perf bpf: Allow BPF program attach to uprobe events

This patch adds a new syntax to the BPF object section name to support
probing at uprobe event. Now we can use BPF program like this:

  SEC(
  "exec=/lib64/libc.so.6;"
  "libcwrite=__write"
  )
  int libcwrite(void *ctx)
  {
      return 1;
  }

Where, in section name of a program, before the main config string, we
can use 'key=value' style options. Now the only option key is "exec",
for uprobes.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1447675815-166222-4-git-send-email-wangnan0@huawei.com
[ Changed the separator from \n to ; ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 4c50411371db31208c361115331695571fe545b7..84169d6f25859e33ba893d0abd379239876308ec 100644 (file)
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -109,6 +109,113 @@ bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused,
        free(priv);
 }
 
+static int
+config__exec(const char *value, struct perf_probe_event *pev)
+{
+       pev->uprobes = true;
+       pev->target = strdup(value);
+       if (!pev->target)
+               return -ENOMEM;
+       return 0;
+}
+
+static struct {
+       const char *key;
+       const char *usage;
+       const char *desc;
+       int (*func)(const char *, struct perf_probe_event *);
+} bpf_config_terms[] = {
+       {
+               .key    = "exec",
+               .usage  = "exec=<full path of file>",
+               .desc   = "Set uprobe target",
+               .func   = config__exec,
+       },
+};
+
+static int
+do_config(const char *key, const char *value,
+         struct perf_probe_event *pev)
+{
+       unsigned int i;
+
+       pr_debug("config bpf program: %s=%s\n", key, value);
+       for (i = 0; i < ARRAY_SIZE(bpf_config_terms); i++)
+               if (strcmp(key, bpf_config_terms[i].key) == 0)
+                       return bpf_config_terms[i].func(value, pev);
+
+       pr_debug("BPF: ERROR: invalid config option in object: %s=%s\n",
+                key, value);
+
+       pr_debug("\nHint: Currently valid options are:\n");
+       for (i = 0; i < ARRAY_SIZE(bpf_config_terms); i++)
+               pr_debug("\t%s:\t%s\n", bpf_config_terms[i].usage,
+                        bpf_config_terms[i].desc);
+       pr_debug("\n");
+
+       return -BPF_LOADER_ERRNO__CONFIG_TERM;
+}
+
+static const char *
+parse_config_kvpair(const char *config_str, struct perf_probe_event *pev)
+{
+       char *text = strdup(config_str);
+       char *sep, *line;
+       const char *main_str = NULL;
+       int err = 0;
+
+       if (!text) {
+               pr_debug("No enough memory: dup config_str failed\n");
+               return ERR_PTR(-ENOMEM);
+       }
+
+       line = text;
+       while ((sep = strchr(line, ';'))) {
+               char *equ;
+
+               *sep = '\0';
+               equ = strchr(line, '=');
+               if (!equ) {
+                       pr_warning("WARNING: invalid config in BPF object: %s\n",
+                                  line);
+                       pr_warning("\tShould be 'key=value'.\n");
+                       goto nextline;
+               }
+               *equ = '\0';
+
+               err = do_config(line, equ + 1, pev);
+               if (err)
+                       break;
+nextline:
+               line = sep + 1;
+       }
+
+       if (!err)
+               main_str = config_str + (line - text);
+       free(text);
+
+       return err ? ERR_PTR(err) : main_str;
+}
+
+static int
+parse_config(const char *config_str, struct perf_probe_event *pev)
+{
+       int err;
+       const char *main_str = parse_config_kvpair(config_str, pev);
+
+       if (IS_ERR(main_str))
+               return PTR_ERR(main_str);
+
+       err = parse_perf_probe_command(main_str, pev);
+       if (err < 0) {
+               pr_debug("bpf: '%s' is not a valid config string\n",
+                        config_str);
+               /* parse failed, don't need clear pev. */
+               return -BPF_LOADER_ERRNO__CONFIG;
+       }
+       return 0;
+}
+
 static int
 config_bpf_program(struct bpf_program *prog)
 {
@@ -131,13 +238,9 @@ config_bpf_program(struct bpf_program *prog)
        pev = &priv->pev;
 
        pr_debug("bpf: config program '%s'\n", config_str);
-       err = parse_perf_probe_command(config_str, pev);
-       if (err < 0) {
-               pr_debug("bpf: '%s' is not a valid config string\n",
-                        config_str);
-               err = -BPF_LOADER_ERRNO__CONFIG;
+       err = parse_config(config_str, pev);
+       if (err)
                goto errout;
-       }
 
        if (pev->group && strcmp(pev->group, PERF_BPF_PROBE_GROUP)) {
                pr_debug("bpf: '%s': group for event is set and not '%s'.\n",
@@ -340,6 +443,7 @@ static const char *bpf_loader_strerror_table[NR_ERRNO] = {
        [ERRCODE_OFFSET(EVENTNAME)]     = "No event name found in config string",
        [ERRCODE_OFFSET(INTERNAL)]      = "BPF loader internal error",
        [ERRCODE_OFFSET(COMPILE)]       = "Error when compiling BPF scriptlet",
+       [ERRCODE_OFFSET(CONFIG_TERM)]   = "Invalid config term in config string",
 };
 
 static int
@@ -420,6 +524,10 @@ int bpf__strerror_probe(struct bpf_object *obj __maybe_unused,
                        int err, char *buf, size_t size)
 {
        bpf__strerror_head(err, buf, size);
+       case BPF_LOADER_ERRNO__CONFIG_TERM: {
+               scnprintf(buf, size, "%s (add -v to see detail)", emsg);
+               break;
+       }
        bpf__strerror_entry(EEXIST, "Probe point exist. Try use 'perf probe -d \"*\"'");
        bpf__strerror_entry(EACCES, "You need to be root");
        bpf__strerror_entry(EPERM, "You need to be root, and /proc/sys/kernel/kptr_restrict should be 0");

diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 9caf3ae4acf3d018a87d92bb62f16c4337bd6388..d19f5c5d6d74ea2ee0d298e3186c20162792a937 100644 (file)
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -20,6 +20,7 @@ enum bpf_loader_errno {
        BPF_LOADER_ERRNO__EVENTNAME,    /* Event name is missing */
        BPF_LOADER_ERRNO__INTERNAL,     /* BPF loader internal error */
        BPF_LOADER_ERRNO__COMPILE,      /* Error when compiling BPF scriptlet */
+       BPF_LOADER_ERRNO__CONFIG_TERM,  /* Invalid config term in config term */
        __BPF_LOADER_ERRNO__END,
 };