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bpf: Use MAX_BPF_FUNC_REG_ARGS macro

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Instead of using integer literal here and there use macro name for
better context.

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225202629.585485-1-me@ubique.spb.ru
This commit is contained in:
Dmitrii Banshchikov 2021-02-26 00:26:29 +04:00 committed by Alexei Starovoitov
parent a7d24d9582
commit 523a4cf491
3 changed files with 20 additions and 12 deletions
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5
include/linux/bpf.h
View File

@ -506,6 +506,11 @@ enum bpf_cgroup_storage_type {
*/
#define MAX_BPF_FUNC_ARGS 12
/* The maximum number of arguments passed through registers
* a single function may have.
*/
#define MAX_BPF_FUNC_REG_ARGS 5
struct btf_func_model {
u8 ret_size;
u8 nr_args;

25
kernel/bpf/btf.c
View File

@ -4594,8 +4594,10 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
}
arg = off / 8;
args = (const struct btf_param *)(t + 1);
/* if (t == NULL) Fall back to default BPF prog with 5 u64 arguments */
nr_args = t ? btf_type_vlen(t) : 5;
/* if (t == NULL) Fall back to default BPF prog with
* MAX_BPF_FUNC_REG_ARGS u64 arguments.
*/
nr_args = t ? btf_type_vlen(t) : MAX_BPF_FUNC_REG_ARGS;
if (prog->aux->attach_btf_trace) {
/* skip first 'void *__data' argument in btf_trace_##name typedef */
args++;
@ -4651,7 +4653,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
}
} else {
if (!t)
/* Default prog with 5 args */
/* Default prog with MAX_BPF_FUNC_REG_ARGS args */
return true;
t = btf_type_by_id(btf, args[arg].type);
}
@ -5102,12 +5104,12 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
if (!func) {
/* BTF function prototype doesn't match the verifier types.
* Fall back to 5 u64 args.
* Fall back to MAX_BPF_FUNC_REG_ARGS u64 args.
*/
for (i = 0; i < 5; i++)
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
m->arg_size[i] = 8;
m->ret_size = 8;
m->nr_args = 5;
m->nr_args = MAX_BPF_FUNC_REG_ARGS;
return 0;
}
args = (const struct btf_param *)(func + 1);
@ -5330,8 +5332,9 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > 5) {
bpf_log(log, "Function %s has %d > 5 args\n", tname, nargs);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "Function %s has %d > %d args\n", tname, nargs,
MAX_BPF_FUNC_REG_ARGS);
goto out;
}
@ -5460,9 +5463,9 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > 5) {
bpf_log(log, "Global function %s() with %d > 5 args. Buggy compiler.\n",
tname, nargs);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
tname, nargs, MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
}
/* check that function returns int */

2
kernel/bpf/verifier.c
View File

@ -5544,7 +5544,7 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
meta.func_id = func_id;
/* check args */
for (i = 0; i < 5; i++) {
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
err = check_func_arg(env, i, &meta, fn);
if (err)
return err;