From 586411dcd1935f91796d5e8a29aa3cfdf01a01f4 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 11 May 2009 15:43:33 +0200 Subject: 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 Signed-off-by: Chris Zankel --- arch/xtensa/kernel/traps.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'arch/xtensa/kernel/traps.c') diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c index 9f0b71189e94..ba9ab9349782 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: "); -- cgit v1.2.3-59-g8ed1b