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s390/bpf: Fix optimizing out zero-extensions
commitdb7bee6538
upstream. Currently the JIT completely removes things like `reg32 += 0`, however, the BPF_ALU semantics requires the target register to be zero-extended in such cases. Fix by optimizing out only the arithmetic operation, but not the subsequent zero-extension. Reported-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Fixes:0546231057
("s390/bpf: Add s390x eBPF JIT compiler backend") Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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f7f1bac898
commit
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1 changed files with 30 additions and 28 deletions
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@ -569,10 +569,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT4(0xb9080000, dst_reg, src_reg);
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break;
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case BPF_ALU | BPF_ADD | BPF_K: /* dst = (u32) dst + (u32) imm */
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if (!imm)
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break;
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/* alfi %dst,imm */
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EMIT6_IMM(0xc20b0000, dst_reg, imm);
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if (imm != 0) {
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/* alfi %dst,imm */
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EMIT6_IMM(0xc20b0000, dst_reg, imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_ADD | BPF_K: /* dst = dst + imm */
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@ -594,10 +594,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT4(0xb9090000, dst_reg, src_reg);
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break;
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case BPF_ALU | BPF_SUB | BPF_K: /* dst = (u32) dst - (u32) imm */
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if (!imm)
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break;
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/* alfi %dst,-imm */
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EMIT6_IMM(0xc20b0000, dst_reg, -imm);
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if (imm != 0) {
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/* alfi %dst,-imm */
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EMIT6_IMM(0xc20b0000, dst_reg, -imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_SUB | BPF_K: /* dst = dst - imm */
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@ -619,10 +619,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT4(0xb90c0000, dst_reg, src_reg);
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break;
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case BPF_ALU | BPF_MUL | BPF_K: /* dst = (u32) dst * (u32) imm */
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if (imm == 1)
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break;
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/* msfi %r5,imm */
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EMIT6_IMM(0xc2010000, dst_reg, imm);
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if (imm != 1) {
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/* msfi %r5,imm */
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EMIT6_IMM(0xc2010000, dst_reg, imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_MUL | BPF_K: /* dst = dst * imm */
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@ -675,6 +675,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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if (BPF_OP(insn->code) == BPF_MOD)
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/* lhgi %dst,0 */
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EMIT4_IMM(0xa7090000, dst_reg, 0);
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else
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EMIT_ZERO(dst_reg);
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break;
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}
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/* lhi %w0,0 */
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@ -769,10 +771,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT4(0xb9820000, dst_reg, src_reg);
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break;
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case BPF_ALU | BPF_XOR | BPF_K: /* dst = (u32) dst ^ (u32) imm */
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if (!imm)
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break;
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/* xilf %dst,imm */
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EMIT6_IMM(0xc0070000, dst_reg, imm);
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if (imm != 0) {
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/* xilf %dst,imm */
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EMIT6_IMM(0xc0070000, dst_reg, imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_XOR | BPF_K: /* dst = dst ^ imm */
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@ -793,10 +795,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT6_DISP_LH(0xeb000000, 0x000d, dst_reg, dst_reg, src_reg, 0);
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break;
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case BPF_ALU | BPF_LSH | BPF_K: /* dst = (u32) dst << (u32) imm */
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if (imm == 0)
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break;
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/* sll %dst,imm(%r0) */
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EMIT4_DISP(0x89000000, dst_reg, REG_0, imm);
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if (imm != 0) {
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/* sll %dst,imm(%r0) */
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EMIT4_DISP(0x89000000, dst_reg, REG_0, imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_LSH | BPF_K: /* dst = dst << imm */
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@ -818,10 +820,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT6_DISP_LH(0xeb000000, 0x000c, dst_reg, dst_reg, src_reg, 0);
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break;
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case BPF_ALU | BPF_RSH | BPF_K: /* dst = (u32) dst >> (u32) imm */
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if (imm == 0)
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break;
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/* srl %dst,imm(%r0) */
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EMIT4_DISP(0x88000000, dst_reg, REG_0, imm);
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if (imm != 0) {
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/* srl %dst,imm(%r0) */
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EMIT4_DISP(0x88000000, dst_reg, REG_0, imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_RSH | BPF_K: /* dst = dst >> imm */
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@ -843,10 +845,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
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EMIT6_DISP_LH(0xeb000000, 0x000a, dst_reg, dst_reg, src_reg, 0);
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break;
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case BPF_ALU | BPF_ARSH | BPF_K: /* ((s32) dst >> imm */
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if (imm == 0)
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break;
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/* sra %dst,imm(%r0) */
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EMIT4_DISP(0x8a000000, dst_reg, REG_0, imm);
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if (imm != 0) {
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/* sra %dst,imm(%r0) */
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EMIT4_DISP(0x8a000000, dst_reg, REG_0, imm);
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}
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EMIT_ZERO(dst_reg);
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break;
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case BPF_ALU64 | BPF_ARSH | BPF_K: /* ((s64) dst) >>= imm */
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