bpf, x86: Fix signed 32-bit div/mod in the i386 JIT#12801
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bpf, x86: Fix signed 32-bit div/mod in the i386 JIT#12801kernel-patches-daemon-bpf[bot] wants to merge 1 commit into
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emit_ia32_div_mod_r() always emits an unsigned divide (xor edx,edx + div ecx), regardless of the BPF instruction's signedness. Signed ALU32 BPF_DIV and BPF_MOD (off=1) therefore get an unsigned quotient and remainder in the i386 JIT, diverging from the verifier's and the interpreter's signed result for negative operands. Thread is_signed = (insn->off == 1) into emit_ia32_div_mod_r() and emit cdq + idiv ecx on the signed path, xor edx,edx + div ecx unchanged on the unsigned path, mirroring the cdq/idiv-vs-xor/div split the x86_64 JIT uses for the same instructions. bpf_do_misc_fixups() rewrites the zero-divisor and INT_MIN/-1 cases out of the instruction stream before the JIT runs. The RV32 JIT has the same gap. Fixes: ec0e2da ("bpf: Support new signed div/mod instructions.") Signed-off-by: Nicholas Dudar <main.kalliope@gmail.com> Assisted-by: Claude:claude-opus-4-8
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1126868 expired. Closing PR. |
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Pull request for series with
subject: bpf, x86: Fix signed 32-bit div/mod in the i386 JIT
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1126868