[tip:perf/probes] tracing/kprobes: Add argument name support
From: tip-bot for Masami Hiramatsu
Date: Sat Oct 17 2009 - 06:00:57 EST
Commit-ID: eca0d916f6429785bbc88db3ff66631cde62b432
Gitweb: http://git.kernel.org/tip/eca0d916f6429785bbc88db3ff66631cde62b432
Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Thu, 10 Sep 2009 19:53:38 -0400
Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CommitDate: Fri, 11 Sep 2009 06:08:00 +0200
tracing/kprobes: Add argument name support
Add argument name assignment support and remove "alias" lines from format.
This allows user to assign unique name to each argument. For example,
$ echo p do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > kprobe_events
This assigns dfd, filename, flags, and mode to 1st - 4th arguments
respectively. Trace buffer shows those names too.
<...>-1439 [000] 1200885.933147: do_sys_open+0x0/0xdf: dfd=ffffff9c filename=bfa898ac flags=8000 mode=0
This helps users to know what each value means.
Users can filter each events by these names too. Note that you can not
filter by argN anymore.
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Jim Keniston <jkenisto@xxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Frank Ch. Eigler <fche@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: K.Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Tom Zanussi <tzanussi@xxxxxxxxx>
LKML-Reference: <20090910235337.22412.77383.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
---
Documentation/trace/kprobetrace.txt | 46 ++++++-------
kernel/trace/trace_kprobe.c | 128 +++++++++++++++++-----------------
2 files changed, 84 insertions(+), 90 deletions(-)
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 8f882eb..aaa6c10 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -42,7 +42,8 @@ Synopsis of kprobe_events
aN : Fetch function argument. (N >= 0)(*)
rv : Fetch return value.(**)
ra : Fetch return address.(**)
- +|-offs(FETCHARG) : fetch memory at FETCHARG +|- offs address.(***)
+ +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
+ NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
(*) aN may not correct on asmlinkaged functions and at the middle of
function body.
@@ -62,12 +63,10 @@ enabled:
You can enable/disable the probe by writing 1 or 0 on it.
format:
- This shows the format of this probe event. It also shows aliases of arguments
- which you specified to kprobe_events.
+ This shows the format of this probe event.
filter:
- You can write filtering rules of this event. And you can use both of aliase
- names and field names for describing filters.
+ You can write filtering rules of this event.
id:
This shows the id of this probe event.
@@ -85,10 +84,11 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events
as below.
- echo p:myprobe do_sys_open a0 a1 a2 a3 > /sys/kernel/debug/tracing/kprobe_events
+ echo p:myprobe do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > /sys/kernel/debug/tracing/kprobe_events
This sets a kprobe on the top of do_sys_open() function with recording
-1st to 4th arguments as "myprobe" event.
+1st to 4th arguments as "myprobe" event. As this example shows, users can
+choose more familiar names for each arguments.
echo r:myretprobe do_sys_open rv ra >> /sys/kernel/debug/tracing/kprobe_events
@@ -99,7 +99,7 @@ recording return value and return address as "myretprobe" event.
cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format
name: myprobe
-ID: 23
+ID: 75
format:
field:unsigned short common_type; offset:0; size:2;
field:unsigned char common_flags; offset:2; size:1;
@@ -109,21 +109,15 @@ format:
field: unsigned long ip; offset:16;tsize:8;
field: int nargs; offset:24;tsize:4;
- field: unsigned long arg0; offset:32;tsize:8;
- field: unsigned long arg1; offset:40;tsize:8;
- field: unsigned long arg2; offset:48;tsize:8;
- field: unsigned long arg3; offset:56;tsize:8;
+ field: unsigned long dfd; offset:32;tsize:8;
+ field: unsigned long filename; offset:40;tsize:8;
+ field: unsigned long flags; offset:48;tsize:8;
+ field: unsigned long mode; offset:56;tsize:8;
- alias: a0; original: arg0;
- alias: a1; original: arg1;
- alias: a2; original: arg2;
- alias: a3; original: arg3;
+print fmt: "%lx: dfd=%lx filename=%lx flags=%lx mode=%lx", ip, REC->dfd, REC->filename, REC->flags, REC->mode
-print fmt: "%lx: 0x%lx 0x%lx 0x%lx 0x%lx", ip, arg0, arg1, arg2, arg3
-
- You can see that the event has 4 arguments and alias expressions
-corresponding to it.
