[PATCH v1 1/2] perf callchain lbr: Make the leaf IP that of the sample

[PATCH v1 1/2] perf callchain lbr: Make the leaf IP that of the sample

[Ian Rogers]

The current IP of a leaf function when reported from a perf record
with "--call-graph lbr" is the "to" field of the LBR branch stack
record. The sample for the event being recorded may be further into
the function and there may be inlining information associated with
it. Rather than use the branch stack "to" field in this case switch to
the callchain appending the sample->ip and thereby allowing the inline
information to show.

Before this change:
```
$ perf record --call-graph lbr perf test -w inlineloop
...
$ perf script --fields +srcline
...
perf-inlineloop  467586  4649.344493:     950905 cpu_core/cycles/P:
           55dfda2829c0 parent+0x0 (perf)
 inlineloop.c:31
           55dfda282a96 inlineloop+0x86 (perf)
 inlineloop.c:47
           55dfda236420 run_workload+0x59 (perf)
 builtin-test.c:715
           55dfda236b03 cmd_test+0x413 (perf)
 builtin-test.c:825
...
```

After this change:
```
$ perf record --call-graph lbr perf test -w inlineloop
...
$ perf script --fields +srcline
...
perf-inlineloop  529703 11878.680815:     950905 cpu_core/cycles/P:
            555ce86be9e6 leaf+0x26
  inlineloop.c:20 (inlined)
            555ce86be9e6 middle+0x26
  inlineloop.c:27 (inlined)
            555ce86be9e6 parent+0x26 (perf)
  inlineloop.c:32
            555ce86bea96 inlineloop+0x86 (perf)
  inlineloop.c:47
            555ce8672420 run_workload+0x59 (perf)
  builtin-test.c:715
            555ce8672b03 cmd_test+0x413 (perf)
  builtin-test.c:825
...
```

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/machine.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 5b0f5a48ffd4..e76f8c86e62a 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2423,8 +2423,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
 	}
 
 	if (callee) {
-		/* Add LBR ip from first entries.to */
-		ip = entries[0].to;
+		/*
+		 * Set the (first) leaf function's IP to sample->ip (the
+		 * location of the sample) but if not recorded use entries.to
+		 */
+		if (sample->ip)
+			ip = sample->ip;
+		else
+			ip = entries[0].to;
 		flags = &entries[0].flags;
 		*branch_from = entries[0].from;
 		err = add_callchain_ip(thread, cursor, parent,
@@ -2477,8 +2483,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
 	}
 
 	if (lbr_nr > 0) {
-		/* Add LBR ip from first entries.to */
-		ip = entries[0].to;
+		/*
+		 * Set the (first) leaf function's IP to sample->ip (the
+		 * location of the sample) but if not recorded use entries.to
+		 */
+		if (sample->ip)
+			ip = sample->ip;
+		else
+			ip = entries[0].to;
 		flags = &entries[0].flags;
 		*branch_from = entries[0].from;
 		err = add_callchain_ip(thread, cursor, parent,
-- 
2.53.0.rc2.204.g2597b5adb4-goog

[PATCH v1 2/2] perf test addr2line_inlines: Ensure inline information shows on LBR leaves

[Ian Rogers]

Expand the addr2line inline function testing to also run for an LBR
callchain, skipping if LBR support isn't present.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/shell/addr2line_inlines.sh | 28 +++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/tools/perf/tests/shell/addr2line_inlines.sh b/tools/perf/tests/shell/addr2line_inlines.sh
index ce30d9c7e0bf..e8754ef2d7f2 100755
--- a/tools/perf/tests/shell/addr2line_inlines.sh
+++ b/tools/perf/tests/shell/addr2line_inlines.sh
@@ -61,8 +61,36 @@ test_dwarf() {
     fi
 }
 
