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Date: Wed, 04 Sep 2013 23:20:09 +0530
From: Hemant <hkshaw@...ux.vnet.ibm.com>
To: Namhyung Kim <namhyung@...nel.org>
CC: linux-kernel@...r.kernel.org, srikar@...ux.vnet.ibm.com,
peterz@...radead.org, oleg@...hat.com, mingo@...hat.com,
anton@...hat.com, systemtap@...rceware.org,
masami.hiramatsu.pt@...achi.com
Subject: Re: [PATCH 2/2] Support to perf to probe on SDT markers:
On 09/04/2013 12:30 PM, Namhyung Kim wrote:
> On Tue, 03 Sep 2013 13:07:03 +0530, Hemant Kumar wrote:
>> This patch enables perf to probe on the marker name specified on the command line.
> It looks like you didn't consider prelinked libraries. You need to check
> the address of .stapsdt.base section too. And obviously this patch
Will make the required changes to handle prelinking as well in the next
iteration.
> ignores any argument the SDT has which I think pretty important info.
> But we can add it later once the uprobes arg fetch patches are in.
Yes, will add the arguments' support too in the next iteration.
> Also please see my previous comment on mixed usage of 'note' and
> 'marker'.
Yeah, made a note of that and make the required modifications.
Thanks
Hemant
>
> Thanks,
> Namhyung
>
>
>> ---
>> tools/perf/builtin-probe.c | 7 +++
>> tools/perf/util/probe-event.c | 11 ++++
>> tools/perf/util/symbol-elf.c | 112 +++++++++++++++++++++++++++++++++++++++++
>> tools/perf/util/symbol.h | 5 ++
>> 4 files changed, 135 insertions(+)
>>
>> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
>> index 3d8dcdf..8382853 100644
>> --- a/tools/perf/builtin-probe.c
>> +++ b/tools/perf/builtin-probe.c
>> @@ -378,6 +378,13 @@ int cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
>> " (%d)\n", ret);
>> return ret;
>> }
>> + params.uprobes = true;
>> + ret = probe_marker(params.target,
>> + params.events[0].point.function);
>> + if (ret < 0)
>> + pr_err("Could not probe at %s marker\n",
>> + params.events[0].point.function);
>> + return ret;
>> }
>>
>> if (params.list_events) {
>> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
>> index 7f846f9..014d642 100644
>> --- a/tools/perf/util/probe-event.c
>> +++ b/tools/perf/util/probe-event.c
>> @@ -2378,3 +2378,14 @@ int show_available_markers(const char *target)
>> setup_pager();
>> return list_markers(target);
>> }
>> +
>> +int probe_marker(const char *name, char *mark)
>> +{
>> + int fd;
>> +
>> + fd = open_uprobe_events(true);
>> + if (fd == -1)
>> + return fd;
>> + else
>> + return probe__marker(name, mark, fd);
>> +}
>> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
>> index f3630f2..60938a5 100644
>> --- a/tools/perf/util/symbol-elf.c
>> +++ b/tools/perf/util/symbol-elf.c
>> @@ -1040,6 +1040,118 @@ out_ret:
>> return ret;
>> }
>>
>> +static void extract_first_name(const char *target, char *fname)
>> +{
>> + int i, len;
>> + char *file;
>> +
>> + file = strrchr(target, DIR_SEP);
>> + file++;
>> + len = strlen(file);
>> + for (i = 0; i <= len; i++) {
>> + if (!isalpha(file[i]))
>> + break;
>> + fname[i] = file[i];
>> + }
>> + fname[i] = '\0';
>> +}
>> +
>> +static int probe_at_note(struct sdt_note *r_note, const char *target, bool exec,
>> + int fd)
>> +{
>> + char buf[MAX_CMDLEN];
>> + int len, err = -1;
>> + Elf64_Addr offset;
>> + char *fname = NULL;
>> +
>> + if (exec)
>> + offset = r_note->addr.a64[0] - TEXT_SCN;
>> + else
>> + offset = r_note->addr.a64[0];
>> +
>> + fname = (char *)zalloc(sizeof(char) * strlen(target));
>> + if (fname == NULL) {
>> + pr_err("Error in allocating memory to fname\n");
>> + goto out_ret;
>> + }
>> +
>> + extract_first_name(target, fname);
>> + len = snprintf(buf, MAX_CMDLEN, "%c:%s%s/%s %s:0x%x", 'p', "probe_",
>> + fname, r_note->name, target, (unsigned)offset);
>> +
>> + len = write(fd, buf, MAX_CMDLEN);
>> + if (len < 0) {
>> + pr_err("Couldn't write into uprobe_events!\n");
>> + goto out_close;
>> + } else {
>> + printf("Added new event :\n");
>> + printf("event = %s \t (on 0x%x)\n\n", r_note->name,
>> + (unsigned)offset);
>> + printf("You can now use it on all perf tools such as :\n\n");
>> + printf("\t perf record -e %s%s:%s -aR sleep 1\n\n", "probe_", fname, r_note->name);
>> + err = 0;
>> + }
>> +
>> +out_close:
>> + close(fd);
>> + free(fname);
>> +out_ret:
>> + return err;
>> +}
>> +
>> +static int search_and_probe_at_note(char *key, struct sdt_note **start,
>> + const char *target, bool exec, int fd)
>> +{
>> + int ret = -1;
>> + struct sdt_note *req;
>> +
>> + for (req = (*start); req != NULL; req = req->next) {
>> + if (!strcmp(key, req->name))
>> + break;
>> + }
>> + if (!req) {
>> + pr_err("Could not find marker %s\n", key);
>> + return ret;
>> + }
>> +
>> + ret = probe_at_note(req, target, exec, fd);
>> + return ret;
>> +}
>> +
>> +int probe__marker(const char *name, char *mark, int evfd)
>> +{
>> + int ret = -1, fd;
>> + Elf *elf;
>> + bool exec = false;
>> + struct sdt_note *head = NULL;
>> +
>> + fd = open(name, O_RDONLY);
>> + if (fd < 0) {
>> + pr_err("Failed to open the file\n");
>> + goto out_ret;
>> + }
>> +
>> + symbol__elf_init();
>> + elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
>> + if (elf == NULL) {
>> + pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
>> + goto out_close;
>> + }
>> +
>> + head = get_elf_markers(elf, &exec, true);
>> + if (head) {
>> + ret = search_and_probe_at_note(mark, &head, name, exec, evfd);
>> + cleanup_notes(head);
>> + }
>> +
>> + elf_end(elf);
>> +
>> +out_close:
>> + close(fd);
>> +out_ret:
>> + return ret;
>> +}
>> +
>> void cleanup_notes(struct sdt_note *start)
>> {
>> struct sdt_note *tmp;
>> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
>> index f2d17b7..95289fd 100644
>> --- a/tools/perf/util/symbol.h
>> +++ b/tools/perf/util/symbol.h
>> @@ -262,8 +262,13 @@ void __map_groups__fixup_end(struct map_groups *mg, enum map_type type);
>> int show_available_markers(const char *module);
>> int list_markers(const char *name);
>> void cleanup_notes(struct sdt_note *start);
>> +int probe_marker(const char *name, char *mark);
>> +int probe__marker(const char *name, char *mark, int fd);
>>
>> #define SDT_NOTE_TYPE 3
>> #define NOTE_SCN ".note.stapsdt"
>> +#define TEXT_SCN 0x400000
>> +#define DIR_SEP '/'
>> +#define MAX_CMDLEN 256
>>
>> #endif /* __PERF_SYMBOL */
--
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