diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/core.c | 57 | ||||
| -rw-r--r-- | kernel/bpf/fixups.c | 1 |
2 files changed, 58 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 6e32db9777c2..fc22d66d194a 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2637,11 +2637,68 @@ static bool bpf_prog_select_interpreter(struct bpf_prog *fp) return select_interpreter; } +/* + * Whether a function has an insn that works with the arena base, which a JIT + * sets up in the prologue when bpf_prog_uses_arena_insns() says so. Decided on + * the final insns of the function: an access through an arena pointer, or + * through a number in a program loaded with BPF_F_ARENA_SCALAR, has been + * rewritten to a BPF_PROBE_MEM32 form by then, a cast to the user address + * space keeps BPF_ADDR_SPACE_CAST, and a kfunc call with an __arena argument, + * which the JIT rebases, has a function model that says so. A load of an + * __arena struct member is rewritten with an immediate and needs none; + * dereferencing the result does. + */ +bool bpf_prog_has_arena_insns(const struct bpf_prog *prog) +{ + const struct bpf_insn *insn = prog->insnsi; + const struct btf_func_model *m; + int i, j; + + if (!prog->aux->arena) + return false; + + for (i = 0; i < prog->len; i++, insn++) { + switch (BPF_CLASS(insn->code)) { + case BPF_LDX: + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32 || + BPF_MODE(insn->code) == BPF_PROBE_MEM32SX) + return true; + break; + case BPF_ST: + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) + return true; + break; + case BPF_STX: + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32 || + BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) + return true; + break; + case BPF_ALU64: + if (BPF_OP(insn->code) == BPF_MOV && BPF_SRC(insn->code) == BPF_X && + insn->off == BPF_ADDR_SPACE_CAST) + return true; + break; + case BPF_JMP: + if (!bpf_pseudo_kfunc_call(insn)) + break; + m = bpf_jit_find_kfunc_model(prog, insn); + if (!m) + break; + for (j = 0; j < m->nr_args; j++) + if (m->arg_flags[j] & BTF_FMODEL_ARENA_ARG) + return true; + break; + } + } + return false; +} + static struct bpf_prog *bpf_prog_jit_compile(struct bpf_verifier_env *env, struct bpf_prog *prog) { #ifdef CONFIG_BPF_JIT struct bpf_prog *orig_prog; + prog->aux->uses_arena_insns = bpf_prog_has_arena_insns(prog); if (!bpf_prog_need_blind(prog)) return bpf_int_jit_compile(env, prog); diff --git a/kernel/bpf/fixups.c b/kernel/bpf/fixups.c index 34b53ebb5841..409b9104c723 100644 --- a/kernel/bpf/fixups.c +++ b/kernel/bpf/fixups.c @@ -1448,6 +1448,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) func[i]->aux->jited_linfo = prog->aux->jited_linfo; func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx; func[i]->aux->arena = prog->aux->arena; + func[i]->aux->uses_arena_insns = bpf_prog_has_arena_insns(func[i]); func[i]->aux->used_maps = env->used_maps; func[i]->aux->used_map_cnt = env->used_map_cnt; num_exentries = 0; |