From: Alexei Starovoitov <ast@xxxxxxxxxx>
Introduce 'struct bpf_timer' that can be embedded in most BPF map types
and helpers to operate on it:
long bpf_timer_init(struct bpf_timer *timer, void *callback, int flags)
long bpf_timer_mod(struct bpf_timer *timer, u64 msecs)
long bpf_timer_del(struct bpf_timer *timer)
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
This is work in progress, but gives an idea on how API will look.
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 25 ++++
kernel/bpf/helpers.c | 106 +++++++++++++++++
kernel/bpf/verifier.c | 110 ++++++++++++++++++
kernel/trace/bpf_trace.c | 2 +-
scripts/bpf_doc.py | 2 +
tools/include/uapi/linux/bpf.h | 25 ++++
.../testing/selftests/bpf/prog_tests/timer.c | 42 +++++++
tools/testing/selftests/bpf/progs/timer.c | 53 +++++++++
9 files changed, 365 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/timer.c
create mode 100644 tools/testing/selftests/bpf/progs/timer.c
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 9dc44ba97584..18e09cc0c410 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -312,6 +312,7 @@ enum bpf_arg_type {
ARG_PTR_TO_FUNC, /* pointer to a bpf program function */
ARG_PTR_TO_STACK_OR_NULL, /* pointer to stack or NULL */
ARG_PTR_TO_CONST_STR, /* pointer to a null terminated read-only string */
+ ARG_PTR_TO_TIMER, /* pointer to bpf_timer */
__BPF_ARG_TYPE_MAX,
};
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 418b9b813d65..c95d7854d9fb 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4761,6 +4761,24 @@ union bpf_attr {
* Execute close syscall for given FD.
* Return
* A syscall result.
+ *
+ * long bpf_timer_init(struct bpf_timer *timer, void *callback, int flags)
+ * Description
+ * Initialize the timer to call given static function.
+ * Return
+ * zero
+ *
+ * long bpf_timer_mod(struct bpf_timer *timer, u64 msecs)
+ * Description
+ * Set the timer expiration N msecs from the current time.
+ * Return
+ * zero
+ *
+ * long bpf_timer_del(struct bpf_timer *timer)
+ * Description
+ * Deactivate the timer.
+ * Return
+ * zero
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -4932,6 +4950,9 @@ union bpf_attr {
FN(sys_bpf), \
FN(btf_find_by_name_kind), \
FN(sys_close), \
+ FN(timer_init), \
+ FN(timer_mod), \
+ FN(timer_del), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -6038,6 +6059,10 @@ struct bpf_spin_lock {
__u32 val;
};
+struct bpf_timer {
+ __u64 opaque;
+};
+
struct bpf_sysctl {
__u32 write; /* Sysctl is being read (= 0) or written (= 1).
* Allows 1,2,4-byte read, but no write.
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 544773970dbc..8ef0ad23c991 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -985,6 +985,106 @@ const struct bpf_func_proto bpf_snprintf_proto = {
.arg5_type = ARG_CONST_SIZE_OR_ZERO,
};
+struct bpf_timer_list {
+ struct timer_list tl;
+ struct bpf_map *map;
+ struct bpf_prog *prog;
+ void *callback_fn;
+ void *key;
+ void *value;
+};
+
+static void timer_cb(struct timer_list *timer)
+{
+ struct bpf_timer_list *tl = from_timer(tl, timer, tl);
+ struct bpf_map *map;
+ int ret;
+
+ ret = BPF_CAST_CALL(tl->callback_fn)((u64)(long)tl->map,
+ (u64)(long)tl->key,
+ (u64)(long)tl->value, 0, 0);
+ WARN_ON(ret != 0); /* todo: define 0 vs 1 or disallow 1 in the verifier */
+ bpf_prog_put(tl->prog);
+}
+
+BPF_CALL_5(bpf_timer_init, struct bpf_timer *, timer, void *, cb, int, flags,
+ struct bpf_map *, map, struct bpf_prog *, prog)
+{
+ struct bpf_timer_list *tl;
+
+ if (timer->opaque)
+ return -EBUSY;
+ tl = kcalloc(1, sizeof(*tl), GFP_ATOMIC);
+ if (!tl)
+ return -ENOMEM;
+ tl->callback_fn = cb;
+ tl->value = (void *)timer /* - offset of bpf_timer inside elem */;
+ tl->key = tl->value - round_up(map->key_size, 8);
+ tl->map = map;
+ tl->prog = prog;
+ timer_setup(&tl->tl, timer_cb, 0);
+ timer->opaque = (long)tl;
+ return 0;
+}
+
+const struct bpf_func_proto bpf_timer_init_proto = {
+ .func = bpf_timer_init,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_TIMER,
+ .arg2_type = ARG_PTR_TO_FUNC,
+ .arg3_type = ARG_ANYTHING,
+};
+
+BPF_CALL_2(bpf_timer_mod, struct bpf_timer *, timer, u64, msecs)
+{
+ struct bpf_timer_list *tl;
+
+ tl = (struct bpf_timer_list *)timer->opaque;
+ if (!tl)
+ return -EINVAL;
+ /* keep the prog alive until callback is invoked */
+ if (!mod_timer(&tl->tl, jiffies + msecs_to_jiffies(msecs))) {
+ /* The timer was inactive.
