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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.
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: e8536dd47a ("perf ftrace latency: Introduce --bucket-range to ask for linear bucketing")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241214002938.1027546-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.