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Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
-rw-r--r--arch/x86/net/bpf_jit_comp.c10
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;