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bpf: Record basic-block ends in insn_aux_data

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SCEV needs information about the program's basic-block structure.
Piggyback on compute_predecessors() and set
insn_aux_data->bb_end for an instruction if:
- it has multiple successors, or
- its sole successor has multiple predecessors, or
- it is a jump instruction.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261009-scev-minimal-rebase-v3-31-bcba9bc53ac9@gmail.com
This commit is contained in:
Eduard Zingerman 2026-10-09 03:47:49 -07:00 committed by Alexei Starovoitov
parent 1291ad5906
commit 2fa579694d
No known key found for this signature in database
2 changed files with 20 additions and 0 deletions
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1
include/linux/bpf_verifier.h
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@ -741,6 +741,7 @@ struct bpf_insn_aux_data {
bool is_iter_next; /* bpf_iter_<type>_next() kfunc call */
bool call_with_percpu_alloc_ptr; /* {this,per}_cpu_ptr() with prog percpu alloc */
bool arena_scalar; /* ldx/stx/st/atomic through a number, it's an address in arena */
bool bb_end; /* last instruction of a basic block */
u8 alu_state; /* used in combination with alu_limit */
/* true if STX or LDX instruction is a part of a spill/fill
* pattern for a bpf_fastcall call.

19
kernel/bpf/loops.c
View File

@ -5,8 +5,23 @@
#include <linux/sched/signal.h>
#include <linux/bpf_verifier.h>
static bool is_cfg_jump(struct bpf_insn *insn)
{
u8 class = BPF_CLASS(insn->code);
u8 opcode = BPF_OP(insn->code);
switch (class) {
case BPF_JMP:
case BPF_JMP32:
return opcode != BPF_CALL;
default:
return false;
}
}
static struct bpf_iarray **compute_predecessors(struct bpf_verifier_env *env)
{
struct bpf_insn_aux_data *aux = env->insn_aux_data;
struct bpf_iarray *succ, *preds, **result;
struct bpf_prog *prog = env->prog;
u32 *num_preds, i, s, len = prog->len;
@ -54,6 +69,10 @@ static struct bpf_iarray **compute_predecessors(struct bpf_verifier_env *env)
preds = result[s];
preds->items[preds->cnt++] = i;
}
if (succ->cnt > 1 ||
(succ->cnt == 1 && num_preds[succ->items[0]] > 1) ||
is_cfg_jump(insn))
aux[i].bb_end = true;
if (bpf_is_ldimm64(insn))
i++;
}