Commit 752ec621 authored by Li Huafei's avatar Li Huafei Committed by Russell King (Oracle)
Browse files

ARM: 9234/1: stacktrace: Avoid duplicate saving of exception PC value 



Because an exception stack frame is not created in the exception entry,
save_trace() does special handling for the exception PC, but this is
only needed when CONFIG_FRAME_POINTER_UNWIND=y. When
CONFIG_ARM_UNWIND=y, unwind annotations have been added to the exception
entry and save_trace() will repeatedly save the exception PC:

    [0x7f000090] hrtimer_hander+0x8/0x10 [hrtimer]
    [0x8019ec50] __hrtimer_run_queues+0x18c/0x394
    [0x8019f760] hrtimer_run_queues+0xbc/0xd0
    [0x8019def0] update_process_times+0x34/0x80
    [0x801ad2a4] tick_periodic+0x48/0xd0
    [0x801ad3dc] tick_handle_periodic+0x1c/0x7c
    [0x8010f2e0] twd_handler+0x30/0x40
    [0x80177620] handle_percpu_devid_irq+0xa0/0x23c
    [0x801718d0] generic_handle_domain_irq+0x24/0x34
    [0x80502d28] gic_handle_irq+0x74/0x88
    [0x8085817c] generic_handle_arch_irq+0x58/0x78
    [0x80100ba8] __irq_svc+0x88/0xc8
    [0x80108114] arch_cpu_idle+0x38/0x3c
    [0x80108114] arch_cpu_idle+0x38/0x3c    <==== duplicate saved exception PC
    [0x80861bf8] default_idle_call+0x38/0x130
    [0x8015d5cc] do_idle+0x150/0x214
    [0x8015d978] cpu_startup_entry+0x18/0x1c
    [0x808589c0] rest_init+0xd8/0xdc
    [0x80c00a44] arch_post_acpi_subsys_init+0x0/0x8

We can move the special handling of the exception PC in save_trace() to
the unwind_frame() of the frame pointer unwinder.

Signed-off-by: default avatarLi Huafei <lihuafei1@huawei.com>
Reviewed-by: default avatarLinus Waleij <linus.walleij@linaro.org>
Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
parent 5854e4d8

arch/arm/include/asm/stacktrace.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -21,6 +21,9 @@ struct stackframe { 
	struct llist_node *kr_cur;

	struct llist_node *kr_cur;

	struct task_struct *tsk;

	struct task_struct *tsk;

#endif

#endif

#ifdef CONFIG_UNWINDER_FRAME_POINTER

	bool ex_frame;

#endif

};

};





static __always_inline

static __always_inline
@@ -34,6 +37,9 @@ void arm_get_current_stackframe(struct pt_regs *regs, struct stackframe *frame) 
		frame->kr_cur = NULL;

		frame->kr_cur = NULL;

		frame->tsk = current;

		frame->tsk = current;

#endif

#endif

#ifdef CONFIG_UNWINDER_FRAME_POINTER

		frame->ex_frame = in_entry_text(frame->pc);

#endif

}

}





extern int unwind_frame(struct stackframe *frame);

extern int unwind_frame(struct stackframe *frame);

arch/arm/kernel/return_address.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -47,6 +47,7 @@ void *return_address(unsigned int level) 
	frame.kr_cur = NULL;

	frame.kr_cur = NULL;

	frame.tsk = current;

	frame.tsk = current;

#endif

#endif

	frame.ex_frame = false;





	walk_stackframe(&frame, save_return_addr, &data);

	walk_stackframe(&frame, save_return_addr, &data);

arch/arm/kernel/stacktrace.c

+30 −14
Original line number Original line Diff line number Diff line
@@ -82,6 +82,27 @@ int notrace unwind_frame(struct stackframe *frame) 
	if (frame_pointer_check(frame))

	if (frame_pointer_check(frame))

		return -EINVAL;

		return -EINVAL;





	/*

	 * When we unwind through an exception stack, include the saved PC

	 * value into the stack trace.

	 */

	if (frame->ex_frame) {

		struct pt_regs *regs = (struct pt_regs *)frame->sp;



		/*

		 * We check that 'regs + sizeof(struct pt_regs)' (that is,

		 * &regs[1]) does not exceed the bottom of the stack to avoid

		 * accessing data outside the task's stack. This may happen

		 * when frame->ex_frame is a false positive.

		 */

		if ((unsigned long)&regs[1] > ALIGN(frame->sp, THREAD_SIZE))

			return -EINVAL;



		frame->pc = regs->ARM_pc;

		frame->ex_frame = false;

		return 0;

	}



	/* restore the registers from the stack frame */

	/* restore the registers from the stack frame */

#ifdef CONFIG_CC_IS_CLANG

#ifdef CONFIG_CC_IS_CLANG

	frame->sp = frame->fp;

	frame->sp = frame->fp;
@@ -98,6 +119,9 @@ int notrace unwind_frame(struct stackframe *frame) 
					(void *)frame->fp, &frame->kr_cur);

					(void *)frame->fp, &frame->kr_cur);

#endif

#endif





	if (in_entry_text(frame->pc))

		frame->ex_frame = true;



	return 0;

	return 0;

}

}

#endif

#endif
@@ -128,7 +152,6 @@ static int save_trace(struct stackframe *frame, void *d) 
{

{

	struct stack_trace_data *data = d;

	struct stack_trace_data *data = d;

	struct stack_trace *trace = data->trace;

	struct stack_trace *trace = data->trace;

	struct pt_regs *regs;

	unsigned long addr = frame->pc;

	unsigned long addr = frame->pc;





	if (data->no_sched_functions && in_sched_functions(addr))

	if (data->no_sched_functions && in_sched_functions(addr))
@@ -139,19 +162,6 @@ static int save_trace(struct stackframe *frame, void *d) 
	}

	}





	trace->entries[trace->nr_entries++] = addr;

	trace->entries[trace->nr_entries++] = addr;



	if (trace->nr_entries >= trace->max_entries)

		return 1;



	if (!in_entry_text(frame->pc))

		return 0;



	regs = (struct pt_regs *)frame->sp;

	if ((unsigned long)&regs[1] > ALIGN(frame->sp, THREAD_SIZE))

		return 0;



	trace->entries[trace->nr_entries++] = regs->ARM_pc;



	return trace->nr_entries >= trace->max_entries;

	return trace->nr_entries >= trace->max_entries;

}

}
@@ -193,6 +203,9 @@ static noinline void __save_stack_trace(struct task_struct *tsk, 
	frame.kr_cur = NULL;

	frame.kr_cur = NULL;

	frame.tsk = tsk;

	frame.tsk = tsk;

#endif

#endif

#ifdef CONFIG_UNWINDER_FRAME_POINTER

	frame.ex_frame = false;

#endif





	walk_stackframe(&frame, save_trace, &data);

	walk_stackframe(&frame, save_trace, &data);

}

}
@@ -214,6 +227,9 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 
	frame.kr_cur = NULL;

	frame.kr_cur = NULL;

	frame.tsk = current;

	frame.tsk = current;

#endif

#endif

#ifdef CONFIG_UNWINDER_FRAME_POINTER

	frame.ex_frame = in_entry_text(frame.pc);

#endif





	walk_stackframe(&frame, save_trace, &data);

	walk_stackframe(&frame, save_trace, &data);

}

}