linux-kernel - Re: [PATCH v2 1/2] perf probe: add test for regression introduced by switch to die_get_decl

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Date:   Thu, 27 Jul 2023 10:45:21 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Georg Müller <georgmueller@....net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        regressions@...ts.linux.dev,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] perf probe: add test for regression introduced by
 switch to die_get_decl_file

On Wed, Jun 28, 2023 at 1:25 AM Georg Müller <georgmueller@....net> wrote:
>
> This patch adds a test to validate that perf probe works for binaries
> where DWARF info is split into multiple CUs
>
> Signed-off-by: Georg Müller <georgmueller@....net>
> Link: https://lore.kernel.org/r/5a00d5a5-7be7-ef8a-4044-9a16249fff25@gmx.net/
> ---
>  .../shell/test_uprobe_from_different_cu.sh    | 77 +++++++++++++++++++
>  1 file changed, 77 insertions(+)
>  create mode 100755 tools/perf/tests/shell/test_uprobe_from_different_cu.sh
>
> diff --git a/tools/perf/tests/shell/test_uprobe_from_different_cu.sh b/tools/perf/tests/shell/test_uprobe_from_different_cu.sh
> new file mode 100755
> index 000000000000..00d2e0e2e0c2
> --- /dev/null
> +++ b/tools/perf/tests/shell/test_uprobe_from_different_cu.sh
> @@ -0,0 +1,77 @@
> +#!/bin/bash
> +# test perf probe of function from different CU
> +# SPDX-License-Identifier: GPL-2.0
> +
> +set -e
> +
> +temp_dir=$(mktemp -d /tmp/perf-uprobe-different-cu-sh.XXXXXXXXXX)
> +
> +cleanup()
> +{
> +       trap - EXIT TERM INT
> +       if [[ "${temp_dir}" =~ ^/tmp/perf-uprobe-different-cu-sh.*$ ]]; then
> +               echo "--- Cleaning up ---"
> +               perf probe -x ${temp_dir}/testfile -d foo
> +               rm -f "${temp_dir}/"*
> +               rmdir "${temp_dir}"
> +       fi
> +}
> +
> +trap_cleanup()
> +{
> +        cleanup
> +        exit 1
> +}
> +
> +trap trap_cleanup EXIT TERM INT
> +
> +cat > ${temp_dir}/testfile-foo.h << EOF
> +struct t
> +{
> +  int *p;
> +  int c;
> +};
> +
> +extern int foo (int i, struct t *t);
> +EOF
> +
> +cat > ${temp_dir}/testfile-foo.c << EOF
> +#include "testfile-foo.h"
> +
> +int
> +foo (int i, struct t *t)
> +{
> +  int j, res = 0;
> +  for (j = 0; j < i && j < t->c; j++)
> +    res += t->p[j];
> +
> +  return res;
> +}
> +EOF
> +
> +cat > ${temp_dir}/testfile-main.c << EOF
> +#include "testfile-foo.h"
> +
> +static struct t g;
> +
> +int
> +main (int argc, char **argv)
> +{
> +  int i;
> +  int j[argc];
> +  g.c = argc;
> +  g.p = j;
> +  for (i = 0; i < argc; i++)
> +    j[i] = (int) argv[i][0];
> +  return foo (3, &g);
> +}
> +EOF
> +
> +gcc -g -Og -flto -c ${temp_dir}/testfile-foo.c -o ${temp_dir}/testfile-foo.o
> +gcc -g -Og -c ${temp_dir}/testfile-main.c -o ${temp_dir}/testfile-main.o
> +gcc -g -Og -o ${temp_dir}/testfile ${temp_dir}/testfile-foo.o ${temp_dir}/testfile-main.o

Thanks for the test Georg! By directly relying on gcc this test fails
for me in some constrained environments, like containers. I think
there should be a skip if gcc isn't present. A different option is to
just build the test code into the perf binary itself as a test
workload:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/tests/workloads?h=perf-tools-next

Wdyt? Thanks,
Ian

> +
> +perf probe -x ${temp_dir}/testfile --funcs foo
> +perf probe -x ${temp_dir}/testfile foo
> +
> +cleanup
> --
> 2.41.0
>