bpf: Fix immediate JMP JEQ/JNE on MIPS32

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An addu instruction was emitted instead of addiu, causing the immediate
value 1 to be interpreted as register $at. This made the comparison
result invalid when the immediate operand was negative. Note that $at
is mapped to BPF_REG_AX, which is used for constant blinding.

Fix the instruction to use the immediate form.

Found with test_bpf on MIPS32r1 emulated by QEMU.

Fixes: eb63cfcd2e ("mips, bpf: Add eBPF JIT for 32-bit MIPS")
Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260923105158.3514342-1-johan.almbladh@anyfinetworks.com

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Johan Almbladh 2026-09-23 12:51:57 +02:00 • committed by Alexei Starovoitov

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arch/mips/net/bpf_jit_comp32.c

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