jsauer/torvalds-linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-01-12 01:20:14 +00:00
Code

bpf: Allow union argument in trampoline based programs

Browse Source 
Currently, functions with 'union' arguments cannot be traced with
fentry/fexit:

bpftrace -e 'fentry:release_pages { exit(); }' -v

The function release_pages arg0 type UNION is unsupported.

The type of the 'release_pages' arg0 is defined as:

typedef union {
	struct page **pages;
	struct folio **folios;
	struct encoded_page **encoded_pages;
} release_pages_arg __attribute__ ((__transparent_union__));

This patch relaxes the restriction by allowing function arguments of type
'union' to be traced in verifier.

Reviewed-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20250919044110.23729-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Leon Hwang 2025-09-19 12:41:09 +08:00 committed by Alexei Starovoitov
parent 2383e45f1d
commit ccb4f5d91e
2 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/bpf.h
View File

@ -1128,7 +1128,7 @@ struct bpf_prog_offload {
*/
#define MAX_BPF_FUNC_REG_ARGS 5
/* The argument is a structure. */
/* The argument is a structure or a union. */
#define BTF_FMODEL_STRUCT_ARG BIT(0)
/* The argument is signed. */

8
kernel/bpf/btf.c
View File

@ -6751,7 +6751,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
/* skip modifiers */
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (btf_type_is_small_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
if (btf_type_is_small_int(t) || btf_is_any_enum(t) || btf_type_is_struct(t))
/* accessing a scalar */
return true;
if (!btf_type_is_ptr(t)) {
@ -7323,7 +7323,7 @@ static int __get_type_size(struct btf *btf, u32 btf_id,
if (btf_type_is_ptr(t))
/* kernel size of pointer. Not BPF's size of pointer*/
return sizeof(void *);
if (btf_type_is_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
if (btf_type_is_int(t) || btf_is_any_enum(t) || btf_type_is_struct(t))
return t->size;
return -EINVAL;
}
@ -7332,7 +7332,7 @@ static u8 __get_type_fmodel_flags(const struct btf_type *t)
{
u8 flags = 0;
if (__btf_type_is_struct(t))
if (btf_type_is_struct(t))
flags |= BTF_FMODEL_STRUCT_ARG;
if (btf_type_is_signed_int(t))
flags |= BTF_FMODEL_SIGNED_ARG;
@ -7373,7 +7373,7 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
return -EINVAL;
}
ret = __get_type_size(btf, func->type, &t);
if (ret < 0 || __btf_type_is_struct(t)) {
if (ret < 0 || btf_type_is_struct(t)) {
bpf_log(log,
"The function %s return type %s is unsupported.\n",
tname, btf_type_str(t));