diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/filter.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index 4edba8182db1..15d83684c6e9 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -414,6 +414,30 @@ static inline bool bpf_atomic_is_load_acq(const struct bpf_insn *insn) insn->imm == BPF_LOAD_ACQ; } +/* + * Given an instruction @insn, return the number of the BPF register that a + * BPF_ATOMIC reads the value at its memory operand into, or -1 if there is + * no such register. That is the register a BPF_PROBE_ATOMIC has to clear when + * the access faults. Like bpf_atomic_is_load_acq(), @insn is not assumed to + * be a BPF_ATOMIC here. + */ +static inline int bpf_atomic_load_reg(const struct bpf_insn *insn) +{ + if (BPF_CLASS(insn->code) != BPF_STX || + (BPF_MODE(insn->code) != BPF_ATOMIC && + BPF_MODE(insn->code) != BPF_PROBE_ATOMIC)) + return -1; + + switch (insn->imm) { + case BPF_LOAD_ACQ: + return insn->dst_reg; + case BPF_CMPXCHG: + return BPF_REG_0; + default: + return (insn->imm & BPF_FETCH) ? insn->src_reg : -1; + } +} + /* Memory store, *(uint *) (dst_reg + off16) = imm32 */ #define BPF_ST_MEM(SIZE, DST, OFF, IMM) \ |