diff --git a/include/linux/user_events.h b/include/linux/user_events.h
index 3d747c45d2fae480563469e5fca656e500d32192..0120b3dd5b037ebd1f7aa24043497714047331ce 100644
--- a/include/linux/user_events.h
+++ b/include/linux/user_events.h
@@ -9,13 +9,63 @@
#ifndef _LINUX_USER_EVENTS_H
#define _LINUX_USER_EVENTS_H
+#include <linux/list.h>
+#include <linux/refcount.h>
+#include <linux/mm_types.h>
+#include <linux/workqueue.h>
#include <uapi/linux/user_events.h>
#ifdef CONFIG_USER_EVENTS
struct user_event_mm {
+ struct list_head link;
+ struct list_head enablers;
+ struct mm_struct *mm;
+ struct user_event_mm *next;
+ refcount_t refcnt;
+ refcount_t tasks;
+ struct rcu_work put_rwork;
};
-#endif
+extern void user_event_mm_dup(struct task_struct *t,
+ struct user_event_mm *old_mm);
+
+extern void user_event_mm_remove(struct task_struct *t);
+
+static inline void user_events_fork(struct task_struct *t,
+ unsigned long clone_flags)
+{
+ struct user_event_mm *old_mm;
+
+ if (!t || !current->user_event_mm)
+ return;
+
+ old_mm = current->user_event_mm;
+
+ if (clone_flags & CLONE_VM) {
+ t->user_event_mm = old_mm;
+ refcount_inc(&old_mm->tasks);
+ return;
+ }
+
+ user_event_mm_dup(t, old_mm);
+}
+
+static inline void user_events_execve(struct task_struct *t)
+{
+ if (!t || !t->user_event_mm)
+ return;
+
+ user_event_mm_remove(t);
+}
+
+static inline void user_events_exit(struct task_struct *t)
+{
+ if (!t || !t->user_event_mm)
+ return;
+
+ user_event_mm_remove(t);
+}
+#else
static inline void user_events_fork(struct task_struct *t,
unsigned long clone_flags)
{
@@ -28,5 +78,6 @@ static inline void user_events_execve(struct task_struct *t)
static inline void user_events_exit(struct task_struct *t)
{
}
+#endif /* CONFIG_USER_EVENTS */
#endif /* _LINUX_USER_EVENTS_H */
diff --git a/include/uapi/linux/user_events.h b/include/uapi/linux/user_events.h
index 03f92366068d2ecc6b5086b3164d10ecebd85ae4..22521bc622db211a5e2f22db7be9d9b0541601b8 100644
--- a/include/uapi/linux/user_events.h
+++ b/include/uapi/linux/user_events.h
@@ -27,12 +27,21 @@ struct user_reg {
/* Input: Size of the user_reg structure being used */
__u32 size;
+ /* Input: Bit in enable address to use */
+ __u8 enable_bit;
+
+ /* Input: Enable size in bytes at address */
+ __u8 enable_size;
+
+ /* Input: Flags for future use, set to 0 */
+ __u16 flags;
+
+ /* Input: Address to update when enabled */
+ __u64 enable_addr;
+
/* Input: Pointer to string with event name, description and flags */
__u64 name_args;
- /* Output: Bitwise index of the event within the status page */
- __u32 status_bit;
-
/* Output: Index of the event to use when writing data */
__u32 write_index;
} __attribute__((__packed__));
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 5b1e7fa41ca84e4808ce94f81ed889dd3f970461..c7020e071bf9bece8412154302b7d1b30dec3d4c 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -798,9 +798,10 @@ config USER_EVENTS
can be used like an existing kernel trace event. User trace
events are generated by writing to a tracefs file. User
processes can determine if their tracing events should be
- generated by memory mapping a tracefs file and checking for
- an associated byte being non-zero.
+ generated by registering a value and bit with the kernel
+ that reflects when it is enabled or not.
+ See Documentation/trace/user_events.rst.
