lib/arm/stack.c

/*
 * backtrace support (this is a modified lib/x86/stack.c)
 *
 * Copyright (C) 2016, Red Hat Inc, Andrew Jones <drjones@redhat.com>
 *
 * This work is licensed under the terms of the GNU LGPL, version 2.
 */
#include <libcflat.h>
#include <stack.h>

/*
 * APCS stack frames are generated by code like this:
 * | mov  ip, sp
 * | push {..., fp, ip, lr, pc}
 * | sub  fp, ip, #4
 */
#ifdef APCS_FRAMES
# define FP_IDX -3
# define LR_IDX -1
#else
# define FP_IDX -1
# define LR_IDX 0
#endif

int arch_backtrace_frame(const void *frame, const void **return_addrs,
			 int max_depth, bool current_frame)
{
	static int walking;
	int depth;
	const unsigned long *fp = (unsigned long *)frame;

	if (current_frame)
		fp = __builtin_frame_address(0);

	if (walking) {
		printf("RECURSIVE STACK WALK!!!\n");
		return 0;
	}
	walking = 1;

	for (depth = 0; depth < max_depth; depth++) {
		if (!fp)
			break;
		return_addrs[depth] = (void *)fp[LR_IDX];
		if (return_addrs[depth] == 0)
			break;
		fp = (unsigned long *)fp[FP_IDX];
	}

	walking = 0;
	return depth;
}