 tells much about how this cmpxchg
implementation should not be used in a SMP context. However, the cmpxchg_local
can perfectly use this fallback, since it only needs to be atomic wrt the local
cpu.

This patch adds a cmpxchg_486_u64 and uses it as a fallback for cmpxchg64
and cmpxchg64_local on 80386 and 80486.

Q:
but why is it called cmpxchg_486 when the other functions are called

A:
Because the standard cmpxchg is missing only on 386, but cmpxchg8b is
missing both on 386 and 486.

Citing Intel's Instruction set reference:

cmpxchg:
This instruction is not supported on Intel processors earlier than the
Intel486 processors.

cmpxchg8b:
This instruction encoding is not supported on Intel processors earlier
than the Pentium processors.

Q:
What's the reason to have cmpxchg64_local on 32 bit architectures?
Without that need all this would just be a few simple defines.

A:
cmpxchg64_local on 32 bits architectures takes unsigned long long
parameters, but cmpxchg_local only takes longs. Since we have cmpxchg8b
to execute a 8 byte cmpxchg atomically on pentium and +, it makes sense
to provide a flavor of cmpxchg and cmpxchg_local using this instruction.

Also, for 32 bits architectures lacking the 64 bits atomic cmpxchg, it
makes sense _not_ to define cmpxchg64 while cmpxchg could still be
available.

Moreover, the fallback for cmpxchg8b on i386 for 386 and 486 is a
different case than cmpxchg (which is only required for 386). Using
different code makes this easier.

However, cmpxchg64_local will be emulated by disabling interrupts on all
architectures where it is not supported atomically.

Therefore, we *could* turn cmpxchg64_local into a cmpxchg_local, but it
would make the 386/486 fallbacks ugly, make its design different from
cmpxchg/cmpxchg64 (which really depends on atomic operations and cannot
be emulated) and require the __cmpxchg_local to be expressed as a macro
rather than an inline function so the parameters would not be fixed to
unsigned long long in every case.

So I think cmpxchg64_local makes sense there, but I am open to
suggestions.


Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: clameter@sgi.com
CC: mingo@redhat.com
---
 arch/i386/kernel/cpu/intel.c |   17 +++++++
 include/asm-i386/cmpxchg.h   |  100 +++++++++++++++++++++++++++++--------------
 2 files changed, 85 insertions(+), 32 deletions(-)

Index: linux-2.6-lttng/arch/i386/kernel/cpu/intel.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/cpu/intel.c	2007-08-07 11:00:43.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/cpu/intel.c	2007-08-07 11:11:07.000000000 -0400
@@ -329,5 +329,22 @@ unsigned long cmpxchg_386_u32(volatile v
 EXPORT_SYMBOL(cmpxchg_386_u32);
 #endif
 
+#ifndef CONFIG_X86_CMPXCHG64
+unsigned long long cmpxchg_486_u64(volatile void *ptr, u64 old, u64 new)
+{
+	u64 prev;
+	unsigned long flags;
+
+	/* Poor man's cmpxchg8b for 386 and 486. Unsuitable for SMP */
+	local_irq_save(flags);
+	prev = *(u64 *)ptr;
+	if (prev == old)
+		*(u64 *)ptr = new;
+	local_irq_restore(flags);
+	return prev;
+}
+EXPORT_SYMBOL(cmpxchg_486_u64);
+#endif
+
 // arch_initcall(intel_cpu_init);
 
Index: linux-2.6-lttng/include/asm-i386/cmpxchg.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-i386/cmpxchg.h	2007-08-07 11:01:17.000000000 -0400
+++ linux-2.6-lttng/include/asm-i386/cmpxchg.h	2007-08-07 11:16:42.000000000 -0400
@@ -116,6 +116,15 @@ static inline unsigned long __xchg(unsig
 					(unsigned long)(n),sizeof(*(ptr))))
 #endif
 
+#ifdef CONFIG_X86_CMPXCHG64
+#define cmpxchg64(ptr,o,n)\
+	((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
+					(unsigned long long)(n)))
+#define cmpxchg64_local(ptr,o,n)\
+	((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\
+					(unsigned long long)(n)))
+#endif
+
 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 				      unsigned long new, int size)
 {
@@ -203,6 +212,34 @@ static inline unsigned long __cmpxchg_lo
 	return old;
 }
 
+static inline unsigned long long __cmpxchg64(volatile void *ptr,
+			unsigned long long old, unsigned long long new)
+{
+	unsigned long long prev;
+	__asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
+			     : "=A"(prev)
+			     : "b"((unsigned long)new),
+			       "c"((unsigned long)(new >> 32)),
+			       "m"(*__xg(ptr)),
+			       "0"(old)
+			     : "memory");
+	return prev;
+}
+
+static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
+			unsigned long long old, unsigned long long new)
+{
+	unsigned long long prev;
+	__asm__ __volatile__("cmpxchg8b %3"
+			     : "=A"(prev)
+			     : "b"((unsigned long)new),
+			       "c"((unsigned long)(new >> 32)),
+			       "m"(*__xg(ptr)),
+			       "0"(old)
+			     : "memory");
+	return prev;
+}
+
 #ifndef CONFIG_X86_CMPXCHG
 /*
  * Building a kernel capable running on 80386. It may be necessary to
@@ -252,38 +289,37 @@ static inline unsigned long cmpxchg_386(
 })
 #endif
 
-static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,
-				      unsigned long long new)
-{
-	unsigned long long prev;
-	__asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
-			     : "=A"(prev)
-			     : "b"((unsigned long)new),
-			       "c"((unsigned long)(new >> 32)),
-			       "m"(*__xg(ptr)),
-			       "0"(old)
-			     : "memory");
-	return prev;
-}
+#ifndef CONFIG_X86_CMPXCHG64
+/*
+ * Building a kernel capable running on 80386 and 80486. It may be necessary
+ * to simulate the cmpxchg8b on the 80386 and 80486 CPU.
+ */
+
+extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
+
+#define cmpxchg64(ptr,o,n)						\
+({									\
+	__typeof__(*(ptr)) __ret;					\
+	if (likely(boot_cpu_data.x86 > 4))				\
+		__ret = __cmpxchg64((ptr), (unsigned long long)(o),	\
+				(unsigned long long)(n));		\
+	else								\
+		__ret = cmpxchg_486_u64((ptr), (unsigned long long)(o),	\
+				(unsigned long long)(n));		\
+	__ret;								\
+})
+#define cmpxchg64_local(ptr,o,n)					\
+({									\
+	__typeof__(*(ptr)) __ret;					\
+	if (likely(boot_cpu_data.x86 > 4))				\
+		__ret = __cmpxchg64_local((ptr), (unsigned long long)(o), \
+				(unsigned long long)(n));		\
+	else								\
+		__ret = cmpxchg_486_u64((ptr), (unsigned long long)(o),	\
+				(unsigned long long)(n));		\
+	__ret;								\
+})
 
-static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
-			unsigned long long old, unsigned long long new)
-{
-	unsigned long long prev;
-	__asm__ __volatile__("cmpxchg8b %3"
-			     : "=A"(prev)
-			     : "b"((unsigned long)new),
-			       "c"((unsigned long)(new >> 32)),
-			       "m"(*__xg(ptr)),
-			       "0"(old)
-			     : "memory");
-	return prev;
-}
+#endif
 
-#define cmpxchg64(ptr,o,n)\
-	((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
-					(unsigned long long)(n)))
-#define cmpxchg64_local(ptr,o,n)\
-	((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\
-					(unsigned long long)(n)))
 #endif

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 02/11] Kprobes - use a mutex to protect the instruction pages list.

