diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2021-09-06 15:04:14 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-22 12:26:46 +0200 |
| commit | a5fc48000b0ed5c389d426c341b43f580faa7904 (patch) | |
| tree | 9b289e4930f85697441dc1080adbcd0cfd8f1e11 | |
| parent | f7f1bac8983f65dd974079c3cfd5644a87fbf177 (diff) | |
s390/bpf: Fix optimizing out zero-extensions
commit db7bee653859ef7179be933e7d1384644f795f26 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: 054623105728 ("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>
| -rw-r--r-- | arch/s390/net/bpf_jit_comp.c | 58 |
1 files changed, 30 insertions, 28 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 3e6612d8b921..9ae86f60dae5 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -569,10 +569,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT4(0xb9080000, dst_reg, src_reg); break; case BPF_ALU | BPF_ADD | BPF_K: /* dst = (u32) dst + (u32) imm */ - if (!imm) - break; - /* alfi %dst,imm */ - EMIT6_IMM(0xc20b0000, dst_reg, imm); + if (imm != 0) { + /* alfi %dst,imm */ + EMIT6_IMM(0xc20b0000, dst_reg, imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_ADD | BPF_K: /* dst = dst + imm */ @@ -594,10 +594,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT4(0xb9090000, dst_reg, src_reg); break; case BPF_ALU | BPF_SUB | BPF_K: /* dst = (u32) dst - (u32) imm */ - if (!imm) - break; - /* alfi %dst,-imm */ - EMIT6_IMM(0xc20b0000, dst_reg, -imm); + if (imm != 0) { + /* alfi %dst,-imm */ + EMIT6_IMM(0xc20b0000, dst_reg, -imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_SUB | BPF_K: /* dst = dst - imm */ @@ -619,10 +619,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT4(0xb90c0000, dst_reg, src_reg); break; case BPF_ALU | BPF_MUL | BPF_K: /* dst = (u32) dst * (u32) imm */ - if (imm == 1) - break; - /* msfi %r5,imm */ - EMIT6_IMM(0xc2010000, dst_reg, imm); + if (imm != 1) { + /* msfi %r5,imm */ + EMIT6_IMM(0xc2010000, dst_reg, imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_MUL | BPF_K: /* dst = dst * imm */ @@ -675,6 +675,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, if (BPF_OP(insn->code) == BPF_MOD) /* lhgi %dst,0 */ EMIT4_IMM(0xa7090000, dst_reg, 0); + else + EMIT_ZERO(dst_reg); break; } /* lhi %w0,0 */ @@ -769,10 +771,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT4(0xb9820000, dst_reg, src_reg); break; case BPF_ALU | BPF_XOR | BPF_K: /* dst = (u32) dst ^ (u32) imm */ - if (!imm) - break; - /* xilf %dst,imm */ - EMIT6_IMM(0xc0070000, dst_reg, imm); + if (imm != 0) { + /* xilf %dst,imm */ + EMIT6_IMM(0xc0070000, dst_reg, imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_XOR | BPF_K: /* dst = dst ^ imm */ @@ -793,10 +795,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT6_DISP_LH(0xeb000000, 0x000d, dst_reg, dst_reg, src_reg, 0); break; case BPF_ALU | BPF_LSH | BPF_K: /* dst = (u32) dst << (u32) imm */ - if (imm == 0) - break; - /* sll %dst,imm(%r0) */ - EMIT4_DISP(0x89000000, dst_reg, REG_0, imm); + if (imm != 0) { + /* sll %dst,imm(%r0) */ + EMIT4_DISP(0x89000000, dst_reg, REG_0, imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_LSH | BPF_K: /* dst = dst << imm */ @@ -818,10 +820,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT6_DISP_LH(0xeb000000, 0x000c, dst_reg, dst_reg, src_reg, 0); break; case BPF_ALU | BPF_RSH | BPF_K: /* dst = (u32) dst >> (u32) imm */ - if (imm == 0) - break; - /* srl %dst,imm(%r0) */ - EMIT4_DISP(0x88000000, dst_reg, REG_0, imm); + if (imm != 0) { + /* srl %dst,imm(%r0) */ + EMIT4_DISP(0x88000000, dst_reg, REG_0, imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_RSH | BPF_K: /* dst = dst >> imm */ @@ -843,10 +845,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, EMIT6_DISP_LH(0xeb000000, 0x000a, dst_reg, dst_reg, src_reg, 0); break; case BPF_ALU | BPF_ARSH | BPF_K: /* ((s32) dst >> imm */ - if (imm == 0) - break; - /* sra %dst,imm(%r0) */ - EMIT4_DISP(0x8a000000, dst_reg, REG_0, imm); + if (imm != 0) { + /* sra %dst,imm(%r0) */ + EMIT4_DISP(0x8a000000, dst_reg, REG_0, imm); + } EMIT_ZERO(dst_reg); break; case BPF_ALU64 | BPF_ARSH | BPF_K: /* ((s64) dst) >>= imm */ |