I rarely emit a single patch for a fix wrt LTTng (I usually just release
a new version), but this one is worth it. It will be in 0.11 pretty
soon, but if you want to apply it to 0.10 meanwhile, it's highly
recommended.
Caused a kernel OOPS when loading the tracepoint probes once in a while
on a 8-way x86_64.
Immedate Values Optimized Jump Fix
Fix the immediate values optimized jump fallback, which parameters were wrong
following the last changes. It should be a 5 bytes instruction (not 2) with a 4
bytes operand.
Signed-off-by: Mathieu Desnoyers <[email protected]>
---
arch/x86/kernel/immediate.c | 2 +-
include/asm-x86/immediate.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6-lttng/arch/x86/kernel/immediate.c
===================================================================
--- linux-2.6-lttng.orig/arch/x86/kernel/immediate.c 2008-07-16 22:50:35.000000000 -0400
+++ linux-2.6-lttng/arch/x86/kernel/immediate.c 2008-07-16 22:51:07.000000000 -0400
@@ -500,7 +500,7 @@ __kprobes int arch_imv_update(struct __i
"Jump target fallback at %lX, nr fail %d\n",
imv->imv, ++nr_fail);
#endif
- imv->size = 1;
+ imv->size = 4; /* Fallback on movl */
} else {
#ifdef DEBUG_IMMEDIATE
static int nr_success;
Index: linux-2.6-lttng/include/asm-x86/immediate.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-x86/immediate.h 2008-07-16 22:49:19.000000000 -0400
+++ linux-2.6-lttng/include/asm-x86/immediate.h 2008-07-16 22:51:07.000000000 -0400
@@ -132,7 +132,7 @@ struct __imv {
BUILD_BUG_ON(sizeof(__typeof__(name##__imv)) > 1); \
asm (".section __imv,\"aw\",@progbits\n\t" \
_ASM_PTR "%c1, (3f)-4\n\t" \
- ".byte 0, 2\n\t" \
+ ".byte 0, 5\n\t" \
".previous\n\t" \
"mov $0,%0\n\t" \
"3:\n\t" \
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
LTTng 0.11 is released, which contains this bugfix.
http://ltt.polymtl.ca/lttng/patch-2.6.26-0.11.tar.bz2
Mathieu
* Mathieu Desnoyers ([email protected]) wrote:
> I rarely emit a single patch for a fix wrt LTTng (I usually just release
> a new version), but this one is worth it. It will be in 0.11 pretty
> soon, but if you want to apply it to 0.10 meanwhile, it's highly
> recommended.
>
> Caused a kernel OOPS when loading the tracepoint probes once in a while
> on a 8-way x86_64.
>
>
> Immedate Values Optimized Jump Fix
>
> Fix the immediate values optimized jump fallback, which parameters were wrong
> following the last changes. It should be a 5 bytes instruction (not 2) with a 4
> bytes operand.
>
> Signed-off-by: Mathieu Desnoyers <[email protected]>
> ---
> arch/x86/kernel/immediate.c | 2 +-
> include/asm-x86/immediate.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> Index: linux-2.6-lttng/arch/x86/kernel/immediate.c
> ===================================================================
> --- linux-2.6-lttng.orig/arch/x86/kernel/immediate.c 2008-07-16 22:50:35.000000000 -0400
> +++ linux-2.6-lttng/arch/x86/kernel/immediate.c 2008-07-16 22:51:07.000000000 -0400
> @@ -500,7 +500,7 @@ __kprobes int arch_imv_update(struct __i
> "Jump target fallback at %lX, nr fail %d\n",
> imv->imv, ++nr_fail);
> #endif
> - imv->size = 1;
> + imv->size = 4; /* Fallback on movl */
> } else {
> #ifdef DEBUG_IMMEDIATE
> static int nr_success;
> Index: linux-2.6-lttng/include/asm-x86/immediate.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/asm-x86/immediate.h 2008-07-16 22:49:19.000000000 -0400
> +++ linux-2.6-lttng/include/asm-x86/immediate.h 2008-07-16 22:51:07.000000000 -0400
> @@ -132,7 +132,7 @@ struct __imv {
> BUILD_BUG_ON(sizeof(__typeof__(name##__imv)) > 1); \
> asm (".section __imv,\"aw\",@progbits\n\t" \
> _ASM_PTR "%c1, (3f)-4\n\t" \
> - ".byte 0, 2\n\t" \
> + ".byte 0, 5\n\t" \
> ".previous\n\t" \
> "mov $0,%0\n\t" \
> "3:\n\t" \
>
> --
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
>
> _______________________________________________
> ltt-dev mailing list
> [email protected]
> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68