diff options
| author | Brendan Jackman <jackmanb@google.com> | 2021-02-17 13:45:09 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-02-26 23:05:07 +0300 |
| commit | e6ac593372aadacc14e02b198e4a1acfef1db595 (patch) | |
| tree | 2c4784ea0af06554e8b81f0ebe0b6dde72fcdc6c /kernel | |
| parent | 523a4cf491b3c9e2d546040d57250f1a0ca84f03 (diff) | |
| download | linux-e6ac593372aadacc14e02b198e4a1acfef1db595.tar.xz | |
bpf: Rename fixup_bpf_calls and add some comments
This function has become overloaded, it actually does lots of diverse
things in a single pass. Rename it to avoid confusion, and add some
concise commentary.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210217104509.2423183-1-jackmanb@google.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9f7e35590fc6..9336bac39027 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5877,7 +5877,7 @@ static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, aux->alu_limit != alu_limit)) return -EACCES; - /* Corresponding fixup done in fixup_bpf_calls(). */ + /* Corresponding fixup done in do_misc_fixups(). */ aux->alu_state = alu_state; aux->alu_limit = alu_limit; return 0; @@ -11535,12 +11535,10 @@ static int fixup_call_args(struct bpf_verifier_env *env) return err; } -/* fixup insn->imm field of bpf_call instructions - * and inline eligible helpers as explicit sequence of BPF instructions - * - * this function is called after eBPF program passed verification +/* Do various post-verification rewrites in a single program pass. + * These rewrites simplify JIT and interpreter implementations. */ -static int fixup_bpf_calls(struct bpf_verifier_env *env) +static int do_misc_fixups(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; bool expect_blinding = bpf_jit_blinding_enabled(prog); @@ -11555,6 +11553,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) int i, ret, cnt, delta = 0; for (i = 0; i < insn_cnt; i++, insn++) { + /* Make divide-by-zero exceptions impossible. */ if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) || insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) || insn->code == (BPF_ALU | BPF_MOD | BPF_X) || @@ -11595,6 +11594,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; } + /* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */ if (BPF_CLASS(insn->code) == BPF_LD && (BPF_MODE(insn->code) == BPF_ABS || BPF_MODE(insn->code) == BPF_IND)) { @@ -11614,6 +11614,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) continue; } + /* Rewrite pointer arithmetic to mitigate speculation attacks. */ if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) || insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) { const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X; @@ -11835,6 +11836,7 @@ patch_map_ops_generic: goto patch_call_imm; } + /* Implement bpf_jiffies64 inline. */ if (prog->jit_requested && BITS_PER_LONG == 64 && insn->imm == BPF_FUNC_jiffies64) { struct bpf_insn ld_jiffies_addr[2] = { @@ -12645,7 +12647,7 @@ skip_full_check: ret = convert_ctx_accesses(env); if (ret == 0) - ret = fixup_bpf_calls(env); + ret = do_misc_fixups(env); /* do 32-bit optimization after insn patching has done so those patched * insns could be handled correctly. |