+test_lbr() {
+    echo "Inline unwinding LBR verification test"
+    if [ ! -f /sys/bus/event_source/devices/cpu/caps/branches ] &&
+       [ ! -f /sys/bus/event_source/devices/cpu_core/caps/branches ]
+    then
+        echo "Skip: only x86 CPUs support LBR"
+        return
+    fi
+
+    # Record data. Currently only dwarf callchains support inlined functions.
+    perf record --call-graph lbr -e cycles:u -o "${perf_data}" -- perf test -w inlineloop 1
+
+    # Check output with inline (default) and srcline
+    perf script -i "${perf_data}" --fields +srcline > "${perf_script_txt}"
+
+    # Expect the leaf and middle functions to occur on lines in the 20s, with
+    # the non-inlined parent function on a line in the 30s.
+    if grep -q "inlineloop.c:2. (inlined)" "${perf_script_txt}" &&
+       grep -q "inlineloop.c:3.$" "${perf_script_txt}"
+    then
+        echo "Inline unwinding lbr verification test [Success]"
+    else
+        echo "Inline unwinding lbr verification test [Failed missing inlined functions]"
+        err=1
+    fi
+}
+
 test_fp
 test_dwarf
+test_lbr
 
 cleanup
 exit $err
-- 
2.53.0.rc2.204.g2597b5adb4-goog

Re: [PATCH v1 1/2] perf callchain lbr: Make the leaf IP that of the sample

[Andi Kleen]

> Signed-off-by: Ian Rogers <irogers@google.com>

Makes sense.

Reviewed-by: Andi Kleen <ak@linux.intel.com>

Re: [PATCH v1 1/2] perf callchain lbr: Make the leaf IP that of the sample

[Mi, Dapeng]

On 2/6/2026 4:56 AM, Ian Rogers wrote:
> The current IP of a leaf function when reported from a perf record
> with "--call-graph lbr" is the "to" field of the LBR branch stack
> record. The sample for the event being recorded may be further into
> the function and there may be inlining information associated with
> it. Rather than use the branch stack "to" field in this case switch to
> the callchain appending the sample->ip and thereby allowing the inline
> information to show.
>
> Before this change:
> ```
> $ perf record --call-graph lbr perf test -w inlineloop
> ...
> $ perf script --fields +srcline
> ...
> perf-inlineloop  467586  4649.344493:     950905 cpu_core/cycles/P:
>            55dfda2829c0 parent+0x0 (perf)
>  inlineloop.c:31
>            55dfda282a96 inlineloop+0x86 (perf)
>  inlineloop.c:47
>            55dfda236420 run_workload+0x59 (perf)
>  builtin-test.c:715
>            55dfda236b03 cmd_test+0x413 (perf)
>  builtin-test.c:825
> ...
> ```
>
> After this change:
> ```
> $ perf record --call-graph lbr perf test -w inlineloop
> ...
> $ perf script --fields +srcline
> ...
> perf-inlineloop  529703 11878.680815:     950905 cpu_core/cycles/P:
>             555ce86be9e6 leaf+0x26
>   inlineloop.c:20 (inlined)
>             555ce86be9e6 middle+0x26
>   inlineloop.c:27 (inlined)
>             555ce86be9e6 parent+0x26 (perf)
>   inlineloop.c:32
>             555ce86bea96 inlineloop+0x86 (perf)
>   inlineloop.c:47
>             555ce8672420 run_workload+0x59 (perf)
>   builtin-test.c:715
>             555ce8672b03 cmd_test+0x413 (perf)
>   builtin-test.c:825
> ...
> ```
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/machine.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 5b0f5a48ffd4..e76f8c86e62a 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2423,8 +2423,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
>  	}
>  
>  	if (callee) {
> -		/* Add LBR ip from first entries.to */
> -		ip = entries[0].to;
> +		/*
> +		 * Set the (first) leaf function's IP to sample->ip (the
> +		 * location of the sample) but if not recorded use entries.to
> +		 */
> +		if (sample->ip)
> +			ip = sample->ip;
> +		else
> +			ip = entries[0].to;
>  		flags = &entries[0].flags;
>  		*branch_from = entries[0].from;
>  		err = add_callchain_ip(thread, cursor, parent,
> @@ -2477,8 +2483,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
>  	}
>  
>  	if (lbr_nr > 0) {
> -		/* Add LBR ip from first entries.to */
> -		ip = entries[0].to;
> +		/*
> +		 * Set the (first) leaf function's IP to sample->ip (the
> +		 * location of the sample) but if not recorded use entries.to
> +		 */
> +		if (sample->ip)
> +			ip = sample->ip;
> +		else
> +			ip = entries[0].to;
>  		flags = &entries[0].flags;
>  		*branch_from = entries[0].from;
>  		err = add_callchain_ip(thread, cursor, parent,

LGTM. Thanks.

