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[PATCH 0/2] A couple of small updates/fixes for kprobes tracer

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  [PATCH 0/2] A couple of small updates/fixes for kprobes tracer "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-06-21 21:00 +0200
    [PATCH 1/2] trace/kprobes: Sanitize derived event names "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-06-21 21:00 +0200
      Re: [PATCH 1/2] trace/kprobes: Sanitize derived event names Masami Hiramatsu <mhiramat@kernel.org> - 2017-06-22 11:40 +0200
        Re: [PATCH 1/2] trace/kprobes: Sanitize derived event names "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-06-22 21:10 +0200
          Re: [PATCH 1/2] trace/kprobes: Sanitize derived event names Masami Hiramatsu <mhiramat@kernel.org> - 2017-06-23 19:40 +0200

#1671952 — [PATCH 0/2] A couple of small updates/fixes for kprobes tracer

Two simple updates for kprobes tracer:
- the first patch is a convenience and allows to probe module symbols
  as well as any dot symbols (necessary on powerpc64 elfv1) without
  having to provide a name for the probepoint.
- the second patch updates the newly added multiple_kprobes.tc test
  case for powerpc.

Thanks,
Naveen

Naveen N. Rao (2):
  trace/kprobes: Sanitize derived event names
  selftests/ftrace: Update multiple kprobes test for powerpc

 kernel/trace/trace_kprobe.c                                      | 9 +++++++++
 tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc | 8 ++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

-- 
2.13.1

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#1671953 — [PATCH 1/2] trace/kprobes: Sanitize derived event names

When we derive event names, convert some expected symbols (such as ':'
used to specify module:name and '.' present in some symbols) into
underscores so that the event name is not rejected.

Before this patch:
    # echo 'p kobject_example:foo_store' > kprobe_events
    trace_kprobe: Failed to allocate trace_probe.(-22)
    -sh: write error: Invalid argument

After this patch:
    # echo 'p kobject_example:foo_store' > kprobe_events
    # cat kprobe_events
    p:kprobes/p_kobject_example_foo_store_0 kobject_example:foo_store

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 kernel/trace/trace_kprobe.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c129fca6ec99..44fd819aa33d 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -598,6 +598,14 @@ static struct notifier_block trace_kprobe_module_nb = {
 	.priority = 1	/* Invoked after kprobe module callback */
 };
 
+/* Convert certain expected symbols into '_' when generating event names */
+static inline void sanitize_event_name(char *name)
+{
+	while (*name++ != '\0')
+		if (*name == ':' || *name == '.')
+			*name = '_';
+}
+
 static int create_trace_kprobe(int argc, char **argv)
 {
 	/*
@@ -740,6 +748,7 @@ static int create_trace_kprobe(int argc, char **argv)
 		else
 			snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
 				 is_return ? 'r' : 'p', addr);
+		sanitize_event_name(buf);
 		event = buf;
 	}
 	tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
-- 
2.13.1

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#1672470 — Re: [PATCH 1/2] trace/kprobes: Sanitize derived event names

On Thu, 22 Jun 2017 00:20:27 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> When we derive event names, convert some expected symbols (such as ':'
> used to specify module:name and '.' present in some symbols) into
> underscores so that the event name is not rejected.

Oops, ok, this is my mistake.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

This must be marked as bugfix for stable trees.

Could you also add a testcase for this (module name) bug?

MODNAME=`lsmod | head -n 2 | tail -n 1 | cut -f 1 -d " "`
FUNCNAME=`grep -m 1 "\\[$MODNAME\\]" /proc/kallsyms | xargs | cut -f 3 -d " "`

May gives you a target name :)

Thank you,

> 
> Before this patch:
>     # echo 'p kobject_example:foo_store' > kprobe_events
>     trace_kprobe: Failed to allocate trace_probe.(-22)
>     -sh: write error: Invalid argument
> 
> After this patch:
>     # echo 'p kobject_example:foo_store' > kprobe_events
>     # cat kprobe_events
>     p:kprobes/p_kobject_example_foo_store_0 kobject_example:foo_store
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> ---
>  kernel/trace/trace_kprobe.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index c129fca6ec99..44fd819aa33d 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -598,6 +598,14 @@ static struct notifier_block trace_kprobe_module_nb = {
>  	.priority = 1	/* Invoked after kprobe module callback */
>  };
>  
> +/* Convert certain expected symbols into '_' when generating event names */
> +static inline void sanitize_event_name(char *name)
> +{
> +	while (*name++ != '\0')
> +		if (*name == ':' || *name == '.')
> +			*name = '_';
> +}
> +
>  static int create_trace_kprobe(int argc, char **argv)
>  {
>  	/*
> @@ -740,6 +748,7 @@ static int create_trace_kprobe(int argc, char **argv)
>  		else
>  			snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
>  				 is_return ? 'r' : 'p', addr);
> +		sanitize_event_name(buf);
>  		event = buf;
>  	}
>  	tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
> -- 
> 2.13.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

