diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2021-09-06 15:04:14 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-26 13:37:27 +0200 |
| commit | daf48f68fca9040b542282a5cd17397af316dd89 (patch) | |
| tree | d7afa3da5fc02720f9ed46f6c5d471bf56e6f674 /arch | |
| parent | 8ea4f73cfa7e0555dc03aedde52db54a6587ab43 (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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/net/bpf_jit_comp.c | 50 |
1 files changed, 26 insertions, 24 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 1241e365af5d..60029baaa72a 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -592,10 +592,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ @@ -617,10 +617,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ @@ -647,10 +647,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ @@ -711,6 +711,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ @@ -803,10 +805,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ @@ -827,10 +829,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ @@ -852,10 +854,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 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 */ |