From: Yonghong Song <yonghong.song@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eduard Zingerman <eddyz87@gmail.com>,
kernel-team@fb.com
Subject: [PATCH bpf-next v4 04/15] bpf: Index global function arguments by argument slot
Date: Sat, 12 Sep 2026 12:52:16 -0700 [thread overview]
Message-ID: <20260912195216.987189-1-yonghong.song@linux.dev> (raw)
In-Reply-To: <20260912195156.980886-1-yonghong.song@linux.dev>
btf_prepare_func_args() indexes sub->args[] by BTF parameter, so a
parameter can only ever stand for a single argument register. Give the
loop a second index: 'i' keeps walking the BTF parameters while
'slots_used' walks the argument slots, and sub->arg_slot_cnt becomes the
number of slots, so that a later patch can give a parameter two of them.
No functional change: every parameter still takes exactly one slot.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
kernel/bpf/btf.c | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 9b0bd3898882..cdbae53bb94d 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8037,7 +8037,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
const struct btf_param *args;
const struct btf_type *t, *ref_t, *fn_t;
int err;
- u32 i, nargs, btf_id;
+ u32 i, slots_used, nargs, btf_id;
const char *tname;
if (sub->args_cached)
@@ -8122,8 +8122,9 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
/* Convert BTF function arguments into verifier types.
* Only PTR_TO_CTX and SCALAR are supported atm.
*/
- for (i = 0; i < nargs; i++) {
+ for (i = 0, slots_used = 0; i < nargs; i++) {
u32 tags = 0;
+
err = btf_scan_decl_tags(env, btf, fn_t, i, is_global, &tags);
if (err)
return err;
@@ -8145,7 +8146,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
btf_validate_prog_ctx_type(log, btf, t, i, prog_type,
prog->expected_attach_type))
return -EINVAL;
- sub->args[i].arg_type = ARG_PTR_TO_CTX;
+ sub->args[slots_used++].arg_type = ARG_PTR_TO_CTX;
continue;
}
if (btf_is_dynptr_ptr(btf, t)) {
@@ -8153,7 +8154,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
bpf_log(log, "arg#%d has invalid combination of tags\n", i);
return -EINVAL;
}
- sub->args[i].arg_type = ARG_PTR_TO_DYNPTR;
+ sub->args[slots_used++].arg_type = ARG_PTR_TO_DYNPTR;
continue;
}
if (tags & ARG_TAG_TRUSTED) {
@@ -8168,10 +8169,11 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
if (kern_type_id < 0)
return kern_type_id;
- sub->args[i].arg_type = ARG_PTR_TO_BTF_ID | PTR_TRUSTED;
+ sub->args[slots_used].arg_type = ARG_PTR_TO_BTF_ID | PTR_TRUSTED;
if (tags & ARG_TAG_NULLABLE)
- sub->args[i].arg_type |= PTR_MAYBE_NULL;
- sub->args[i].btf_id = kern_type_id;
+ sub->args[slots_used].arg_type |= PTR_MAYBE_NULL;
+ sub->args[slots_used].btf_id = kern_type_id;
+ slots_used++;
continue;
}
if (tags & ARG_TAG_UNTRUSTED) {
@@ -8185,8 +8187,10 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
ref_t = btf_type_skip_modifiers(btf, t->type, NULL);
if (btf_type_is_void(ref_t) || btf_type_is_primitive(ref_t)) {
- sub->args[i].arg_type = ARG_PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED;
- sub->args[i].mem_size = 0;
+ sub->args[slots_used].arg_type = ARG_PTR_TO_MEM | MEM_RDONLY |
+ PTR_UNTRUSTED;
+ sub->args[slots_used].mem_size = 0;
+ slots_used++;
continue;
}
@@ -8202,8 +8206,9 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
i, btf_type_str(ref_t), tname);
return -EINVAL;
}
- sub->args[i].arg_type = ARG_PTR_TO_BTF_ID | PTR_UNTRUSTED;
- sub->args[i].btf_id = kern_type_id;
+ sub->args[slots_used].arg_type = ARG_PTR_TO_BTF_ID | PTR_UNTRUSTED;
