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

[Yonghong Song <yonghong.song@linux.dev>]

On 7/27/26 9:22 PM, Leon Hwang wrote:
> 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.

Sorry about this. Looks like there are still some issues related to x390x.
I will invesgitate.

>
>
>>    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
>>