If in doubt, say N.
config HIST_TRIGGERS
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index 070551480747f70a49aa217194c601c87bcd20ab..553a82ee7aeb07c7de3128493a39cc8df7707d40 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -19,6 +19,7 @@
#include <linux/tracefs.h>
#include <linux/types.h>
#include <linux/uaccess.h>
+#include <linux/highmem.h>
#include <linux/user_events.h>
#include "trace.h"
#include "trace_dynevent.h"
@@ -29,34 +30,11 @@
#define FIELD_DEPTH_NAME 1
#define FIELD_DEPTH_SIZE 2
-/*
- * Limits how many trace_event calls user processes can create:
- * Must be a power of two of PAGE_SIZE.
- */
-#define MAX_PAGE_ORDER 0
-#define MAX_PAGES (1 << MAX_PAGE_ORDER)
-#define MAX_BYTES (MAX_PAGES * PAGE_SIZE)
-#define MAX_EVENTS (MAX_BYTES * 8)
-
/* Limit how long of an event name plus args within the subsystem. */
#define MAX_EVENT_DESC 512
#define EVENT_NAME(user_event) ((user_event)->tracepoint.name)
#define MAX_FIELD_ARRAY_SIZE 1024
-/*
- * The MAP_STATUS_* macros are used for taking a index and determining the
- * appropriate byte and the bit in the byte to set/reset for an event.
- *
- * The lower 3 bits of the index decide which bit to set.
- * The remaining upper bits of the index decide which byte to use for the bit.
- *
- * This is used when an event has a probe attached/removed to reflect live
- * status of the event wanting tracing or not to user-programs via shared
- * memory maps.
- */
-#define MAP_STATUS_BYTE(index) ((index) >> 3)
-#define MAP_STATUS_MASK(index) BIT((index) & 7)
-
/*
* Internal bits (kernel side only) to keep track of connected probes:
* These are used when status is requested in text form about an event. These
@@ -70,20 +48,14 @@
#define EVENT_STATUS_OTHER BIT(7)
/*
- * Stores the pages, tables, and locks for a group of events.
- * Each logical grouping of events has its own group, with a
- * matching page for status checks within user programs. This
- * allows for isolation of events to user programs by various
- * means.
+ * Stores the system name, tables, and locks for a group of events. This
+ * allows isolation for events by various means.
*/
struct user_event_group {
- struct page *pages;
- char *register_page_data;
char *system_name;
struct hlist_node node;
struct mutex reg_mutex;
DECLARE_HASHTABLE(register_table, 8);
- DECLARE_BITMAP(page_bitmap, MAX_EVENTS);
};
/* Group for init_user_ns mapping, top-most group */
@@ -106,12 +78,34 @@ struct user_event {
struct list_head fields;
struct list_head validators;
refcount_t refcnt;
- int index;
- int flags;
int min_size;
char status;
};
+/*
+ * Stores per-mm/event properties that enable an address to be
+ * updated properly for each task. As tasks are forked, we use
+ * these to track enablement sites that are tied to an event.
+ */
+struct user_event_enabler {
+ struct list_head link;
+ struct user_event *event;
+ unsigned long addr;
+
+ /* Track enable bit, flags, etc. Aligned for bitops. */
+ unsigned int values;
+};
+
+/* Bits 0-5 are for the bit to update upon enable/disable (0-63 allowed) */
+#define ENABLE_VAL_BIT_MASK 0x3F
+
+/* Only duplicate the bit value */
+#define ENABLE_VAL_DUP_MASK ENABLE_VAL_BIT_MASK
+
+/* Global list of memory descriptors using user_events */
+static LIST_HEAD(user_event_mms);
+static DEFINE_SPINLOCK(user_event_mms_lock);
+
/*
* Stores per-file events references, as users register events
* within a file this structure is modified and freed via RCU.