[Mathieu Desnoyers]

[-- Attachment #1: kprobes-use-mutex-for-insn-pages.patch --]
[-- Type: text/plain, Size: 3592 bytes --]

Protect the instruction pages list by a specific insn pages mutex, called in 
get_insn_slot() and free_insn_slot(). It makes sure that architectures that does
not need to call arch_remove_kprobe() does not take an unneeded kprobes mutex.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: hch@infradead.org
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 kernel/kprobes.c |   27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

Index: linux-2.6-lttng/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/kernel/kprobes.c	2007-07-14 15:47:19.000000000 -0400
+++ linux-2.6-lttng/kernel/kprobes.c	2007-07-14 15:48:51.000000000 -0400
@@ -101,6 +101,10 @@ enum kprobe_slot_state {
 	SLOT_USED = 2,
 };
 
+/*
+ * Protects the kprobe_insn_pages list. Can nest into kprobe_mutex.
+ */
+static DEFINE_MUTEX(kprobe_insn_mutex);
 static struct hlist_head kprobe_insn_pages;
 static int kprobe_garbage_slots;
 static int collect_garbage_slots(void);
@@ -137,7 +141,9 @@ kprobe_opcode_t __kprobes *get_insn_slot
 {
 	struct kprobe_insn_page *kip;
 	struct hlist_node *pos;
+	kprobe_opcode_t *ret;
 
+	mutex_lock(&kprobe_insn_mutex);
  retry:
 	hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
 		if (kip->nused < INSNS_PER_PAGE) {
@@ -146,7 +152,8 @@ kprobe_opcode_t __kprobes *get_insn_slot
 				if (kip->slot_used[i] == SLOT_CLEAN) {
 					kip->slot_used[i] = SLOT_USED;
 					kip->nused++;
-					return kip->insns + (i * MAX_INSN_SIZE);
+					ret = kip->insns + (i * MAX_INSN_SIZE);
+					goto end;
 				}
 			}
 			/* Surprise!  No unused slots.  Fix kip->nused. */
@@ -160,8 +167,10 @@ kprobe_opcode_t __kprobes *get_insn_slot
 	}
 	/* All out of space.  Need to allocate a new page. Use slot 0. */
 	kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
-	if (!kip)
-		return NULL;
+	if (!kip) {
+		ret = NULL;
+		goto end;
+	}
 
 	/*
 	 * Use module_alloc so this page is within +/- 2GB of where the
@@ -171,7 +180,8 @@ kprobe_opcode_t __kprobes *get_insn_slot
 	kip->insns = module_alloc(PAGE_SIZE);
 	if (!kip->insns) {
 		kfree(kip);
-		return NULL;
+		ret = NULL;
+		goto end;
 	}
 	INIT_HLIST_NODE(&kip->hlist);
 	hlist_add_head(&kip->hlist, &kprobe_insn_pages);
@@ -179,7 +189,10 @@ kprobe_opcode_t __kprobes *get_insn_slot
 	kip->slot_used[0] = SLOT_USED;
 	kip->nused = 1;
 	kip->ngarbage = 0;
-	return kip->insns;
+	ret = kip->insns;
+end:
+	mutex_unlock(&kprobe_insn_mutex);
+	return ret;
 }
 
 /* Return 1 if all garbages are collected, otherwise 0. */
@@ -213,7 +226,7 @@ static int __kprobes collect_garbage_slo
 	struct kprobe_insn_page *kip;
 	struct hlist_node *pos, *next;
 
-	/* Ensure no-one is preepmted on the garbages */
+	/* Ensure no-one is preempted on the garbages */
 	if (check_safety() != 0)
 		return -EAGAIN;
 
@@ -237,6 +250,7 @@ void __kprobes free_insn_slot(kprobe_opc
 	struct kprobe_insn_page *kip;
 	struct hlist_node *pos;
 
+	mutex_lock(&kprobe_insn_mutex);
 	hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
 		if (kip->insns <= slot &&
 		    slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
@@ -253,6 +267,7 @@ void __kprobes free_insn_slot(kprobe_opc
 
 	if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
 		collect_garbage_slots();
+	mutex_unlock(&kprobe_insn_mutex);
 }
 #endif
 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 03/11] Kprobes - do not use kprobes mutex in arch code

[Mathieu Desnoyers]

[-- Attachment #1: kprobes-dont-use-kprobes-mutex-in-arch-code.patch --]
[-- Type: text/plain, Size: 5101 bytes --]

Remove the kprobes mutex from kprobes.h, since it does not belong there. Also
remove all use of this mutex in the architecture specific code, replacing it by
a proper mutex lock/unlock in the architecture agnostic code.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 arch/i386/kernel/kprobes.c    |    2 --
 arch/ia64/kernel/kprobes.c    |    2 --
 arch/powerpc/kernel/kprobes.c |    2 --
 arch/s390/kernel/kprobes.c    |    2 --
 arch/x86_64/kernel/kprobes.c  |    2 --
 include/linux/kprobes.h       |    2 --
 kernel/kprobes.c              |    2 ++
 7 files changed, 2 insertions(+), 12 deletions(-)

Index: linux-2.6-lttng/include/linux/kprobes.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/kprobes.h	2007-08-07 15:28:05.000000000 -0400
+++ linux-2.6-lttng/include/linux/kprobes.h	2007-08-07 15:28:22.000000000 -0400
@@ -35,7 +35,6 @@
 #include <linux/percpu.h>
 #include <linux/spinlock.h>
 #include <linux/rcupdate.h>
-#include <linux/mutex.h>
 
 #ifdef CONFIG_KPROBES
 #include <asm/kprobes.h>
@@ -177,7 +176,6 @@ static inline void kretprobe_assert(stru
 }
 
 extern spinlock_t kretprobe_lock;
-extern struct mutex kprobe_mutex;
 extern int arch_prepare_kprobe(struct kprobe *p);
 extern void arch_arm_kprobe(struct kprobe *p);
 extern void arch_disarm_kprobe(struct kprobe *p);
Index: linux-2.6-lttng/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
@@ -180,9 +180,7 @@ void __kprobes arch_disarm_kprobe(struct
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-	mutex_lock(&kprobe_mutex);
 	free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
-	mutex_unlock(&kprobe_mutex);
 }
 
 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
Index: linux-2.6-lttng/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
+++ linux-2.6-lttng/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
@@ -656,7 +656,9 @@ valid_p:
 			list_del_rcu(&p->list);
 			kfree(old_p);
 		}
+		mutex_lock(&kprobe_mutex);
 		arch_remove_kprobe(p);
+		mutex_unlock(&kprobe_mutex);
 	} else {
 		mutex_lock(&kprobe_mutex);
 		if (p->break_handler)
Index: linux-2.6-lttng/arch/ia64/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/ia64/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
+++ linux-2.6-lttng/arch/ia64/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
@@ -565,9 +565,7 @@ void __kprobes arch_disarm_kprobe(struct
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-	mutex_lock(&kprobe_mutex);
 	free_insn_slot(p->ainsn.insn, 0);
-	mutex_unlock(&kprobe_mutex);
 }
 /*
  * We are resuming execution after a single step fault, so the pt_regs
Index: linux-2.6-lttng/arch/powerpc/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/powerpc/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
+++ linux-2.6-lttng/arch/powerpc/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
@@ -86,9 +86,7 @@ void __kprobes arch_disarm_kprobe(struct
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-	mutex_lock(&kprobe_mutex);
 	free_insn_slot(p->ainsn.insn, 0);
-	mutex_unlock(&kprobe_mutex);
 }
 
 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
Index: linux-2.6-lttng/arch/s390/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/s390/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
+++ linux-2.6-lttng/arch/s390/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
@@ -218,9 +218,7 @@ void __kprobes arch_disarm_kprobe(struct
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-	mutex_lock(&kprobe_mutex);
 	free_insn_slot(p->ainsn.insn, 0);
-	mutex_unlock(&kprobe_mutex);
 }
 
 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
Index: linux-2.6-lttng/arch/x86_64/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/x86_64/kernel/kprobes.c	2007-08-07 15:28:06.000000000 -0400
+++ linux-2.6-lttng/arch/x86_64/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
@@ -219,9 +219,7 @@ void __kprobes arch_disarm_kprobe(struct
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-	mutex_lock(&kprobe_mutex);
 	free_insn_slot(p->ainsn.insn, 0);
-	mutex_unlock(&kprobe_mutex);
 }
 
 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 04/11] Kprobes - declare kprobe_mutex static

[Mathieu Desnoyers]

[-- Attachment #1: kprobes-declare-kprobes-mutex-static.patch --]
[-- Type: text/plain, Size: 1194 bytes --]

Since it will not be used by other kernel objects, it makes sense to declare it
static.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: hch@infradead.org
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 kernel/kprobes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6-lttng/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/kernel/kprobes.c	2007-08-19 09:09:15.000000000 -0400
+++ linux-2.6-lttng/kernel/kprobes.c	2007-08-19 17:18:07.000000000 -0400
@@ -68,7 +68,7 @@ static struct hlist_head kretprobe_inst_
 /* NOTE: change this value only with kprobe_mutex held */
 static bool kprobe_enabled;
 
-DEFINE_MUTEX(kprobe_mutex);		/* Protects kprobe_table */
+static DEFINE_MUTEX(kprobe_mutex);	/* Protects kprobe_table */
 DEFINE_SPINLOCK(kretprobe_lock);	/* Protects kretprobe_inst_table */
 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 05/11] Text Edit Lock - Architecture Independent Code

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-architecture-independent-code.patch --]
[-- Type: text/plain, Size: 3160 bytes --]

This is an architecture independant synchronization around kernel text
modifications through use of a global mutex.