+ You can see that the event has 4 arguments as in the expressions you specified.
echo > /sys/kernel/debug/tracing/kprobe_events
@@ -135,12 +129,12 @@ corresponding to it.
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
- <...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: 0x3 0x7fffd1ec4440 0x8000 0x0
- <...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: 0xfffffffffffffffe 0xffffffff81367a3a
- <...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: 0xffffff9c 0x40413c 0x8000 0x1b6
- <...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a
- <...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: 0xffffff9c 0x4041c6 0x98800 0x10
- <...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a
+ <...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
+ <...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: rv=fffffffffffffffe ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=40413c flags=8000 mode=1b6
+ <...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=4041c6 flags=98800 mode=10
+ <...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a
Each line shows when the kernel hits a probe, and <- SYMBOL means kernel
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 730e992..44dad1a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -176,9 +176,14 @@ static __kprobes void free_indirect_fetch_data(struct indirect_fetch_data *data)
}
/**
- * kprobe_trace_core
+ * Kprobe tracer core functions
*/
+struct probe_arg {
+ struct fetch_func fetch;
+ const char *name;
+};
+
struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
@@ -187,12 +192,12 @@ struct trace_probe {
struct ftrace_event_call call;
struct trace_event event;
unsigned int nr_args;
- struct fetch_func args[];
+ struct probe_arg args[];
};
#define SIZEOF_TRACE_PROBE(n) \
(offsetof(struct trace_probe, args) + \
- (sizeof(struct fetch_func) * (n)))
+ (sizeof(struct probe_arg) * (n)))
static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_trace_func(struct kretprobe_instance *ri,
@@ -301,15 +306,21 @@ error:
return ERR_PTR(-ENOMEM);
}
+static void free_probe_arg(struct probe_arg *arg)
+{
+ if (arg->fetch.func == fetch_symbol)
+ free_symbol_cache(arg->fetch.data);
+ else if (arg->fetch.func == fetch_indirect)
+ free_indirect_fetch_data(arg->fetch.data);
+ kfree(arg->name);
+}
+
static void free_trace_probe(struct trace_probe *tp)
{
int i;
for (i = 0; i < tp->nr_args; i++)
- if (tp->args[i].func == fetch_symbol)
- free_symbol_cache(tp->args[i].data);
- else if (tp->args[i].func == fetch_indirect)
- free_indirect_fetch_data(tp->args[i].data);
+ free_probe_arg(&tp->args[i]);
kfree(tp->call.name);
kfree(tp->symbol);
@@ -532,11 +543,13 @@ static int create_trace_probe(int argc, char **argv)
* %REG : fetch register REG
* Indirect memory fetch:
* +|-offs(ARG) : fetch memory at ARG +|- offs address.
+ * Alias name of args:
+ * NAME=FETCHARG : set NAME as alias of FETCHARG.
