3 files changed, 171 insertions, 0 deletions

diff --git a/tools/lib/api/Makefile b/tools/lib/api/Makefile
new file mode 100644
index 000000000000..ed2f51e11b80
--- /dev/null
+++ b/tools/lib/api/Makefile
@@ -0,0 +1,42 @@
+include ../../scripts/Makefile.include
+include ../../perf/config/utilities.mak         # QUIET_CLEAN
+
+CC = $(CROSS_COMPILE)gcc
+AR = $(CROSS_COMPILE)ar
+
+# guard against environment variables
+LIB_H=
+LIB_OBJS=
+
+LIB_H += fs/debugfs.h
+
+LIB_OBJS += $(OUTPUT)fs/debugfs.o
+
+LIBFILE = libapikfs.a
+
+CFLAGS = -ggdb3 -Wall -Wextra -std=gnu99 -Werror -O6 -D_FORTIFY_SOURCE=2 $(EXTRA_WARNINGS) $(EXTRA_CFLAGS) -fPIC
+EXTLIBS = -lelf -lpthread -lrt -lm
+ALL_CFLAGS = $(CFLAGS) $(BASIC_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
+ALL_LDFLAGS = $(LDFLAGS)
+
+RM = rm -f
+
+$(LIBFILE): $(LIB_OBJS)
+        $(QUIET_AR)$(RM) $@ && $(AR) rcs $(OUTPUT)$@ $(LIB_OBJS)
+
+$(LIB_OBJS): $(LIB_H)
+
+libapi_dirs:
+        $(QUIET_MKDIR)mkdir -p $(OUTPUT)fs/
+
+$(OUTPUT)%.o: %.c libapi_dirs
+        $(QUIET_CC)$(CC) -o $@ -c $(ALL_CFLAGS) $<
+$(OUTPUT)%.s: %.c libapi_dirs
+        $(QUIET_CC)$(CC) -S $(ALL_CFLAGS) $<
+$(OUTPUT)%.o: %.S libapi_dirs
+        $(QUIET_CC)$(CC) -o $@ -c $(ALL_CFLAGS) $<
+
+clean:
+        $(call QUIET_CLEAN, libapi) $(RM) $(LIB_OBJS) $(LIBFILE)
+
+.PHONY: clean
diff --git a/tools/lib/api/fs/debugfs.c b/tools/lib/api/fs/debugfs.c
new file mode 100644
index 000000000000..7c4347962353
--- /dev/null
+++ b/tools/lib/api/fs/debugfs.c
@@ -0,0 +1,100 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <sys/vfs.h>
+#include <sys/mount.h>
+#include <linux/kernel.h>
+
+#include "debugfs.h"
+
+char debugfs_mountpoint[PATH_MAX + 1] = "/sys/kernel/debug";
+
+static const char * const debugfs_known_mountpoints[] = {
+        "/sys/kernel/debug/",
+        "/debug/",
+        0,
+};
+
+static bool debugfs_found;
+
+/* find the path to the mounted debugfs */
+const char *debugfs_find_mountpoint(void)
+{
+        const char * const *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 = true;
+                        strcpy(debugfs_mountpoint, *ptr);
+                        return debugfs_mountpoint;
+                }
+                ptr++;
+        }
+
+        /* give up and parse /proc/mounts */
+        fp = fopen("/proc/mounts", "r");
+        if (fp == NULL)
+                return NULL;
+
+        while (fscanf(fp, "%*s %" STR(PATH_MAX) "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 = true;
+
+        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;
+}
+
+/* mount the debugfs somewhere if it's not mounted */
+char *debugfs_mount(const char *mountpoint)
+{
+        /* see if it's already mounted */
+        if (debugfs_find_mountpoint())
+                goto out;
+
+        /* 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";
+        }
+
+        if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
+                return NULL;
+
+        /* save the mountpoint */
+        debugfs_found = true;
+        strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
+out:
+        return debugfs_mountpoint;
+}
diff --git a/tools/lib/api/fs/debugfs.h b/tools/lib/api/fs/debugfs.h
new file mode 100644
index 000000000000..f19d3df9609d
--- /dev/null
+++ b/tools/lib/api/fs/debugfs.h
@@ -0,0 +1,29 @@
+#ifndef __API_DEBUGFS_H__
+#define __API_DEBUGFS_H__
+
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+/*
+ * On most systems <limits.h> would have given us this, but  not on some systems
+ * (e.g. GNU/Hurd).
+ */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+#ifndef DEBUGFS_MAGIC
+#define DEBUGFS_MAGIC          0x64626720
+#endif
+
+#ifndef PERF_DEBUGFS_ENVIRONMENT
+#define PERF_DEBUGFS_ENVIRONMENT "PERF_DEBUGFS_DIR"
+#endif
+
+const char *debugfs_find_mountpoint(void);
+int debugfs_valid_mountpoint(const char *debugfs);
+char *debugfs_mount(const char *mountpoint);
+
+extern char debugfs_mountpoint[];
+
+#endif /* __API_DEBUGFS_H__ */