diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 79e7a0ec1da5..6926d0ca6c71 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1349,6 +1349,7 @@ st: if (is_imm8(insn->off)) insn->imm == (BPF_XOR | BPF_FETCH)) { u8 *branch_target; bool is64 = BPF_SIZE(insn->code) == BPF_DW; + u32 real_src_reg = src_reg; /* * Can't be implemented with a single x86 insn. @@ -1357,6 +1358,9 @@ st: if (is_imm8(insn->off)) /* Will need RAX as a CMPXCHG operand so save R0 */ emit_mov_reg(&prog, true, BPF_REG_AX, BPF_REG_0); + if (src_reg == BPF_REG_0) + real_src_reg = BPF_REG_AX; + branch_target = prog; /* Load old value */ emit_ldx(&prog, BPF_SIZE(insn->code), @@ -1366,9 +1370,9 @@ st: if (is_imm8(insn->off)) * put the result in the AUX_REG. */ emit_mov_reg(&prog, is64, AUX_REG, BPF_REG_0); - maybe_emit_mod(&prog, AUX_REG, src_reg, is64); + maybe_emit_mod(&prog, AUX_REG, real_src_reg, is64); EMIT2(simple_alu_opcodes[BPF_OP(insn->imm)], - add_2reg(0xC0, AUX_REG, src_reg)); + add_2reg(0xC0, AUX_REG, real_src_reg)); /* Attempt to swap in new value */ err = emit_atomic(&prog, BPF_CMPXCHG, dst_reg, AUX_REG, insn->off, @@ -1381,7 +1385,7 @@ st: if (is_imm8(insn->off)) */ EMIT2(X86_JNE, -(prog - branch_target) - 2); /* Return the pre-modification value */ - emit_mov_reg(&prog, is64, src_reg, BPF_REG_0); + emit_mov_reg(&prog, is64, real_src_reg, BPF_REG_0); /* Restore R0 after clobbering RAX */ emit_mov_reg(&prog, true, BPF_REG_0, BPF_REG_AX); break; |