dwarf-unwind.c

// SPDX-License-Identifier: GPL-2.0
#include <string.h>
#include "perf_regs.h"
#include "thread.h"
#include "map.h"
#include "maps.h"
#include "event.h"
#include "debug.h"
#include "tests/tests.h"

#define STACK_SIZE 8192

static int sample_ustack(struct perf_sample *sample,
			 struct thread *thread, u64 *regs)
{
	struct stack_dump *stack = &sample->user_stack;
	struct map *map;
	unsigned long sp;
	u64 stack_size, *buf;

	buf = malloc(STACK_SIZE);
	if (!buf) {
		pr_debug("failed to allocate sample uregs data\n");
		return -1;
	}

	sp = (unsigned long) regs[PERF_REG_X86_SP];

	map = maps__find(thread__maps(thread), (u64)sp);
	if (!map) {
		pr_debug("failed to get stack map\n");
		free(buf);
		return -1;
	}

	stack_size = map__end(map) - sp;
	map__put(map);
	stack_size = stack_size > STACK_SIZE ? STACK_SIZE : stack_size;

	memcpy(buf, (void *) sp, stack_size);
#ifdef MEMORY_SANITIZER
	/*
	 * Copying the stack may copy msan poison, avoid false positives in the
	 * unwinder by removing the poison here.
	 */
	__msan_unpoison(buf, stack_size);
#endif
	stack->data = (char *) buf;
	stack->size = stack_size;
	return 0;
}

int test__arch_unwind_sample(struct perf_sample *sample,
			     struct thread *thread)
{
	struct regs_dump *regs = perf_sample__user_regs(sample);
	u64 *buf;

	buf = malloc(sizeof(u64) * PERF_REGS_MAX);
	if (!buf) {
		pr_debug("failed to allocate sample uregs data\n");
		return -1;
	}

#ifdef MEMORY_SANITIZER
	/*
	 * Assignments to buf in the assembly function perf_regs_load aren't
	 * seen by memory sanitizer. Zero the memory to convince memory
	 * sanitizer the memory is initialized.
	 */
	memset(buf, 0, sizeof(u64) * PERF_REGS_MAX);
#endif
	perf_regs_load(buf);
	regs->abi  = PERF_SAMPLE_REGS_ABI;
	regs->regs = buf;
	regs->mask = PERF_REGS_MASK;

	return sample_ustack(sample, thread, buf);
}