* [PATCH v3] arm: fix a wrong value returned from CALLER_ADDRn
@ 2013-03-14 4:35 kpark3469 at gmail.com
2013-03-15 17:34 ` Russell King - ARM Linux
0 siblings, 1 reply; 2+ messages in thread
From: kpark3469 at gmail.com @ 2013-03-14 4:35 UTC (permalink / raw)
To: linux-arm-kernel
From: Sahara <keun-o.park@windriver.com>
This makes return_address() return a correct value for CALLER_ADDRn.
To have a correct value from CALLER_ADDRn, we need to fix three points.
* The unwind_frame() does not update frame->lr but frame->pc for backtrace.
So frame->pc is meaningful for backtrace.
* data.level should be adjusted by adding 2 additional iteration levels.
With the current +1 level adjustment, the result of CALLER_ADDR1 will
be the same return address with CALLER_ADDR0.
* The initialization of data.addr to NULL is needed.
When unwind_fame() fails right after data.level reaches zero,
the routine returns data.addr which has uninitialized garbage value.
Signed-off-by: Sahara <keun-o.park@windriver.com>
Reviewed-by: Dave Martin <dave.martin@linaro.org>
---
arch/arm/kernel/return_address.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/arm/kernel/return_address.c b/arch/arm/kernel/return_address.c
index 8085417..fafedd8 100644
--- a/arch/arm/kernel/return_address.c
+++ b/arch/arm/kernel/return_address.c
@@ -26,7 +26,7 @@ static int save_return_addr(struct stackframe *frame, void *d)
struct return_address_data *data = d;
if (!data->level) {
- data->addr = (void *)frame->lr;
+ data->addr = (void *)frame->pc;
return 1;
} else {
@@ -41,7 +41,8 @@ void *return_address(unsigned int level)
struct stackframe frame;
register unsigned long current_sp asm ("sp");
- data.level = level + 1;
+ data.level = level + 2;
+ data.addr = NULL;
frame.fp = (unsigned long)__builtin_frame_address(0);
frame.sp = current_sp;
--
1.7.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH v3] arm: fix a wrong value returned from CALLER_ADDRn
2013-03-14 4:35 [PATCH v3] arm: fix a wrong value returned from CALLER_ADDRn kpark3469 at gmail.com
@ 2013-03-15 17:34 ` Russell King - ARM Linux
0 siblings, 0 replies; 2+ messages in thread
From: Russell King - ARM Linux @ 2013-03-15 17:34 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Mar 14, 2013 at 01:35:01PM +0900, kpark3469 at gmail.com wrote:
> From: Sahara <keun-o.park@windriver.com>
>
> This makes return_address() return a correct value for CALLER_ADDRn.
> To have a correct value from CALLER_ADDRn, we need to fix three points.
>
> * The unwind_frame() does not update frame->lr but frame->pc for backtrace.
> So frame->pc is meaningful for backtrace.
>
> * data.level should be adjusted by adding 2 additional iteration levels.
> With the current +1 level adjustment, the result of CALLER_ADDR1 will
> be the same return address with CALLER_ADDR0.
>
> * The initialization of data.addr to NULL is needed.
> When unwind_fame() fails right after data.level reaches zero,
> the routine returns data.addr which has uninitialized garbage value.
>
> Signed-off-by: Sahara <keun-o.park@windriver.com>
> Reviewed-by: Dave Martin <dave.martin@linaro.org>
Please send this to the patch system. I think we should let this sit
in -next for a bit (which we'll get anyway) to see what the effect is.
^ permalink raw reply [flat|nested] 2+ messages in thread
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