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authorJohannes Weiner <jw@emlix.com>2009-05-11 15:43:33 +0200
committerChris Zankel <chris@zankel.net>2009-05-11 21:59:43 -0700
commit586411dcd1935f91796d5e8a29aa3cfdf01a01f4 (patch)
treefac1b05ad8c5a708080251b17d4a3fc0b9018c4f
parent7dbe5c542464a511f0ea6a14e3ff08874d7e21d5 (diff)
xtensa: always use correct stack pointer for stack traces
Commit '28a0ce7 xtensa: use correct stack pointer for stack traces' changed the stack tracer from always reading the stack pointer register to always using the saved value in the task descriptor. The author was too dense to consider the fact that the saved stack value is stale for a running process und thus unusable for 'current'. What we do now is to use the stack pointer register (a1) for when the task is unknown - we can't help it then - or when the task is 'current'. For everything else use the saved stack pointer value contained in the task descriptor. Signed-off-by: Johannes Weiner <jw@emlix.com> Signed-off-by: Chris Zankel <chris@zankel.net>
-rw-r--r--arch/xtensa/kernel/traps.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index 9f0b71189e9..ba9ab934978 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -369,6 +369,18 @@ void show_regs(struct pt_regs * regs)
regs->syscall);
}
+static __always_inline unsigned long *stack_pointer(struct task_struct *task)
+{
+ unsigned long *sp;
+
+ if (!task || task == current)
+ __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
+ else
+ sp = (unsigned long *)task->thread.sp;
+
+ return sp;
+}
+
void show_trace(struct task_struct *task, unsigned long *sp)
{
unsigned long a0, a1, pc;
@@ -377,7 +389,7 @@ void show_trace(struct task_struct *task, unsigned long *sp)
if (sp)
a1 = (unsigned long)sp;
else
- a1 = task->thread.sp;
+ a1 = (unsigned long)stack_pointer(task);
sp_start = a1 & ~(THREAD_SIZE-1);
sp_end = sp_start + THREAD_SIZE;
@@ -420,7 +432,7 @@ void show_stack(struct task_struct *task, unsigned long *sp)
unsigned long *stack;
if (!sp)
- sp = (unsigned long *)task->thread.sp;
+ sp = stack_pointer(task);
stack = sp;
printk("\nStack: ");