Commit 07b40341 authored by Russell King's avatar Russell King
Browse files

ARM: stacktrace: include exception PC value in stacktrace output 



When we unwind through an exception stack, include the saved PC value
into the stack trace: this fills in an otherwise missed functions from
the trace (as indicated below):

 [<c03f4424>] fec_enet_interrupt+0xa0/0xe8
 [<c0066c0c>] handle_irq_event_percpu+0x68/0x228
 [<c0066e18>] handle_irq_event+0x4c/0x6c
 [<c006a024>] handle_fasteoi_irq+0xac/0x198
 [<c00664b0>] generic_handle_irq+0x4c/0x60
 [<c000f014>] handle_IRQ+0x40/0x98
 [<c0008554>] gic_handle_irq+0x30/0x64
 [<c0012900>] __irq_svc+0x40/0x50
 [<c0029030>] __do_softirq+0xe0/0x2fc		<====
 [<c0029500>] irq_exit+0xb0/0x100
 [<c000f018>] handle_IRQ+0x44/0x98
 [<c0008554>] gic_handle_irq+0x30/0x64
 [<c0012900>] __irq_svc+0x40/0x50
 [<c000f34c>] arch_cpu_idle+0x30/0x38		<====
 [<c005e1e4>] cpu_startup_entry+0xac/0x214
 [<c066297c>] rest_init+0x68/0x80
 [<c08ccb10>] start_kernel+0x2fc/0x358

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 3683f44c

arch/arm/kernel/stacktrace.c

+23 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
#include <linux/stacktrace.h>



#include <asm/stacktrace.h>

#include <asm/traps.h>



#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)

/*
@@ -61,6 +62,7 @@ EXPORT_SYMBOL(walk_stackframe); 
#ifdef CONFIG_STACKTRACE

struct stack_trace_data {

	struct stack_trace *trace;

	unsigned long last_pc;

	unsigned int no_sched_functions;

	unsigned int skip;

};
@@ -69,6 +71,7 @@ static int save_trace(struct stackframe *frame, void *d) 
{

	struct stack_trace_data *data = d;

	struct stack_trace *trace = data->trace;

	struct pt_regs *regs;

	unsigned long addr = frame->pc;



	if (data->no_sched_functions && in_sched_functions(addr))
@@ -80,6 +83,25 @@ static int save_trace(struct stackframe *frame, void *d) 


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



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

		return 1;



	/*

	 * in_exception_text() is designed to test if the PC is one of

	 * the functions which has an exception stack above it, but

	 * unfortunately what is in frame->pc is the return LR value,

	 * not the saved PC value.  So, we need to track the previous

	 * frame PC value when doing this.

	 */

	addr = data->last_pc;

	data->last_pc = frame->pc;

	if (!in_exception_text(addr))

		return 0;



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



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



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

}
@@ -91,6 +113,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk, 
	struct stackframe frame;



	data.trace = trace;

	data.last_pc = ULONG_MAX;

	data.skip = trace->skip;

	data.no_sched_functions = nosched;

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