Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 1 | /* |
| 2 | * Ftrace trace backend |
| 3 | * |
| 4 | * Copyright (C) 2013 Hitachi, Ltd. |
| 5 | * Created by Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com> |
| 6 | * |
| 7 | * This work is licensed under the terms of the GNU GPL, version 2. See |
| 8 | * the COPYING file in the top-level directory. |
| 9 | * |
| 10 | */ |
| 11 | |
Peter Maydell | d38ea87 | 2016-01-29 17:50:05 +0000 | [diff] [blame] | 12 | #include "qemu/osdep.h" |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 13 | #include "trace/control.h" |
Daniel P. Berrange | 0ab8ed1 | 2017-01-25 16:14:15 +0000 | [diff] [blame] | 14 | #include "trace/ftrace.h" |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 15 | |
| 16 | int trace_marker_fd; |
| 17 | |
Namhyung Kim | babfff8 | 2017-11-08 00:31:35 +0900 | [diff] [blame] | 18 | static int find_mount(char *mount_point, const char *fstype) |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 19 | { |
| 20 | char type[100]; |
| 21 | FILE *fp; |
Namhyung Kim | 5070570 | 2017-11-08 00:31:34 +0900 | [diff] [blame] | 22 | int ret = 0; |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 23 | |
| 24 | fp = fopen("/proc/mounts", "r"); |
| 25 | if (fp == NULL) { |
| 26 | return 0; |
| 27 | } |
| 28 | |
| 29 | while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", |
Namhyung Kim | babfff8 | 2017-11-08 00:31:35 +0900 | [diff] [blame] | 30 | mount_point, type) == 2) { |
| 31 | if (strcmp(type, fstype) == 0) { |
Namhyung Kim | 5070570 | 2017-11-08 00:31:34 +0900 | [diff] [blame] | 32 | ret = 1; |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 33 | break; |
| 34 | } |
| 35 | } |
| 36 | fclose(fp); |
| 37 | |
Namhyung Kim | 5070570 | 2017-11-08 00:31:34 +0900 | [diff] [blame] | 38 | return ret; |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 39 | } |
| 40 | |
LluĂs Vilanova | 5b80827 | 2014-05-27 15:02:14 +0200 | [diff] [blame] | 41 | bool ftrace_init(void) |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 42 | { |
Namhyung Kim | babfff8 | 2017-11-08 00:31:35 +0900 | [diff] [blame] | 43 | char mount_point[PATH_MAX]; |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 44 | char path[PATH_MAX]; |
Namhyung Kim | c9add62 | 2017-11-08 00:31:36 +0900 | [diff] [blame] | 45 | int tracefs_found; |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 46 | int trace_fd = -1; |
Namhyung Kim | c9add62 | 2017-11-08 00:31:36 +0900 | [diff] [blame] | 47 | const char *subdir = ""; |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 48 | |
Namhyung Kim | c9add62 | 2017-11-08 00:31:36 +0900 | [diff] [blame] | 49 | tracefs_found = find_mount(mount_point, "tracefs"); |
| 50 | if (!tracefs_found) { |
| 51 | tracefs_found = find_mount(mount_point, "debugfs"); |
| 52 | subdir = "/tracing"; |
| 53 | } |
| 54 | |
| 55 | if (tracefs_found) { |
Stefan Hajnoczi | fd98583 | 2019-03-21 17:08:30 +0000 | [diff] [blame] | 56 | if (snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir) |
| 57 | >= sizeof(path)) { |
| 58 | fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n"); |
| 59 | return false; |
| 60 | } |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 61 | trace_fd = open(path, O_WRONLY); |
| 62 | if (trace_fd < 0) { |
Daniel P. Berrange | 8ed5372 | 2016-10-04 14:35:51 +0100 | [diff] [blame] | 63 | if (errno == EACCES) { |
| 64 | trace_marker_fd = open("/dev/null", O_WRONLY); |
| 65 | if (trace_marker_fd != -1) { |
| 66 | return true; |
| 67 | } |
| 68 | } |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 69 | perror("Could not open ftrace 'tracing_on' file"); |
| 70 | return false; |
| 71 | } else { |
| 72 | if (write(trace_fd, "1", 1) < 0) { |
| 73 | perror("Could not write to 'tracing_on' file"); |
| 74 | close(trace_fd); |
| 75 | return false; |
| 76 | } |
| 77 | close(trace_fd); |
| 78 | } |
Stefan Hajnoczi | fd98583 | 2019-03-21 17:08:30 +0000 | [diff] [blame] | 79 | if (snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir) |
| 80 | >= sizeof(path)) { |
| 81 | fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n"); |
| 82 | return false; |
| 83 | } |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 84 | trace_marker_fd = open(path, O_WRONLY); |
| 85 | if (trace_marker_fd < 0) { |
| 86 | perror("Could not open ftrace 'trace_marker' file"); |
| 87 | return false; |
| 88 | } |
| 89 | } else { |
Namhyung Kim | c9add62 | 2017-11-08 00:31:36 +0900 | [diff] [blame] | 90 | fprintf(stderr, "tracefs is not mounted\n"); |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 91 | return false; |
| 92 | } |
| 93 | |
Eiichi Tsukata | 781e954 | 2013-04-11 20:25:15 +0900 | [diff] [blame] | 94 | return true; |
| 95 | } |