@@ -145,33 +139,17 @@ static int user_event_parse(struct user_event_group *group, char *name,
char *args, char *flags,
struct user_event **newuser);
+static struct user_event_mm *user_event_mm_get(struct user_event_mm *mm);
+static struct user_event_mm *user_event_mm_get_all(struct user_event *user);
+static void user_event_mm_put(struct user_event_mm *mm);
+
static u32 user_event_key(char *name)
{
return jhash(name, strlen(name), 0);
}
-static void set_page_reservations(char *pages, bool set)
-{
- int page;
-
- for (page = 0; page < MAX_PAGES; ++page) {
- void *addr = pages + (PAGE_SIZE * page);
-
- if (set)
- SetPageReserved(virt_to_page(addr));
- else
- ClearPageReserved(virt_to_page(addr));
- }
-}
-
static void user_event_group_destroy(struct user_event_group *group)
{
- if (group->register_page_data)
- set_page_reservations(group->register_page_data, false);
-
- if (group->pages)
- __free_pages(group->pages, MAX_PAGE_ORDER);
-
kfree(group->system_name);
kfree(group);
}
@@ -242,19 +220,6 @@ static struct user_event_group
if (!group->system_name)
goto error;
- group->pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER);
-
- if (!group->pages)
- goto error;
-
- group->register_page_data = page_address(group->pages);
-
- set_page_reservations(group->register_page_data, true);
-
- /* Zero all bits beside 0 (which is reserved for failures) */
- bitmap_zero(group->page_bitmap, MAX_EVENTS);
- set_bit(0, group->page_bitmap);
-
mutex_init(&group->reg_mutex);
hash_init(group->register_table);
@@ -266,20 +231,367 @@ static struct user_event_group
return NULL;
};
-static __always_inline
-void user_event_register_set(struct user_event *user)
+static void user_event_enabler_destroy(struct user_event_enabler *enabler)
+{
+ list_del_rcu(&enabler->link);
+
+ /* No longer tracking the event via the enabler */
+ refcount_dec(&enabler->event->refcnt);
+
+ kfree(enabler);
+}
+
+static int user_event_mm_fault_in(struct user_event_mm *mm, unsigned long uaddr)
+{
+ bool unlocked;
+ int ret;
+
+ mmap_read_lock(mm->mm);
+
+ /* Ensure MM has tasks, cannot use after exit_mm() */
+ if (refcount_read(&mm->tasks) == 0) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ ret = fixup_user_fault(mm->mm, uaddr, FAULT_FLAG_WRITE | FAULT_FLAG_REMOTE,
+ &unlocked);
+out:
+ mmap_read_unlock(mm->mm);
+
+ return ret;
+}
+
+static int user_event_enabler_write(struct user_event_mm *mm,
+ struct user_event_enabler *enabler)
+{
+ unsigned long uaddr = enabler->addr;
+ unsigned long *ptr;
+ struct page *page;
+ void *kaddr;
+ int ret;
+
+ lockdep_assert_held(&event_mutex);
+ mmap_assert_locked(mm->mm);
+
+ /* Ensure MM has tasks, cannot use after exit_mm() */
+ if (refcount_read(&mm->tasks) == 0)
+ return -ENOENT;
+
+ ret = pin_user_pages_remote(mm->mm, uaddr, 1, FOLL_WRITE | FOLL_NOFAULT,
+ &page, NULL, NULL);
+
+ if (ret <= 0) {
+ pr_warn("user_events: Enable write failed\n");
+ return -EFAULT;
+ }
+
+ kaddr = kmap_local_page(page);
+ ptr = kaddr + (uaddr & ~PAGE_MASK);
+
+ /* Update bit atomically, user tracers must be atomic as well */
+ if (enabler->event && enabler->event->status)
+ set_bit(enabler->values & ENABLE_VAL_BIT_MASK, ptr);
+ else
+ clear_bit(enabler->values & ENABLE_VAL_BIT_MASK, ptr);
+
+ kunmap_local(kaddr);
+ unpin_user_pages_dirty_lock(&page, 1, true);
+
+ return 0;
+}
+
+static void user_event_enabler_update(struct user_event *user)
+{
+ struct user_event_enabler *enabler;
+ struct user_event_mm *mm = user_event_mm_get_all(user);
+ struct user_event_mm *next;
+
+ while (mm) {
+ next = mm->next;
+ mmap_read_lock(mm->mm);
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(enabler, &mm->enablers, link)
+ if (enabler->event == user)
+ user_event_enabler_write(mm, enabler);
+
+ rcu_read_unlock();
+ mmap_read_unlock(mm->mm);
+ user_event_mm_put(mm);
+ mm = next;
+ }
+}
+
+static bool user_event_enabler_dup(struct user_event_enabler *orig,
+ struct user_event_mm *mm)
+{
+ struct user_event_enabler *enabler;
+
+ enabler = kzalloc(sizeof(*enabler), GFP_NOWAIT);
+
+ if (!enabler)
+ return false;