A mutex has been chosen so that kprobes, the main user of this, can sleep during
memory allocation between the memory read of the instructions it must replace
and the memory write of the breakpoint.

Other user of this interface: immediate values.

Paravirt and alternatives are always done when SMP is inactive, so there is no
need to use locks.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
---
 include/linux/memory.h |    7 +++++++
 mm/memory.c            |   34 ++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

Index: linux-2.6-lttng/include/linux/memory.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/memory.h	2007-08-09 14:52:47.000000000 -0400
+++ linux-2.6-lttng/include/linux/memory.h	2007-08-09 15:22:49.000000000 -0400
@@ -86,4 +86,11 @@ extern int remove_memory_block(unsigned 
 	register_memory_notifier(&fn##_mem_nb);			\
 }
 
+/*
+ * Take and release the kernel text modification lock, used for code patching.
+ * Users of this lock can sleep.
+ */
+extern void kernel_text_lock(void);
+extern void kernel_text_unlock(void);
+
 #endif /* _LINUX_MEMORY_H_ */
Index: linux-2.6-lttng/mm/memory.c
===================================================================
--- linux-2.6-lttng.orig/mm/memory.c	2007-08-09 15:21:10.000000000 -0400
+++ linux-2.6-lttng/mm/memory.c	2007-08-09 16:38:51.000000000 -0400
@@ -50,6 +50,8 @@
 #include <linux/delayacct.h>
 #include <linux/init.h>
 #include <linux/writeback.h>
+#include <linux/kprobes.h>
+#include <linux/mutex.h>
 
 #include <asm/pgalloc.h>
 #include <asm/uaccess.h>
@@ -84,6 +86,12 @@ EXPORT_SYMBOL(high_memory);
 
 int randomize_va_space __read_mostly = 1;
 
+/*
+ * mutex protecting text section modification (dynamic code patching).
+ * some users need to sleep (allocating memory...) while they hold this lock.
+ */
+static DEFINE_MUTEX(text_mutex);
+
 static int __init disable_randmaps(char *s)
 {
 	randomize_va_space = 0;
@@ -2758,3 +2766,29 @@ int access_process_vm(struct task_struct
 	return buf - old_buf;
 }
 EXPORT_SYMBOL_GPL(access_process_vm);
+
+/**
+ * kernel_text_lock     -   Take the kernel text modification lock
+ *
+ * Insures mutual write exclusion of kernel and modules text live text
+ * modification. Should be used for code patching.
+ * Users of this lock can sleep.
+ */
+void __kprobes kernel_text_lock(void)
+{
+	mutex_lock(&text_mutex);
+}
+EXPORT_SYMBOL_GPL(kernel_text_lock);
+
+/**
+ * kernel_text_unlock   -   Release the kernel text modification lock
+ *
+ * Insures mutual write exclusion of kernel and modules text live text
+ * modification. Should be used for code patching.
+ * Users of this lock can sleep.
+ */
+void __kprobes kernel_text_unlock(void)
+{
+	mutex_unlock(&text_mutex);
+}
+EXPORT_SYMBOL_GPL(kernel_text_unlock);

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 06/11] Text Edit Lock - Alternative code for i386 and x86_64

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-alternative-i386-and-x86_64.patch --]
[-- Type: text/plain, Size: 11153 bytes --]

Fix a memcpy that should be a text_poke (in apply_alternatives).

Use kernel_wp_save/kernel_wp_restore in text_poke to support DEBUG_RODATA
correctly and so the CPU HOTPLUG special case can be removed.

clflush all the cachelines touched by text_poke.

Add text_set(), which is basically a memset-like text_poke.

Add text_poke_early and text_set_early, for alternatives and paravirt boot-time
and module load time patching.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: pageexec@freemail.hu
---
 arch/i386/kernel/alternative.c   |  106 ++++++++++++++++++++++++++++++---------
 arch/i386/kernel/paravirt.c      |    6 +-
 include/asm-i386/alternative.h   |   40 ++++++++++++++
 include/asm-x86_64/alternative.h |   38 +++++++++++++
 4 files changed, 161 insertions(+), 29 deletions(-)

Index: linux-2.6-lttng/arch/i386/kernel/alternative.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/alternative.c	2007-08-19 21:58:29.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/alternative.c	2007-08-19 23:44:49.000000000 -0400
@@ -14,6 +14,66 @@
 #ifdef CONFIG_HOTPLUG_CPU
 static int smp_alt_once;
 
+/*
+ * Warning:
+ * When you use this code to patch more than one byte of an instruction
+ * you need to make sure that other CPUs cannot execute this code in parallel.
+ * Also no thread must be currently preempted in the middle of these
+ * instructions.  And on the local CPU you need to be protected again NMI or MCE
+ * handlers seeing an inconsistent instruction while you patch.
+ * Warning: read_cr0 is modified by paravirt, this is why we have _early
+ * versions. They are not in the __init section because they can be used at
+ * module load time.
+ */
+static inline void text_sync(void *addr, size_t len)
+{
+	void *faddr;
+
+	sync_core();
+	/* Not strictly needed, but can speed CPU recovery up. */
+	if (cpu_has_clflush)
+		for (faddr = addr; faddr < addr + len;
+				faddr += boot_cpu_data.x86_clflush_size)
+			asm("clflush (%0) " :: "r" (faddr) : "memory");
+}
+
+void * text_poke_early(void *addr, const void *opcode,
+					size_t len)
+{
+	memcpy(addr, opcode, len);
+	text_sync(addr, len);
+	return addr;
+}
+
+void * text_set_early(void *addr, int c, size_t len)
+{
+	memset(addr, c, len);
+	text_sync(addr, len);
+	return addr;
+}
+
+void * __kprobes text_poke(void *addr, const void *opcode, size_t len)
+{
+	unsigned long cr0;
+
+	kernel_wp_save(cr0);
+	memcpy(addr, opcode, len);
+	kernel_wp_restore(cr0);
+	text_sync(addr, len);
+	return addr;
+}
+
+void * __kprobes text_set(void *addr, int c, size_t len)
+{
+	unsigned long cr0;
+
+	kernel_wp_save(cr0);
+	memset(addr, c, len);
+	kernel_wp_restore(cr0);
+	text_sync(addr, len);
+	return addr;
+}
+
 static int __init bootonly(char *str)
 {
 	smp_alt_once = 1;
@@ -148,7 +208,7 @@ static unsigned char** find_nop_table(vo
 
 #endif /* CONFIG_X86_64 */
 
-static void nop_out(void *insns, unsigned int len)
+static void nop_out_early(void *insns, unsigned int len)
 {
 	unsigned char **noptable = find_nop_table();
 
@@ -156,12 +216,28 @@ static void nop_out(void *insns, unsigne
 		unsigned int noplen = len;
 		if (noplen > ASM_NOP_MAX)
 			noplen = ASM_NOP_MAX;
-		text_poke(insns, noptable[noplen], noplen);
+		text_poke_early(insns, noptable[noplen], noplen);
 		insns += noplen;
 		len -= noplen;
 	}
 }
 
