[PATCH bpf-next] bpf: add bpf_map_lookup_percpu_elem for percpu map

From: Feng zhou
Date: Fri May 06 2022 - 22:53:10 EST

Next message: Lai Jiangshan: "Re: [PATCH 3/6] x86/entry: Use PUSH_AND_CLEAR_REGS for compat"
Previous message: Lai Jiangshan: "Re: [PATCH 4/6] x86/entry: Remove skip_r11rcx"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

From: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>

Trace some functions, such as enqueue_task_fair, need to access the
corresponding cpu, not the current cpu, and bpf_map_lookup_elem percpu map
cannot do it. So add bpf_map_lookup_percpu_elem to accomplish it for
percpu_array_map, percpu_hash_map, lru_percpu_hash_map.

The implementation method is relatively simple, refer to the implementation
method of map_lookup_elem of percpu map, increase the parameters of cpu, and
obtain it according to the specified cpu.

Signed-off-by: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
---
include/linux/bpf.h | 2 ++
include/uapi/linux/bpf.h | 9 +++++++++
kernel/bpf/arraymap.c | 15 +++++++++++++++
kernel/bpf/core.c | 1 +
kernel/bpf/hashtab.c | 32 ++++++++++++++++++++++++++++++++
kernel/bpf/helpers.c | 18 ++++++++++++++++++
kernel/bpf/verifier.c | 17 +++++++++++++++--
kernel/trace/bpf_trace.c | 2 ++
tools/include/uapi/linux/bpf.h | 9 +++++++++
9 files changed, 103 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index be94833d390a..6b5cf5a90d73 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -89,6 +89,7 @@ struct bpf_map_ops {
int (*map_push_elem)(struct bpf_map *map, void *value, u64 flags);
int (*map_pop_elem)(struct bpf_map *map, void *value);
int (*map_peek_elem)(struct bpf_map *map, void *value);
+ void *(*map_lookup_percpu_elem)(struct bpf_map *map, void *key, u32 cpu);

/* funcs called by prog_array and perf_event_array map */
void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
@@ -2161,6 +2162,7 @@ extern const struct bpf_func_proto bpf_map_delete_elem_proto;
extern const struct bpf_func_proto bpf_map_push_elem_proto;
extern const struct bpf_func_proto bpf_map_pop_elem_proto;
extern const struct bpf_func_proto bpf_map_peek_elem_proto;
+extern const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto;

extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 444fe6f1cf35..024fb9f319a8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5154,6 +5154,14 @@ union bpf_attr {
* if not NULL, is a reference which must be released using its
* corresponding release function, or moved into a BPF map before
* program exit.
+ *
+ * void *bpf_map_lookup_percpu_elem(struct bpf_map *map, const void *key, u32 cpu)
+ * Description
+ * Perform a lookup in *percpu map* for an entry associated to
+ * *key* on *cpu*.
+ * Return
+ * Map value associated to *key* on *cpu*, or **NULL** if no entry
+ * was found or *cpu* is invalid.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5351,6 +5359,7 @@ union bpf_attr {
FN(skb_set_tstamp), \
FN(ima_file_hash), \
FN(kptr_xchg), \
+ FN(map_lookup_percpu_elem), \
/* */

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index b3bf31fd9458..71d9db976ab0 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -243,6 +243,20 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
return this_cpu_ptr(array->pptrs[index & array->index_mask]);
}

