[Crash-utility] backtrace failure on x86_64 and x86 in 2.6.33/34 kernels due to "thread_return" removal
Just an FYI -- I'm delaying a new release that I had hoped to do today
because backtraces for blocked x86_64 tasks no longer work with recent
kernels because this commit removed the "thread_return" label:
commit c12a229bc5971534537a7d0e49e44f9f1f5d0336
Author: Masami Hiramatsu <mhiramat(a)redhat.com>
Date: Thu Nov 5 11:03:59 2009 -0500
x86: Remove unused thread_return label from switch_to()
Remove unused thread_return label from switch_to() macro on
x86-64. Since this symbol cuts into schedule(), backtrace at the
latter half of schedule() was always shown as thread_return().
Signed-off-by: Masami Hiramatsu <mhiramat(a)redhat.com>
Cc: systemtap <systemtap(a)sources.redhat.com>
Cc: DLE <dle-develop(a)lists.sourceforge.net>
LKML-Reference: <20091105160359.5181.26225.stgit@harusame>
Signed-off-by: Ingo Molnar <mingo(a)elte.hu>
diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index f08f973..1a953e2 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -128,8 +128,6 @@ do {
\
"movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */ \
"movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */ \
"call __switch_to\n\t" \
- ".globl thread_return\n" \
- "thread_return:\n\t" \
"movq "__percpu_arg([current_task])",%%rsi\n\t"
\
__switch_canary \
"movq %P[thread_info](%%rsi),%%r8\n\t" \
I've got a fix for x86_64 -- which have always depended on the existence of
the "thread_return" label. But I note that x86 backtraces also are not
working,
which I'll take a look at today.
Dave