diff options
| author | Yonghong Song <yonghong.song@linux.dev> | 2023-07-27 18:12:07 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-07-27 18:52:33 -0700 |
| commit | 1f1e864b65554e33fe74e3377e58b12f4302f2eb (patch) | |
| tree | 9effb1a9e6dfd2f9bd97b90965f50d984612f7f5 /kernel | |
| parent | 8100928c881482a73ed8bd499d602bab0fe55608 (diff) | |
bpf: Handle sign-extenstin ctx member accesses
Currently, if user accesses a ctx member with signed types,
the compiler will generate an unsigned load followed by
necessary left and right shifts.
With the introduction of sign-extension load, compiler may
just emit a ldsx insn instead. Let us do a final movsx sign
extension to the final unsigned ctx load result to
satisfy original sign extension requirement.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011207.3712528-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2f3eebcd962f..7a6945be07e3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -17716,6 +17716,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) for (i = 0; i < insn_cnt; i++, insn++) { bpf_convert_ctx_access_t convert_ctx_access; + u8 mode; if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || insn->code == (BPF_LDX | BPF_MEM | BPF_H) || @@ -17797,6 +17798,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; size = BPF_LDST_BYTES(insn); + mode = BPF_MODE(insn->code); /* If the read access is a narrower load of the field, * convert to a 4/8-byte load, to minimum program type specific @@ -17856,6 +17858,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) (1ULL << size * 8) - 1); } } + if (mode == BPF_MEMSX) + insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X, + insn->dst_reg, insn->dst_reg, + size * 8, 0); new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); if (!new_prog) |