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(cb: add_entry, arg: &entries, thread, data: sample, max_stack: 2, best_effort: 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}
71

source code of linux/tools/perf/util/arm64-frame-pointer-unwind-support.c