+/*
+ * Only atomic nop outs should be allowed when not doing early patching.
+ * It means the size must be writable atomically and the address must be aligned
+ * in a way that permits an atomic write.
+ */
+static void nop_out(void *insns, unsigned int len)
+{
+	unsigned char **noptable = find_nop_table();
+
+	BUG_ON(len > sizeof(long));
+	BUG_ON((((long)insns + len - 1) | ~(sizeof(long) - 1))
+		- ((long)insns | ~(sizeof(long) - 1)));
+	text_poke(insns, noptable[len], len);
+}
+
+
 extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
 extern u8 *__smp_locks[], *__smp_locks_end[];
 
@@ -191,9 +267,9 @@ void apply_alternatives(struct alt_instr
 				__FUNCTION__, a->instr, instr);
 		}
 #endif
-		memcpy(instr, a->replacement, a->replacementlen);
+		text_poke_early(instr, a->replacement, a->replacementlen);
 		diff = a->instrlen - a->replacementlen;
-		nop_out(instr + a->replacementlen, diff);
+		nop_out_early(instr + a->replacementlen, diff);
 	}
 }
 
@@ -208,7 +284,7 @@ static void alternatives_smp_lock(u8 **s
 			continue;
 		if (*ptr > text_end)
 			continue;
-		text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock prefix */
+		text_set(*ptr, 0xf0, 1); /* add lock prefix */
 	};
 }
 
@@ -364,7 +440,7 @@ void apply_paravirt(struct paravirt_patc
 		BUG_ON(used > p->len);
 
 		/* Pad the rest with nops */
-		nop_out(p->instr + used, p->len - used);
+		nop_out_early(p->instr + used, p->len - used);
 	}
 }
 extern struct paravirt_patch_site __start_parainstructions[],
@@ -421,21 +497,3 @@ void __init alternative_instructions(voi
 	restart_mce();
 #endif
 }
-
-/*
- * Warning:
- * When you use this code to patch more than one byte of an instruction
- * you need to make sure that other CPUs cannot execute this code in parallel.
- * Also no thread must be currently preempted in the middle of these instructions.
- * And on the local CPU you need to be protected again NMI or MCE handlers
- * seeing an inconsistent instruction while you patch.
- */
-void __kprobes text_poke(void *addr, unsigned char *opcode, int len)
-{
-	memcpy(addr, opcode, len);
-	sync_core();
-	/* Not strictly needed, but can speed CPU recovery up. Ignore cross cacheline
-	   case. */
-	if (cpu_has_clflush)
-		asm("clflush (%0) " :: "r" (addr) : "memory");
-}
Index: linux-2.6-lttng/include/asm-i386/alternative.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-i386/alternative.h	2007-08-19 21:58:29.000000000 -0400
+++ linux-2.6-lttng/include/asm-i386/alternative.h	2007-08-19 22:15:02.000000000 -0400
@@ -4,6 +4,7 @@
 #include <asm/types.h>
 #include <linux/stddef.h>
 #include <linux/types.h>
+#include <asm/processor-flags.h>
 
 struct alt_instr {
 	u8 *instr; 		/* original instruction */
@@ -149,6 +150,43 @@ apply_paravirt(struct paravirt_patch_sit
 #define __parainstructions_end	NULL
 #endif
 
-extern void text_poke(void *addr, unsigned char *opcode, int len);
+/*
+ * Clear and restore the kernel write-protection flag on the local CPU.
+ * Allows the kernel to edit read-only pages.
+ * Side-effect: any interrupt handler running between save and restore will have
+ * the ability to write to read-only pages.
+ *
+ * Warning:
+ * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
+ * no thread can be preempted in the instructions being modified (no iret to an
+ * invalid instruction possible) or if the instructions are changed from a
+ * consistent state to another consistent state atomically.
+ * More care must be taken when modifying code in the SMP case because of
+ * Intel's errata.
+ * On the local CPU you need to be protected again NMI or MCE handlers seeing an
+ * inconsistent instruction while you patch.
+ */
+
+extern void *text_poke(void *addr, const void *opcode, size_t len);
+extern void *text_set(void *addr, int c, size_t len);
+extern void *text_poke_early(void *addr, const void *opcode, size_t len);
+extern void *text_set_early(void *addr, int c, size_t len);
+
+#define kernel_wp_save(cr0)					\
+	do {							\
+		typecheck(unsigned long, cr0);			\
+		preempt_disable();				\
+		cr0 = read_cr0();				\
+		if (cpu_data[smp_processor_id()].wp_works_ok)	\
+			write_cr0(cr0 & ~X86_CR0_WP);		\
+	} while (0)
+
+#define kernel_wp_restore(cr0)					\
+	do {							\
+		typecheck(unsigned long, cr0);			\
+		if (cpu_data[smp_processor_id()].wp_works_ok)	\
+			write_cr0(cr0);				\
+		preempt_enable();				\
+	} while (0)
 
 #endif /* _I386_ALTERNATIVE_H */
Index: linux-2.6-lttng/include/asm-x86_64/alternative.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-x86_64/alternative.h	2007-08-19 21:58:29.000000000 -0400
+++ linux-2.6-lttng/include/asm-x86_64/alternative.h	2007-08-19 22:15:02.000000000 -0400
@@ -5,6 +5,7 @@
 
 #include <linux/types.h>
 #include <linux/stddef.h>
+#include <asm/processor-flags.h>
 
 /*
  * Alternative inline assembly for SMP.
@@ -154,6 +155,41 @@ apply_paravirt(struct paravirt_patch *st
 #define __parainstructions_end NULL
 #endif
 
-extern void text_poke(void *addr, unsigned char *opcode, int len);
+/*
+ * Clear and restore the kernel write-protection flag on the local CPU.
+ * Allows the kernel to edit read-only pages.
+ * Side-effect: any interrupt handler running between save and restore will have
+ * the ability to write to read-only pages.
+ *
+ * Warning:
+ * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
+ * no thread can be preempted in the instructions being modified (no iret to an
+ * invalid instruction possible) or if the instructions are changed from a
+ * consistent state to another consistent state atomically.
+ * More care must be taken when modifying code in the SMP case because of
+ * Intel's errata.
+ * On the local CPU you need to be protected again NMI or MCE handlers seeing an
+ * inconsistent instruction while you patch.
+ */
+
+extern void *text_poke(void *addr, const void *opcode, size_t len);
+extern void *text_set(void *addr, int c, size_t len);
+extern void *text_poke_early(void *addr, const void *opcode, size_t len);
+extern void *text_set_early(void *addr, int c, size_t len);
+
+#define kernel_wp_save(cr0)					\
+	do {							\
+		typecheck(unsigned long, cr0);			\
+		preempt_disable();				\
+		cr0 = read_cr0();				\
+		write_cr0(cr0 & ~X86_CR0_WP);			\
+	} while (0)
+
+#define kernel_wp_restore(cr0)					\
+	do {							\
+		typecheck(unsigned long, cr0);			\
+		write_cr0(cr0);					\
+		preempt_enable();				\
+	} while (0)
 
 #endif /* _X86_64_ALTERNATIVE_H */
Index: linux-2.6-lttng/arch/i386/kernel/paravirt.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/paravirt.c	2007-08-19 21:58:29.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/paravirt.c	2007-08-19 22:15:02.000000000 -0400
@@ -145,7 +145,7 @@ unsigned paravirt_patch_call(void *targe
 	b.opcode = 0xe8; /* call */
 	b.delta = delta;
 	BUILD_BUG_ON(sizeof(b) != 5);
-	text_poke(call, (unsigned char *)&b, 5);
+	text_poke_early(call, (unsigned char *)&b, 5);
 
 	return 5;
 }
@@ -161,7 +161,7 @@ unsigned paravirt_patch_jmp(void *target
 
 	b.opcode = 0xe9;	/* jmp */
 	b.delta = delta;
-	text_poke(jmp, (unsigned char *)&b, 5);
+	text_poke_early(jmp, (unsigned char *)&b, 5);
 
 	return 5;
 }
@@ -198,7 +198,7 @@ unsigned paravirt_patch_insns(void *site
 	if (insn_len > len || start == NULL)
 		insn_len = len;
 	else
-		memcpy(site, start, insn_len);
+		text_poke_early(site, start, insn_len);
 
 	return insn_len;
 }

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 07/11] Text Edit Lock - kprobes architecture independent support