+
+ enabler->event = orig->event;
+ enabler->addr = orig->addr;
+
+ /* Only dup part of value (ignore future flags, etc) */
+ enabler->values = orig->values & ENABLE_VAL_DUP_MASK;
+
+ refcount_inc(&enabler->event->refcnt);
+ list_add_rcu(&enabler->link, &mm->enablers);
+
+ return true;
+}
+
+static struct user_event_mm *user_event_mm_get(struct user_event_mm *mm)
+{
+ refcount_inc(&mm->refcnt);
+
+ return mm;
+}
+
+static struct user_event_mm *user_event_mm_get_all(struct user_event *user)
+{
+ struct user_event_mm *found = NULL;
+ struct user_event_enabler *enabler;
+ struct user_event_mm *mm;
+
+ /*
+ * We do not want to block fork/exec while enablements are being
+ * updated, so we use RCU to walk the current tasks that have used
+ * user_events ABI for 1 or more events. Each enabler found in each
+ * task that matches the event being updated has a write to reflect
+ * the kernel state back into the process. Waits/faults must not occur
+ * during this. So we scan the list under RCU for all the mm that have
+ * the event within it. This is needed because mm_read_lock() can wait.
+ * Each user mm returned has a ref inc to handle remove RCU races.
+ */
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(mm, &user_event_mms, link)
+ list_for_each_entry_rcu(enabler, &mm->enablers, link)
+ if (enabler->event == user) {
+ mm->next = found;
+ found = user_event_mm_get(mm);
+ break;
+ }
+
+ rcu_read_unlock();
+
+ return found;
+}
+
+static struct user_event_mm *user_event_mm_create(struct task_struct *t)
+{
+ struct user_event_mm *user_mm;
+ unsigned long flags;
+
+ user_mm = kzalloc(sizeof(*user_mm), GFP_KERNEL);
+
+ if (!user_mm)
+ return NULL;
+
+ user_mm->mm = t->mm;
+ INIT_LIST_HEAD(&user_mm->enablers);
+ refcount_set(&user_mm->refcnt, 1);
+ refcount_set(&user_mm->tasks, 1);
+
+ spin_lock_irqsave(&user_event_mms_lock, flags);
+ list_add_rcu(&user_mm->link, &user_event_mms);
+ spin_unlock_irqrestore(&user_event_mms_lock, flags);
+
+ t->user_event_mm = user_mm;
+
+ /*
+ * The lifetime of the memory descriptor can slightly outlast
+ * the task lifetime if a ref to the user_event_mm is taken
+ * between list_del_rcu() and call_rcu(). Therefore we need
+ * to take a reference to it to ensure it can live this long
+ * under this corner case. This can also occur in clones that
+ * outlast the parent.
+ */
+ mmgrab(user_mm->mm);
+
+ return user_mm;
+}
+
+static struct user_event_mm *current_user_event_mm(void)
+{
+ struct user_event_mm *user_mm = current->user_event_mm;
+
+ if (user_mm)
+ goto inc;
+
+ user_mm = user_event_mm_create(current);
+
+ if (!user_mm)
+ goto error;
+inc:
+ refcount_inc(&user_mm->refcnt);
+error:
+ return user_mm;
+}
+
+static void user_event_mm_destroy(struct user_event_mm *mm)
+{
+ struct user_event_enabler *enabler, *next;
+
+ list_for_each_entry_safe(enabler, next, &mm->enablers, link)
+ user_event_enabler_destroy(enabler);
+
+ mmdrop(mm->mm);
+ kfree(mm);
+}
+
+static void user_event_mm_put(struct user_event_mm *mm)
+{
+ if (mm && refcount_dec_and_test(&mm->refcnt))
+ user_event_mm_destroy(mm);
+}
+
+static void delayed_user_event_mm_put(struct work_struct *work)
+{
+ struct user_event_mm *mm;
+
+ mm = container_of(to_rcu_work(work), struct user_event_mm, put_rwork);
+ user_event_mm_put(mm);
+}
+
+void user_event_mm_remove(struct task_struct *t)
{
- int i = user->index;
+ struct user_event_mm *mm;
+ unsigned long flags;
+
+ might_sleep();
+
+ mm = t->user_event_mm;
+ t->user_event_mm = NULL;
+
+ /* Clone will increment the tasks, only remove if last clone */
+ if (!refcount_dec_and_test(&mm->tasks))
+ return;
+
+ /* Remove the mm from the list, so it can no longer be enabled */
+ spin_lock_irqsave(&user_event_mms_lock, flags);
+ list_del_rcu(&mm->link);
+ spin_unlock_irqrestore(&user_event_mms_lock, flags);
+
+ /*
+ * We need to wait for currently occurring writes to stop within
+ * the mm. This is required since exit_mm() snaps the current rss
+ * stats and clears them. On the final mmdrop(), check_mm() will
+ * report a bug if these increment.