Re: [PATCH v1 1/2] perf callchain lbr: Make the leaf IP that of the sample

[Arnaldo Carvalho de Melo]

On Fri, Feb 06, 2026 at 09:44:04AM +0800, Mi, Dapeng wrote:
> 
> On 2/6/2026 4:56 AM, Ian Rogers wrote:
> > The current IP of a leaf function when reported from a perf record
> > with "--call-graph lbr" is the "to" field of the LBR branch stack
> > record. The sample for the event being recorded may be further into
> > the function and there may be inlining information associated with
> > it. Rather than use the branch stack "to" field in this case switch to
> > the callchain appending the sample->ip and thereby allowing the inline
> > information to show.
> >
> > Before this change:
> > ```
> > $ perf record --call-graph lbr perf test -w inlineloop
> > ...
> > $ perf script --fields +srcline
> > ...
> > perf-inlineloop  467586  4649.344493:     950905 cpu_core/cycles/P:
> >            55dfda2829c0 parent+0x0 (perf)
> >  inlineloop.c:31
> >            55dfda282a96 inlineloop+0x86 (perf)
> >  inlineloop.c:47
> >            55dfda236420 run_workload+0x59 (perf)
> >  builtin-test.c:715
> >            55dfda236b03 cmd_test+0x413 (perf)
> >  builtin-test.c:825
> > ...
> > ```
> >
> > After this change:
> > ```
> > $ perf record --call-graph lbr perf test -w inlineloop
> > ...
> > $ perf script --fields +srcline
> > ...
> > perf-inlineloop  529703 11878.680815:     950905 cpu_core/cycles/P:
> >             555ce86be9e6 leaf+0x26
> >   inlineloop.c:20 (inlined)
> >             555ce86be9e6 middle+0x26
> >   inlineloop.c:27 (inlined)
> >             555ce86be9e6 parent+0x26 (perf)
> >   inlineloop.c:32
> >             555ce86bea96 inlineloop+0x86 (perf)
> >   inlineloop.c:47
> >             555ce8672420 run_workload+0x59 (perf)
> >   builtin-test.c:715
> >             555ce8672b03 cmd_test+0x413 (perf)
> >   builtin-test.c:825
> > ...
> > ```
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/util/machine.c | 20 ++++++++++++++++----
> >  1 file changed, 16 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > index 5b0f5a48ffd4..e76f8c86e62a 100644
> > --- a/tools/perf/util/machine.c
> > +++ b/tools/perf/util/machine.c
> > @@ -2423,8 +2423,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
> >  	}
> >  
> >  	if (callee) {
> > -		/* Add LBR ip from first entries.to */
> > -		ip = entries[0].to;
> > +		/*
> > +		 * Set the (first) leaf function's IP to sample->ip (the
> > +		 * location of the sample) but if not recorded use entries.to
> > +		 */
> > +		if (sample->ip)
> > +			ip = sample->ip;
> > +		else
> > +			ip = entries[0].to;
> >  		flags = &entries[0].flags;
> >  		*branch_from = entries[0].from;
> >  		err = add_callchain_ip(thread, cursor, parent,
> > @@ -2477,8 +2483,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
> >  	}
> >  
> >  	if (lbr_nr > 0) {
> > -		/* Add LBR ip from first entries.to */
> > -		ip = entries[0].to;
> > +		/*
> > +		 * Set the (first) leaf function's IP to sample->ip (the
> > +		 * location of the sample) but if not recorded use entries.to
> > +		 */
> > +		if (sample->ip)
> > +			ip = sample->ip;
> > +		else
> > +			ip = entries[0].to;
> >  		flags = &entries[0].flags;
> >  		*branch_from = entries[0].from;
> >  		err = add_callchain_ip(thread, cursor, parent,
> 
> LGTM. Thanks.

Next time please express that with an Acked-by, that way b4 will collect
it.

I'm adding it this time:

Acked-by: Dapeng Mi <dapeng1.mi@linux.intel.com>

ok?

