[PATCH] perf test: Add LBR call stack branch filter test

[PATCH] perf test: Add LBR call stack branch filter test

[lv.yating]

From: lvyating <lv.yating@zte.com.cn>

While debugging a NULL deref in resolve_lbr_callchain_sample()
triggered by "perf record -j stack" (fixed in commit
4626d370ae89b8af4d46a45372b269f926ec662d "perf machine:
Fix NULL deref in thread__resolve_callchain_sample()"), the "-j
stack" filter was found to lack coverage in the perf record LBR
tests.

Add "call stack" tests, sequentially and in parallel.
Use a 100% empty stack threshold, as with ind_jmp and ind_call,u,
since the stack filter is more restrictive and can leave branch
stacks empty more often.

Signed-off-by: lvyating <lv.yating@zte.com.cn>
---
 tools/perf/tests/shell/record_lbr.sh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/shell/record_lbr.sh b/tools/perf/tests/shell/record_lbr.sh
index 8d51afeb437b..d52124355f06 100755
--- a/tools/perf/tests/shell/record_lbr.sh
+++ b/tools/perf/tests/shell/record_lbr.sh
@@ -109,7 +109,7 @@ lbr_test() {
   sam_nr=$(echo "$out" | grep -c 'PERF_RECORD_SAMPLE' || true)
   echo "$test: $sam_nr samples"

-  bs_nr=$(echo "$out" | grep -c 'branch stack: nr:' || true)
+  bs_nr=$(echo "$out" | grep -cE 'branch (call)?stack: nr:' || true)
   if [ $sam_nr -ne $bs_nr ]
   then
     echo "$test [Failed samples missing branch stacks]"
@@ -146,6 +146,7 @@ lbr_test "-j ind_call" "any indirect call" 2
 lbr_test "-j ind_jmp" "any indirect jump" 100
 lbr_test "-j call" "direct calls" 2
 lbr_test "-j ind_call,u" "any indirect user call" 100
+lbr_test "-j stack" "call stack" 100
 if ! ParanoidAndNotRoot 1
 then
   lbr_test "-a -b" "system wide any branch" 2
@@ -177,8 +178,10 @@ else
   parallel_lbr_test "-a -j any_call" "parallel system wide any call" 100 &
   pid9=$!
 fi
+parallel_lbr_test "-j stack" "parallel call stack" 100 &
+pid10=$!

-for pid in $pid1 $pid2 $pid3 $pid4 $pid5 $pid6 $pid7 $pid8 $pid9
+for pid in $pid1 $pid2 $pid3 $pid4 $pid5 $pid6 $pid7 $pid8 $pid9 $pid10
 do
   set +e
   wait $pid
-- 
2.27.0

Re: [PATCH] perf test: Add LBR call stack branch filter test

[sashiko-bot]

> From: lvyating <lv.yating@zte.com.cn>
> 
> While debugging a NULL deref in resolve_lbr_callchain_sample()
> triggered by "perf record -j stack" (fixed in commit
> 4626d370ae89b8af4d46a45372b269f926ec662d "perf machine:
> Fix NULL deref in thread__resolve_callchain_sample()"), the "-j
> stack" filter was found to lack coverage in the perf record LBR
> tests.
> 
> Add "call stack" tests, sequentially and in parallel.
> Use a 100% empty stack threshold, as with ind_jmp and ind_call,u,
> since the stack filter is more restrictive and can leave branch
> stacks empty more often.
> 
> Signed-off-by: lvyating <lv.yating@zte.com.cn>

Sashiko has reviewed this patch and found no issues.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/202611021227.6A2CRwkO000175@mse-fl1.zte.com.cn?part=1