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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>
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Jason Baron authored and Peter Zijlstra committed Jul 22, 2009
1 parent f6bdafe commit 5beeded
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Showing 5 changed files with 102 additions and 17 deletions.
77 changes: 76 additions & 1 deletion tools/perf/perf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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]";
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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)
{
Expand All @@ -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:
*
Expand All @@ -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;
Expand Down
1 change: 1 addition & 0 deletions tools/perf/util/cache.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#define PERFATTRIBUTES_FILE ".perfattributes"
#define INFOATTRIBUTES_FILE "info/attributes"
#define ATTRIBUTE_MACRO_PREFIX "[attr]"
#define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"

typedef int (*config_fn_t)(const char *, const char *, void *);
extern int perf_default_config(const char *, const char *, void *);
Expand Down
33 changes: 17 additions & 16 deletions tools/perf/util/parse-events.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,22 +5,23 @@
#include "parse-events.h"
#include "exec_cmd.h"
#include "string.h"
#include "cache.h"

extern char *strcasestr(const char *haystack, const char *needle);

int nr_counters;

struct perf_counter_attr attrs[MAX_COUNTERS];

static char default_debugfs_path[] = "/sys/kernel/debug/tracing/events";

struct event_symbol {
u8 type;
u64 config;
char *symbol;
char *alias;
};

char debugfs_path[MAXPATHLEN];

#define CHW(x) .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_##x
#define CSW(x) .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_##x

Expand Down Expand Up @@ -114,27 +115,27 @@ static unsigned long hw_cache_stat[C(MAX)] = {

#define for_each_subsystem(sys_dir, sys_dirent, sys_next, file, st) \
while (!readdir_r(sys_dir, &sys_dirent, &sys_next) && sys_next) \
if (snprintf(file, MAXPATHLEN, "%s/%s", default_debugfs_path, \
sys_dirent.d_name) && \
if (snprintf(file, MAXPATHLEN, "%s/%s", debugfs_path, \
sys_dirent.d_name) && \
(!stat(file, &st)) && (S_ISDIR(st.st_mode)) && \
(strcmp(sys_dirent.d_name, ".")) && \
(strcmp(sys_dirent.d_name, "..")))

#define for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next, file, st) \
while (!readdir_r(evt_dir, &evt_dirent, &evt_next) && evt_next) \
if (snprintf(file, MAXPATHLEN, "%s/%s/%s", default_debugfs_path, \
sys_dirent.d_name, evt_dirent.d_name) && \
if (snprintf(file, MAXPATHLEN, "%s/%s/%s", debugfs_path, \
sys_dirent.d_name, evt_dirent.d_name) && \
(!stat(file, &st)) && (S_ISDIR(st.st_mode)) && \
(strcmp(evt_dirent.d_name, ".")) && \
(strcmp(evt_dirent.d_name, "..")))

#define MAX_EVENT_LENGTH 30

static int valid_debugfs_mount(void)
int valid_debugfs_mount(const char *debugfs)
{
struct statfs st_fs;

if (statfs(default_debugfs_path, &st_fs) < 0)
if (statfs(debugfs, &st_fs) < 0)
return -ENOENT;
else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
return -ENOENT;
Expand All @@ -152,10 +153,10 @@ static char *tracepoint_id_to_name(u64 config)
u64 id;
char evt_path[MAXPATHLEN];

if (valid_debugfs_mount())
if (valid_debugfs_mount(debugfs_path))
return "unkown";

sys_dir = opendir(default_debugfs_path);
sys_dir = opendir(debugfs_path);
if (!sys_dir)
goto cleanup;

Expand All @@ -166,7 +167,7 @@ static char *tracepoint_id_to_name(u64 config)
for_each_event(sys_dirent, evt_dir, evt_dirent, evt_next,
evt_path, st) {
snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id",
default_debugfs_path, sys_dirent.d_name,
debugfs_path, sys_dirent.d_name,
evt_dirent.d_name);
fd = open(evt_path, O_RDONLY);
if (fd < 0)
Expand Down Expand Up @@ -363,7 +364,7 @@ static int parse_tracepoint_event(const char **strp,
u64 id;
char evt_path[MAXPATHLEN];

if (valid_debugfs_mount())
if (valid_debugfs_mount(debugfs_path))
return 0;

evt_name = strchr(*strp, ':');
Expand All @@ -381,8 +382,8 @@ static int parse_tracepoint_event(const char **strp,
if (evt_length >= MAX_EVENT_LENGTH)
return 0;

snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", default_debugfs_path,
sys_name, evt_name);
snprintf(evt_path, MAXPATHLEN, "%s/%s/%s/id", debugfs_path,
sys_name, evt_name);
fd = open(evt_path, O_RDONLY);
if (fd < 0)
return 0;
Expand Down Expand Up @@ -568,10 +569,10 @@ static void print_tracepoint_events(void)
struct stat st;
char evt_path[MAXPATHLEN];

if (valid_debugfs_mount())
if (valid_debugfs_mount(debugfs_path))
return;

sys_dir = opendir(default_debugfs_path);
sys_dir = opendir(debugfs_path);
if (!sys_dir)
goto cleanup;

Expand Down
5 changes: 5 additions & 0 deletions tools/perf/util/parse-events.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@
* Parse symbolic events/counts passed in as options:
*/

struct option;

extern int nr_counters;

extern struct perf_counter_attr attrs[MAX_COUNTERS];
Expand All @@ -15,3 +17,6 @@ extern int parse_events(const struct option *opt, const char *str, int unset);

extern void print_events(void);

extern char debugfs_path[];
extern int valid_debugfs_mount(const char *debugfs);

3 changes: 3 additions & 0 deletions tools/perf/util/string.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,4 +5,7 @@

int hex2u64(const char *ptr, u64 *val);

#define _STR(x) #x
#define STR(x) _STR(x)

#endif

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