+ *
+ * All writes/pins are done under mmap_read lock, take the write
+ * lock to ensure in-progress faults have completed. Faults that
+ * are pending but yet to run will check the task count and skip
+ * the fault since the mm is going away.
+ */
+ mmap_write_lock(mm->mm);
+ mmap_write_unlock(mm->mm);
- user->group->register_page_data[MAP_STATUS_BYTE(i)] |= MAP_STATUS_MASK(i);
+ /*
+ * Put for mm must be done after RCU delay to handle new refs in
+ * between the list_del_rcu() and now. This ensures any get refs
+ * during rcu_read_lock() are accounted for during list removal.
+ *
+ * CPU A | CPU B
+ * ---------------------------------------------------------------
+ * user_event_mm_remove() | rcu_read_lock();
+ * list_del_rcu() | list_for_each_entry_rcu();
+ * call_rcu() | refcount_inc();
+ * . | rcu_read_unlock();
+ * schedule_work() | .
+ * user_event_mm_put() | .
+ *
+ * mmdrop() cannot be called in the softirq context of call_rcu()
+ * so we use a work queue after call_rcu() to run within.
+ */
+ INIT_RCU_WORK(&mm->put_rwork, delayed_user_event_mm_put);
+ queue_rcu_work(system_wq, &mm->put_rwork);
}
-static __always_inline
-void user_event_register_clear(struct user_event *user)
+void user_event_mm_dup(struct task_struct *t, struct user_event_mm *old_mm)
{
- int i = user->index;
+ struct user_event_mm *mm = user_event_mm_create(t);
+ struct user_event_enabler *enabler;
- user->group->register_page_data[MAP_STATUS_BYTE(i)] &= ~MAP_STATUS_MASK(i);
+ if (!mm)
+ return;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(enabler, &old_mm->enablers, link)
+ if (!user_event_enabler_dup(enabler, mm))
+ goto error;
+
+ rcu_read_unlock();
+
+ return;
+error:
+ rcu_read_unlock();
+ user_event_mm_remove(t);
+}
+
+static struct user_event_enabler
+*user_event_enabler_create(struct user_reg *reg, struct user_event *user,
+ int *write_result)
+{
+ struct user_event_enabler *enabler;
+ struct user_event_mm *user_mm;
+ unsigned long uaddr = (unsigned long)reg->enable_addr;
+
+ user_mm = current_user_event_mm();
+
+ if (!user_mm)
+ return NULL;
+
+ enabler = kzalloc(sizeof(*enabler), GFP_KERNEL);
+
+ if (!enabler)
+ goto out;
+
+ enabler->event = user;
+ enabler->addr = uaddr;
+ enabler->values = reg->enable_bit;
+retry:
+ /* Prevents state changes from racing with new enablers */
+ mutex_lock(&event_mutex);
+
+ /* Attempt to reflect the current state within the process */
+ mmap_read_lock(user_mm->mm);
+ *write_result = user_event_enabler_write(user_mm, enabler);
+ mmap_read_unlock(user_mm->mm);
+
+ /*
+ * If the write works, then we will track the enabler. A ref to the
+ * underlying user_event is held by the enabler to prevent it going
+ * away while the enabler is still in use by a process. The ref is
+ * removed when the enabler is destroyed. This means a event cannot
+ * be forcefully deleted from the system until all tasks using it
+ * exit or run exec(), which includes forks and clones.