*/
struct trace_probe *tp;
int i, ret = 0;
int is_return = 0;
- char *symbol = NULL, *event = NULL;
+ char *symbol = NULL, *event = NULL, *arg = NULL;
unsigned long offset = 0;
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
@@ -596,12 +609,21 @@ static int create_trace_probe(int argc, char **argv)
/* parse arguments */
ret = 0;
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
- if (strlen(argv[i]) > MAX_ARGSTR_LEN) {
- pr_info("Argument%d(%s) is too long.\n", i, argv[i]);
+ /* Parse argument name */
+ arg = strchr(argv[i], '=');
+ if (arg)
+ *arg++ = '\0';
+ else
+ arg = argv[i];
+ tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+
+ /* Parse fetch argument */
+ if (strlen(arg) > MAX_ARGSTR_LEN) {
+ pr_info("Argument%d(%s) is too long.\n", i, arg);
ret = -ENOSPC;
goto error;
}
- ret = parse_probe_arg(argv[i], &tp->args[i], is_return);
+ ret = parse_probe_arg(arg, &tp->args[i].fetch, is_return);
if (ret)
goto error;
}
@@ -664,12 +686,12 @@ static int probes_seq_show(struct seq_file *m, void *v)
seq_printf(m, " 0x%p", tp->rp.kp.addr);
for (i = 0; i < tp->nr_args; i++) {
- ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
+ ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i].fetch);
if (ret < 0) {
pr_warning("Argument%d decoding error(%d).\n", i, ret);
return ret;
}
- seq_printf(m, " %s", buf);
+ seq_printf(m, " %s=%s", tp->args[i].name, buf);
}
seq_printf(m, "\n");
return 0;
@@ -824,7 +846,7 @@ static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
entry->nargs = tp->nr_args;
entry->ip = (unsigned long)kp->addr;
for (i = 0; i < tp->nr_args; i++)
- entry->args[i] = call_fetch(&tp->args[i], regs);
+ entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
if (!filter_current_check_discard(buffer, call, entry, event))
trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
@@ -858,7 +880,7 @@ static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,
entry->func = (unsigned long)tp->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
for (i = 0; i < tp->nr_args; i++)
- entry->args[i] = call_fetch(&tp->args[i], regs);
+ entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
if (!filter_current_check_discard(buffer, call, entry, event))
trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
@@ -872,9 +894,13 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
{
struct kprobe_trace_entry *field;
struct trace_seq *s = &iter->seq;
+ struct trace_event *event;
+ struct trace_probe *tp;
int i;
field = (struct kprobe_trace_entry *)iter->ent;
+ event = ftrace_find_event(field->ent.type);
+ tp = container_of(event, struct trace_probe, event);
if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;
@@ -883,7 +909,8 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
goto partial;
for (i = 0; i < field->nargs; i++)
- if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
+ if (!trace_seq_printf(s, " %s=%lx",
+ tp->args[i].name, field->args[i]))
goto partial;
if (!trace_seq_puts(s, "\n"))
@@ -899,9 +926,13 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
{
struct kretprobe_trace_entry *field;
struct trace_seq *s = &iter->seq;
+ struct trace_event *event;
+ struct trace_probe *tp;
int i;
field = (struct kretprobe_trace_entry *)iter->ent;
+ event = ftrace_find_event(field->ent.type);
+ tp = container_of(event, struct trace_probe, event);
if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;
@@ -916,7 +947,8 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
goto partial;
for (i = 0; i < field->nargs; i++)
- if (!trace_seq_printf(s, " 0x%lx", field->args[i]))
+ if (!trace_seq_printf(s, " %s=%lx",
+ tp->args[i].name, field->args[i]))
goto partial;
if (!trace_seq_puts(s, "\n"))
@@ -972,7 +1004,6 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
struct kprobe_trace_entry field;
- char buf[MAX_ARGSTR_LEN + 1];
struct trace_probe *tp = (struct trace_probe *)event_call->data;
ret = trace_define_common_fields(event_call);
@@ -981,16 +1012,9 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
DEFINE_FIELD(unsigned long, ip, "ip", 0);
DEFINE_FIELD(int, nargs, "nargs", 1);
- for (i = 0; i < tp->nr_args; i++) {
- /* Set argN as a field */
- sprintf(buf, "arg%d", i);
- DEFINE_FIELD(unsigned long, args[i], buf, 0);