+ * Keep the prog alive until callback is invoked
+ */
+ bpf_prog_inc(tl->prog);
+ }
+ return 0;
+}
+
+const struct bpf_func_proto bpf_timer_mod_proto = {
+ .func = bpf_timer_mod,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_TIMER,
+ .arg2_type = ARG_ANYTHING,
+};
+
+BPF_CALL_1(bpf_timer_del, struct bpf_timer *, timer)
+{
+ struct bpf_timer_list *tl;
+
+ tl = (struct bpf_timer_list *)timer->opaque;
+ if (!tl)
+ return -EINVAL;
+ if (del_timer(&tl->tl)) {
+ /* The timer was active,
+ * drop the prog refcnt, since callback
+ * will not be invoked.
+ */
+ bpf_prog_put(tl->prog);
+ }
+ return 0;
+}
+
+const struct bpf_func_proto bpf_timer_del_proto = {
+ .func = bpf_timer_del,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_TIMER,
+};
+
const struct bpf_func_proto bpf_get_current_task_proto __weak;
const struct bpf_func_proto bpf_probe_read_user_proto __weak;
const struct bpf_func_proto bpf_probe_read_user_str_proto __weak;
@@ -1033,6 +1133,12 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_ringbuf_query_proto;
case BPF_FUNC_for_each_map_elem:
return &bpf_for_each_map_elem_proto;
+ case BPF_FUNC_timer_init:
+ return &bpf_timer_init_proto;
+ case BPF_FUNC_timer_mod:
+ return &bpf_timer_mod_proto;
+ case BPF_FUNC_timer_del:
+ return &bpf_timer_del_proto;
default:
break;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9189eecb26dd..606c713be60a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4656,6 +4656,35 @@ static int process_spin_lock(struct bpf_verifier_env *env, int regno,
return 0;
}
+static int process_timer_func(struct bpf_verifier_env *env, int regno,
+ struct bpf_call_arg_meta *meta)
+{
+ struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
+ bool is_const = tnum_is_const(reg->var_off);
+ struct bpf_map *map = reg->map_ptr;
+ u64 val = reg->var_off.value;
+
+ if (!is_const) {
+ verbose(env,
+ "R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n",
+ regno);
+ return -EINVAL;
+ }
+ if (!map->btf) {
+ verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n",
+ map->name);
+ return -EINVAL;
+ }
+ if (val) {
+ /* todo: relax this requirement */
+ verbose(env, "bpf_timer field can only be first in the map value element\n");
+ return -EINVAL;
+ }
+ WARN_ON(meta->map_ptr);
+ meta->map_ptr = map;
+ return 0;
+}
+
static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
{
return type == ARG_PTR_TO_MEM ||
@@ -4788,6 +4817,7 @@ static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_PER
static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
+static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
[ARG_PTR_TO_MAP_KEY] = &map_key_value_types,
@@ -4819,6 +4849,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
[ARG_PTR_TO_FUNC] = &func_ptr_types,
[ARG_PTR_TO_STACK_OR_NULL] = &stack_ptr_types,
[ARG_PTR_TO_CONST_STR] = &const_str_ptr_types,
+ [ARG_PTR_TO_TIMER] = &timer_types,
};
static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
@@ -5000,6 +5031,9 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
verbose(env, "verifier internal error\n");
return -EFAULT;
}
+ } else if (arg_type == ARG_PTR_TO_TIMER) {
+ if (process_timer_func(env, regno, meta))
+ return -EACCES;
} else if (arg_type == ARG_PTR_TO_FUNC) {
meta->subprogno = reg->subprogno;
} else if (arg_type_is_mem_ptr(arg_type)) {
@@ -5742,6 +5776,43 @@ static int set_map_elem_callback_state(struct bpf_verifier_env *env,
return 0;
}
+static int set_timer_init_callback_state(struct bpf_verifier_env *env,
+ struct bpf_func_state *caller,
+ struct bpf_func_state *callee,
+ int insn_idx)
+{
+ struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx];
+ struct bpf_map *map_ptr;
+
+ if (bpf_map_ptr_poisoned(insn_aux)) {
+ verbose(env, "bpf_timer_init abusing map_ptr\n");
+ return -EINVAL;
+ }
+
+ map_ptr = BPF_MAP_PTR(insn_aux->map_ptr_state);
+
+ /* bpf_timer_init(struct bpf_timer *timer, void *callback_fn, u64 flags);
+ * callback_fn(struct bpf_map *map, void *key, void *value);
+ */
+ callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
+ __mark_reg_known_zero(&callee->regs[BPF_REG_1]);
+ callee->regs[BPF_REG_1].map_ptr = map_ptr;
+
+ callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
+ __mark_reg_known_zero(&callee->regs[BPF_REG_2]);
+ callee->regs[BPF_REG_2].map_ptr = map_ptr;
+
+ callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
+ __mark_reg_known_zero(&callee->regs[BPF_REG_3]);
+ callee->regs[BPF_REG_3].map_ptr = map_ptr;
+
+ /* unused */
+ __mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
+ __mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
+ callee->in_callback_fn = true;
+ return 0;
+}
+
static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
{
struct bpf_verifier_state *state = env->cur_state;
@@ -5837,6 +5908,7 @@ 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_timer_init &&
func_id != BPF_FUNC_redirect_map)
return 0;
@@ -6069,6 +6141,13 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
return -EINVAL;
}
+ if (func_id == BPF_FUNC_timer_init) {
+ err = __check_func_call(env, insn, insn_idx_p, meta.subprogno,
+ set_timer_init_callback_state);
+ if (err < 0)
+ return -EINVAL;
+ }
+
if (func_id == BPF_FUNC_snprintf) {
err = check_bpf_snprintf_call(env, regs);
if (err < 0)
@@ -12526,6 +12605,37 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
insn = new_prog->insnsi + i + delta;
continue;
}
+ if (insn->imm == BPF_FUNC_timer_init) {
+
+ aux = &env->insn_aux_data[i + delta];
+ if (bpf_map_ptr_poisoned(aux)) {
+ verbose(env, "bpf_timer_init abusing map_ptr\n");
+ return -EINVAL;
+ }
+ map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
+ {
+ struct bpf_insn ld_addrs[4] = {
+ BPF_LD_IMM64(BPF_REG_4, (long)map_ptr),
+ BPF_LD_IMM64(BPF_REG_5, (long)prog),
+ };
+
+ insn_buf[0] = ld_addrs[0];
+ insn_buf[1] = ld_addrs[1];
+ insn_buf[2] = ld_addrs[2];
+ insn_buf[3] = ld_addrs[3];
+ }
+ insn_buf[4] = *insn;
+ cnt = 5;
+
+ new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
+ if (!new_prog)
+ return -ENOMEM;
+
+ delta += cnt - 1;
+ env->prog = prog = new_prog;
+ insn = new_prog->insnsi + i + delta;
+ goto patch_call_imm;
+ }
/* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
* and other inlining handlers are currently limited to 64 bit
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d2d7cf6cfe83..453a46c2d732 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1065,7 +1065,7 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_snprintf:
return &bpf_snprintf_proto;
default:
- return NULL;
+ return bpf_base_func_proto(func_id);
}
}
diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index 2d94025b38e9..00ac7b79cddb 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -547,6 +547,7 @@ COMMANDS
'struct inode',
'struct socket',
'struct file',
+ 'struct bpf_timer',
]
known_types = {
'...',
@@ -594,6 +595,7 @@ COMMANDS
'struct inode',
'struct socket',
'struct file',
+ 'struct bpf_timer',
}
mapped_types = {
'u8': '__u8',
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 418b9b813d65..c95d7854d9fb 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4761,6 +4761,24 @@ union bpf_attr {
* Execute close syscall for given FD.