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-kprobes-architecture-independent.patch --]
[-- Type: text/plain, Size: 3099 bytes --]

Use the mutual exclusion provided by the text edit lock in the kprobes code. It
allows coherent manipulation of the kernel code by other subsystems.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 kernel/kprobes.c |   21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

Index: linux-2.6-lttng/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/kernel/kprobes.c	2007-08-09 15:22:49.000000000 -0400
+++ linux-2.6-lttng/kernel/kprobes.c	2007-08-09 15:25:00.000000000 -0400
@@ -43,6 +43,7 @@
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <linux/kdebug.h>
+#include <linux/memory.h>
 
 #include <asm-generic/sections.h>
 #include <asm/cacheflush.h>
@@ -568,9 +569,10 @@ static int __kprobes __register_kprobe(s
 		goto out;
 	}
 
+	kernel_text_lock();
 	ret = arch_prepare_kprobe(p);
 	if (ret)
-		goto out;
+		goto out_unlock_text;
 
 	INIT_HLIST_NODE(&p->hlist);
 	hlist_add_head_rcu(&p->hlist,
@@ -578,7 +580,8 @@ static int __kprobes __register_kprobe(s
 
 	if (kprobe_enabled)
 		arch_arm_kprobe(p);
-
+out_unlock_text:
+	kernel_text_unlock();
 out:
 	mutex_unlock(&kprobe_mutex);
 
@@ -621,8 +624,11 @@ valid_p:
 		 * enabled - otherwise, the breakpoint would already have
 		 * been removed. We save on flushing icache.
 		 */
-		if (kprobe_enabled)
+		if (kprobe_enabled) {
+			kernel_text_lock();
 			arch_disarm_kprobe(p);
+			kernel_text_unlock();
+		}
 		hlist_del_rcu(&old_p->hlist);
 		cleanup_p = 1;
 	} else {
@@ -644,9 +650,7 @@ valid_p:
 			list_del_rcu(&p->list);
 			kfree(old_p);
 		}
-		mutex_lock(&kprobe_mutex);
 		arch_remove_kprobe(p);
-		mutex_unlock(&kprobe_mutex);
 	} else {
 		mutex_lock(&kprobe_mutex);
 		if (p->break_handler)
@@ -716,8 +720,9 @@ static int __kprobes pre_handler_kretpro
 				 struct kretprobe_instance, uflist);
 		ri->rp = rp;
 		ri->task = current;
+		kernel_text_lock();
 		arch_prepare_kretprobe(ri, regs);
-
+		kernel_text_unlock();
 		/* XXX(hch): why is there no hlist_move_head? */
 		hlist_del(&ri->uflist);
 		hlist_add_head(&ri->uflist, &ri->rp->used_instances);
@@ -917,8 +922,10 @@ static void __kprobes enable_all_kprobes
 
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
+		kernel_text_lock();
 		hlist_for_each_entry_rcu(p, node, head, hlist)
 			arch_arm_kprobe(p);
+		kernel_text_unlock();
 	}
 
 	kprobe_enabled = true;
@@ -946,10 +953,12 @@ static void __kprobes disable_all_kprobe
 	printk(KERN_INFO "Kprobes globally disabled\n");
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
+		kernel_text_lock();
 		hlist_for_each_entry_rcu(p, node, head, hlist) {
 			if (!arch_trampoline_kprobe(p))
 				arch_disarm_kprobe(p);
 		}
+		kernel_text_unlock();
 	}
 
 	mutex_unlock(&kprobe_mutex);

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 08/11] Text Edit Lock - kprobes i386

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-kprobes-i386.patch --]
[-- Type: text/plain, Size: 1233 bytes --]

Make kprobes use text_set instead of text_poke.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 arch/i386/kernel/kprobes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6-lttng/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/kprobes.c	2007-08-19 18:37:43.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/kprobes.c	2007-08-19 18:38:17.000000000 -0400
@@ -170,12 +170,12 @@ int __kprobes arch_prepare_kprobe(struct
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+	text_set(p->addr, BREAKPOINT_INSTRUCTION, 1);
 }
 
 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, &p->opcode, 1);
+	text_set(p->addr, p->opcode, 1);
 }
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 09/11] Text Edit Lock - kprobes x86_64

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-kprobes-x86_64.patch --]
[-- Type: text/plain, Size: 1241 bytes --]

Make kprobes use text_set instead of text_poke.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 arch/x86_64/kernel/kprobes.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6-lttng/arch/x86_64/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/x86_64/kernel/kprobes.c	2007-08-19 21:56:42.000000000 -0400
+++ linux-2.6-lttng/arch/x86_64/kernel/kprobes.c	2007-08-19 22:27:54.000000000 -0400
@@ -209,12 +209,12 @@ static void __kprobes arch_copy_kprobe(s
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+	text_set(p->addr, BREAKPOINT_INSTRUCTION, 1);
 }
 
 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, &p->opcode, 1);
+	text_set(p->addr, p->opcode, 1);
 }
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 10/11] Text Edit Lock - i386 standardize debug rodata

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-i386-standardize-debug-rodata.patch --]
[-- Type: text/plain, Size: 1722 bytes --]

Standardize DEBUG_RODATA, removing special cases for hotplug and kprobes.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: pageexec@freemail.hu
---
 arch/i386/mm/init.c |   17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

Index: linux-2.6-lttng/arch/i386/mm/init.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/mm/init.c	2007-08-19 22:28:00.000000000 -0400
+++ linux-2.6-lttng/arch/i386/mm/init.c	2007-08-19 22:34:39.000000000 -0400
@@ -794,23 +794,15 @@ static int noinline do_test_wp_bit(void)
 }
 
 #ifdef CONFIG_DEBUG_RODATA
-
 void mark_rodata_ro(void)
 {
 	unsigned long start = PFN_ALIGN(_text);
 	unsigned long size = PFN_ALIGN(_etext) - start;
 
-#ifndef CONFIG_KPROBES
-#ifdef CONFIG_HOTPLUG_CPU
-	/* It must still be possible to apply SMP alternatives. */
-	if (num_possible_cpus() <= 1)
-#endif
-	{
-		change_page_attr(virt_to_page(start),
-		                 size >> PAGE_SHIFT, PAGE_KERNEL_RX);
-		printk("Write protecting the kernel text: %luk\n", size >> 10);
-	}
-#endif
+	change_page_attr(virt_to_page(start),
+	                 size >> PAGE_SHIFT, PAGE_KERNEL_RX);
+	printk("Write protecting the kernel text: %luk\n", size >> 10);
+
 	start += size;
 	size = (unsigned long)__end_rodata - start;
 	change_page_attr(virt_to_page(start),
@@ -826,6 +818,7 @@ void mark_rodata_ro(void)
 	 */
 	global_flush_tlb();
 }
+
 #endif
 
 void free_init_pages(char *what, unsigned long begin, unsigned long end)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 11/11] Text Edit Lock - x86_64 standardize debug rodata

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-x86_64-standardize-debug-rodata.patch --]
[-- Type: text/plain, Size: 1807 bytes --]

Standardize DEBUG_RODATA, removing special cases for hotplug and kprobes.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: pageexec@freemail.hu
---
 arch/x86_64/mm/init.c           |   23 +++++------------------
 include/asm-x86_64/cacheflush.h |   22 ++++++++++++++++++++++
 2 files changed, 27 insertions(+), 18 deletions(-)

Index: linux-2.6-lttng/arch/x86_64/mm/init.c
===================================================================
--- linux-2.6-lttng.orig/arch/x86_64/mm/init.c	2007-08-18 10:02:58.000000000 -0400
+++ linux-2.6-lttng/arch/x86_64/mm/init.c	2007-08-18 10:04:14.000000000 -0400
@@ -598,25 +598,11 @@ void free_initmem(void)
 
 void mark_rodata_ro(void)
 {
-	unsigned long start = (unsigned long)_stext, end;
+	unsigned long start = PFN_ALIGN(_stext);
+	unsigned long end = PFN_ALIGN(__end_rodata);
 
