(2013/10/07 15:47), Hemant Kumar wrote:
> @@ -325,6 +326,7 @@ int cmd_probe(int argc, const char **argv, const char
> *prefix __maybe_unused)
> opt_set_filter),
> OPT_CALLBACK('x', "exec", NULL, "executable|path",
> "target executable name or path", opt_set_target),
> + OPT_BOOLEAN('S', "markers", ¶ms.sdt, "Show probe-able sdt notes"),
BTW, "-S" for short of "--markers" option is a bit odd. Would we better use -M
? :)
[...]
> @@ -355,6 +357,26 @@ int cmd_probe(int argc, const char **argv, const char
> *prefix __maybe_unused)
> */
> symbol_conf.try_vmlinux_path = (symbol_conf.vmlinux_name == NULL);
>
> + if (params.sdt) {
> + if (params.show_lines) {
> + pr_err("Error: Don't use --markers with --lines.\n");
> + usage_with_options(probe_usage, options);
> + }
> + if (params.show_vars) {
> + pr_err("Error: Don't use --markers with --vars.\n");
> + usage_with_options(probe_usage, options);
> + }
> + if (params.show_funcs) {
> + pr_err("Error: Don't use --markers with --funcs.\n");
> + usage_with_options(probe_usage, options);
> + }
> + ret = show_sdt_notes(params.target);
You have to ensure params.target is set before use it.
> + if (ret < 0) {
> + pr_err(" Error : Failed to find SDT markers!"
> + "(%d)\n", ret);
> + }
> + return ret;
> + }
> if (params.list_events) {
> if (params.mod_events) {
> pr_err(" Error: Don't use --list with --add/--del.\n");
[...]
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 4b12bf8..6b17260 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -846,6 +846,182 @@ out_elf_end:
> return err;
> }
>
> +/*
> + * Populate the name, type, offset in the SDT note structure and
> + * ignore the argument fields (for now)
> + */
> +static struct sdt_note *populate_sdt_note(Elf **elf, const char *data,
> + size_t len, int type)
> +{
> + const char *provider, *name;
> + struct sdt_note *note;
> +
> + /*
> + * Three addresses need to be obtained :
> + * Marker location, address of base section and semaphore location
> + */
> + union {
> + Elf64_Addr a64[3];
> + Elf32_Addr a32[3];
> + } buf;
> +
> + /*
> + * dst and src are required for translation from file to memory
> + * representation
> + */
> + Elf_Data dst = {
> + .d_buf = &buf, .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,
> + .d_size = gelf_fsize((*elf), ELF_T_ADDR, 3, EV_CURRENT),
> + .d_off = 0, .d_align = 0
> + };
> +
> + Elf_Data src = {
> + .d_buf = (void *) data, .d_type = ELF_T_ADDR,
> + .d_version = EV_CURRENT, .d_size = dst.d_size, .d_off = 0,
> + .d_align = 0
> + };
> +
> + /* Check the type of each of the notes */
> + if (type != SDT_NOTE_TYPE)
> + goto out_ret;
> +
> + note = (struct sdt_note *)zalloc(sizeof(struct sdt_note));
> + if (note == NULL) {
> + pr_err("Memory allocation error\n");
No need to state out of memory for each place...
If you hit an out of memory for such small piece, you'd better
abort execution. For that purpose, I recommend you to return
errno from each function, and caller must check it.
> + goto out_ret;
> + }
> + INIT_LIST_HEAD(¬e->note_list);
> +
> + if (len < dst.d_size + 3)
> + goto out_free;
> +
> + /* Translation from file representation to memory representation */
> + if (gelf_xlatetom(*elf, &dst, &src,
> + elf_getident(*elf, NULL)[EI_DATA]) == NULL)
> + pr_debug("gelf_xlatetom : %s", elf_errmsg(-1));
> +
> + /* Populate the fields of sdt_note */
> + provider = data + dst.d_size;
> +
> + name = (const char *)memchr(provider, '\0', data + len - provider);
> + if (name++ == NULL)
> + goto out_free;
> + note->provider = strdup(provider);
> + note->name = strdup(name);
> +
> + /* Obtain the addresses and ignore notes with semaphores set*/
> + if (gelf_getclass(*elf) == ELFCLASS32) {
> + note->addr.a32[0] = buf.a32[0];
> + note->addr.a32[1] = buf.a32[1];
> + note->addr.a32[2] = buf.a32[2];
> + note->bit32 = true;
> + if (buf.a32[2] != 0)
> + goto out_free;
> + } else {
> + note->addr.a64[0] = buf.a64[0];
> + note->addr.a64[1] = buf.a64[1];
> + note->addr.a64[2] = buf.a64[2];
> + note->bit32 = false;
> + if (buf.a64[2] != 0)
> + goto out_free;
> + }
> + return note;
> +
> +out_free:
> + free(note);
> +out_ret:
> + return NULL;
> +}
> +
> +static struct list_head *construct_sdt_notes_list(Elf *elf)
This also would better return errno.
> +{
> + GElf_Ehdr ehdr;
> + Elf_Scn *scn = NULL;
> + Elf_Data *data;
> + GElf_Shdr shdr;
> + size_t shstrndx;
> + size_t next;
> + GElf_Nhdr nhdr;
> + size_t name_off, desc_off, offset;
> + struct sdt_note *tmp = NULL, *note = NULL;
> +
> + if (gelf_getehdr(elf, &ehdr) == NULL) {
> + pr_debug("%s: Can't get elf header.\n", __func__);
> + goto out_err;
> + }
> + if (elf_getshdrstrndx(elf, &shstrndx) != 0) {
> + pr_debug("getshdrstrndx failed\n");
> + goto out_err;
> + }
> +
> + /*
> + * Look for section type = SHT_NOTE, flags = no SHF_ALLOC
> + * and name = .note.stapsdt
> + */
> + scn = elf_section_by_name(elf, &ehdr, &shdr, NOTE_SCN, NULL);
> + if (!scn) {
> + printf("SDT markers not present!\n");
Why you don't use pr_err() here ? :)
And also, as I commented, I'd like to know which binary doesn't have SDT
markers,
at least with -v (verbose) option.
> + goto out_err;
> + }
> + if (!(shdr.sh_type == SHT_NOTE) || (shdr.sh_flags & SHF_ALLOC))
> + goto out_err;
> +
> + data = elf_getdata(scn, NULL);
> +
> + /* Get the SDT notes */
> + for (offset = 0; (next = gelf_getnote(data, offset, &nhdr, &name_off,
> + &desc_off)) > 0; offset = next) {
> + if (nhdr.n_namesz == sizeof(SDT_NOTE_NAME) &&
> + !memcmp(data->d_buf + name_off, SDT_NOTE_NAME,
> + sizeof(SDT_NOTE_NAME))) {
> + tmp = populate_sdt_note(&elf, (const char *)
> + ((long)(data->d_buf) +
> + (long)desc_off),
> + nhdr.n_descsz, nhdr.n_type);
> + if (!note && tmp)
> + note = tmp;
> + else if (tmp)
> + list_add_tail(&tmp->note_list,
> + &(note->note_list));
> + }
> + }
> + if (tmp)
> + return &tmp->note_list;
> +out_err:
> + return NULL;
> +}
> +
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
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