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bpf: Classify kfunc mem_size args from BTF without register state

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check_kfunc_args() already makes sure a scalar value is passed to a
scalar kfunc argument. Drop the check in is_kfunc_arg_mem_size() and
is_kfunc_arg_const_mem_size() to further decouple
get_kfunc_ptr_arg_type() from register state (a prerequisite for
generating a helper-like prototype from kfunc's BTF).

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260801074633.1595644-13-ameryhung@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
This commit is contained in:
Amery Hung
2026-08-01 00:46:27 -07:00
committed by Kumar Kartikeya Dwivedi
parent f88caee62e
commit ea5ab23898
1 changed files with 9 additions and 11 deletions
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20
kernel/bpf/verifier.c
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@@ -10785,26 +10785,24 @@ static bool is_kfunc_rcu_protected(struct bpf_call_arg_meta *meta)
}
static bool is_kfunc_arg_mem_size(const struct btf *btf,
const struct btf_param *arg,
const struct bpf_reg_state *reg)
const struct btf_param *arg)
{
const struct btf_type *t;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
if (!btf_type_is_scalar(t))
return false;
return btf_param_match_suffix(btf, arg, "__sz");
}
static bool is_kfunc_arg_const_mem_size(const struct btf *btf,
const struct btf_param *arg,
const struct bpf_reg_state *reg)
const struct btf_param *arg)
{
const struct btf_type *t;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
if (!btf_type_is_scalar(t))
return false;
return btf_param_match_suffix(btf, arg, "__szk");
@@ -11338,7 +11336,7 @@ bool bpf_is_kfunc_pkt_changing(struct bpf_call_arg_meta *meta)
}
static enum kfunc_ptr_arg_type
get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, struct bpf_func_state *caller,
get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, struct bpf_call_arg_meta *meta,
const struct btf_type *t, const struct btf_type *ref_t,
const char *ref_tname, const struct btf_param *args,
@@ -11352,8 +11350,8 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, struct bpf_func_state *call
return KF_ARG_PTR_TO_CTX;
if (arg + 1 < nargs &&
(is_kfunc_arg_mem_size(meta->btf, &args[arg + 1], get_func_arg_reg(caller, regs, arg + 1)) ||
is_kfunc_arg_const_mem_size(meta->btf, &args[arg + 1], get_func_arg_reg(caller, regs, arg + 1))))
(is_kfunc_arg_mem_size(meta->btf, &args[arg + 1]) ||
is_kfunc_arg_const_mem_size(meta->btf, &args[arg + 1])))
arg_mem_size = true;
/* In this function, we verify the kfunc's BTF as per the argument type,
@@ -12084,7 +12082,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
}
if (is_kfunc_arg_constant(meta->btf, &args[i]) ||
is_kfunc_arg_const_mem_size(meta->btf, &args[i], reg)) {
is_kfunc_arg_const_mem_size(meta->btf, &args[i])) {
ret = process_const_arg(env, reg, argno, meta);
if (ret < 0)
return ret;
@@ -12129,7 +12127,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_call_arg_me
ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
kf_arg_type = get_kfunc_ptr_arg_type(env, caller, regs, meta, t, ref_t, ref_tname,
kf_arg_type = get_kfunc_ptr_arg_type(env, regs, meta, t, ref_t, ref_tname,
args, i, nargs, argno, reg);
if (kf_arg_type < 0)
return kf_arg_type;