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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
This commit is contained in:
Brendan Jackman 2021-02-17 10:45:09 +00:00 committed by Alexei Starovoitov
parent 523a4cf491
commit e6ac593372
1 changed files with 9 additions and 7 deletions
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16
kernel/bpf/verifier.c
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@ -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 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
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 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
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.