* [PATCH] perf ftrace latency: Fix compiler error for clang 12
@ 2024-12-14 0:29 Namhyung Kim
2024-12-16 16:44 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 2+ messages in thread
From: Namhyung Kim @ 2024-12-14 0:29 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo
Cc: Ian Rogers, Jiri Olsa, Adrian Hunter, Peter Zijlstra, Ingo Molnar,
LKML, linux-perf-users, Gabriele Monaco
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<i32* @bucket_range> 0, util/bpf_skel/func_latency.bpf.c:119:19 @[ util/bpf_skel/func_latency.bpf.c:84:5 ]
0x55829ee68808: i64 = TargetGlobalAddress<i32* @bucket_range> 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.
Fixes: e8536dd47a98b5db ("perf ftrace latency: Introduce --bucket-range to ask for linear bucketing")
Cc: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_skel/func_latency.bpf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/bpf_skel/func_latency.bpf.c b/tools/perf/util/bpf_skel/func_latency.bpf.c
index 50ae153bf26e7a13..4df54e1b1411b10a 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;
--
2.47.1.613.gc27f4b7a9f-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] perf ftrace latency: Fix compiler error for clang 12
2024-12-14 0:29 [PATCH] perf ftrace latency: Fix compiler error for clang 12 Namhyung Kim
@ 2024-12-16 16:44 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 2+ messages in thread
From: Arnaldo Carvalho de Melo @ 2024-12-16 16:44 UTC (permalink / raw)
To: Namhyung Kim
Cc: Ian Rogers, Jiri Olsa, Adrian Hunter, Peter Zijlstra, Ingo Molnar,
LKML, linux-perf-users, Gabriele Monaco
On Fri, Dec 13, 2024 at 04:29:38PM -0800, Namhyung Kim wrote:
> 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<i32* @bucket_range> 0, util/bpf_skel/func_latency.bpf.c:119:19 @[ util/bpf_skel/func_latency.bpf.c:84:5 ]
> 0x55829ee68808: i64 = TargetGlobalAddress<i32* @bucket_range> 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.
>
> Fixes: e8536dd47a98b5db ("perf ftrace latency: Introduce --bucket-range to ask for linear bucketing")
> Cc: Gabriele Monaco <gmonaco@redhat.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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:~#
Thanks, applied to perf-tools-next.
- Arnaldo
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2024-12-14 0:29 [PATCH] perf ftrace latency: Fix compiler error for clang 12 Namhyung Kim
2024-12-16 16:44 ` Arnaldo Carvalho de Melo
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