* Return
* A syscall result.
+ *
+ * long bpf_timer_init(struct bpf_timer *timer, void *callback, int flags)
+ * Description
+ * Initialize the timer to call given static function.
+ * Return
+ * zero
+ *
+ * long bpf_timer_mod(struct bpf_timer *timer, u64 msecs)
+ * Description
+ * Set the timer expiration N msecs from the current time.
+ * Return
+ * zero
+ *
+ * long bpf_timer_del(struct bpf_timer *timer)
+ * Description
+ * Deactivate the timer.
+ * Return
+ * zero
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -4932,6 +4950,9 @@ union bpf_attr {
FN(sys_bpf), \
FN(btf_find_by_name_kind), \
FN(sys_close), \
+ FN(timer_init), \
+ FN(timer_mod), \
+ FN(timer_del), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -6038,6 +6059,10 @@ struct bpf_spin_lock {
__u32 val;
};
+struct bpf_timer {
+ __u64 opaque;
+};
+
struct bpf_sysctl {
__u32 write; /* Sysctl is being read (= 0) or written (= 1).
* Allows 1,2,4-byte read, but no write.
diff --git a/tools/testing/selftests/bpf/prog_tests/timer.c b/tools/testing/selftests/bpf/prog_tests/timer.c
new file mode 100644
index 000000000000..6b7a16a54e70
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/timer.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+#include <test_progs.h>
+#include "timer.skel.h"
+
+static int timer(struct timer *timer_skel)
+{
+ int err, prog_fd;
+ __u32 duration = 0, retval;
+
+ err = timer__attach(timer_skel);
+ if (!ASSERT_OK(err, "timer_attach"))
+ return err;
+
+ prog_fd = bpf_program__fd(timer_skel->progs.test1);
+ err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
+ NULL, NULL, &retval, &duration);
+ ASSERT_OK(err, "test_run");
+ ASSERT_EQ(retval, 0, "test_run");
+
+ ASSERT_EQ(timer_skel->data->callback_check, 52, "callback_check1");
+ usleep(50 * 1000); /* 10 msecs should be enough, but give it extra */
+ ASSERT_EQ(timer_skel->data->callback_check, 42, "callback_check2");
+
+ timer__detach(timer_skel);
+ return 0;
+}
+
+void test_timer(void)
+{
+ struct timer *timer_skel = NULL;
+ int err;
+
+ timer_skel = timer__open_and_load();
+ if (!ASSERT_OK_PTR(timer_skel, "timer_skel_load"))
+ goto cleanup;
+
+ err = timer(timer_skel);
+ ASSERT_OK(err, "timer");
+cleanup:
+ timer__destroy(timer_skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/timer.c b/tools/testing/selftests/bpf/progs/timer.c
new file mode 100644
index 000000000000..2cf0634f10c9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/timer.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_tcp_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+struct map_elem {
+ struct bpf_timer timer;
+ int counter;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 1000);
+ __type(key, int);
+ __type(value, struct map_elem);
+} hmap SEC(".maps");
+
+__u64 callback_check = 52;
+
+static int timer_cb(struct bpf_map *map, int *key, struct map_elem *val)
+{
+ callback_check--;
+ if (--val->counter)
+ /* re-arm the timer again to execute after 1 msec */
+ bpf_timer_mod(&val->timer, 1);
+ return 0;
+}
+
+int bpf_timer_test(void)
+{
+ struct map_elem *val;
+ int key = 0;
+
+ val = bpf_map_lookup_elem(&hmap, &key);
+ if (val) {
+ bpf_timer_init(&val->timer, timer_cb, 0);
+ bpf_timer_mod(&val->timer, 1);
+ }
+ return 0;
+}
+
+SEC("fentry/bpf_fentry_test1")
+int BPF_PROG(test1, int a)
+{
+ struct map_elem val = {};
+ int key = 0;
+
+ val.counter = 10, /* number of times to trigger timer_cb */
+ bpf_map_update_elem(&hmap, &key, &val, 0);
+ return bpf_timer_test();
+}
--
2.30.2
