Re: [PATCH bpf-next v2 1/3] bpf, s390: Mask the count of 32-bit shifts by register

[patchwork-bot+netdevbpf@kernel.org]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri, 16 Oct 2026 12:18:20 +0200 you wrote:
> RFC9669 defines the shifts as dst <<= (src & mask), dst >>= (src & mask)
> and sign extending dst >>= (src & mask), where "shift operations use a mask
> of 0x3F (63) for 64-bit operations and 0x1F (31) for 32-bit operations"
> (Section 4.1), which the interpreter implements. On x86-64 and arm64 the
> hardware does so by itself, so both JITs emit the shift alone and conform.
> 
> The 32-bit shifts by register of the s390x JIT do not conform to the spec.
> They emit sll, srl and sra with the count in the address of the second
> operand, of which the "rightmost six bits indicate the number of bit
> positions to be shifted" (z/Architecture Principles of Operation,
> SA22-7832-13), so a count of 32 to 63 clears the register, or fills it
> with the sign for sra, instead of shifting by the count masked with 31.
> The 64-bit sllg, srlg and srag take six bits as well, which is the mask
> there, so only the 32-bit forms differ.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v2,1/3] bpf, s390: Mask the count of 32-bit shifts by register
    https://git.kernel.org/bpf/bpf-next/c/4d8c247f1a21
  - [bpf-next,v2,2/3] selftests/bpf: Restore the je <-> jmp distance in convergence check
    https://git.kernel.org/bpf/bpf-next/c/b5fc954c39d4
  - [bpf-next,v2,3/3] selftests/bpf: Follow-up to JIT instruction tests
    https://git.kernel.org/bpf/bpf-next/c/b4e14f47371c

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html