Re: [PATCH] tools/perf/tests: Fix objdump in Object code reading test to look for all sections

[Namhyung Kim <namhyung@kernel.org>]

On Mon, Jul 3, 2023 at 10:04 PM Athira Rajeev
<atrajeev@linux.vnet.ibm.com> wrote:
>
> Object code reading test fails intermittently with below logs:
>
>    Reading object code for memory address: 0xc008000001dd34fc
>    File is: /lib/modules/6.3.0-rc7+/kernel/fs/xfs/xfs.ko
>    On file address is: 0x11359c
>    Objdump command is: objdump -z -d --start-address=0x1134fc --stop-address=0x11357c /lib/modules/6.3.0-rc7+/kernel/fs/xfs/xfs.ko
>    objdump read too few bytes: 128
>    test child finished with -1
>    ---- end ----
>    Object code reading: FAILED!
>
> This issue happens ramdomly depending on the sample ip
> captured during the test run. In some cases, the same ip falls
> in the xfs module. The test does an objdump on the xfs.ko file and
> compares it with the dump from the dso that perf captures. But
> since the range of ip address falls in debug info section, it fails

This is strange.  Why did it fall into the debug section?

Thanks,
Namhyung


> to find the address range with objdump. Fix the objdump option so
> as to disasseble all sections to check the address range.
>
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> ---
>  tools/perf/tests/code-reading.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
> index ed3815163d1b..02132478856a 100644
> --- a/tools/perf/tests/code-reading.c
> +++ b/tools/perf/tests/code-reading.c
> @@ -184,7 +184,7 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
>         FILE *f;
>         int ret;
>
> -       fmt = "%s -z -d --start-address=0x%"PRIx64" --stop-address=0x%"PRIx64" %s";
> +       fmt = "%s -z -D --start-address=0x%"PRIx64" --stop-address=0x%"PRIx64" %s";
>         ret = snprintf(cmd, sizeof(cmd), fmt, "objdump", addr, addr + len,
>                        filename);
>         if (ret <= 0 || (size_t)ret >= sizeof(cmd))
> --
> 2.35.3
>