arm64-frame-pointer-unwind-support.c

 1// SPDX-License-Identifier: GPL-2.0
 2#include "arm64-frame-pointer-unwind-support.h"
 3#include "callchain.h"
 4#include "event.h"
 5#include "perf_regs.h" // SMPL_REG_MASK
 6#include "unwind.h"
 7#include <string.h>
 8
 9#define perf_event_arm_regs perf_event_arm64_regs
10#include "../../arch/arm64/include/uapi/asm/perf_regs.h"
11#undef perf_event_arm_regs
12
13struct entries {
14	u64 stack[2];
15	size_t length;
16};
17
18static bool get_leaf_frame_caller_enabled(struct perf_sample *sample)
19{
20	struct regs_dump *regs;
21
22	if (callchain_param.record_mode != CALLCHAIN_FP)
23		return false;
24
25	regs = perf_sample__user_regs(sample);
26	return  regs->regs && regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_LR);
27}
28
29static int add_entry(struct unwind_entry *entry, void *arg)
30{
31	struct entries *entries = arg;
32
33	entries->stack[entries->length++] = entry->ip;
34	return 0;
35}
36
37u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thread, int usr_idx)
38{
39	int ret;
40	struct entries entries = {};
41	struct regs_dump old_regs, *regs;
42
43	if (!get_leaf_frame_caller_enabled(sample))
44		return 0;
45
46	/*
47	 * If PC and SP are not recorded, get the value of PC from the stack
48	 * and set its mask. SP is not used when doing the unwinding but it
49	 * still needs to be set to prevent failures.
50	 */
51	regs = perf_sample__user_regs(sample);
52	memcpy(&old_regs, regs, sizeof(*regs));
53	if (!(regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_PC))) {
54		regs->cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_PC);
55		regs->cache_regs[PERF_REG_ARM64_PC] = sample->callchain->ips[usr_idx+1];
56	}
57
58	if (!(regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_SP))) {
59		regs->cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_SP);
60		regs->cache_regs[PERF_REG_ARM64_SP] = 0;
61	}
62
63	ret = unwind__get_entries(add_entry, &entries, thread, sample, 2, true);
64	memcpy(regs, &old_regs, sizeof(*regs));
65
66	if (ret || entries.length != 2)
67		return ret;
68
69	return callchain_param.order == ORDER_CALLER ? entries.stack[0] : entries.stack[1];
70}