[MIPS] Improve unwind_stack()
This patch allows unwind_stack() to return ra for leaf function.
But it tries to detects cases where get_frame_info() wrongly
consider nested function as a leaf one.
It also pass 'unsinged long *sp' instead of 'unsigned long **sp'
as second parameter. The code looks cleaner.
Signed-off-by: Franck Bui-Huu <vagabon.xyz@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 309bfa4..951bf9c 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -448,15 +448,16 @@
}
#ifdef CONFIG_KALLSYMS
-/* used by show_frametrace() */
-unsigned long unwind_stack(struct task_struct *task,
- unsigned long **sp, unsigned long pc)
+/* used by show_backtrace() */
+unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
+ unsigned long pc, unsigned long ra)
{
unsigned long stack_page;
struct mips_frame_info info;
char *modname;
char namebuf[KSYM_NAME_LEN + 1];
unsigned long size, ofs;
+ int leaf;
stack_page = (unsigned long)task_stack_page(task);
if (!stack_page)
@@ -469,18 +470,26 @@
info.func = (void *)(pc - ofs);
info.func_size = ofs; /* analyze from start to ofs */
- if (get_frame_info(&info)) {
- /* leaf or unknown */
- *sp += info.frame_size / sizeof(long);
- return 0;
- }
- if ((unsigned long)*sp < stack_page ||
- (unsigned long)*sp + info.frame_size / sizeof(long) >
- stack_page + THREAD_SIZE - 32)
+ leaf = get_frame_info(&info);
+ if (leaf < 0)
return 0;
- pc = (*sp)[info.pc_offset];
- *sp += info.frame_size / sizeof(long);
- return pc;
+ if (*sp < stack_page ||
+ *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
+ return 0;
+
+ if (leaf)
+ /*
+ * For some extreme cases, get_frame_info() can
+ * consider wrongly a nested function as a leaf
+ * one. In that cases avoid to return always the
+ * same value.
+ */
+ pc = pc != ra ? ra : 0;
+ else
+ pc = ((unsigned long *)(*sp))[info.pc_offset];
+
+ *sp += info.frame_size;
+ return __kernel_text_address(pc) ? pc : 0;
}
#endif