- Arnaldo

Re: [PATCH v1 1/2] perf callchain lbr: Make the leaf IP that of the sample

[Mi, Dapeng]

On 2/7/2026 5:10 AM, Arnaldo Carvalho de Melo wrote:
> On Fri, Feb 06, 2026 at 09:44:04AM +0800, Mi, Dapeng wrote:
>> On 2/6/2026 4:56 AM, Ian Rogers wrote:
>>> The current IP of a leaf function when reported from a perf record
>>> with "--call-graph lbr" is the "to" field of the LBR branch stack
>>> record. The sample for the event being recorded may be further into
>>> the function and there may be inlining information associated with
>>> it. Rather than use the branch stack "to" field in this case switch to
>>> the callchain appending the sample->ip and thereby allowing the inline
>>> information to show.
>>>
>>> Before this change:
>>> ```
>>> $ perf record --call-graph lbr perf test -w inlineloop
>>> ...
>>> $ perf script --fields +srcline
>>> ...
>>> perf-inlineloop  467586  4649.344493:     950905 cpu_core/cycles/P:
>>>            55dfda2829c0 parent+0x0 (perf)
>>>  inlineloop.c:31
>>>            55dfda282a96 inlineloop+0x86 (perf)
>>>  inlineloop.c:47
>>>            55dfda236420 run_workload+0x59 (perf)
>>>  builtin-test.c:715
>>>            55dfda236b03 cmd_test+0x413 (perf)
>>>  builtin-test.c:825
>>> ...
>>> ```
>>>
>>> After this change:
>>> ```
>>> $ perf record --call-graph lbr perf test -w inlineloop
>>> ...
>>> $ perf script --fields +srcline
>>> ...
>>> perf-inlineloop  529703 11878.680815:     950905 cpu_core/cycles/P:
>>>             555ce86be9e6 leaf+0x26
>>>   inlineloop.c:20 (inlined)
>>>             555ce86be9e6 middle+0x26
>>>   inlineloop.c:27 (inlined)
>>>             555ce86be9e6 parent+0x26 (perf)
>>>   inlineloop.c:32
>>>             555ce86bea96 inlineloop+0x86 (perf)
>>>   inlineloop.c:47
>>>             555ce8672420 run_workload+0x59 (perf)
>>>   builtin-test.c:715
>>>             555ce8672b03 cmd_test+0x413 (perf)
>>>   builtin-test.c:825
>>> ...
>>> ```
>>>
>>> Signed-off-by: Ian Rogers <irogers@google.com>
>>> ---
>>>  tools/perf/util/machine.c | 20 ++++++++++++++++----
>>>  1 file changed, 16 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
>>> index 5b0f5a48ffd4..e76f8c86e62a 100644
>>> --- a/tools/perf/util/machine.c
>>> +++ b/tools/perf/util/machine.c
>>> @@ -2423,8 +2423,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
>>>  	}
>>>  
>>>  	if (callee) {
>>> -		/* Add LBR ip from first entries.to */
>>> -		ip = entries[0].to;
>>> +		/*
>>> +		 * Set the (first) leaf function's IP to sample->ip (the
>>> +		 * location of the sample) but if not recorded use entries.to
>>> +		 */
>>> +		if (sample->ip)
>>> +			ip = sample->ip;
>>> +		else
>>> +			ip = entries[0].to;
>>>  		flags = &entries[0].flags;
>>>  		*branch_from = entries[0].from;
>>>  		err = add_callchain_ip(thread, cursor, parent,
>>> @@ -2477,8 +2483,14 @@ static int lbr_callchain_add_lbr_ip(struct thread *thread,
>>>  	}
>>>  
>>>  	if (lbr_nr > 0) {
>>> -		/* Add LBR ip from first entries.to */
>>> -		ip = entries[0].to;
>>> +		/*
>>> +		 * Set the (first) leaf function's IP to sample->ip (the
>>> +		 * location of the sample) but if not recorded use entries.to
>>> +		 */
>>> +		if (sample->ip)
>>> +			ip = sample->ip;
>>> +		else
>>> +			ip = entries[0].to;
>>>  		flags = &entries[0].flags;
>>>  		*branch_from = entries[0].from;
>>>  		err = add_callchain_ip(thread, cursor, parent,
>> LGTM. Thanks.
> Next time please express that with an Acked-by, that way b4 will collect
> it.
>
> I'm adding it this time:
>
> Acked-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
>
> ok?

Yeah. Thanks.


>
> - Arnaldo
>
>