From: Nicholas Dudar Date: Thu, 23 Jul 2026 14:27:35 +0000 (+0800) Subject: LoongArch: BPF: Zero-extend signed ALU32 div/mod results X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=dacd348b8a993373576fe2ee2d8b114740ba57a6;p=thirdparty%2Fkernel%2Flinux.git LoongArch: BPF: Zero-extend signed ALU32 div/mod results ALU32 operations write a 32-bit result and leave the upper 32 bits of the BPF register zero. The LoongArch JIT sign-extends the result of signed ALU32 BPF_DIV and BPF_MOD (off=1), so a negative 32-bit quotient or remainder leaves bits 63:32 set in JITted code while the verifier and interpreter model those bits as zero. Keep sign-extension on the operands, which signed divide needs, and zero-extend the ALU32 result after the divide or modulo instruction, matching the unsigned ALU32 div/mod paths and every other ALU32 operation in this JIT. Fixes: 2425c9e002d2 ("LoongArch: BPF: Support signed div instructions") Fixes: 7b6b13d32965 ("LoongArch: BPF: Support signed mod instructions") Assisted-by: Claude:claude-opus-4-8 Acked-by: Tiezhu Yang Tested-by: Tiezhu Yang Signed-off-by: Nicholas Dudar Signed-off-by: Huacai Chen --- diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 2738b4db1165..c91d474faba7 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -835,7 +835,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext move_reg(ctx, t1, src); emit_sext_32(ctx, t1, is32); emit_insn(ctx, divd, dst, dst, t1); - emit_sext_32(ctx, dst, is32); + emit_zext_32(ctx, dst, is32); } break; @@ -852,7 +852,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext emit_sext_32(ctx, t1, is32); emit_sext_32(ctx, dst, is32); emit_insn(ctx, divd, dst, dst, t1); - emit_sext_32(ctx, dst, is32); + emit_zext_32(ctx, dst, is32); } break; @@ -870,7 +870,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext move_reg(ctx, t1, src); emit_sext_32(ctx, t1, is32); emit_insn(ctx, modd, dst, dst, t1); - emit_sext_32(ctx, dst, is32); + emit_zext_32(ctx, dst, is32); } break; @@ -887,7 +887,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext emit_sext_32(ctx, t1, is32); emit_sext_32(ctx, dst, is32); emit_insn(ctx, modd, dst, dst, t1); - emit_sext_32(ctx, dst, is32); + emit_zext_32(ctx, dst, is32); } break;