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Subject[RFC] [PATCH 2/2] perf/probe: Detect probe target when m/x options are absent
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Options -m and -x explicitly allow tracing of modules / user space
binaries. In absense of these options, check if the first argument
can be used as a target.

perf probe /bin/zsh zfree is equivalent to perf probe -x /bin/zsh
zfree.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---
tools/perf/Documentation/perf-probe.txt | 8 ++++--
tools/perf/builtin-probe.c | 43 +++++++++++++++++++++++++++++--
2 files changed, 46 insertions(+), 5 deletions(-)
diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index fb673be..51205f0 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -104,6 +104,10 @@ OPTIONS
Specify path to the executable or shared library file for user
space tracing. Can also be used with --funcs option.

+In absence of -m/-x options, perf probe checks if the first argument after
+the options is an absolute path name. If its an absolute path, perf probe
+uses it as a target module/target user space binary to probe.
+
PROBE SYNTAX
------------
Probe points are defined by following syntax.
@@ -190,11 +194,11 @@ Delete all probes on schedule().

Add probes at zfree() function on /bin/zsh

- ./perf probe -x /bin/zsh zfree
+ ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree

Add probes at malloc() function on libc

- ./perf probe -x /lib/libc.so.6 malloc
+ ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc

SEE ALSO
--------
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index ee3d84a..e215ae6 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -85,21 +85,58 @@ static int parse_probe_event(const char *str)
return ret;
}

+static int set_target(const char *ptr)
+{
+ int found = 0;
+ const char *buf;
+
+ /*
+ * The first argument after options can be an absolute path
+ * to an executable / library or kernel module.
+ *
+ * TODO: Support relative path, and $PATH, $LD_LIBRARY_PATH,
+ * short module name.
+ */
+ if (!params.target && ptr && *ptr == '/') {
+ params.target = ptr;
+ found = 1;
+ buf = ptr + (strlen(ptr) - 3);
+
+ if (strcmp(buf, ".ko"))
+ params.uprobes = true;
+
+ }
+
+ return found;
+}
+
static int parse_probe_event_argv(int argc, const char **argv)
{
- int i, len, ret;
+ int i, len, ret, found_target;
char *buf;

+ found_target = set_target(argv[0]);
+ if (found_target && argc == 1)
+ return 0;
+
/* Bind up rest arguments */
len = 0;
- for (i = 0; i < argc; i++)
+ for (i = 0; i < argc; i++) {
+ if (i == 0 && found_target)
+ continue;
+
len += strlen(argv[i]) + 1;
+ }
buf = zalloc(len + 1);
if (buf == NULL)
return -ENOMEM;
len = 0;
- for (i = 0; i < argc; i++)
+ for (i = 0; i < argc; i++) {
+ if (i == 0 && found_target)
+ continue;
+
len += sprintf(&buf[len], "%s ", argv[i]);
+ }
params.mod_events = true;
ret = parse_probe_event(buf);
free(buf);



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