perf tools: Add debugfs utility routines for perf
authorClark Williams <williams@redhat.com>
Sun, 8 Nov 2009 15:01:37 +0000 (09:01 -0600)
committerIngo Molnar <mingo@elte.hu>
Sun, 8 Nov 2009 17:01:34 +0000 (18:01 +0100)
Add routines to locate the debugfs mount point and to manage the
mounting and unmounting of the debugfs.

Signed-off-by: Clark Williams <williams@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091101155621.2b3503ee@torg>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
tools/perf/Makefile
tools/perf/util/debugfs.c [new file with mode: 0644]
tools/perf/util/debugfs.h [new file with mode: 0644]

index 542b29e2e3822135c345a1cc441ce2816c2da604..b9509b1cc32ce4ae4cd4b8fbdd589c8092f07651 100644 (file)
@@ -353,6 +353,7 @@ LIB_H += util/include/asm/swab.h
 LIB_H += util/include/asm/system.h
 LIB_H += util/include/asm/uaccess.h
 LIB_H += perf.h
+LIB_H += util/debugfs.h
 LIB_H += util/event.h
 LIB_H += util/types.h
 LIB_H += util/levenshtein.h
@@ -378,6 +379,7 @@ LIB_OBJS += util/abspath.o
 LIB_OBJS += util/alias.o
 LIB_OBJS += util/config.o
 LIB_OBJS += util/ctype.o
+LIB_OBJS += util/debugfs.o
 LIB_OBJS += util/environment.o
 LIB_OBJS += util/event.o
 LIB_OBJS += util/exec_cmd.o
diff --git a/tools/perf/util/debugfs.c b/tools/perf/util/debugfs.c
new file mode 100644 (file)
index 0000000..06b73ee
--- /dev/null
@@ -0,0 +1,241 @@
+#include "util.h"
+#include "debugfs.h"
+#include "cache.h"
+
+static int debugfs_premounted;
+static char debugfs_mountpoint[MAX_PATH+1];
+
+static const char *debugfs_known_mountpoints[] = {
+       "/sys/kernel/debug/",
+       "/debug/",
+       0,
+};
+
+/* use this to force a umount */
+void debugfs_force_cleanup(void)
+{
+       debugfs_find_mountpoint();
+       debugfs_premounted = 0;
+       debugfs_umount();
+}
+
+/* construct a full path to a debugfs element */
+int debugfs_make_path(const char *element, char *buffer, int size)
+{
+       int len;
+
+       if (strlen(debugfs_mountpoint) == 0) {
+               buffer[0] = '\0';
+               return -1;
+       }
+
+       len = strlen(debugfs_mountpoint) + strlen(element) + 1;
+       if (len >= size)
+               return len+1;
+
+       snprintf(buffer, size-1, "%s/%s", debugfs_mountpoint, element);
+       return 0;
+}
+
+static int debugfs_found;
+
+/* find the path to the mounted debugfs */
+const char *debugfs_find_mountpoint(void)
+{
+       const char **ptr;
+       char type[100];
+       FILE *fp;
+
+       if (debugfs_found)
+               return (const char *) debugfs_mountpoint;
+
+       ptr = debugfs_known_mountpoints;
+       while (*ptr) {
+               if (debugfs_valid_mountpoint(*ptr) == 0) {
+                       debugfs_found = 1;
+                       strcpy(debugfs_mountpoint, *ptr);
+                       return debugfs_mountpoint;
+               }
+               ptr++;
+       }
+
+       /* give up and parse /proc/mounts */
+       fp = fopen("/proc/mounts", "r");
+       if (fp == NULL)
+               die("Can't open /proc/mounts for read");
+
+       while (fscanf(fp, "%*s %"
+                     STR(MAX_PATH)
+                     "s %99s %*s %*d %*d\n",
+                     debugfs_mountpoint, type) == 2) {
+               if (strcmp(type, "debugfs") == 0)
+                       break;
+       }
+       fclose(fp);
+
+       if (strcmp(type, "debugfs") != 0)
+               return NULL;
+
+       debugfs_found = 1;
+
+       return debugfs_mountpoint;
+}
+
+/* verify that a mountpoint is actually a debugfs instance */
+
+int debugfs_valid_mountpoint(const char *debugfs)
+{
+       struct statfs st_fs;
+
+       if (statfs(debugfs, &st_fs) < 0)
+               return -ENOENT;
+       else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+               return -ENOENT;
+
+       return 0;
+}
+
+
+int debugfs_valid_entry(const char *path)
+{
+       struct stat st;
+
+       if (stat(path, &st))
+               return -errno;
+
+       return 0;
+}
+
+/* mount the debugfs somewhere */
+
+int debugfs_mount(const char *mountpoint)
+{
+       char mountcmd[128];
+
+       /* see if it's already mounted */
+       if (debugfs_find_mountpoint()) {