-#ifdef CONFIG_HOTPLUG_CPU
-	/* It must still be possible to apply SMP alternatives. */
-	if (num_possible_cpus() > 1)
-		start = (unsigned long)_etext;
-#endif
-
-#ifdef CONFIG_KPROBES
-	start = (unsigned long)__start_rodata;
-#endif
-	
-	end = (unsigned long)__end_rodata;
-	start = (start + PAGE_SIZE - 1) & PAGE_MASK;
-	end &= PAGE_MASK;
-	if (end <= start)
-		return;
-
-	change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, PAGE_KERNEL_RO);
+	change_page_attr_addr(start, (end - start) >> PAGE_SHIFT,
+				PAGE_KERNEL_RO);
 
 	printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
 	       (end - start) >> 10);
@@ -629,6 +615,7 @@ void mark_rodata_ro(void)
 	 */
 	global_flush_tlb();
 }
+
 #endif
 
 #ifdef CONFIG_BLK_DEV_INITRD

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [patch 01/11] Fall back on interrupt disable in cmpxchg8b on 80386 and 80486

[Mathieu Desnoyers]

Clearly this signle patch is a duplicate from the previous patchset,
please do not apply.

* Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) wrote:
> Actually, on 386, cmpxchg and cmpxchg_local fall back on
> cmpxchg_386_u8/16/32: it disables interruptions around non atomic
> updates to mimic the cmpxchg behavior.
> 
> The comment:
> /* Poor man's cmpxchg for 386. Unsuitable for SMP */
> 
> already present in cmpxchg_386_u32 tells much about how this cmpxchg
> implementation should not be used in a SMP context. However, the cmpxchg_local
> can perfectly use this fallback, since it only needs to be atomic wrt the local
> cpu.
> 
> This patch adds a cmpxchg_486_u64 and uses it as a fallback for cmpxchg64
> and cmpxchg64_local on 80386 and 80486.
> 
> Q:
> but why is it called cmpxchg_486 when the other functions are called
> 
> A:
> Because the standard cmpxchg is missing only on 386, but cmpxchg8b is
> missing both on 386 and 486.
> 
> Citing Intel's Instruction set reference:
> 
> cmpxchg:
> This instruction is not supported on Intel processors earlier than the
> Intel486 processors.
> 
> cmpxchg8b:
> This instruction encoding is not supported on Intel processors earlier
> than the Pentium processors.
> 
> Q:
> What's the reason to have cmpxchg64_local on 32 bit architectures?
> Without that need all this would just be a few simple defines.
> 
> A:
> cmpxchg64_local on 32 bits architectures takes unsigned long long
> parameters, but cmpxchg_local only takes longs. Since we have cmpxchg8b
> to execute a 8 byte cmpxchg atomically on pentium and +, it makes sense
> to provide a flavor of cmpxchg and cmpxchg_local using this instruction.
> 
> Also, for 32 bits architectures lacking the 64 bits atomic cmpxchg, it
> makes sense _not_ to define cmpxchg64 while cmpxchg could still be
> available.
> 
> Moreover, the fallback for cmpxchg8b on i386 for 386 and 486 is a
> different case than cmpxchg (which is only required for 386). Using
> different code makes this easier.
> 
> However, cmpxchg64_local will be emulated by disabling interrupts on all
> architectures where it is not supported atomically.
> 
> Therefore, we *could* turn cmpxchg64_local into a cmpxchg_local, but it
> would make the 386/486 fallbacks ugly, make its design different from
> cmpxchg/cmpxchg64 (which really depends on atomic operations and cannot
> be emulated) and require the __cmpxchg_local to be expressed as a macro
> rather than an inline function so the parameters would not be fixed to
> unsigned long long in every case.
> 
> So I think cmpxchg64_local makes sense there, but I am open to
> suggestions.
> 
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> CC: clameter@sgi.com
> CC: mingo@redhat.com
> ---
>  arch/i386/kernel/cpu/intel.c |   17 +++++++
>  include/asm-i386/cmpxchg.h   |  100 +++++++++++++++++++++++++++++--------------
>  2 files changed, 85 insertions(+), 32 deletions(-)
> 
> Index: linux-2.6-lttng/arch/i386/kernel/cpu/intel.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/i386/kernel/cpu/intel.c	2007-08-07 11:00:43.000000000 -0400
> +++ linux-2.6-lttng/arch/i386/kernel/cpu/intel.c	2007-08-07 11:11:07.000000000 -0400
> @@ -329,5 +329,22 @@ unsigned long cmpxchg_386_u32(volatile v
>  EXPORT_SYMBOL(cmpxchg_386_u32);
>  #endif
>  
> +#ifndef CONFIG_X86_CMPXCHG64
> +unsigned long long cmpxchg_486_u64(volatile void *ptr, u64 old, u64 new)
> +{
> +	u64 prev;
> +	unsigned long flags;
> +
> +	/* Poor man's cmpxchg8b for 386 and 486. Unsuitable for SMP */
> +	local_irq_save(flags);
> +	prev = *(u64 *)ptr;
> +	if (prev == old)
> +		*(u64 *)ptr = new;
> +	local_irq_restore(flags);
> +	return prev;
> +}
> +EXPORT_SYMBOL(cmpxchg_486_u64);
> +#endif
> +
>  // arch_initcall(intel_cpu_init);
>  
> Index: linux-2.6-lttng/include/asm-i386/cmpxchg.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/asm-i386/cmpxchg.h	2007-08-07 11:01:17.000000000 -0400
> +++ linux-2.6-lttng/include/asm-i386/cmpxchg.h	2007-08-07 11:16:42.000000000 -0400
> @@ -116,6 +116,15 @@ static inline unsigned long __xchg(unsig
>  					(unsigned long)(n),sizeof(*(ptr))))
>  #endif
>  
> +#ifdef CONFIG_X86_CMPXCHG64
> +#define cmpxchg64(ptr,o,n)\
> +	((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
> +					(unsigned long long)(n)))
> +#define cmpxchg64_local(ptr,o,n)\
> +	((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\
> +					(unsigned long long)(n)))
> +#endif
> +
>  static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
>  				      unsigned long new, int size)
>  {
> @@ -203,6 +212,34 @@ static inline unsigned long __cmpxchg_lo
>  	return old;
>  }
>  
> +static inline unsigned long long __cmpxchg64(volatile void *ptr,
> +			unsigned long long old, unsigned long long new)
> +{
> +	unsigned long long prev;
> +	__asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
> +			     : "=A"(prev)
> +			     : "b"((unsigned long)new),
> +			       "c"((unsigned long)(new >> 32)),
> +			       "m"(*__xg(ptr)),
> +			       "0"(old)
> +			     : "memory");
> +	return prev;
> +}
> +
> +static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
> +			unsigned long long old, unsigned long long new)
> +{
> +	unsigned long long prev;
> +	__asm__ __volatile__("cmpxchg8b %3"
> +			     : "=A"(prev)
> +			     : "b"((unsigned long)new),
> +			       "c"((unsigned long)(new >> 32)),
> +			       "m"(*__xg(ptr)),
> +			       "0"(old)
> +			     : "memory");
> +	return prev;
> +}
> +
>  #ifndef CONFIG_X86_CMPXCHG
>  /*
>   * Building a kernel capable running on 80386. It may be necessary to
> @@ -252,38 +289,37 @@ static inline unsigned long cmpxchg_386(
>  })
>  #endif
>  
> -static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,
> -				      unsigned long long new)
> -{
> -	unsigned long long prev;
> -	__asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
> -			     : "=A"(prev)
> -			     : "b"((unsigned long)new),
> -			       "c"((unsigned long)(new >> 32)),
> -			       "m"(*__xg(ptr)),
> -			       "0"(old)
> -			     : "memory");
> -	return prev;
> -}
> +#ifndef CONFIG_X86_CMPXCHG64
> +/*
> + * Building a kernel capable running on 80386 and 80486. It may be necessary
> + * to simulate the cmpxchg8b on the 80386 and 80486 CPU.
> + */
> +
> +extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
> +
> +#define cmpxchg64(ptr,o,n)						\
> +({									\
> +	__typeof__(*(ptr)) __ret;					\
> +	if (likely(boot_cpu_data.x86 > 4))				\
> +		__ret = __cmpxchg64((ptr), (unsigned long long)(o),	\
> +				(unsigned long long)(n));		\
> +	else								\
> +		__ret = cmpxchg_486_u64((ptr), (unsigned long long)(o),	\
> +				(unsigned long long)(n));		\
> +	__ret;								\
> +})
> +#define cmpxchg64_local(ptr,o,n)					\
> +({									\
> +	__typeof__(*(ptr)) __ret;					\
> +	if (likely(boot_cpu_data.x86 > 4))				\
> +		__ret = __cmpxchg64_local((ptr), (unsigned long long)(o), \
> +				(unsigned long long)(n));		\
> +	else								\
> +		__ret = cmpxchg_486_u64((ptr), (unsigned long long)(o),	\
> +				(unsigned long long)(n));		\
> +	__ret;								\
> +})
>  
> -static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
> -			unsigned long long old, unsigned long long new)
> -{
> -	unsigned long long prev;
> -	__asm__ __volatile__("cmpxchg8b %3"
> -			     : "=A"(prev)
> -			     : "b"((unsigned long)new),
> -			       "c"((unsigned long)(new >> 32)),
> -			       "m"(*__xg(ptr)),
> -			       "0"(old)
> -			     : "memory");
> -	return prev;
> -}
> +#endif
>  
> -#define cmpxchg64(ptr,o,n)\
> -	((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
> -					(unsigned long long)(n)))
> -#define cmpxchg64_local(ptr,o,n)\
> -	((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\
> -					(unsigned long long)(n)))
>  #endif
> 
> -- 
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [patch 02/11] Kprobes - use a mutex to protect the instruction pages list.

