linux-kernel - Re: [PATCH bpf-next v6 2/2] selftests/bpf: test the jited inline of bpf_get_current

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Message-ID: <CAEf4BzYzT2OUQ37BvzTRyo5Ah_t_CXv=AJixtAmU_pgr8eLpLg@mail.gmail.com>
Date: Tue, 20 Jan 2026 17:05:42 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Menglong Dong <menglong8.dong@...il.com>
Cc: ast@...nel.org, eddyz87@...il.com, davem@...emloft.net, dsahern@...nel.org, 
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev, 
	song@...nel.org, yonghong.song@...ux.dev, john.fastabend@...il.com, 
	kpsingh@...nel.org, sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, 
	tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, 
	dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com, 
	netdev@...r.kernel.org, bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v6 2/2] selftests/bpf: test the jited inline of bpf_get_current_task

On Mon, Jan 19, 2026 at 11:06 PM Menglong Dong <menglong8.dong@...il.com> wrote:
>
> Add the testcase for the jited inline of bpf_get_current_task().
>
> Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>
> ---
> v6:
> * remove unnecessary 'ifdef' and __description
> ---
>  .../selftests/bpf/prog_tests/verifier.c       |  2 ++
>  .../selftests/bpf/progs/verifier_jit_inline.c | 20 +++++++++++++++++++
>  2 files changed, 22 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/progs/verifier_jit_inline.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
> index 38c5ba70100c..2ae7b096bd64 100644
> --- a/tools/testing/selftests/bpf/prog_tests/verifier.c
> +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
> @@ -111,6 +111,7 @@
>  #include "verifier_xdp_direct_packet_access.skel.h"
>  #include "verifier_bits_iter.skel.h"
>  #include "verifier_lsm.skel.h"
> +#include "verifier_jit_inline.skel.h"
>  #include "irq.skel.h"
>
>  #define MAX_ENTRIES 11
> @@ -253,6 +254,7 @@ void test_verifier_bits_iter(void) { RUN(verifier_bits_iter); }
>  void test_verifier_lsm(void)                  { RUN(verifier_lsm); }
>  void test_irq(void)                          { RUN(irq); }
>  void test_verifier_mtu(void)                 { RUN(verifier_mtu); }
> +void test_verifier_jit_inline(void)               { RUN(verifier_jit_inline); }
>
>  static int init_test_val_map(struct bpf_object *obj, char *map_name)
>  {
> diff --git a/tools/testing/selftests/bpf/progs/verifier_jit_inline.c b/tools/testing/selftests/bpf/progs/verifier_jit_inline.c
> new file mode 100644
> index 000000000000..4ea254063646
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/verifier_jit_inline.c
> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <vmlinux.h>
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_misc.h"
> +
> +SEC("fentry/bpf_fentry_test1")
> +__success __retval(0)
> +__arch_x86_64
> +__jited("      addq    %gs:{{.*}}, %rax")
> +__arch_arm64
> +__jited("      mrs     x7, SP_EL0")

I was confused to see this, as your patch actually implements inlining
only on x86-64. And then it turned out that on arm64 we inline this in
JIT. But Eduard also noticed that we actually SKIP this test on arm64
because of missing LLVM dependency, so that's not great.

So we should do something about silently skipped tests at least...

> +int inline_bpf_get_current_task(void)
> +{
> +       bpf_get_current_task();
> +
> +       return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.52.0
>