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#1672969 — Re: [PATCH 1/2] trace/kprobes: Sanitize derived event names

On 2017/06/22 06:29PM, Masami Hiramatsu wrote:
> On Thu, 22 Jun 2017 00:20:27 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> 
> > When we derive event names, convert some expected symbols (such as ':'
> > used to specify module:name and '.' present in some symbols) into
> > underscores so that the event name is not rejected.
> 
> Oops, ok, this is my mistake.
> 
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> 
> This must be marked as bugfix for stable trees.
> 
> Could you also add a testcase for this (module name) bug?
> 
> MODNAME=`lsmod | head -n 2 | tail -n 1 | cut -f 1 -d " "`
> FUNCNAME=`grep -m 1 "\\[$MODNAME\\]" /proc/kallsyms | xargs | cut -f 3 -d " "`
> 
> May gives you a target name :)

Sure. Here is a test.

Thanks for the review,
Naveen

-
[PATCH] selftests/ftrace: Add a test to probe module functions

Add a kprobes test to ensure that we are able to add a probe on a
module function using 'p <mod>:<func>' format, without having to
specify a probe name.

Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 .../testing/selftests/ftrace/test.d/kprobe/probe_module.tc | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc

diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc b/tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc
new file mode 100644
index 000000000000..ea7657041ba6
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc
@@ -0,0 +1,14 @@
+#!/bin/sh
+# description: Kprobe dynamic event - probing module
+
+[ -f kprobe_events ] || exit_unsupported # this is configurable
+
+echo 0 > events/enable
+echo > kprobe_events
+export MOD=`lsmod | head -n 2 | tail -n 1 | cut -f1 -d" "`
+export FUNC=`grep -m 1 ".* t .*\\[$MOD\\]" /proc/kallsyms | xargs | cut -f3 -d" "`
+[ "x" != "x$MOD" -a "y" != "y$FUNC" ] || exit_untested
+echo p $MOD:$FUNC > kprobe_events
+grep $MOD kprobe_events
+echo > kprobe_events
+clear_trace
-- 
2.13.1

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#1673709 — Re: [PATCH 1/2] trace/kprobes: Sanitize derived event names

On Fri, 23 Jun 2017 00:33:45 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> On 2017/06/22 06:29PM, Masami Hiramatsu wrote:
> > On Thu, 22 Jun 2017 00:20:27 +0530
> > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> > 
> > > When we derive event names, convert some expected symbols (such as ':'
> > > used to specify module:name and '.' present in some symbols) into
> > > underscores so that the event name is not rejected.
> > 
> > Oops, ok, this is my mistake.
> > 
> > Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> > 
> > This must be marked as bugfix for stable trees.
> > 
> > Could you also add a testcase for this (module name) bug?
> > 
> > MODNAME=`lsmod | head -n 2 | tail -n 1 | cut -f 1 -d " "`
> > FUNCNAME=`grep -m 1 "\\[$MODNAME\\]" /proc/kallsyms | xargs | cut -f 3 -d " "`
> > 
> > May gives you a target name :)
> 
> Sure. Here is a test.
> 
> Thanks for the review,
> Naveen
> 
> -
> [PATCH] selftests/ftrace: Add a test to probe module functions
> 
> Add a kprobes test to ensure that we are able to add a probe on a
> module function using 'p <mod>:<func>' format, without having to
> specify a probe name.
> 
> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Perfect! :)

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks!

> ---
>  .../testing/selftests/ftrace/test.d/kprobe/probe_module.tc | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>  create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc b/tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc
> new file mode 100644
> index 000000000000..ea7657041ba6
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/probe_module.tc
> @@ -0,0 +1,14 @@
> +#!/bin/sh
> +# description: Kprobe dynamic event - probing module
> +
> +[ -f kprobe_events ] || exit_unsupported # this is configurable
> +
> +echo 0 > events/enable
> +echo > kprobe_events
> +export MOD=`lsmod | head -n 2 | tail -n 1 | cut -f1 -d" "`
> +export FUNC=`grep -m 1 ".* t .*\\[$MOD\\]" /proc/kallsyms | xargs | cut -f3 -d" "`
> +[ "x" != "x$MOD" -a "y" != "y$FUNC" ] || exit_untested
> +echo p $MOD:$FUNC > kprobe_events
> +grep $MOD kprobe_events
> +echo > kprobe_events
> +clear_trace
> -- 
> 2.13.1
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

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