[PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[Jiri Olsa]

Recent commit [1] changed branch stack data indication from
br_stack pointer to sample_flags in perf_sample_data struct.

We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
bit for valid branch stack data.

[1] a9a931e26668 ("perf: Use sample_flags for branch stack")

Cc: Kan Liang <kan.liang@linux.intel.com>
Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
NOTE sending on top of tip/master because [1] is not
     merged in bpf-next/master yet

 kernel/trace/bpf_trace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd24cef..1fcd1234607e 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1507,6 +1507,9 @@ BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
 	if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
 		return -EINVAL;
 
+	if (unlikely(!(ctx->data->sample_flags & PERF_SAMPLE_BRANCH_STACK)))
+		return -ENOENT;
+
 	if (unlikely(!br_stack))
 		return -ENOENT;
 
-- 
2.37.3

Re: [PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[Liang, Kan]

On 2022-09-27 4:32 p.m., Jiri Olsa wrote:
> Recent commit [1] changed branch stack data indication from
> br_stack pointer to sample_flags in perf_sample_data struct.
> 
> We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
> bit for valid branch stack data.
> 
> [1] a9a931e26668 ("perf: Use sample_flags for branch stack")
> 
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Thanks for the fix.

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>

Thanks,
Kan

> ---
> NOTE sending on top of tip/master because [1] is not
>      merged in bpf-next/master yet
> 
>  kernel/trace/bpf_trace.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 68e5cdd24cef..1fcd1234607e 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1507,6 +1507,9 @@ BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
>  	if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
>  		return -EINVAL;
>  
> +	if (unlikely(!(ctx->data->sample_flags & PERF_SAMPLE_BRANCH_STACK)))
> +		return -ENOENT;
> +
>  	if (unlikely(!br_stack))
>  		return -ENOENT;
>  

Re: [PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[Peter Zijlstra]

On Tue, Sep 27, 2022 at 10:32:59PM +0200, Jiri Olsa wrote:
> Recent commit [1] changed branch stack data indication from
> br_stack pointer to sample_flags in perf_sample_data struct.
> 
> We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
> bit for valid branch stack data.
> 
> [1] a9a931e26668 ("perf: Use sample_flags for branch stack")
> 
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> NOTE sending on top of tip/master because [1] is not
>      merged in bpf-next/master yet

Shall I stick this in tip/perf/core right along with [1] then?

Re: [PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[Jiri Olsa]

On Tue, Sep 27, 2022 at 10:46:12PM +0200, Peter Zijlstra wrote:
> On Tue, Sep 27, 2022 at 10:32:59PM +0200, Jiri Olsa wrote:
> > Recent commit [1] changed branch stack data indication from
> > br_stack pointer to sample_flags in perf_sample_data struct.
> > 
> > We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
> > bit for valid branch stack data.
> > 
> > [1] a9a931e26668 ("perf: Use sample_flags for branch stack")
> > 
> > Cc: Kan Liang <kan.liang@linux.intel.com>
> > Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > NOTE sending on top of tip/master because [1] is not
> >      merged in bpf-next/master yet
> 
> Shall I stick this in tip/perf/core right along with [1] then?

yes, sounds good

thanks,
jirka

Re: [PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[Song Liu]

> On Sep 27, 2022, at 1:32 PM, Jiri Olsa <jolsa@kernel.org> wrote:
> 
> Recent commit [1] changed branch stack data indication from
> br_stack pointer to sample_flags in perf_sample_data struct.
> 
> We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
> bit for valid branch stack data.
> 
> [1] a9a931e26668 ("perf: Use sample_flags for branch stack")
> 
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Thanks for the fix! I noticed the issue last week, but haven't
got time to look into it. 

Song

> ---
> NOTE sending on top of tip/master because [1] is not
>     merged in bpf-next/master yet
> 
> kernel/trace/bpf_trace.c | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 68e5cdd24cef..1fcd1234607e 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1507,6 +1507,9 @@ BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
> 	if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
> 		return -EINVAL;
> 
> +	if (unlikely(!(ctx->data->sample_flags & PERF_SAMPLE_BRANCH_STACK)))
> +		return -ENOENT;
> +
> 	if (unlikely(!br_stack))
> 		return -ENOENT;
> 
> -- 
> 2.37.3
> 

Re: [PATCH -tip] bpf: Check flags for branch stack in bpf_read_branch_records helper

[Song Liu]

> On Sep 27, 2022, at 2:49 PM, Song Liu <songliubraving@fb.com> wrote:
> 
> 
> 
>> On Sep 27, 2022, at 1:32 PM, Jiri Olsa <jolsa@kernel.org> wrote:
>> 
>> Recent commit [1] changed branch stack data indication from
>> br_stack pointer to sample_flags in perf_sample_data struct.
>> 
>> We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
>> bit for valid branch stack data.
>> 
>> [1] a9a931e26668 ("perf: Use sample_flags for branch stack")
>> 
>> Cc: Kan Liang <kan.liang@linux.intel.com>
>> Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
>> Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Acked-by: Song Liu <song@kernel.org>

> 
> Thanks for the fix! I noticed the issue last week, but haven't
> got time to look into it. 
> 
> Song
> 
>> ---
>> NOTE sending on top of tip/master because [1] is not
>>    merged in bpf-next/master yet
>> 
>> kernel/trace/bpf_trace.c | 3 +++
>> 1 file changed, 3 insertions(+)
>> 
>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
>> index 68e5cdd24cef..1fcd1234607e 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -1507,6 +1507,9 @@ BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
>> 	if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
>> 		return -EINVAL;
>> 
>> +	if (unlikely(!(ctx->data->sample_flags & PERF_SAMPLE_BRANCH_STACK)))
>> +		return -ENOENT;
>> +
>> 	if (unlikely(!br_stack))
>> 		return -ENOENT;
>> 
>> -- 
>> 2.37.3

[tip: perf/core] bpf: Check flags for branch stack in bpf_read_branch_records helper

[tip-bot2 for Jiri Olsa]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     cce6a2d7e0e494c453ad73e1e78bd50684f20cca
Gitweb:        https://git.kernel.org/tip/cce6a2d7e0e494c453ad73e1e78bd50684f20cca
Author:        Jiri Olsa <jolsa@kernel.org>
AuthorDate:    Tue, 27 Sep 2022 22:32:59 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 27 Sep 2022 22:50:25 +02:00

bpf: Check flags for branch stack in bpf_read_branch_records helper

Recent commit [1] changed branch stack data indication from
br_stack pointer to sample_flags in perf_sample_data struct.

We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
bit for valid branch stack data.

[1] a9a931e26668 ("perf: Use sample_flags for branch stack")

Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20220927203259.590950-1-jolsa@kernel.org
---
 kernel/trace/bpf_trace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd..1fcd123 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1507,6 +1507,9 @@ BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
 	if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
 		return -EINVAL;
 
+	if (unlikely(!(ctx->data->sample_flags & PERF_SAMPLE_BRANCH_STACK)))
+		return -ENOENT;
+
 	if (unlikely(!br_stack))
 		return -ENOENT;