Re: [PATCH bpf-next v4 0/3] bpf: Fix trampoline handling of 128-bit values

[Leon Hwang <leon.hwang@linux.dev>]

On 28/7/26 11:54, Yonghong Song wrote:
> The BPF trampoline preserves only 8 bytes of a target function's return
> value (R0), and its register save area under-allocates space for 128-bit
> arguments for x86_64. These two problems lead to memory corruption or
> incorrect values observed by BPF programs and the real caller.
> 
> This series fixes both issues and adds two selftests, otherwise, each of
> them will fail if without the corresponding fix.
> 
> Changelogs:
>   v3 -> v4:
>     - v3: https://lore.kernel.org/bpf/20260710225206.4013062-1-yonghong.song@linux.dev/
>     - Add Ack from Leon Hwang


Seems you changed my tag from Acked-by to Reviewed-by.

No worries, Reviewed-by is fine with me.


>   v2 -> v3:
>     - v2: https://lore.kernel.org/bpf/20260710182204.1085329-1-yonghong.song@linux.dev/
>     - Align __int128 argument at even position enforced by arm64.
>   v1 -> v2:
>     - v1: https://lore.kernel.org/bpf/20260710144404.2579671-1-yonghong.song@linux.dev/
>     - Also handle __int128 arguments for x86_64.
> 
> Yonghong Song (3):
>   bpf: Reject >8 byte return values on return-reading trampoline paths
>   bpf, x86: Fix trampoline stack size for 128-bit arguments
>   selftests/bpf: Add tests for >8 byte return value and 128-bit
>     arguments
> 
>  arch/x86/net/bpf_jit_comp.c                   |  7 ++--
>  kernel/bpf/bpf_struct_ops.c                   | 12 +++++++
>  kernel/bpf/verifier.c                         | 25 +++++++++++++
>  .../bpf/prog_tests/tracing_failure.c          | 12 +++++++
>  .../selftests/bpf/prog_tests/tracing_struct.c | 36 +++++++++++++++++++
>  .../selftests/bpf/progs/tracing_failure.c     |  6 ++++
>  .../bpf/progs/tracing_struct_int128.c         | 18 ++++++++++
>  .../selftests/bpf/test_kmods/bpf_testmod.c    | 32 +++++++++++++++++
>  8 files changed, 143 insertions(+), 5 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/progs/tracing_struct_int128.c
>