Subject: Make the 32 bit Frame Pointer backtracer fall back to traditional
From: Arjan van de Ven <[EMAIL PROTECTED]>
The 32 bit Frame Pointer backtracer code checks if the EBP is valid
to do a backtrace; however currently on a failure it just gives up
and prints nothing. That's not very nice; we can do better and still
print a decent backtrace.
This patch changes the backtracer to fall back to the non-framepointer
backtracer if the EBP value isn't within the expected range; so on weird
stack corruption cases we get at least something out...
Signed-off-by: Arjan van de Ven <[EMAIL PROTECTED]>
---
arch/x86/kernel/traps_32.c | 43 ++++++++++++++++++++++---------------------
1 file changed, 22 insertions(+), 21 deletions(-)
Index: linux-2.6.24-rc7/arch/x86/kernel/traps_32.c
===================================================================
--- linux-2.6.24-rc7.orig/arch/x86/kernel/traps_32.c
+++ linux-2.6.24-rc7/arch/x86/kernel/traps_32.c
@@ -119,26 +119,28 @@ static inline unsigned long print_contex
{
#ifdef CONFIG_FRAME_POINTER
struct stack_frame *frame = (struct stack_frame *)ebp;
- while (valid_stack_ptr(tinfo, frame, sizeof(*frame))) {
- struct stack_frame *next;
- unsigned long addr;
-
- addr = frame->return_address;
- if (__kernel_text_address(addr))
- ops->address(data, addr);
- /*
- * break out of recursive entries (such as
- * end_of_stack_stop_unwind_function). Also,
- * we can never allow a frame pointer to
- * move downwards!
- */
- next = frame->next_frame;
- ebp = (unsigned long) next;
- if (next <= frame)
- break;
- frame = next;
- }
-#else
+ if (valid_stack_ptr(tinfo, frame, sizeof(*frame)))
+ while (valid_stack_ptr(tinfo, frame, sizeof(*frame))) {
+ struct stack_frame *next;
+ unsigned long addr;
+
+ addr = frame->return_address;
+ if (__kernel_text_address(addr))
+ ops->address(data, addr);
+ /*
+ * break out of recursive entries (such as
+ * end_of_stack_stop_unwind_function). Also,
+ * we can never allow a frame pointer to
+ * move downwards!
+ */
+ next = frame->next_frame;
+ ebp = (unsigned long) next;
+ if (next <= frame)
+ break;
+ frame = next;
+ }
+ else
+#endif
while (valid_stack_ptr(tinfo, stack, sizeof(*stack))) {
unsigned long addr;
@@ -146,7 +148,6 @@ static inline unsigned long print_contex
if (__kernel_text_address(addr))
ops->address(data, addr);
}
-#endif
return ebp;
}
--
If you want to reach me at my work email, use [EMAIL PROTECTED]
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