+static void *percpu_array_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ u32 index = *(u32 *)key;
+
+ if (cpu >= nr_cpu_ids)
+ return NULL;
+
+ if (unlikely(index >= array->map.max_entries))
+ return NULL;
+
+ return per_cpu_ptr(array->pptrs[index & array->index_mask], cpu);
+}
+
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
@@ -725,6 +739,7 @@ const struct bpf_map_ops percpu_array_map_ops = {
.map_lookup_elem = percpu_array_map_lookup_elem,
.map_update_elem = array_map_update_elem,
.map_delete_elem = array_map_delete_elem,
+ .map_lookup_percpu_elem = percpu_array_map_lookup_percpu_elem,
.map_seq_show_elem = percpu_array_map_seq_show_elem,
.map_check_btf = array_map_check_btf,
.map_lookup_batch = generic_map_lookup_batch,
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 13e9dbeeedf3..76f68d0a7ae8 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2619,6 +2619,7 @@ const struct bpf_func_proto bpf_map_delete_elem_proto __weak;
const struct bpf_func_proto bpf_map_push_elem_proto __weak;
const struct bpf_func_proto bpf_map_pop_elem_proto __weak;
const struct bpf_func_proto bpf_map_peek_elem_proto __weak;
+const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto __weak;
const struct bpf_func_proto bpf_spin_lock_proto __weak;
const struct bpf_func_proto bpf_spin_unlock_proto __weak;
const struct bpf_func_proto bpf_jiffies64_proto __weak;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 3e00e62b2218..9c45b07dd5b6 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -2191,6 +2191,20 @@ static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
return NULL;
}

+static void *htab_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+ struct htab_elem *l;
+
+ if (cpu >= nr_cpu_ids)
+ return NULL;
+
+ l = __htab_map_lookup_elem(map, key);
+ if (l)
+ return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
+ else
+ return NULL;
+}
+
static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
{
struct htab_elem *l = __htab_map_lookup_elem(map, key);
@@ -2203,6 +2217,22 @@ static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
return NULL;
}

+static void *htab_lru_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+ struct htab_elem *l;
+
+ if (cpu >= nr_cpu_ids)
+ return NULL;
+
+ l = __htab_map_lookup_elem(map, key);
+ if (l) {
+ bpf_lru_node_set_ref(&l->lru_node);
+ return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
+ }
+
+ return NULL;
+}
+
int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
{
struct htab_elem *l;
@@ -2292,6 +2322,7 @@ const struct bpf_map_ops htab_percpu_map_ops = {
.map_lookup_and_delete_elem = htab_percpu_map_lookup_and_delete_elem,
.map_update_elem = htab_percpu_map_update_elem,
.map_delete_elem = htab_map_delete_elem,
+ .map_lookup_percpu_elem = htab_percpu_map_lookup_percpu_elem,
.map_seq_show_elem = htab_percpu_map_seq_show_elem,
.map_set_for_each_callback_args = map_set_for_each_callback_args,
.map_for_each_callback = bpf_for_each_hash_elem,
@@ -2310,6 +2341,7 @@ const struct bpf_map_ops htab_lru_percpu_map_ops = {
.map_lookup_and_delete_elem = htab_lru_percpu_map_lookup_and_delete_elem,
.map_update_elem = htab_lru_percpu_map_update_elem,
.map_delete_elem = htab_lru_map_delete_elem,
+ .map_lookup_percpu_elem = htab_lru_percpu_map_lookup_percpu_elem,
.map_seq_show_elem = htab_percpu_map_seq_show_elem,
.map_set_for_each_callback_args = map_set_for_each_callback_args,
.map_for_each_callback = bpf_for_each_hash_elem,
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 3e709fed5306..d5f104a39092 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -119,6 +119,22 @@ const struct bpf_func_proto bpf_map_peek_elem_proto = {
.arg2_type = ARG_PTR_TO_UNINIT_MAP_VALUE,
};

