perf_callchain.c

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
 3
 4#include <linux/perf_event.h>
 5#include <linux/uaccess.h>
 6
 7#include <asm/stacktrace.h>
 8
 9static bool fill_callchain(void *entry, unsigned long pc)
10{
11	return perf_callchain_store(entry, pc) == 0;
12}
13
14/*
15 * This will be called when the target is in user mode
16 * This function will only be called when we use
17 * "PERF_SAMPLE_CALLCHAIN" in
18 * kernel/events/core.c:perf_prepare_sample()
19 *
20 * How to trigger perf_callchain_[user/kernel] :
21 * $ perf record -e cpu-clock --call-graph fp ./program
22 * $ perf report --call-graph
23 *
24 * On RISC-V platform, the program being sampled and the C library
25 * need to be compiled with -fno-omit-frame-pointer, otherwise
26 * the user stack will not contain function frame.
27 */
28void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
29			 struct pt_regs *regs)
30{
31	if (perf_guest_state()) {
32		/* TODO: We don't support guest os callchain now */
33		return;
34	}
35
36	arch_stack_walk_user(fill_callchain, entry, regs);
37}
38
39void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
40			   struct pt_regs *regs)
41{
42	if (perf_guest_state()) {
43		/* TODO: We don't support guest os callchain now */
44		return;
45	}
46
47	walk_stackframe(NULL, regs, fill_callchain, entry);
48}