+               debugfs_premounted = 1;
+               return 0;
+       }
+
+       /* if not mounted and no argument */
+       if (mountpoint == NULL) {
+               /* see if environment variable set */
+               mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
+               /* if no environment variable, use default */
+               if (mountpoint == NULL)
+                       mountpoint = "/sys/kernel/debug";
+       }
+
+       /* save the mountpoint */
+       strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
+
+       /* mount it */
+       snprintf(mountcmd, sizeof(mountcmd),
+                "/bin/mount -t debugfs debugfs %s", mountpoint);
+       return system(mountcmd);
+}
+
+/* umount the debugfs */
+
+int debugfs_umount(void)
+{
+       char umountcmd[128];
+       int ret;
+
+       /* if it was already mounted, leave it */
+       if (debugfs_premounted)
+               return 0;
+
+       /* make sure it's a valid mount point */
+       ret = debugfs_valid_mountpoint(debugfs_mountpoint);
+       if (ret)
+               return ret;
+
+       snprintf(umountcmd, sizeof(umountcmd),
+                "/bin/umount %s", debugfs_mountpoint);
+       return system(umountcmd);
+}
+
+int debugfs_write(const char *entry, const char *value)
+{
+       char path[MAX_PATH+1];
+       int ret, count;
+       int fd;
+
+       /* construct the path */
+       snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
+
+       /* verify that it exists */
+       ret = debugfs_valid_entry(path);
+       if (ret)
+               return ret;
+
+       /* get how many chars we're going to write */
+       count = strlen(value);
+
+       /* open the debugfs entry */
+       fd = open(path, O_RDWR);
+       if (fd < 0)
+               return -errno;
+
+       while (count > 0) {
+               /* write it */
+               ret = write(fd, value, count);
+               if (ret <= 0) {
+                       if (ret == EAGAIN)
+                               continue;
+                       close(fd);
+                       return -errno;
+               }
+               count -= ret;
+       }
+
+       /* close it */
+       close(fd);
+
+       /* return success */
+       return 0;
+}
+
+/*
+ * read a debugfs entry
+ * returns the number of chars read or a negative errno
+ */
+int debugfs_read(const char *entry, char *buffer, size_t size)
+{
+       char path[MAX_PATH+1];
+       int ret;
+       int fd;
+
+       /* construct the path */
+       snprintf(path, sizeof(path), "%s/%s", debugfs_mountpoint, entry);
+
+       /* verify that it exists */
+       ret = debugfs_valid_entry(path);
+       if (ret)
+               return ret;
+
+       /* open the debugfs entry */
+       fd = open(path, O_RDONLY);
+       if (fd < 0)
+               return -errno;
+
+       do {
+               /* read it */
+               ret = read(fd, buffer, size);
+               if (ret == 0) {
+                       close(fd);
+                       return EOF;
+               }
+       } while (ret < 0 && errno == EAGAIN);
+
+       /* close it */
+       close(fd);
+
+       /* make *sure* there's a null character at the end */
+       buffer[ret] = '\0';
+
+       /* return the number of chars read */
+       return ret;
+}
diff --git a/tools/perf/util/debugfs.h b/tools/perf/util/debugfs.h
new file mode 100644 (file)
index 0000000..3cd14f9
--- /dev/null
@@ -0,0 +1,25 @@
+#ifndef __DEBUGFS_H__
+#define __DEBUGFS_H__
+
+#include <sys/mount.h>
+
+#ifndef MAX_PATH
+# define MAX_PATH 256
+#endif
+
+#ifndef STR
+# define _STR(x) #x
+# define STR(x) _STR(x)
+#endif
+
+extern const char *debugfs_find_mountpoint(void);
+extern int debugfs_valid_mountpoint(const char *debugfs);
+extern int debugfs_valid_entry(const char *path);
+extern int debugfs_mount(const char *mountpoint);
+extern int debugfs_umount(void);
+extern int debugfs_write(const char *entry, const char *value);
+extern int debugfs_read(const char *entry, char *buffer, size_t size);
+extern void debugfs_force_cleanup(void);
+extern int debugfs_make_path(const char *element, char *buffer, int size);
+
+#endif /* __DEBUGFS_H__ */