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Message-ID: <20091007222740.1684.91170.stgit@dhcp-100-2-132.bos.redhat.com>
Date: Wed, 07 Oct 2009 18:27:40 -0400
From: Masami Hiramatsu <mhiramat@...hat.com>
To: Frederic Weisbecker <fweisbec@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...e.hu>,
lkml <linux-kernel@...r.kernel.org>
Cc: systemtap <systemtap@...rces.redhat.com>,
DLE <dle-develop@...ts.sourceforge.net>,
Masami Hiramatsu <mhiramat@...hat.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Ingo Molnar <mingo@...e.hu>,
Thomas Gleixner <tglx@...utronix.de>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Mike Galbraith <efault@....de>,
Paul Mackerras <paulus@...ba.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Christoph Hellwig <hch@...radead.org>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Jim Keniston <jkenisto@...ibm.com>,
"Frank Ch. Eigler" <fche@...hat.com>
Subject: [PATCH tracing/kprobes v3 1/7] tracing/kprobes: Add $ prefix to
special variables
Add $ prefix to the special variables(e.g. sa, rv) of kprobe-tracer.
This resolves consistency issue between kprobe_events and perf-kprobe.
Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Mike Galbraith <efault@....de>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Jim Keniston <jkenisto@...ibm.com>
Cc: Frank Ch. Eigler <fche@...hat.com>
---
Documentation/trace/kprobetrace.txt | 20 ++++++------
kernel/trace/trace_kprobe.c | 60 ++++++++++++++++++++++-------------
2 files changed, 47 insertions(+), 33 deletions(-)
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index 9b8f7c6..33f5318 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -36,13 +36,13 @@ Synopsis of kprobe_events
FETCHARGS : Arguments. Each probe can have up to 128 args.
%REG : Fetch register REG
- sN : Fetch Nth entry of stack (N >= 0)
- sa : Fetch stack address.
@ADDR : Fetch memory at ADDR (ADDR should be in kernel)
@SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
- aN : Fetch function argument. (N >= 0)(*)
- rv : Fetch return value.(**)
- ra : Fetch return address.(**)
+ $sN : Fetch Nth entry of stack (N >= 0)
+ $sa : Fetch stack address.
+ $aN : Fetch function argument. (N >= 0)(*)
+ $rv : Fetch return value.(**)
+ $ra : Fetch return address.(**)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***)
NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
@@ -85,13 +85,13 @@ Usage examples
To add a probe as a new event, write a new definition to kprobe_events
as below.
- echo p:myprobe do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > /sys/kernel/debug/tracing/kprobe_events
+ echo p:myprobe do_sys_open dfd=$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. 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
+ echo r:myretprobe do_sys_open $rv $ra >> /sys/kernel/debug/tracing/kprobe_events
This sets a kretprobe on the return point of do_sys_open() function with
recording return value and return address as "myretprobe" event.
@@ -138,11 +138,11 @@ events, you need to enable it.
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
<...>-1447 [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0
- <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) rv=fffffffffffffffe ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe $ra=ffffffff81367a3a
<...>-1447 [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6
- <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a
<...>-1447 [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10
- <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) rv=3 ra=ffffffff81367a3a
+ <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 $ra=ffffffff81367a3a
Each line shows when the kernel hits an event, and <- SYMBOL means kernel
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 97309d4..f63ead0 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -220,24 +220,24 @@ static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
int ret = -EINVAL;
if (ff->func == fetch_argument)
- ret = snprintf(buf, n, "a%lu", (unsigned long)ff->data);
+ ret = snprintf(buf, n, "$a%lu", (unsigned long)ff->data);
else if (ff->func == fetch_register) {
const char *name;
name = regs_query_register_name((unsigned int)((long)ff->data));
ret = snprintf(buf, n, "%%%s", name);
} else if (ff->func == fetch_stack)
- ret = snprintf(buf, n, "s%lu", (unsigned long)ff->data);
+ ret = snprintf(buf, n, "$s%lu", (unsigned long)ff->data);
else if (ff->func == fetch_memory)
ret = snprintf(buf, n, "@0x%p", ff->data);
else if (ff->func == fetch_symbol) {
struct symbol_cache *sc = ff->data;
ret = snprintf(buf, n, "@%s%+ld", sc->symbol, sc->offset);
} else if (ff->func == fetch_retvalue)
- ret = snprintf(buf, n, "rv");
+ ret = snprintf(buf, n, "$rv");
else if (ff->func == fetch_ip)
- ret = snprintf(buf, n, "ra");
+ ret = snprintf(buf, n, "$ra");
else if (ff->func == fetch_stack_address)
- ret = snprintf(buf, n, "sa");
+ ret = snprintf(buf, n, "$sa");
else if (ff->func == fetch_indirect) {
struct indirect_fetch_data *id = ff->data;
size_t l = 0;
@@ -429,12 +429,10 @@ static int split_symbol_offset(char *symbol, unsigned long *offset)
#define PARAM_MAX_ARGS 16
#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
-static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+static int parse_probe_vars(char *arg, struct fetch_func *ff, int is_return)
{
int ret = 0;
unsigned long param;
- long offset;
- char *tmp;
switch (arg[0]) {
case 'a': /* argument */
@@ -456,14 +454,6 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
} else
ret = -EINVAL;
break;
- case '%': /* named register */
- ret = regs_query_register_offset(arg + 1);
- if (ret >= 0) {
- ff->func = fetch_register;
- ff->data = (void *)(unsigned long)ret;
- ret = 0;
- }
- break;
case 's': /* stack */
if (arg[1] == 'a') {
ff->func = fetch_stack_address;
@@ -478,6 +468,31 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
}
}
break;
+ default:
+ ret = -EINVAL;
+ }
+ return ret;
+}
+
+static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
+{
+ int ret = 0;
+ unsigned long param;
+ long offset;
+ char *tmp;
+
+ switch (arg[0]) {
+ case '$':
+ ret = parse_probe_vars(arg + 1, ff, is_return);
+ break;
+ case '%': /* named register */
+ ret = regs_query_register_offset(arg + 1);
+ if (ret >= 0) {
+ ff->func = fetch_register;
+ ff->data = (void *)(unsigned long)ret;
+ ret = 0;
+ }
+ break;
case '@': /* memory or symbol */
if (isdigit(arg[1])) {
ret = strict_strtoul(arg + 1, 0, ¶m);
@@ -489,8 +504,7 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
ret = split_symbol_offset(arg + 1, &offset);
if (ret)
break;
- ff->data = alloc_symbol_cache(arg + 1,
- offset);
+ ff->data = alloc_symbol_cache(arg + 1, offset);
if (ff->data)
ff->func = fetch_symbol;
else
@@ -544,11 +558,11 @@ static int create_trace_probe(int argc, char **argv)
* - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
* - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
* Fetch args:
- * aN : fetch Nth of function argument. (N:0-)
- * rv : fetch return value
- * ra : fetch return address
- * sa : fetch stack address
- * sN : fetch Nth of stack (N:0-)
+ * $aN : fetch Nth of function argument. (N:0-)
+ * $rv : fetch return value
+ * $ra : fetch return address
+ * $sa : fetch stack address
+ * $sN : fetch Nth of stack (N:0-)
* @ADDR : fetch memory at ADDR (ADDR should be in kernel)
* @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
* %REG : fetch register REG
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@...hat.com
--
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