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bpf: simplify btf_get_prog_ctx_type() into btf_is_prog_ctx_type()

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Return result of btf_get_prog_ctx_type() is never used and callers only
check NULL vs non-NULL case to determine if given type matches expected
PTR_TO_CTX type. So rename function to `btf_is_prog_ctx_type()` and
return a simple true/false. We'll use this simpler interface to handle
kprobe program type's special typedef case in the next patch.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240212233221.2575350-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-02-12 15:32:18 -08:00 committed by Alexei Starovoitov
parent 32e18e7688
commit fb5b86cfd4
3 changed files with 22 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/linux/btf.h
View File

@ -531,10 +531,9 @@ s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
struct module *owner);
struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id);
const struct btf_type *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg);
bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg);
int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
bool btf_types_are_same(const struct btf *btf1, u32 id1,
const struct btf *btf2, u32 id2);
@ -574,12 +573,12 @@ static inline struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf
{
return NULL;
}
static inline const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg)
static inline bool
btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg)
{
return NULL;
return false;
}
static inline int get_kern_ctx_btf_id(struct bpf_verifier_log *log,
enum bpf_prog_type prog_type) {

27
kernel/bpf/btf.c
View File

@ -5694,10 +5694,9 @@ static int find_kern_ctx_type_id(enum bpf_prog_type prog_type)
return ctx_type->type;
}
const struct btf_type *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg)
bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg)
{
const struct btf_type *ctx_type;
const char *tname, *ctx_tname;
@ -5711,26 +5710,26 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
* is not supported yet.
* BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
*/
return NULL;
return false;
}
tname = btf_name_by_offset(btf, t->name_off);
if (!tname) {
bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
return NULL;
return false;
}
ctx_type = find_canonical_prog_ctx_type(prog_type);
if (!ctx_type) {
bpf_log(log, "btf_vmlinux is malformed\n");
/* should not happen */
return NULL;
return false;
}
again:
ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off);
if (!ctx_tname) {
/* should not happen */
bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
return NULL;
return false;
}
/* only compare that prog's ctx type name is the same as
* kernel expects. No need to compare field by field.
@ -5740,20 +5739,20 @@ again:
* { // no fields of skb are ever used }
*/
if (strcmp(ctx_tname, "__sk_buff") == 0 && strcmp(tname, "sk_buff") == 0)
return ctx_type;
return true;
if (strcmp(ctx_tname, "xdp_md") == 0 && strcmp(tname, "xdp_buff") == 0)
return ctx_type;
return true;
if (strcmp(ctx_tname, tname)) {
/* bpf_user_pt_regs_t is a typedef, so resolve it to
* underlying struct and check name again
*/
if (!btf_type_is_modifier(ctx_type))
return NULL;
return false;
while (btf_type_is_modifier(ctx_type))
ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type);
goto again;
}
return ctx_type;
return true;
}
/* forward declarations for arch-specific underlying types of
@ -5905,7 +5904,7 @@ static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
enum bpf_prog_type prog_type,
int arg)
{
if (!btf_get_prog_ctx_type(log, btf, t, prog_type, arg))
if (!btf_is_prog_ctx_type(log, btf, t, prog_type, arg))
return -ENOENT;
return find_kern_ctx_type_id(prog_type);
}
@ -7211,7 +7210,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
if (!btf_type_is_ptr(t))
goto skip_pointer;
if ((tags & ARG_TAG_CTX) || btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
if ((tags & ARG_TAG_CTX) || btf_is_prog_ctx_type(log, btf, t, prog_type, i)) {
if (tags & ~ARG_TAG_CTX) {
bpf_log(log, "arg#%d has invalid combination of tags\n", i);
return -EINVAL;

2
kernel/bpf/verifier.c
View File

@ -11015,7 +11015,7 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
* type to our caller. When a set of conditions hold in the BTF type of
* arguments, we resolve it to a known kfunc_ptr_arg_type.
*/
if (btf_get_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
return KF_ARG_PTR_TO_CTX;
if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno]))