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>

1 files changed, 114 insertions, 6 deletions

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 4c50411371db..84169d6f2585 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -110,6 +110,113 @@ bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused,
 }
 
 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)
 {
         struct perf_probe_event *pev = NULL;
@@ -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");