- /* Set argument string as an alias field */
- ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
- if (ret < 0)
- return ret;
- DEFINE_FIELD(unsigned long, args[i], buf, 0);
- }
+ /* Set argument names as fields */
+ for (i = 0; i < tp->nr_args; i++)
+ DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
return 0;
}
@@ -998,7 +1022,6 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
struct kretprobe_trace_entry field;
- char buf[MAX_ARGSTR_LEN + 1];
struct trace_probe *tp = (struct trace_probe *)event_call->data;
ret = trace_define_common_fields(event_call);
@@ -1008,16 +1031,9 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
DEFINE_FIELD(unsigned long, func, "func", 0);
DEFINE_FIELD(unsigned long, ret_ip, "ret_ip", 0);
DEFINE_FIELD(int, nargs, "nargs", 1);
- for (i = 0; i < tp->nr_args; i++) {
- /* Set argN as a field */
- sprintf(buf, "arg%d", i);
- DEFINE_FIELD(unsigned long, args[i], buf, 0);
- /* Set argument string as an alias field */
- ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
- if (ret < 0)
- return ret;
- DEFINE_FIELD(unsigned long, args[i], buf, 0);
- }
+ /* Set argument names as fields */
+ for (i = 0; i < tp->nr_args; i++)
+ DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
return 0;
}
@@ -1025,31 +1041,21 @@ static int __probe_event_show_format(struct trace_seq *s,
struct trace_probe *tp, const char *fmt,
const char *arg)
{
- int i, ret;
- char buf[MAX_ARGSTR_LEN + 1];
+ int i;
- /* Show aliases */
- for (i = 0; i < tp->nr_args; i++) {
- ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i]);
- if (ret < 0)
- return ret;
- if (!trace_seq_printf(s, "\talias: %s;\toriginal: arg%d;\n",
- buf, i))
- return 0;
- }
/* Show format */
if (!trace_seq_printf(s, "\nprint fmt: \"%s", fmt))
return 0;
for (i = 0; i < tp->nr_args; i++)
- if (!trace_seq_puts(s, " 0x%lx"))
+ if (!trace_seq_printf(s, " %s=%%lx", tp->args[i].name))
return 0;
if (!trace_seq_printf(s, "\", %s", arg))
return 0;
for (i = 0; i < tp->nr_args; i++)
- if (!trace_seq_printf(s, ", arg%d", i))
+ if (!trace_seq_printf(s, ", REC->%s", tp->args[i].name))
return 0;
return trace_seq_puts(s, "\n");
@@ -1071,17 +1077,14 @@ static int kprobe_event_show_format(struct ftrace_event_call *call,
{
struct kprobe_trace_entry field __attribute__((unused));
int ret, i;
- char buf[8];
struct trace_probe *tp = (struct trace_probe *)call->data;
SHOW_FIELD(unsigned long, ip, "ip");
SHOW_FIELD(int, nargs, "nargs");
/* Show fields */
- for (i = 0; i < tp->nr_args; i++) {
- sprintf(buf, "arg%d", i);
- SHOW_FIELD(unsigned long, args[i], buf);
- }
+ for (i = 0; i < tp->nr_args; i++)
+ SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");
return __probe_event_show_format(s, tp, "%lx:", "ip");
@@ -1092,7 +1095,6 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
{
struct kretprobe_trace_entry field __attribute__((unused));
int ret, i;
- char buf[8];
struct trace_probe *tp = (struct trace_probe *)call->data;
SHOW_FIELD(unsigned long, func, "func");
@@ -1100,10 +1102,8 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
SHOW_FIELD(int, nargs, "nargs");
/* Show fields */
- for (i = 0; i < tp->nr_args; i++) {
- sprintf(buf, "arg%d", i);
- SHOW_FIELD(unsigned long, args[i], buf);
- }
+ for (i = 0; i < tp->nr_args; i++)
+ SHOW_FIELD(unsigned long, args[i], tp->args[i].name);
trace_seq_puts(s, "\n");
return __probe_event_show_format(s, tp, "%lx <- %lx:",
@@ -1140,7 +1140,7 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
entry->nargs = tp->nr_args;
entry->ip = (unsigned long)kp->addr;
for (i = 0; i < tp->nr_args; i++)
- entry->args[i] = call_fetch(&tp->args[i], regs);
+ entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
perf_tpcounter_event(call->id, entry->ip, 1, entry, size);
} while (0);
return 0;
@@ -1175,7 +1175,7 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
entry->func = (unsigned long)tp->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
for (i = 0; i < tp->nr_args; i++)
- entry->args[i] = call_fetch(&tp->args[i], regs);
+ entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
perf_tpcounter_event(call->id, entry->ret_ip, 1, entry, size);
} while (0);
return 0;
--
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