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Message-ID: <20061011133640.GG9305@skybase>
Date: Wed, 11 Oct 2006 15:36:40 +0200
From: Martin Schwidefsky <schwidefsky@...ibm.com>
To: linux-kernel@...r.kernel.org, cborntra@...ibm.com
Subject: [S390] stacktrace bug.
From: Christian Borntraeger <cborntra@...ibm.com>
[S390] stacktrace bug.
The latest kernel 2.6.19-rc1 triggers a bug in the s390 specific stack
trace code when compiled with gcc 3.4.
This patch fixes the latest lock dependency validator code (2.6.19-rc1)
on s390 gcc 3.4. The variable sp was fixed to r15 (which is the stack
pointer in the s390 abi) and assigned new values to r15. Therefore,
gcc 3.4 assigns a new value to r15 and does not restore it on exit (r15
is supposed to be call save) - the kernel stack is broken. Avoid trouble
by not assigning any new value to sp (r15).
Signed-off-by: Christian Borntraeger <cborntra@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---
arch/s390/kernel/stacktrace.c | 17 ++++++++---------
1 files changed, 8 insertions(+), 9 deletions(-)
diff -urpN linux-2.6/arch/s390/kernel/stacktrace.c linux-2.6-patched/arch/s390/kernel/stacktrace.c
--- linux-2.6/arch/s390/kernel/stacktrace.c 2006-10-11 15:23:16.000000000 +0200
+++ linux-2.6-patched/arch/s390/kernel/stacktrace.c 2006-10-11 15:23:40.000000000 +0200
@@ -62,27 +62,26 @@ static inline unsigned long save_context
void save_stack_trace(struct stack_trace *trace, struct task_struct *task)
{
register unsigned long sp asm ("15");
- unsigned long orig_sp;
+ unsigned long orig_sp, new_sp;
- sp &= PSW_ADDR_INSN;
- orig_sp = sp;
+ orig_sp = sp & PSW_ADDR_INSN;
- sp = save_context_stack(trace, &trace->skip, sp,
+ new_sp = save_context_stack(trace, &trace->skip, orig_sp,
S390_lowcore.panic_stack - PAGE_SIZE,
S390_lowcore.panic_stack);
- if ((sp != orig_sp) && !trace->all_contexts)
+ if ((new_sp != orig_sp) && !trace->all_contexts)
return;
- sp = save_context_stack(trace, &trace->skip, sp,
+ new_sp = save_context_stack(trace, &trace->skip, new_sp,
S390_lowcore.async_stack - ASYNC_SIZE,
S390_lowcore.async_stack);
- if ((sp != orig_sp) && !trace->all_contexts)
+ if ((new_sp != orig_sp) && !trace->all_contexts)
return;
if (task)
- save_context_stack(trace, &trace->skip, sp,
+ save_context_stack(trace, &trace->skip, new_sp,
(unsigned long) task_stack_page(task),
(unsigned long) task_stack_page(task) + THREAD_SIZE);
else
- save_context_stack(trace, &trace->skip, sp,
+ save_context_stack(trace, &trace->skip, new_sp,
S390_lowcore.thread_info,
S390_lowcore.thread_info + THREAD_SIZE);
return;
-
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