2017-06-22 09:24:52

by Sabrina Dubroca

Subject: [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

Always try to parse an address, since kstrtoul() will safely fail when
given a symbol as input. If that fails (which will be the case for a
symbol), try to parse a symbol instead.

This allows creating a probe such as:

p:probe/vlan_gro_receive 8021q:vlan_gro_receive+0

Which is necessary for this command to work:

perf probe -m 8021q -a vlan_gro_receive

Signed-off-by: Sabrina Dubroca <[email protected]>
---
kernel/trace/trace_kprobe.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c129fca6ec99..b53c8d369163 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -707,20 +707,16 @@ static int create_trace_kprobe(int argc, char **argv)
pr_info("Probe point is not specified.\n");
return -EINVAL;
}
- if (isdigit(argv[1][0])) {
- /* an address specified */
- ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
- if (ret) {
- pr_info("Failed to parse address.\n");
- return ret;
- }
- } else {
+
+ /* try to parse an address. if that fails, try to read the
+ * input as a symbol. */
+ if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
/* a symbol specified */
symbol = argv[1];
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret) {
- pr_info("Failed to parse symbol.\n");
+ pr_info("Failed to parse either an address or a symbol.\n");
return ret;
}
if (offset && is_return &&
--
2.13.1

2017-06-27 08:39:32

by Masami Hiramatsu

Subject: Re: [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

On Thu, 22 Jun 2017 11:24:42 +0200
Sabrina Dubroca <[email protected]> wrote:

> Always try to parse an address, since kstrtoul() will safely fail when
> given a symbol as input. If that fails (which will be the case for a
> symbol), try to parse a symbol instead.
>
> This allows creating a probe such as:
>
> p:probe/vlan_gro_receive 8021q:vlan_gro_receive+0
>
> Which is necessary for this command to work:
>
> perf probe -m 8021q -a vlan_gro_receive
>

Ah, I forgot that case.
Nice catch!

Acked-by: Masami Hiramatsu <[email protected]>

Thanks!

> Signed-off-by: Sabrina Dubroca <[email protected]>
> ---
> kernel/trace/trace_kprobe.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index c129fca6ec99..b53c8d369163 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -707,20 +707,16 @@ static int create_trace_kprobe(int argc, char **argv)
> pr_info("Probe point is not specified.\n");
> return -EINVAL;
> }
> - if (isdigit(argv[1][0])) {
> - /* an address specified */
> - ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
> - if (ret) {
> - pr_info("Failed to parse address.\n");
> - return ret;
> - }
> - } else {
> +
> + /* try to parse an address. if that fails, try to read the
> + * input as a symbol. */
> + if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
> /* a symbol specified */
> symbol = argv[1];
> /* TODO: support .init module functions */
> ret = traceprobe_split_symbol_offset(symbol, &offset);
> if (ret) {
> - pr_info("Failed to parse symbol.\n");
> + pr_info("Failed to parse either an address or a symbol.\n");
> return ret;
> }
> if (offset && is_return &&
> --
> 2.13.1
>


--
Masami Hiramatsu <[email protected]>

2017-06-27 14:07:53

by Steven Rostedt

Subject: Re: [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

On Tue, 27 Jun 2017 17:38:30 +0900
Masami Hiramatsu <[email protected]> wrote:

> On Thu, 22 Jun 2017 11:24:42 +0200
> Sabrina Dubroca <[email protected]> wrote:
>
> > Always try to parse an address, since kstrtoul() will safely fail when
> > given a symbol as input. If that fails (which will be the case for a
> > symbol), try to parse a symbol instead.
> >
> > This allows creating a probe such as:
> >
> > p:probe/vlan_gro_receive 8021q:vlan_gro_receive+0
> >
> > Which is necessary for this command to work:
> >
> > perf probe -m 8021q -a vlan_gro_receive
> >
>
> Ah, I forgot that case.
> Nice catch!
>
> Acked-by: Masami Hiramatsu <[email protected]>
>

Thanks Masami,

I can take this. Should this go to stable?

-- Steve

2017-06-27 22:05:34

by Masami Hiramatsu

Subject: Re: [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

On Tue, 27 Jun 2017 10:07:45 -0400
Steven Rostedt <[email protected]> wrote:

> On Tue, 27 Jun 2017 17:38:30 +0900
> Masami Hiramatsu <[email protected]> wrote:
>
> > On Thu, 22 Jun 2017 11:24:42 +0200
> > Sabrina Dubroca <[email protected]> wrote:
> >
> > > Always try to parse an address, since kstrtoul() will safely fail when
> > > given a symbol as input. If that fails (which will be the case for a
> > > symbol), try to parse a symbol instead.
> > >
> > > This allows creating a probe such as:
> > >
> > > p:probe/vlan_gro_receive 8021q:vlan_gro_receive+0
> > >
> > > Which is necessary for this command to work:
> > >
> > > perf probe -m 8021q -a vlan_gro_receive
> > >
> >
> > Ah, I forgot that case.
> > Nice catch!
> >
> > Acked-by: Masami Hiramatsu <[email protected]>
> >
>
> Thanks Masami,
>
> I can take this. Should this go to stable?

Yes, it should go to stable.

Thank you,

--
Masami Hiramatsu <[email protected]>