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bpf: Add trampoline ip hash table

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Following changes need to lookup trampoline based on its ip address,
adding hash table for that.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20251230145010.103439-8-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2025-12-30 15:50:08 +01:00 committed by Andrii Nakryiko
parent e93672f770
commit 7d0452497c
2 changed files with 24 additions and 13 deletions
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7
include/linux/bpf.h
View File

@ -1329,14 +1329,17 @@ struct bpf_tramp_image {
};
struct bpf_trampoline {
/* hlist for trampoline_table */
struct hlist_node hlist;
/* hlist for trampoline_key_table */
struct hlist_node hlist_key;
/* hlist for trampoline_ip_table */
struct hlist_node hlist_ip;
struct ftrace_ops *fops;
/* serializes access to fields of this trampoline */
struct mutex mutex;
refcount_t refcnt;
u32 flags;
u64 key;
unsigned long ip;
struct {
struct btf_func_model model;
void *addr;

30
kernel/bpf/trampoline.c
View File

@ -24,9 +24,10 @@ const struct bpf_prog_ops bpf_extension_prog_ops = {
#define TRAMPOLINE_HASH_BITS 10
#define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS)
static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE];
static struct hlist_head trampoline_key_table[TRAMPOLINE_TABLE_SIZE];
static struct hlist_head trampoline_ip_table[TRAMPOLINE_TABLE_SIZE];
/* serializes access to trampoline_table */
/* serializes access to trampoline tables */
static DEFINE_MUTEX(trampoline_mutex);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
@ -142,15 +143,15 @@ void bpf_image_ksym_del(struct bpf_ksym *ksym)
PAGE_SIZE, true, ksym->name);
}
static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
static struct bpf_trampoline *bpf_trampoline_lookup(u64 key, unsigned long ip)
{
struct bpf_trampoline *tr;
struct hlist_head *head;
int i;
mutex_lock(&trampoline_mutex);
head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
hlist_for_each_entry(tr, head, hlist) {
head = &trampoline_key_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
hlist_for_each_entry(tr, head, hlist_key) {
if (tr->key == key) {
refcount_inc(&tr->refcnt);
goto out;
@ -171,8 +172,12 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
#endif
tr->key = key;
INIT_HLIST_NODE(&tr->hlist);
hlist_add_head(&tr->hlist, head);
tr->ip = ftrace_location(ip);
INIT_HLIST_NODE(&tr->hlist_key);
INIT_HLIST_NODE(&tr->hlist_ip);
hlist_add_head(&tr->hlist_key, head);
head = &trampoline_ip_table[hash_64(tr->ip, TRAMPOLINE_HASH_BITS)];
hlist_add_head(&tr->hlist_ip, head);
refcount_set(&tr->refcnt, 1);
mutex_init(&tr->mutex);
for (i = 0; i < BPF_TRAMP_MAX; i++)
@ -883,7 +888,7 @@ void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog)
prog->aux->attach_btf_id);
bpf_lsm_find_cgroup_shim(prog, &bpf_func);
tr = bpf_trampoline_lookup(key);
tr = bpf_trampoline_lookup(key, 0);
if (WARN_ON_ONCE(!tr))
return;
@ -903,7 +908,7 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key,
{
struct bpf_trampoline *tr;
tr = bpf_trampoline_lookup(key);
tr = bpf_trampoline_lookup(key, tgt_info->tgt_addr);
if (!tr)
return NULL;
@ -939,7 +944,8 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
* fexit progs. The fentry-only trampoline will be freed via
* multiple rcu callbacks.
*/
hlist_del(&tr->hlist);
hlist_del(&tr->hlist_key);
hlist_del(&tr->hlist_ip);
if (tr->fops) {
ftrace_free_filter(tr->fops);
kfree(tr->fops);
@ -1212,7 +1218,9 @@ static int __init init_trampolines(void)
int i;
for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&trampoline_table[i]);
INIT_HLIST_HEAD(&trampoline_key_table[i]);
for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&trampoline_ip_table[i]);
return 0;
}
late_initcall(init_trampolines);