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perf_counter: Detect debugfs location

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If "/sys/kernel/debug" is not a debugfs mount point, search for the debugfs
filesystem in /proc/mounts, but also allows the user to specify
'--debugfs-dir=blah' or set the environment variable: 'PERF_DEBUGFS_DIR'

Signed-off-by: Jason Baron <jbaron@redhat.com>
[ also made it probe "/debug" by default ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090721181629.GA3094@redhat.com>
This commit is contained in:
Jason Baron
2009-07-21 14:16:29 -04:00
committed by Peter Zijlstra
parent f6bdafef2a
commit 5beeded123
5 changed files with 102 additions and 17 deletions
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77
tools/perf/perf.c
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@@ -12,6 +12,8 @@
#include "util/cache.h"
#include "util/quote.h"
#include "util/run-command.h"
#include "util/parse-events.h"
#include "util/string.h"
const char perf_usage_string[] =
"perf [--version] [--help] COMMAND [ARGS]";
@@ -25,6 +27,8 @@ struct pager_config {
int val;
};
static char debugfs_mntpt[MAXPATHLEN];
static int pager_command_config(const char *var, const char *value, void *data)
{
struct pager_config *c = data;
@@ -56,6 +60,15 @@ static void commit_pager_choice(void) {
}
}
static void set_debugfs_path(void)
{
char *path;
path = getenv(PERF_DEBUGFS_ENVIRONMENT);
snprintf(debugfs_path, MAXPATHLEN, "%s/%s", path ?: debugfs_mntpt,
"tracing/events");
}
static int handle_options(const char*** argv, int* argc, int* envchanged)
{
int handled = 0;
@@ -122,6 +135,22 @@ static int handle_options(const char*** argv, int* argc, int* envchanged)
setenv(PERF_WORK_TREE_ENVIRONMENT, cmd + 12, 1);
if (envchanged)
*envchanged = 1;
} else if (!strcmp(cmd, "--debugfs-dir")) {
if (*argc < 2) {
fprintf(stderr, "No directory given for --debugfs-dir.\n");
usage(perf_usage_string);
}
strncpy(debugfs_mntpt, (*argv)[1], MAXPATHLEN);
debugfs_mntpt[MAXPATHLEN - 1] = '\0';
if (envchanged)
*envchanged = 1;
(*argv)++;
(*argc)--;
} else if (!prefixcmp(cmd, "--debugfs-dir=")) {
strncpy(debugfs_mntpt, cmd + 14, MAXPATHLEN);
debugfs_mntpt[MAXPATHLEN - 1] = '\0';
if (envchanged)
*envchanged = 1;
} else {
fprintf(stderr, "Unknown option: %s\n", cmd);
usage(perf_usage_string);
@@ -228,6 +257,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
if (use_pager == -1 && p->option & USE_PAGER)
use_pager = 1;
commit_pager_choice();
set_debugfs_path();
status = p->fn(argc, argv, prefix);
if (status)
@@ -346,6 +376,49 @@ static int run_argv(int *argcp, const char ***argv)
return done_alias;
}
/* mini /proc/mounts parser: searching for "^blah /mount/point debugfs" */
static void get_debugfs_mntpt(void)
{
FILE *file;
char fs_type[100];
char debugfs[MAXPATHLEN];
/*
* try the standard location
*/
if (valid_debugfs_mount("/sys/kernel/debug/") == 0) {
strcpy(debugfs_mntpt, "/sys/kernel/debug/");
return;
}
/*
* try the sane location
*/
if (valid_debugfs_mount("/debug/") == 0) {
strcpy(debugfs_mntpt, "/debug/");
return;
}
/*
* give up and parse /proc/mounts
*/
file = fopen("/proc/mounts", "r");
if (file == NULL)
return;
while (fscanf(file, "%*s %"
STR(MAXPATHLEN)
"s %99s %*s %*d %*d\n",
debugfs, fs_type) == 2) {
if (strcmp(fs_type, "debugfs") == 0)
break;
}
fclose(file);
if (strcmp(fs_type, "debugfs") == 0) {
strncpy(debugfs_mntpt, debugfs, MAXPATHLEN);
debugfs_mntpt[MAXPATHLEN - 1] = '\0';
}
}
int main(int argc, const char **argv)
{
@@ -354,7 +427,8 @@ int main(int argc, const char **argv)
cmd = perf_extract_argv0_path(argv[0]);
if (!cmd)
cmd = "perf-help";
/* get debugfs mount point from /proc/mounts */
get_debugfs_mntpt();
/*
* "perf-xxxx" is the same as "perf xxxx", but we obviously:
*
@@ -377,6 +451,7 @@ int main(int argc, const char **argv)
argc--;
handle_options(&argv, &argc, NULL);
commit_pager_choice();
set_debugfs_path();
if (argc > 0) {
if (!prefixcmp(argv[0], "--"))
argv[0] += 2;