linux-kernel - Re: [PATCH v3] selftests: add new kallsyms selftests

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Message-ID: <CABCJKudob+8GH2U_QLEngjqjOVmDfm8ZkEfn-Ya9ZG5OEOrRtQ@mail.gmail.com>
Date: Tue, 29 Oct 2024 09:24:30 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Luis Chamberlain <mcgrof@...nel.org>
Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
	petr.pavlu@...e.com, da.gomez@...sung.com, masahiroy@...nel.org, 
	deller@....de, linux-arch@...r.kernel.org, live-patching@...r.kernel.org, 
	kris.van.hees@...cle.com
Subject: Re: [PATCH v3] selftests: add new kallsyms selftests

Hi Luis,

On Mon, Oct 21, 2024 at 12:33 PM Luis Chamberlain <mcgrof@...nel.org> wrote:
>
> diff --git a/lib/tests/module/gen_test_kallsyms.sh b/lib/tests/module/gen_test_kallsyms.sh
> new file mode 100755
> index 000000000000..e85f10dc11bd
> --- /dev/null
> +++ b/lib/tests/module/gen_test_kallsyms.sh
> @@ -0,0 +1,128 @@
[..]
> +gen_template_module_data_b()
> +{
> +       printf "\nextern int auto_test_a_%010d;\n\n" 28
> +       echo "static int auto_runtime_test(void)"
> +       echo "{"
> +       printf "\nreturn auto_test_a_%010d;\n" 28
> +       echo "}"
> +}

FYI, I get a warning when loading test_kallsyms_b because the init
function return value is >0:

# modprobe test_kallsyms_b
[   11.154496] do_init_module: 'test_kallsyms_b'->init suspiciously
returned 255, it should follow 0/-E convention
[   11.154496] do_init_module: loading module anyway...
[   11.156156] CPU: 3 UID: 0 PID: 116 Comm: modprobe Not tainted
6.12.0-rc5-00020-g897cb2ff413d #1
[   11.156832] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
[   11.157762] Call Trace:
[   11.158914]  <TASK>
[   11.159253]  dump_stack_lvl+0x3f/0xb0
[   11.160279]  do_init_module+0x1f4/0x200
[   11.160586]  __se_sys_finit_module+0x30c/0x400
[   11.160948]  do_syscall_64+0xd0/0x1a0
[   11.161255]  ? arch_exit_to_user_mode_prepare+0x11/0x60
[   11.161659]  ? irqentry_exit_to_user_mode+0x8e/0xb0
[   11.162052]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   11.162598] RIP: 0033:0x7f5843968cf6
[   11.163076] Code: 48 89 57 30 48 8b 04 24 48 89 47 38 e9 1e 9a 02
00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24
08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3a fd ff ff c3 48 c7 c6 01 00 00 00
e9 a1
[   11.164465] RSP: 002b:00007ffefcc92d68 EFLAGS: 00000246 ORIG_RAX:
0000000000000139
[   11.165046] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f5843968cf6
[   11.165656] RDX: 0000000000000000 RSI: 00000000320429e0 RDI: 0000000000000003
[   11.166220] RBP: 00000000320429e0 R08: 0000000000000074 R09: 0000000000000000
[   11.166804] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000032042b50
[   11.167378] R13: 0000000000000001 R14: 0000000032042c10 R15: 0000000000000000
[   11.168007]  </TASK>

> diff --git a/tools/testing/selftests/module/find_symbol.sh b/tools/testing/selftests/module/find_symbol.sh
> new file mode 100755
> index 000000000000..140364d3c49f
> --- /dev/null
> +++ b/tools/testing/selftests/module/find_symbol.sh
> @@ -0,0 +1,81 @@
[..]
> +test_reqs()
> +{
> +       if ! which modprobe 2> /dev/null > /dev/null; then
> +               echo "$0: You need modprobe installed" >&2
> +               exit $ksft_skip
> +       fi
> +
> +       if ! which kmod 2> /dev/null > /dev/null; then
> +               echo "$0: You need kmod installed" >&2
> +               exit $ksft_skip
> +       fi

Is there a reason to test for kmod? I don't see it called directly in
this script.

Also, shouldn't you add the module directory to TARGETS in
tools/testing/selftests/Makefile? Otherwise the script won't be
installed with the rest of kselftests.

Sami