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Diffstat (limited to 'arch/mips/kernel/process.c')
-rw-r--r--arch/mips/kernel/process.c36
1 files changed, 31 insertions, 5 deletions
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 695538031c6..045d987bc68 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -399,7 +399,7 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
#ifdef CONFIG_KALLSYMS
/* used by show_backtrace() */
unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
- unsigned long pc, unsigned long ra)
+ unsigned long pc, unsigned long *ra)
{
unsigned long stack_page;
struct mips_frame_info info;
@@ -407,18 +407,42 @@ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
char namebuf[KSYM_NAME_LEN + 1];
unsigned long size, ofs;
int leaf;
+ extern void ret_from_irq(void);
+ extern void ret_from_exception(void);
stack_page = (unsigned long)task_stack_page(task);
if (!stack_page)
return 0;
+ /*
+ * If we reached the bottom of interrupt context,
+ * return saved pc in pt_regs.
+ */
+ if (pc == (unsigned long)ret_from_irq ||
+ pc == (unsigned long)ret_from_exception) {
+ struct pt_regs *regs;
+ if (*sp >= stack_page &&
+ *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
+ regs = (struct pt_regs *)*sp;
+ pc = regs->cp0_epc;
+ if (__kernel_text_address(pc)) {
+ *sp = regs->regs[29];
+ *ra = regs->regs[31];
+ return pc;
+ }
+ }
+ return 0;
+ }
if (!kallsyms_lookup(pc, &size, &ofs, &modname, namebuf))
return 0;
/*
* Return ra if an exception occured at the first instruction
*/
- if (unlikely(ofs == 0))
- return ra;
+ if (unlikely(ofs == 0)) {
+ pc = *ra;
+ *ra = 0;
+ return pc;
+ }
info.func = (void *)(pc - ofs);
info.func_size = ofs; /* analyze from start to ofs */
@@ -437,11 +461,12 @@ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
* one. In that cases avoid to return always the
* same value.
*/
- pc = pc != ra ? ra : 0;
+ pc = pc != *ra ? *ra : 0;
else
pc = ((unsigned long *)(*sp))[info.pc_offset];
*sp += info.frame_size;
+ *ra = 0;
return __kernel_text_address(pc) ? pc : 0;
}
#endif
@@ -454,6 +479,7 @@ unsigned long get_wchan(struct task_struct *task)
unsigned long pc = 0;
#ifdef CONFIG_KALLSYMS
unsigned long sp;
+ unsigned long ra = 0;
#endif
if (!task || task == current || task->state == TASK_RUNNING)
@@ -467,7 +493,7 @@ unsigned long get_wchan(struct task_struct *task)
sp = task->thread.reg29 + schedule_mfi.frame_size;
while (in_sched_functions(pc))
- pc = unwind_stack(task, &sp, pc, 0);
+ pc = unwind_stack(task, &sp, pc, &ra);
#endif
out: