Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946142AbbGQKrP (ORCPT ); Fri, 17 Jul 2015 06:47:15 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:32600 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757675AbbGQKpU (ORCPT ); Fri, 17 Jul 2015 06:45:20 -0400 From: kaixu xia To: , , , , , , CC: , , , , Subject: [RFC PATCH 3/6] bpf: Save the pointer to struct perf_event to map Date: Fri, 17 Jul 2015 18:43:33 +0800 Message-ID: <1437129816-13176-4-git-send-email-xiakaixu@huawei.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1437129816-13176-1-git-send-email-xiakaixu@huawei.com> References: <1437129816-13176-1-git-send-email-xiakaixu@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.110.52.33] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5193 Lines: 185 The user space event FD from perf_event_open() syscall is converted to the pointer to struct perf event and stored in map. Signed-off-by: kaixu xia --- include/linux/perf_event.h | 2 ++ kernel/bpf/syscall.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ kernel/events/core.c | 22 ++++++++++++++ 3 files changed, 92 insertions(+) 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/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 4c2d9e6..ac76792 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -17,6 +17,7 @@ #include #include #include +#include static LIST_HEAD(bpf_map_types); @@ -65,6 +66,19 @@ void bpf_map_put(struct bpf_map *map) } } +static int bpf_map_perf_event_put(void *value) +{ + struct perf_event *event; + + event = (struct perf_event *)(*(unsigned long *)value); + if (!event) + return -EBADF; + + perf_event_release_kernel(event); + + return 0; +} + static int bpf_map_release(struct inode *inode, struct file *filp) { struct bpf_map *map = filp->private_data; @@ -75,6 +89,13 @@ static int bpf_map_release(struct inode *inode, struct file *filp) */ bpf_prog_array_map_clear(map); + if (map->flags & BPF_MAP_FLAG_PERF_EVENT) { + rcu_read_lock(); + if (map->ops->map_traverse_elem(bpf_map_perf_event_put, map) < 0) + return -EINVAL; + rcu_read_unlock(); + } + bpf_map_put(map); return 0; } @@ -176,6 +197,10 @@ static int map_lookup_elem(union bpf_attr *attr) if (IS_ERR(map)) return PTR_ERR(map); + if (map->flags & BPF_MAP_FLAG_PERF_EVENT) + /* prevent user space from reading elem for PMU map */ + return -EACCES; + err = -ENOMEM; key = kmalloc(map->key_size, GFP_USER); if (!key) @@ -215,6 +240,39 @@ err_put: return err; } +static int replace_map_with_perf_event(void *value) +{ + struct perf_event *event; + u32 fd; + + fd = *(u32 *)value; + + event = perf_event_get(fd); + if (IS_ERR(event)) + return PTR_ERR(event); + + if (atomic_long_inc_not_zero(&event->refcount)) + memcpy(value, &event, sizeof(struct perf_event *)); + else + return -ENOENT; + + return 0; +} + +static bool check_map_perf_event_stored(struct bpf_map *map, void *key) +{ + void *value; + bool is_stored = false; + + rcu_read_lock(); + value = map->ops->map_lookup_elem(map, key); + if (value && (*(unsigned long *)value)) + is_stored = true; + rcu_read_unlock(); + + return is_stored; +} + #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags static int map_update_elem(union bpf_attr *attr) @@ -252,6 +310,16 @@ static int map_update_elem(union bpf_attr *attr) if (copy_from_user(value, uvalue, map->value_size) != 0) goto free_value; + if (map->flags & BPF_MAP_FLAG_PERF_EVENT) { + err = -EINVAL; + if (check_map_perf_event_stored(map, key)) + goto free_value; + + err = -EBADF; + if (replace_map_with_perf_event(value) != 0) + goto free_value; + } + /* eBPF program that use maps are running under rcu_read_lock(), * therefore all map accessors rely on this fact, so do the same here */ diff --git a/kernel/events/core.c b/kernel/events/core.c index e965cfa..c4e34b7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8582,6 +8582,28 @@ 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) +{ + struct perf_event *event; + struct fd f; + + f = fdget(fd); + + if (!f.file) + return ERR_PTR(-EBADF); + + if (f.file->f_op != &perf_fops) { + fdput(f); + return ERR_PTR(-EINVAL); + } + + event = f.file->private_data; + + fdput(f); + + return event; +} + /* * inherit a event from parent task to child task: */ -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/