[PATCH v2 0/7] Fix backtrace support in THUMB2 mode

Will Deacon will.deacon at arm.com
Fri May 30 10:19:00 PDT 2014

On Fri, May 30, 2014 at 05:59:44PM +0100, Nikolay Borisov wrote:
> From: Nikolay Borisov <Nikolay.Borisov at arm.com>
> Currently all the code which deals with backtrace support assumes that R11
> is the frame-pointer. While this is the case for ARM mode and is explicitly
> documented in the AAPCS, this is not the case for THUMB2 mode.
> There is no official document requiring that R11 has to be the frame pointer
> and GCC uses R7 as FP and given that R7's usage is so intertwined within GCC's
> mechanics it is unlikely to change, so fixing backtrace in THUMB2 mode seems
> in order.
> This patch series rectifies the problem by first fixing the
> thread_save_fp macro to reference the correct register. Furthermore, there
> a lot of repetetive sequences of code such as :
> stackframe.fp = pt_regs->ARM_fp
> stackframe.lr = pt_regs->ARM_lr
> so introducing a function arm_get_current_stack_frame which both
> hides this repetition and also utilizes teh frame_pointer(regs) macro
> to reference the correct register depending on the mode.
> Finally, change all the call sites so that they utilize the new routine.
> Changes since v1:
>  * Nothing major, just made arg_get_current_stack frame an inline routine.

I already acked most of these, please can you add my tag?



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