+ */
+ if (!*write_result) {
+ refcount_inc(&enabler->event->refcnt);
+ list_add_rcu(&enabler->link, &user_mm->enablers);
+ }
+
+ mutex_unlock(&event_mutex);
+
+ if (*write_result) {
+ /* Attempt to fault-in and retry if it worked */
+ if (!user_event_mm_fault_in(user_mm, uaddr))
+ goto retry;
+
+ kfree(enabler);
+ enabler = NULL;
+ }
+out:
+ user_event_mm_put(user_mm);
+
+ return enabler;
}
static __always_inline __must_check
@@ -824,9 +1136,6 @@ static int destroy_user_event(struct user_event *user)
return ret;
dyn_event_remove(&user->devent);
-
- user_event_register_clear(user);
- clear_bit(user->index, user->group->page_bitmap);
hash_del(&user->node);
user_event_destroy_validators(user);
@@ -972,9 +1281,9 @@ static void user_event_perf(struct user_event *user, struct iov_iter *i,
#endif
/*
- * Update the register page that is shared between user processes.
+ * Update the enabled bit among all user processes.
*/
-static void update_reg_page_for(struct user_event *user)
+static void update_enable_bit_for(struct user_event *user)
{
struct tracepoint *tp = &user->tracepoint;
char status = 0;
@@ -1005,12 +1314,9 @@ static void update_reg_page_for(struct user_event *user)
rcu_read_unlock_sched();
}
- if (status)
- user_event_register_set(user);
- else
- user_event_register_clear(user);
-
user->status = status;
+
+ user_event_enabler_update(user);
}
/*
@@ -1067,10 +1373,10 @@ static int user_event_reg(struct trace_event_call *call,
return ret;
inc:
refcount_inc(&user->refcnt);
- update_reg_page_for(user);
+ update_enable_bit_for(user);
return 0;
dec:
- update_reg_page_for(user);
+ update_enable_bit_for(user);
refcount_dec(&user->refcnt);
return 0;
}
@@ -1266,7 +1572,6 @@ static int user_event_parse(struct user_event_group *group, char *name,
struct user_event **newuser)
{
int ret;
- int index;
u32 key;
struct user_event *user;
@@ -1285,11 +1590,6 @@ static int user_event_parse(struct user_event_group *group, char *name,
return 0;
}
- index = find_first_zero_bit(group->page_bitmap, MAX_EVENTS);
-
- if (index == MAX_EVENTS)
- return -EMFILE;
-
user = kzalloc(sizeof(*user), GFP_KERNEL);
if (!user)
@@ -1335,14 +1635,11 @@ static int user_event_parse(struct user_event_group *group, char *name,
if (ret)
goto put_user_lock;
- user->index = index;
-
/* Ensure we track self ref and caller ref (2) */
refcount_set(&user->refcnt, 2);
dyn_event_init(&user->devent, &user_event_dops);
dyn_event_add(&user->devent, &user->call);
- set_bit(user->index, group->page_bitmap);
hash_add(group->register_table, &user->node, key);
mutex_unlock(&event_mutex);
@@ -1559,6 +1856,37 @@ static long user_reg_get(struct user_reg __user *ureg, struct user_reg *kreg)
if (ret)
return ret;
+ /* Ensure no flags, since we don't support any yet */
+ if (kreg->flags != 0)
+ return -EINVAL;
+
+ /* Ensure supported size */
+ switch (kreg->enable_size) {
+ case 4:
+ /* 32-bit */
+ break;
+#if BITS_PER_LONG >= 64
+ case 8:
+ /* 64-bit */
+ break;
+#endif
+ default:
+ return -EINVAL;
+ }
+
+ /* Ensure natural alignment */
+ if (kreg->enable_addr % kreg->enable_size)
+ return -EINVAL;
+
+ /* Ensure bit range for size */
+ if (kreg->enable_bit > (kreg->enable_size * BITS_PER_BYTE) - 1)
+ return -EINVAL;
+
+ /* Ensure accessible */
+ if (!access_ok((const void __user *)(uintptr_t)kreg->enable_addr,
+ kreg->enable_size))
+ return -EFAULT;
+
kreg->size = size;
return 0;
@@ -1573,8 +1901,10 @@ static long user_events_ioctl_reg(struct user_event_file_info *info,
struct user_reg __user *ureg = (struct user_reg __user *)uarg;
struct user_reg reg;
struct user_event *user;
+ struct user_event_enabler *enabler;
char *name;
long ret;
+ int write_result;
ret = user_reg_get(ureg, ®);
@@ -1605,8 +1935,28 @@ static long user_events_ioctl_reg(struct user_event_file_info *info,
if (ret < 0)
return ret;
+ /*
+ * user_events_ref_add succeeded:
+ * At this point we have a user_event, it's lifetime is bound by the
+ * reference count, not this file. If anything fails, the user_event
+ * still has a reference until the file is released. During release
+ * any remaining references (from user_events_ref_add) are decremented.