[Ananth N Mavinakayanahalli]

On Mon, Aug 20, 2007 at 04:19:04PM -0400, Mathieu Desnoyers wrote:
> Protect the instruction pages list by a specific insn pages mutex, called in 
> get_insn_slot() and free_insn_slot(). It makes sure that architectures that does
> not need to call arch_remove_kprobe() does not take an unneeded kprobes mutex.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

Thanks Mathieu.

> CC: hch@infradead.org
> CC: prasanna@in.ibm.com
> CC: ananth@in.ibm.com
> CC: anil.s.keshavamurthy@intel.com
> CC: davem@davemloft.net
> ---
>  kernel/kprobes.c |   27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
> 
> Index: linux-2.6-lttng/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/kprobes.c	2007-07-14 15:47:19.000000000 -0400
> +++ linux-2.6-lttng/kernel/kprobes.c	2007-07-14 15:48:51.000000000 -0400
> @@ -101,6 +101,10 @@ enum kprobe_slot_state {
>  	SLOT_USED = 2,
>  };
> 
> +/*
> + * Protects the kprobe_insn_pages list. Can nest into kprobe_mutex.
> + */
> +static DEFINE_MUTEX(kprobe_insn_mutex);
>  static struct hlist_head kprobe_insn_pages;
>  static int kprobe_garbage_slots;
>  static int collect_garbage_slots(void);
> @@ -137,7 +141,9 @@ kprobe_opcode_t __kprobes *get_insn_slot
>  {
>  	struct kprobe_insn_page *kip;
>  	struct hlist_node *pos;
> +	kprobe_opcode_t *ret;
> 
> +	mutex_lock(&kprobe_insn_mutex);
>   retry:
>  	hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
>  		if (kip->nused < INSNS_PER_PAGE) {
> @@ -146,7 +152,8 @@ kprobe_opcode_t __kprobes *get_insn_slot
>  				if (kip->slot_used[i] == SLOT_CLEAN) {
>  					kip->slot_used[i] = SLOT_USED;
>  					kip->nused++;
> -					return kip->insns + (i * MAX_INSN_SIZE);
> +					ret = kip->insns + (i * MAX_INSN_SIZE);
> +					goto end;
>  				}
>  			}
>  			/* Surprise!  No unused slots.  Fix kip->nused. */
> @@ -160,8 +167,10 @@ kprobe_opcode_t __kprobes *get_insn_slot
>  	}
>  	/* All out of space.  Need to allocate a new page. Use slot 0. */
>  	kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
> -	if (!kip)
> -		return NULL;
> +	if (!kip) {
> +		ret = NULL;
> +		goto end;
> +	}
> 
>  	/*
>  	 * Use module_alloc so this page is within +/- 2GB of where the
> @@ -171,7 +180,8 @@ kprobe_opcode_t __kprobes *get_insn_slot
>  	kip->insns = module_alloc(PAGE_SIZE);
>  	if (!kip->insns) {
>  		kfree(kip);
> -		return NULL;
> +		ret = NULL;
> +		goto end;
>  	}
>  	INIT_HLIST_NODE(&kip->hlist);
>  	hlist_add_head(&kip->hlist, &kprobe_insn_pages);
> @@ -179,7 +189,10 @@ kprobe_opcode_t __kprobes *get_insn_slot
>  	kip->slot_used[0] = SLOT_USED;
>  	kip->nused = 1;
>  	kip->ngarbage = 0;
> -	return kip->insns;
> +	ret = kip->insns;
> +end:
> +	mutex_unlock(&kprobe_insn_mutex);
> +	return ret;
>  }
> 
>  /* Return 1 if all garbages are collected, otherwise 0. */
> @@ -213,7 +226,7 @@ static int __kprobes collect_garbage_slo
>  	struct kprobe_insn_page *kip;
>  	struct hlist_node *pos, *next;
> 
> -	/* Ensure no-one is preepmted on the garbages */
> +	/* Ensure no-one is preempted on the garbages */
>  	if (check_safety() != 0)
>  		return -EAGAIN;
> 
> @@ -237,6 +250,7 @@ void __kprobes free_insn_slot(kprobe_opc
>  	struct kprobe_insn_page *kip;
>  	struct hlist_node *pos;
> 
> +	mutex_lock(&kprobe_insn_mutex);
>  	hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
>  		if (kip->insns <= slot &&
>  		    slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
> @@ -253,6 +267,7 @@ void __kprobes free_insn_slot(kprobe_opc
> 
>  	if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
>  		collect_garbage_slots();
> +	mutex_unlock(&kprobe_insn_mutex);
>  }
>  #endif
> 
> 
> -- 
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [patch 03/11] Kprobes - do not use kprobes mutex in arch code

[Ananth N Mavinakayanahalli]

On Mon, Aug 20, 2007 at 04:19:05PM -0400, Mathieu Desnoyers wrote:
> Remove the kprobes mutex from kprobes.h, since it does not belong there. Also
> remove all use of this mutex in the architecture specific code, replacing it by
> a proper mutex lock/unlock in the architecture agnostic code.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

