u32 dst_reg = insn->dst_reg;
u32 src_reg = insn->src_reg;
u8 b2 = 0, b3 = 0;
+ u8 *start_of_ldx;
s64 jmp_offset;
u8 jmp_cond;
u8 *func;
case BPF_LDX | BPF_PROBE_MEM | BPF_W:
case BPF_LDX | BPF_MEM | BPF_DW:
case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
+ if (BPF_MODE(insn->code) == BPF_PROBE_MEM) {
+ /* test src_reg, src_reg */
+ maybe_emit_mod(&prog, src_reg, src_reg, true); /* always 1 byte */
+ EMIT2(0x85, add_2reg(0xC0, src_reg, src_reg));
+ /* jne start_of_ldx */
+ EMIT2(X86_JNE, 0);
+ /* xor dst_reg, dst_reg */
+ emit_mov_imm32(&prog, false, dst_reg, 0);
+ /* jmp byte_after_ldx */
+ EMIT2(0xEB, 0);
+
+ /* populate jmp_offset for JNE above */
+ temp[4] = prog - temp - 5 /* sizeof(test + jne) */;
+ start_of_ldx = prog;
+ }
emit_ldx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
if (BPF_MODE(insn->code) == BPF_PROBE_MEM) {
struct exception_table_entry *ex;
u8 *_insn = image + proglen;
s64 delta;
+ /* populate jmp_offset for JMP above */
+ start_of_ldx[-1] = prog - start_of_ldx;
+
if (!bpf_prog->aux->extable)
break;