Introduce a new bpf map type 'BPF_MAP_TYPE_PERF_EVENT_ARRAY'. This map only stores the pointer to struct perf_event. The user space event FDs from perf_event_open() syscall are converted to the pointer to struct perf_event and stored in map.
Signed-off-by: Kaixu Xia <[email protected]> --- include/linux/bpf.h | 1 + include/linux/perf_event.h | 2 ++ include/uapi/linux/bpf.h | 1 + kernel/bpf/arraymap.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 15 ++++++++++++ kernel/events/core.c | 17 ++++++++++++++ 6 files changed, 93 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 610b730..3c9c0eb 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -10,6 +10,7 @@ #include <uapi/linux/bpf.h> #include <linux/workqueue.h> #include <linux/file.h> +#include <linux/perf_event.h> struct bpf_map; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 2027809..2ea4067 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -641,6 +641,7 @@ extern int perf_event_init_task(struct task_struct *child); extern void perf_event_exit_task(struct task_struct *child); extern void perf_event_free_task(struct task_struct *task); extern void perf_event_delayed_put(struct task_struct *task); +extern struct perf_event *perf_event_get(unsigned int fd); extern void perf_event_print_debug(void); extern void perf_pmu_disable(struct pmu *pmu); extern void perf_pmu_enable(struct pmu *pmu); @@ -979,6 +980,7 @@ static inline int perf_event_init_task(struct task_struct *child) { return 0; } static inline void perf_event_exit_task(struct task_struct *child) { } static inline void perf_event_free_task(struct task_struct *task) { } static inline void perf_event_delayed_put(struct task_struct *task) { } +static struct perf_event *perf_event_get(unsigned int fd) { return NULL; } static inline void perf_event_print_debug(void) { } static inline int perf_event_task_disable(void) { return -EINVAL; } static inline int perf_event_task_enable(void) { return -EINVAL; } diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 29ef6f9..69a1f6b 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -114,6 +114,7 @@ enum bpf_map_type { BPF_MAP_TYPE_HASH, BPF_MAP_TYPE_ARRAY, BPF_MAP_TYPE_PROG_ARRAY, + BPF_MAP_TYPE_PERF_EVENT_ARRAY, }; enum bpf_prog_type { diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 4784cdc..a9e0235 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -297,3 +297,60 @@ static int __init register_prog_array_map(void) return 0; } late_initcall(register_prog_array_map); + +static void *perf_event_fd_array_get_ptr(struct bpf_array *array, int fd) +{ + struct perf_event *event; + + event = perf_event_get(fd); + if (IS_ERR(event)) + return event; + + /* + * prevent some crazy events so we can make our life easier + */ + if (event->attr.type != PERF_TYPE_RAW && + event->attr.type != PERF_TYPE_HARDWARE) { + perf_event_release_kernel(event); + return ERR_PTR(-EINVAL); + } + return event; +} + +static void perf_event_fd_array_put_ptr(struct bpf_array *array, void *ptr) +{ + struct perf_event *event = (struct perf_event *)ptr; + + perf_event_release_kernel(event); +} + +static const struct fd_array_map_ops perf_event_fd_array_map_ops = { + .get_ptr = perf_event_fd_array_get_ptr, + .put_ptr = perf_event_fd_array_put_ptr, +}; + +static struct bpf_map *perf_event_array_map_alloc(union bpf_attr *attr) +{ + return fd_array_map_alloc(attr, &perf_event_fd_array_map_ops); +} + +static const struct bpf_map_ops perf_event_array_ops = { + .map_alloc = perf_event_array_map_alloc, + .map_free = fd_array_map_free, + .map_get_next_key = array_map_get_next_key, + .map_lookup_elem = fd_array_map_lookup_elem, + .map_update_elem = fd_array_map_update_elem, + .map_delete_elem = fd_array_map_delete_elem, +}; + +static struct bpf_map_type_list perf_event_array_type __read_mostly = { + .ops = &perf_event_array_ops, + .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY, +}; + +static int __init register_perf_event_array_map(void) +{ + bpf_register_map_type(&perf_event_array_type); + return 0; +} +late_initcall(register_perf_event_array_map); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 039d866..c70f7e7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -924,6 +924,21 @@ static int check_call(struct verifier_env *env, int func_id) */ return -EINVAL; + if (map && map->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && + func_id != BPF_FUNC_perf_event_read) + /* perf_event_array map type needs extra care: + * only allow to pass it into bpf_perf_event_read() for now. + * bpf_map_update/delete_elem() must only be done via syscall + */ + return -EINVAL; + + if (func_id == BPF_FUNC_perf_event_read && + map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) + /* don't allow any other map type to be passed into + * bpf_perf_event_read() + */ + return -EINVAL; + return 0; } diff --git a/kernel/events/core.c b/kernel/events/core.c index d3dae34..58f0d47 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8574,6 +8574,23 @@ void perf_event_delayed_put(struct task_struct *task) WARN_ON_ONCE(task->perf_event_ctxp[ctxn]); } +struct perf_event *perf_event_get(unsigned int fd) +{ + int err; + struct fd f; + struct perf_event *event; + + err = perf_fget_light(fd, &f); + if (err) + return ERR_PTR(err); + + event = f.file->private_data; + atomic_long_inc(&event->refcount); + fdput(f); + + return event; +} + /* * inherit a event from parent task to child task: */ -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