+BPF_CALL_3(bpf_map_lookup_percpu_elem, struct bpf_map *, map, void *, key, u32, cpu)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
+ return (unsigned long) map->ops->map_lookup_percpu_elem(map, key, cpu);
+}
+
+const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto = {
+ .func = bpf_map_lookup_percpu_elem,
+ .gpl_only = false,
+ .pkt_access = true,
+ .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_MAP_KEY,
+ .arg3_type = ARG_ANYTHING,
+};
+
const struct bpf_func_proto bpf_get_prandom_u32_proto = {
.func = bpf_user_rnd_u32,
.gpl_only = false,
@@ -1420,6 +1436,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_map_pop_elem_proto;
case BPF_FUNC_map_peek_elem:
return &bpf_map_peek_elem_proto;
+ case BPF_FUNC_map_lookup_percpu_elem:
+ return &bpf_map_lookup_percpu_elem_proto;
case BPF_FUNC_get_prandom_u32:
return &bpf_get_prandom_u32_proto;
case BPF_FUNC_get_smp_processor_id:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 813f6ee80419..67ac0b047caf 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6138,6 +6138,12 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
goto error;
break;
+ case BPF_FUNC_map_lookup_percpu_elem:
+ if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
+ map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
+ map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH)
+ goto error;
+ break;
case BPF_FUNC_sk_storage_get:
case BPF_FUNC_sk_storage_delete:
if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
@@ -6751,7 +6757,8 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
func_id != BPF_FUNC_map_pop_elem &&
func_id != BPF_FUNC_map_peek_elem &&
func_id != BPF_FUNC_for_each_map_elem &&
- func_id != BPF_FUNC_redirect_map)
+ func_id != BPF_FUNC_redirect_map &&
+ func_id != BPF_FUNC_map_lookup_percpu_elem)
return 0;

if (map == NULL) {
@@ -13811,7 +13818,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
insn->imm == BPF_FUNC_map_pop_elem ||
insn->imm == BPF_FUNC_map_peek_elem ||
insn->imm == BPF_FUNC_redirect_map ||
- insn->imm == BPF_FUNC_for_each_map_elem)) {
+ insn->imm == BPF_FUNC_for_each_map_elem ||
+ insn->imm == BPF_FUNC_map_lookup_percpu_elem)) {
aux = &env->insn_aux_data[i + delta];
if (bpf_map_ptr_poisoned(aux))
goto patch_call_imm;
@@ -13860,6 +13868,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
bpf_callback_t callback_fn,
void *callback_ctx,
u64 flags))NULL));
+ BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem,
+ (void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL));

patch_map_ops_generic:
switch (insn->imm) {
@@ -13887,6 +13897,9 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
case BPF_FUNC_for_each_map_elem:
insn->imm = BPF_CALL_IMM(ops->map_for_each_callback);
continue;
+ case BPF_FUNC_map_lookup_percpu_elem:
+ insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem);
+ continue;
}

goto patch_call_imm;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f15b826f9899..af4125407c20 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1182,6 +1182,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_map_pop_elem_proto;
case BPF_FUNC_map_peek_elem:
return &bpf_map_peek_elem_proto;
+ case BPF_FUNC_map_lookup_percpu_elem:
+ return &bpf_map_lookup_percpu_elem_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_ktime_get_boot_ns:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 444fe6f1cf35..024fb9f319a8 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5154,6 +5154,14 @@ union bpf_attr {
* if not NULL, is a reference which must be released using its
* corresponding release function, or moved into a BPF map before
* program exit.
+ *
+ * void *bpf_map_lookup_percpu_elem(struct bpf_map *map, const void *key, u32 cpu)
+ * Description
+ * Perform a lookup in *percpu map* for an entry associated to
+ * *key* on *cpu*.
+ * Return
+ * Map value associated to *key* on *cpu*, or **NULL** if no entry
+ * was found or *cpu* is invalid.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5351,6 +5359,7 @@ union bpf_attr {
FN(skb_set_tstamp), \
FN(ima_file_hash), \
FN(kptr_xchg), \
+ FN(map_lookup_percpu_elem), \
/* */

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.20.1

Next message: Lai Jiangshan: "Re: [PATCH 3/6] x86/entry: Use PUSH_AND_CLEAR_REGS for compat"
Previous message: Lai Jiangshan: "Re: [PATCH 4/6] x86/entry: Remove skip_r11rcx"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]