1 // SPDX-License-Identifier: LGPL-2.1
2 /*
3 * Copyright (C) 2021, VMware, Tzvetomir Stoyanov <[email protected]>
4 *
5 */
6 #include <unistd.h>
7 #include <sys/syscall.h>
8 #include <sys/mman.h>
9
10 #include "trace-cmd-private.h"
11
default_perf_init_pe(struct perf_event_attr * pe)12 static void default_perf_init_pe(struct perf_event_attr *pe)
13 {
14 pe->type = PERF_TYPE_SOFTWARE;
15 pe->sample_type = PERF_SAMPLE_CPU;
16 pe->size = sizeof(struct perf_event_attr);
17 pe->config = PERF_COUNT_HW_CPU_CYCLES;
18 pe->disabled = 1;
19 pe->exclude_kernel = 1;
20 pe->freq = 1;
21 pe->sample_freq = 1000;
22 pe->inherit = 1;
23 pe->mmap = 1;
24 pe->comm = 1;
25 pe->task = 1;
26 pe->precise_ip = 1;
27 pe->sample_id_all = 1;
28 pe->read_format = PERF_FORMAT_ID |
29 PERF_FORMAT_TOTAL_TIME_ENABLED |
30 PERF_FORMAT_TOTAL_TIME_RUNNING;
31 }
32
33 /**
34 * trace_perf_init - Initialize perf context
35 *
36 * @perf: structure, representing perf context, that will be initialized.
37 * @pages: Number of perf memory mapped pages.
38 * @cpu: CPU number, associated with this perf context.
39 * @pid: PID, associated with this perf context.
40 *
41 * The perf context in initialized with default values. The caller can set
42 * custom perf parameters in perf->pe, before calling trace_perf_open() API.
43 *
44 * Returns 0 on success, or -1 in case of an error.
45 *
46 */
trace_perf_init(struct trace_perf * perf,int pages,int cpu,int pid)47 int __hidden trace_perf_init(struct trace_perf *perf, int pages, int cpu, int pid)
48 {
49 if (!perf)
50 return -1;
51
52 memset(perf, 0, sizeof(struct trace_perf));
53 default_perf_init_pe(&perf->pe);
54 perf->cpu = cpu;
55 perf->pages = pages;
56 perf->pid = pid;
57 perf->fd = -1;
58
59 return 0;
60 }
61
62 /**
63 * trace_perf_close - Close perf session
64 *
65 * @perf: structure, representing context of a running perf session, opened
66 * with trace_perf_open()
67 *
68 */
trace_perf_close(struct trace_perf * perf)69 void __hidden trace_perf_close(struct trace_perf *perf)
70 {
71 if (perf->fd >= 0)
72 close(perf->fd);
73 perf->fd = -1;
74 if (perf->mmap && perf->mmap != MAP_FAILED)
75 munmap(perf->mmap, (perf->pages + 1) * getpagesize());
76 perf->mmap = NULL;
77 }
78
79 /**
80 * trace_perf_open - Open perf session
81 *
82 * @perf: structure, representing perf context that will be opened. It must be
83 * initialized with trace_perf_init().
84 *
85 * Returns 0 on success, or -1 in case of an error. In case of success, the
86 * session must be closed with trace_perf_close()
87 */
trace_perf_open(struct trace_perf * perf)88 int __hidden trace_perf_open(struct trace_perf *perf)
89 {
90 perf->fd = syscall(__NR_perf_event_open, &perf->pe, perf->pid, perf->cpu, -1, 0);
91 if (perf->fd < 0)
92 return -1;
93 fcntl(perf->fd, F_SETFL, O_NONBLOCK);
94
95 perf->mmap = mmap(NULL, (perf->pages + 1) * getpagesize(),
96 PROT_READ | PROT_WRITE, MAP_SHARED, perf->fd, 0);
97 if (perf->mmap == MAP_FAILED)
98 goto error;
99
100 return 0;
101
102 error:
103 trace_perf_close(perf);
104 return -1;
105 }
106