+ sub->args[slots_used].btf_id = kern_type_id;
+ slots_used++;
continue;
}
if (tags & ARG_TAG_ARENA) {
@@ -8211,7 +8216,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
bpf_log(log, "arg#%d arena cannot be combined with any other tags\n", i);
return -EINVAL;
}
- sub->args[i].arg_type = ARG_PTR_TO_ARENA;
+ sub->args[slots_used++].arg_type = ARG_PTR_TO_ARENA;
continue;
}
if (is_global) { /* generic user data pointer */
@@ -8231,10 +8236,11 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
return -EINVAL;
}
- sub->args[i].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL;
+ sub->args[slots_used].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL;
if (tags & ARG_TAG_NONNULL)
- sub->args[i].arg_type &= ~PTR_MAYBE_NULL;
- sub->args[i].mem_size = mem_size;
+ sub->args[slots_used].arg_type &= ~PTR_MAYBE_NULL;
+ sub->args[slots_used].mem_size = mem_size;
+ slots_used++;
continue;
}
@@ -8244,7 +8250,7 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
return -EINVAL;
}
if (btf_type_is_int(t) || btf_is_any_enum(t)) {
- sub->args[i].arg_type = ARG_SCALAR;
+ sub->args[slots_used++].arg_type = ARG_SCALAR;
continue;
}
if (!is_global)
@@ -8254,6 +8260,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
return -EINVAL;
}
+ sub->arg_slot_cnt = slots_used;
+
sub->args_cached = true;
return 0;
--
2.53.0-Meta
next prev parent reply other threads:[~2026-09-12 19:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-12 19:51 [PATCH bpf-next v4 00/15] bpf: Support by-value struct and __int128 arguments Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 01/15] bpf: Read a kfunc's __sz argument only when it is in a register Yonghong Song
2026-09-12 20:06 ` sashiko-bot
2026-09-13 2:40 ` Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 02/15] selftests/bpf: Add a test for an __int128 by-value argument Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 03/15] bpf: Rename bpf_subprog_info::arg_cnt to arg_slot_cnt Yonghong Song
2026-09-12 19:52 ` Yonghong Song [this message]
2026-09-12 19:52 ` [PATCH bpf-next v4 05/15] bpf: Support by-value struct arguments up to 16 bytes Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 06/15] bpf: Support __int128 as a by-value function argument Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 07/15] bpf: Rename bpf_call_summary::num_params to arg_slot_cnt Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 08/15] bpf: Recognize by-value struct and __int128 kfunc arguments Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 09/15] bpf: Prepare kfunc arguments for the JIT from an ABI description Yonghong Song
2026-09-12 20:10 ` sashiko-bot
2026-09-12 19:52 ` [PATCH bpf-next v4 10/15] bpf, x86: Move kfunc arguments into the x86-64 calling convention Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 11/15] bpf, arm64: Place trampoline arguments by the arm64 " Yonghong Song
2026-09-13 2:47 ` Yonghong Song
2026-09-12 19:52 ` [PATCH bpf-next v4 12/15] bpf, arm64: Move kfunc arguments into " Yonghong Song
2026-09-12 19:53 ` [PATCH bpf-next v4 13/15] selftests/bpf: Add C tests for by-value arguments up to 16 bytes Yonghong Song
2026-09-12 19:53 ` [PATCH bpf-next v4 14/15] selftests/bpf: Add inline-asm tests for by-value arguments Yonghong Song
2026-09-12 19:53 ` [PATCH bpf-next v4 15/15] selftests/bpf: Add tests for by-value kfunc arguments Yonghong Song
2026-09-13 4:00 ` [PATCH bpf-next v4 00/15] bpf: Support by-value struct and __int128 arguments patchwork-bot+netdevbpf
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