> CC: prasanna@in.ibm.com
> CC: ananth@in.ibm.com
> CC: anil.s.keshavamurthy@intel.com
> CC: davem@davemloft.net
> ---
>  arch/i386/kernel/kprobes.c    |    2 --
>  arch/ia64/kernel/kprobes.c    |    2 --
>  arch/powerpc/kernel/kprobes.c |    2 --
>  arch/s390/kernel/kprobes.c    |    2 --
>  arch/x86_64/kernel/kprobes.c  |    2 --
>  include/linux/kprobes.h       |    2 --
>  kernel/kprobes.c              |    2 ++
>  7 files changed, 2 insertions(+), 12 deletions(-)
> 
> Index: linux-2.6-lttng/include/linux/kprobes.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/linux/kprobes.h	2007-08-07 15:28:05.000000000 -0400
> +++ linux-2.6-lttng/include/linux/kprobes.h	2007-08-07 15:28:22.000000000 -0400
> @@ -35,7 +35,6 @@
>  #include <linux/percpu.h>
>  #include <linux/spinlock.h>
>  #include <linux/rcupdate.h>
> -#include <linux/mutex.h>
> 
>  #ifdef CONFIG_KPROBES
>  #include <asm/kprobes.h>
> @@ -177,7 +176,6 @@ static inline void kretprobe_assert(stru
>  }
> 
>  extern spinlock_t kretprobe_lock;
> -extern struct mutex kprobe_mutex;
>  extern int arch_prepare_kprobe(struct kprobe *p);
>  extern void arch_arm_kprobe(struct kprobe *p);
>  extern void arch_disarm_kprobe(struct kprobe *p);
> Index: linux-2.6-lttng/arch/i386/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/i386/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
> +++ linux-2.6-lttng/arch/i386/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> @@ -180,9 +180,7 @@ void __kprobes arch_disarm_kprobe(struct
> 
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
>  {
> -	mutex_lock(&kprobe_mutex);
>  	free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
> -	mutex_unlock(&kprobe_mutex);
>  }
> 
>  static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
> Index: linux-2.6-lttng/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> +++ linux-2.6-lttng/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> @@ -656,7 +656,9 @@ valid_p:
>  			list_del_rcu(&p->list);
>  			kfree(old_p);
>  		}
> +		mutex_lock(&kprobe_mutex);
>  		arch_remove_kprobe(p);
> +		mutex_unlock(&kprobe_mutex);
>  	} else {
>  		mutex_lock(&kprobe_mutex);
>  		if (p->break_handler)
> Index: linux-2.6-lttng/arch/ia64/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/ia64/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
> +++ linux-2.6-lttng/arch/ia64/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> @@ -565,9 +565,7 @@ void __kprobes arch_disarm_kprobe(struct
> 
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
>  {
> -	mutex_lock(&kprobe_mutex);
>  	free_insn_slot(p->ainsn.insn, 0);
> -	mutex_unlock(&kprobe_mutex);
>  }
>  /*
>   * We are resuming execution after a single step fault, so the pt_regs
> Index: linux-2.6-lttng/arch/powerpc/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/powerpc/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
> +++ linux-2.6-lttng/arch/powerpc/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> @@ -86,9 +86,7 @@ void __kprobes arch_disarm_kprobe(struct
> 
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
>  {
> -	mutex_lock(&kprobe_mutex);
>  	free_insn_slot(p->ainsn.insn, 0);
> -	mutex_unlock(&kprobe_mutex);
>  }
> 
>  static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
> Index: linux-2.6-lttng/arch/s390/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/s390/kernel/kprobes.c	2007-08-07 15:28:05.000000000 -0400
> +++ linux-2.6-lttng/arch/s390/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> @@ -218,9 +218,7 @@ void __kprobes arch_disarm_kprobe(struct
> 
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
>  {
> -	mutex_lock(&kprobe_mutex);
>  	free_insn_slot(p->ainsn.insn, 0);
> -	mutex_unlock(&kprobe_mutex);
>  }
> 
>  static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
> Index: linux-2.6-lttng/arch/x86_64/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/x86_64/kernel/kprobes.c	2007-08-07 15:28:06.000000000 -0400
> +++ linux-2.6-lttng/arch/x86_64/kernel/kprobes.c	2007-08-07 15:28:22.000000000 -0400
> @@ -219,9 +219,7 @@ void __kprobes arch_disarm_kprobe(struct
> 
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
>  {
> -	mutex_lock(&kprobe_mutex);
>  	free_insn_slot(p->ainsn.insn, 0);
> -	mutex_unlock(&kprobe_mutex);
>  }
> 
>  static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
> 
> -- 
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [patch 04/11] Kprobes - declare kprobe_mutex static

[Ananth N Mavinakayanahalli]

On Mon, Aug 20, 2007 at 04:19:06PM -0400, Mathieu Desnoyers wrote:
> Since it will not be used by other kernel objects, it makes sense to declare it
> static.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

> CC: hch@infradead.org
> CC: prasanna@in.ibm.com
> CC: ananth@in.ibm.com
> CC: anil.s.keshavamurthy@intel.com
> CC: davem@davemloft.net
> ---
>  kernel/kprobes.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-2.6-lttng/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/kprobes.c	2007-08-19 09:09:15.000000000 -0400
> +++ linux-2.6-lttng/kernel/kprobes.c	2007-08-19 17:18:07.000000000 -0400
> @@ -68,7 +68,7 @@ static struct hlist_head kretprobe_inst_
>  /* NOTE: change this value only with kprobe_mutex held */
>  static bool kprobe_enabled;
> 
> -DEFINE_MUTEX(kprobe_mutex);		/* Protects kprobe_table */
> +static DEFINE_MUTEX(kprobe_mutex);	/* Protects kprobe_table */
>  DEFINE_SPINLOCK(kretprobe_lock);	/* Protects kretprobe_inst_table */
>  static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
> 
> 
> -- 
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 08/11] Text Edit Lock - kprobes i386

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-kprobes-i386.patch --]
[-- Type: text/plain, Size: 1300 bytes --]

Make kprobes use text_set instead of text_poke.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 arch/i386/kernel/kprobes.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux-2.6-lttng/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/kprobes.c	2007-09-11 15:47:50.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/kprobes.c	2007-09-11 15:48:52.000000000 -0400
@@ -177,12 +177,13 @@ int __kprobes arch_prepare_kprobe(struct
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+	text_poke(p->addr, INIT_ARRAY(unsigned char, BREAKPOINT_INSTRUCTION, 1),
+			1);
 }
 
 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, &p->opcode, 1);
+	text_poke(p->addr, INIT_ARRAY(unsigned char, p->opcode, 1), 1);
 }
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [patch 08/11] Text Edit Lock - kprobes i386

[Ananth N Mavinakayanahalli]

On Mon, Sep 17, 2007 at 02:40:39PM -0400, Mathieu Desnoyers wrote:
> Make kprobes use text_set instead of text_poke.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

Tested-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

> CC: Andi Kleen <andi@firstfloor.org>
> CC: prasanna@in.ibm.com
> CC: ananth@in.ibm.com
> CC: anil.s.keshavamurthy@intel.com
> CC: davem@davemloft.net
> ---
>  arch/i386/kernel/kprobes.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6-lttng/arch/i386/kernel/kprobes.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/i386/kernel/kprobes.c	2007-09-11 15:47:50.000000000 -0400
> +++ linux-2.6-lttng/arch/i386/kernel/kprobes.c	2007-09-11 15:48:52.000000000 -0400
> @@ -177,12 +177,13 @@ int __kprobes arch_prepare_kprobe(struct
> 
>  void __kprobes arch_arm_kprobe(struct kprobe *p)
>  {
> -	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
> +	text_poke(p->addr, INIT_ARRAY(unsigned char, BREAKPOINT_INSTRUCTION, 1),
> +			1);
>  }
> 
>  void __kprobes arch_disarm_kprobe(struct kprobe *p)
>  {
> -	text_poke(p->addr, &p->opcode, 1);
> +	text_poke(p->addr, INIT_ARRAY(unsigned char, p->opcode, 1), 1);
>  }
> 
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
> 
> -- 
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

[patch 08/11] Text Edit Lock - kprobes i386

[Mathieu Desnoyers]

[-- Attachment #1: text-edit-lock-kprobes-i386.patch --]
[-- Type: text/plain, Size: 1341 bytes --]

Make kprobes use INIT_ARRAY().

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Tested-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
CC: Andi Kleen <andi@firstfloor.org>
CC: prasanna@in.ibm.com
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
---
 arch/i386/kernel/kprobes.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux-2.6-lttng/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/arch/i386/kernel/kprobes.c	2007-09-11 15:47:50.000000000 -0400
+++ linux-2.6-lttng/arch/i386/kernel/kprobes.c	2007-09-11 15:48:52.000000000 -0400
@@ -177,12 +177,13 @@ int __kprobes arch_prepare_kprobe(struct
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+	text_poke(p->addr, INIT_ARRAY(unsigned char, BREAKPOINT_INSTRUCTION, 1),
+			1);
 }
 
 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 {
-	text_poke(p->addr, &p->opcode, 1);
+	text_poke(p->addr, INIT_ARRAY(unsigned char, p->opcode, 1), 1);
 }
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68