Messages in this thread | | | From | Linus Walleij <> | Date | Mon, 18 Jul 2022 10:57:31 +0200 | Subject | Re: [PATCH 1/5] ARM: stacktrace: Skip frame pointer boundary check for call_with_stack() |
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On Tue, Jul 12, 2022 at 4:18 AM Li Huafei <lihuafei1@huawei.com> wrote:
> When using the frame pointer unwinder, it was found that the stack trace > output of stack_trace_save() is incomplete if the stack contains > call_with_stack(): > > [0x7f00002c] dump_stack_task+0x2c/0x90 [hrtimer] > [0x7f0000a0] hrtimer_hander+0x10/0x18 [hrtimer] > [0x801a67f0] __hrtimer_run_queues+0x1b0/0x3b4 > [0x801a7350] hrtimer_run_queues+0xc4/0xd8 > [0x801a597c] update_process_times+0x3c/0x88 > [0x801b5a98] tick_periodic+0x50/0xd8 > [0x801b5bf4] tick_handle_periodic+0x24/0x84 > [0x8010ffc4] twd_handler+0x38/0x48 > [0x8017d220] handle_percpu_devid_irq+0xa8/0x244 > [0x80176e9c] generic_handle_domain_irq+0x2c/0x3c > [0x8052e3a8] gic_handle_irq+0x7c/0x90 > [0x808ab15c] generic_handle_arch_irq+0x60/0x80 > [0x8051191c] call_with_stack+0x1c/0x20 > > For the frame pointer unwinder, unwind_frame() checks stackframe::fp by > stackframe::sp. Since call_with_stack() switches the SP from one stack > to another, stackframe::fp and stackframe: :sp will point to different > stacks, so we can no longer check stackframe::fp by stackframe::sp. Skip > checking stackframe::fp at this point to avoid this problem. > > Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Very nice catch! Took me some time to realize what was going on here.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Nitpick below:
> + /* > + * call_with_stack() is the only place we allow SP to jump from one > + * stack to another, with FP and SP pointing to different stacks, > + * skipping the FP boundary check at this point. > + */ > + if (pc >= (unsigned long)&call_with_stack && > + pc < (unsigned long)&call_with_stack_end) > + return 0;
Can we create a local helper macro to do this, if it needs to happen some other time?
#define ARM_PC_IN_FUNCTION(pc, func) (pc >=. ...)
Yours, Linus Walleij
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