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bpf: Add support for tracing_multi link cookies

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Add support to specify cookies for tracing_multi link.

Cookies are provided in array where each value is paired with provided
BTF ID value with the same array index.

Such cookie can be retrieved by bpf program with bpf_get_attach_cookie
helper call.

We need to sort cookies array together with ids array in check_dup_ids,
to keep the id->cookie relation.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260606123955.345967-15-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jiri Olsa 2026-06-06 14:39:39 +02:00 committed by Alexei Starovoitov
parent c1d32dea5d
commit 46b42af27d
5 changed files with 37 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/bpf.h
View File

@ -1971,6 +1971,7 @@ struct bpf_tracing_multi_data {
struct bpf_tracing_multi_link {
struct bpf_link link;
struct bpf_tracing_multi_data data;
u64 *cookies;
int nodes_cnt;
struct bpf_tracing_multi_node nodes[] __counted_by(nodes_cnt);
};

1
include/uapi/linux/bpf.h
View File

@ -1880,6 +1880,7 @@ union bpf_attr {
} cgroup;
struct {
__aligned_u64 ids;
__aligned_u64 cookies;
__u32 cnt;
} tracing_multi;
};

1
kernel/bpf/trampoline.c
View File

@ -1613,6 +1613,7 @@ int bpf_trampoline_multi_attach(struct bpf_prog *prog, u32 *ids,
mnode->trampoline = tr;
mnode->node.link = &link->link;
mnode->node.cookie = link->cookies ? link->cookies[i] : 0;
cond_resched();
}

37
kernel/trace/bpf_trace.c
View File

@ -3659,6 +3659,7 @@ static void bpf_tracing_multi_link_dealloc(struct bpf_link *link)
struct bpf_tracing_multi_link *tr_link =
container_of(link, struct bpf_tracing_multi_link, link);
kvfree(tr_link->cookies);
kvfree(tr_link);
}
@ -3678,13 +3679,24 @@ static int ids_cmp_r(const void *pa, const void *pb, const void *priv __maybe_un
static void ids_swap_r(void *a, void *b, int size __maybe_unused,
const void *priv __maybe_unused)
{
u32 *id_a = a, *id_b = b;
u64 *cookie_a, *cookie_b, *cookies;
u32 *id_a = a, *id_b = b, *ids;
void **data = (void **) priv;
ids = data[0];
cookies = data[1];
if (cookies) {
cookie_a = cookies + (id_a - ids);
cookie_b = cookies + (id_b - ids);
swap(*cookie_a, *cookie_b);
}
swap(*id_a, *id_b);
}
static int check_dup_ids(u32 *ids, u32 cnt)
static int check_dup_ids(u32 *ids, u64 *cookies, u32 cnt)
{
void *data[2] = { ids, cookies };
int err = 0;
/*
@ -3692,7 +3704,7 @@ static int check_dup_ids(u32 *ids, u32 cnt)
* and check it for duplicates. The ids and cookies arrays
* are left sorted.
*/
sort_r_nonatomic(ids, cnt, sizeof(ids[0]), ids_cmp_r, ids_swap_r, NULL);
sort_r_nonatomic(ids, cnt, sizeof(ids[0]), ids_cmp_r, ids_swap_r, data);
for (int i = 1; i < cnt; i++) {
if (ids[i] == ids[i - 1]) {
@ -3708,6 +3720,8 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
struct bpf_tracing_multi_link *link = NULL;
struct bpf_link_primer link_primer;
u32 cnt, *ids = NULL;
u64 __user *ucookies;
u64 *cookies = NULL;
u32 __user *uids;
int err;
@ -3730,7 +3744,20 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
goto error;
}
err = check_dup_ids(ids, cnt);
ucookies = u64_to_user_ptr(attr->link_create.tracing_multi.cookies);
if (ucookies) {
cookies = kvmalloc_objs(*cookies, cnt);
if (!cookies) {
err = -ENOMEM;
goto error;
}
if (copy_from_user(cookies, ucookies, cnt * sizeof(*cookies))) {
err = -EFAULT;
goto error;
}
}
err = check_dup_ids(ids, cookies, cnt);
if (err)
goto error;
@ -3748,6 +3775,7 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
goto error;
link->nodes_cnt = cnt;
link->cookies = cookies;
err = bpf_trampoline_multi_attach(prog, ids, link);
kvfree(ids);
@ -3758,6 +3786,7 @@ int bpf_tracing_multi_attach(struct bpf_prog *prog, const union bpf_attr *attr)
return bpf_link_settle(&link_primer);
error:
kvfree(cookies);
kvfree(ids);
kvfree(link);
return err;

1
tools/include/uapi/linux/bpf.h
View File

@ -1880,6 +1880,7 @@ union bpf_attr {
} cgroup;
struct {
__aligned_u64 ids;
__aligned_u64 cookies;
__u32 cnt;
} tracing_multi;
};