+ *
+ * Attempt to create an enabler, which too has a lifetime tied in the
+ * same way for the event. Once the task that caused the enabler to be
+ * created exits or issues exec() then the enablers it has created
+ * will be destroyed and the ref to the event will be decremented.
+ */
+ enabler = user_event_enabler_create(®, user, &write_result);
+
+ if (!enabler)
+ return -ENOMEM;
+
+ /* Write failed/faulted, give error back to caller */
+ if (write_result)
+ return write_result;
+
put_user((u32)ret, &ureg->write_index);
- put_user(user->index, &ureg->status_bit);
return 0;
}
@@ -1720,38 +2070,6 @@ static const struct file_operations user_data_fops = {
.release = user_events_release,
};
-static struct user_event_group *user_status_group(struct file *file)
-{
- struct seq_file *m = file->private_data;
-
- if (!m)
- return NULL;
-
- return m->private;
-}
-
-/*
- * Maps the shared page into the user process for checking if event is enabled.
- */
-static int user_status_mmap(struct file *file, struct vm_area_struct *vma)
-{
- char *pages;
- struct user_event_group *group = user_status_group(file);
- unsigned long size = vma->vm_end - vma->vm_start;
-
- if (size != MAX_BYTES)
- return -EINVAL;
-
- if (!group)
- return -EINVAL;
-
- pages = group->register_page_data;
-
- return remap_pfn_range(vma, vma->vm_start,
- virt_to_phys(pages) >> PAGE_SHIFT,
- size, vm_get_page_prot(VM_READ));
-}
-
static void *user_seq_start(struct seq_file *m, loff_t *pos)
{
if (*pos)
@@ -1775,7 +2093,7 @@ static int user_seq_show(struct seq_file *m, void *p)
struct user_event_group *group = m->private;
struct user_event *user;
char status;
- int i, active = 0, busy = 0, flags;
+ int i, active = 0, busy = 0;
if (!group)
return -EINVAL;
@@ -1784,11 +2102,10 @@ static int user_seq_show(struct seq_file *m, void *p)
hash_for_each(group->register_table, i, user, node) {
status = user->status;
- flags = user->flags;
- seq_printf(m, "%d:%s", user->index, EVENT_NAME(user));
+ seq_printf(m, "%s", EVENT_NAME(user));
- if (flags != 0 || status != 0)
+ if (status != 0)
seq_puts(m, " #");
if (status != 0) {
@@ -1811,7 +2128,6 @@ static int user_seq_show(struct seq_file *m, void *p)
seq_puts(m, "\n");
seq_printf(m, "Active: %d\n", active);
seq_printf(m, "Busy: %d\n", busy);
- seq_printf(m, "Max: %ld\n", MAX_EVENTS);
return 0;
}
@@ -1847,7 +2163,6 @@ static int user_status_open(struct inode *node, struct file *file)
static const struct file_operations user_status_fops = {
.open = user_status_open,
- .mmap = user_status_mmap,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
@@ -1868,8 +2183,7 @@ static int create_user_tracefs(void)
goto err;
}
- /* mmap with MAP_SHARED requires writable fd */
- emmap = tracefs_create_file("user_events_status", TRACE_MODE_WRITE,
+ emmap = tracefs_create_file("user_events_status", TRACE_MODE_READ,
NULL, NULL, &user_status_fops);
if (!emmap) {