[PATCH -tip v14 09/12] tracing: Kprobe-tracer supports more than 6 arguments

Masami Hiramatsu
2009-08-13T20:34:33Z

Support up to 128 arguments for each kprobes event.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it>
Cc: Roland McGrath <roland@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
---

Documentation/trace/kprobetrace.txt | 2 +-
kernel/trace/trace_kprobe.c | 21 +++++++++++++--------
2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index efff6eb..c9c09b4 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -32,7 +32,7 @@ Synopsis of kprobe_events
SYMBOL[+offs|-offs] : Symbol+offset where the probe is inserted.
MEMADDR : Address where the probe is inserted.

- FETCHARGS : Arguments.
+ 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.
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d92877a..4704e40 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -32,7 +32,7 @@
#include "trace.h"
#include "trace_output.h"

-#define TRACE_KPROBE_ARGS 6
+#define MAX_TRACE_ARGS 128
#define MAX_ARGSTR_LEN 63

/* currently, trace_kprobe only supports X86. */
@@ -184,11 +184,15 @@ struct trace_probe {
struct kretprobe rp;
};
const char *symbol; /* symbol name */
- unsigned int nr_args;
- struct fetch_func args[TRACE_KPROBE_ARGS];
struct ftrace_event_call call;
+ unsigned int nr_args;
+ struct fetch_func args[];
};

+#define SIZEOF_TRACE_PROBE(n) \
+ (offsetof(struct trace_probe, args) + \
+ (sizeof(struct fetch_func) * (n)))
+
static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_trace_func(struct kretprobe_instance *ri,
struct pt_regs *regs);
@@ -263,11 +267,11 @@ static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);

static struct trace_probe *alloc_trace_probe(const char *symbol,
- const char *event)
+ const char *event, int nargs)
{
struct trace_probe *tp;

- tp = kzalloc(sizeof(struct trace_probe), GFP_KERNEL);
+ tp = kzalloc(SIZEOF_TRACE_PROBE(nargs), GFP_KERNEL);
if (!tp)
return ERR_PTR(-ENOMEM);

@@ -573,9 +577,10 @@ static int create_trace_probe(int argc, char **argv)
if (offset && is_return)
return -EINVAL;
}
+ argc -= 2; argv += 2;

/* setup a probe */
- tp = alloc_trace_probe(symbol, event);
+ tp = alloc_trace_probe(symbol, event, argc);
if (IS_ERR(tp))
return PTR_ERR(tp);

@@ -594,8 +599,8 @@ static int create_trace_probe(int argc, char **argv)
kp->addr = addr;

/* parse arguments */
- argc -= 2; argv += 2; ret = 0;
- for (i = 0; i < argc && i < TRACE_KPROBE_ARGS; i++) {
+ 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]);
ret = -ENOSPC;