From: Namhyung Kim Date: Sat, 14 Dec 2024 00:29:38 +0000 (-0800) Subject: perf ftrace latency: Fix compiler error for clang 12 X-Git-Tag: v6.14-rc1~29^2~130 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=a5bbe6dd69128fe887487fbc45ab0ef1e264e85c;p=linux-block.git perf ftrace latency: Fix compiler error for clang 12 I noticed this error on CentOS 8. CLANG /build/util/bpf_skel/.tmp/func_latency.bpf.o Error at line 119: Unsupport signed division for DAG: 0x55829ee68a10: i64 = sdiv 0x55829ee68bb0, 0x55829ee69090, util/bpf_skel/func_latency.bpf.c:119:17 @[ util/bpf_skel/func_latency.bpf.c:84:5 ]Please convert to unsigned div/mod. fatal error: error in backend: Cannot select: 0x55829ee68a10: i64 = sdiv 0x55829ee68bb0, 0x55829ee69090, util/bpf_skel/func_latency.bpf.c:119:17 @[ util/bpf_skel/func_latency.bpf.c:84:5 ] 0x55829ee68bb0: i64,ch = CopyFromReg 0x55829edc9a78, Register:i64 %5, util/bpf_skel/func_latency.bpf.c:119:17 @[ util/bpf_skel/func_latency.bpf.c:84:5 ] 0x55829ee68e20: i64 = Register %5 0x55829ee69090: i64,ch = load<(volatile dereferenceable load 4 from @bucket_range, !tbaa !160), zext from i32> 0x55829edc9a78, 0x55829ee68fc0, undef:i64, util/bpf_skel/func_latency.bpf.c:119:19 @[ util/bpf_skel/func_latency.bpf.c:84:5 ] 0x55829ee68fc0: i64 = BPFISD::Wrapper TargetGlobalAddress:i64 0, util/bpf_skel/func_latency.bpf.c:119:19 @[ util/bpf_skel/func_latency.bpf.c:84:5 ] 0x55829ee68808: i64 = TargetGlobalAddress 0, util/bpf_skel/func_latency.bpf.c:119:19 @[ util/bpf_skel/func_latency.bpf.c:84:5 ] 0x55829ee68530: i64 = undef In function: func_end PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script. It complains about sdiv which is (s64)delta / (u32)bucket_range. Let's cast the delta to u64 for division. Committer testing: Tested on: $ head -2 /etc/os-release NAME="Fedora Linux" VERSION="40 (Toolbx Container Image)" $ clang --version |& head -1 clang version 18.1.8 (Fedora 18.1.8-1.fc40) $ root@number:~# perf ftrace latency --use-nsec --bucket-range=200 --min-latency 250 --max-latency=5000 -T switch_mm_irqs_off -a sleep 10 # DURATION | COUNT | GRAPH | 0 - 250 ns | 28 | ##### | 250 - 450 ns | 12 | ## | 450 - 650 ns | 10 | # | 650 - 850 ns | 9 | # | 850 - 1050 ns | 20 | ### | 1.05 - 1.25 us | 14 | ## | 1.25 - 1.45 us | 16 | ### | 1.45 - 1.65 us | 8 | # | 1.65 - 1.85 us | 11 | ## | 1.85 - 2.05 us | 7 | # | 2.05 - 2.25 us | 11 | ## | 2.25 - 2.45 us | 10 | # | 2.45 - 2.65 us | 7 | # | 2.65 - 2.85 us | 8 | # | 2.85 - 3.05 us | 7 | # | 3.05 - 3.25 us | 7 | # | 3.25 - 3.45 us | 10 | # | 3.45 - 3.65 us | 5 | | 3.65 - 3.85 us | 9 | # | 3.85 - 4.05 us | 2 | | 4.05 - 4.25 us | 6 | # | 4.25 - ... us | 23 | #### | root@number:~# Fixes: e8536dd47a98b5db ("perf ftrace latency: Introduce --bucket-range to ask for linear bucketing") Signed-off-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Gabriele Monaco Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241214002938.1027546-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/bpf_skel/func_latency.bpf.c b/tools/perf/util/bpf_skel/func_latency.bpf.c index 50ae153bf26e..4df54e1b1411 100644 --- a/tools/perf/util/bpf_skel/func_latency.bpf.c +++ b/tools/perf/util/bpf_skel/func_latency.bpf.c @@ -116,7 +116,8 @@ int BPF_PROG(func_end) // Less than 1 unit (ms or ns), or, in the future, // than the min latency desired. if (delta > 0) { // 1st entry: [ 1 unit .. bucket_range units ) - key = delta / bucket_range + 1; + // clang 12 doesn't like s64 / u32 division + key = (__u64)delta / bucket_range + 1; if (key >= NUM_BUCKET || delta >= max_latency - min_latency) key = NUM_BUCKET - 1;