* these to track enablement sites that are tied to an event.
*/
struct user_event_enabler {
- struct list_head link;
+ struct list_head mm_enablers_link;
struct user_event *event;
unsigned long addr;
/* Track enable bit, flags, etc. Aligned for bitops. */
- unsigned int values;
+ unsigned long values;
};
/* Bits 0-5 are for the bit to update upon enable/disable (0-63 allowed) */
/* Only duplicate the bit value */
#define ENABLE_VAL_DUP_MASK ENABLE_VAL_BIT_MASK
-#define ENABLE_BITOPS(e) ((unsigned long *)&(e)->values)
+#define ENABLE_BITOPS(e) (&(e)->values)
+
+#define ENABLE_BIT(e) ((int)((e)->values & ENABLE_VAL_BIT_MASK))
/* Used for asynchronous faulting in of pages */
struct user_event_enabler_fault {
#define VALIDATOR_REL (1 << 1)
struct user_event_validator {
- struct list_head link;
+ struct list_head user_event_link;
int offset;
int flags;
};
static void user_event_enabler_destroy(struct user_event_enabler *enabler)
{
- list_del_rcu(&enabler->link);
+ list_del_rcu(&enabler->mm_enablers_link);
/* No longer tracking the event via the enabler */
refcount_dec(&enabler->event->refcnt);
/* 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);
+ set_bit(ENABLE_BIT(enabler), ptr);
else
- clear_bit(enabler->values & ENABLE_VAL_BIT_MASK, ptr);
+ clear_bit(ENABLE_BIT(enabler), ptr);
kunmap_local(kaddr);
unpin_user_pages_dirty_lock(&page, 1, true);
unsigned long uaddr, unsigned char bit)
{
struct user_event_enabler *enabler;
- struct user_event_enabler *next;
- list_for_each_entry_safe(enabler, next, &mm->enablers, link) {
- if (enabler->addr == uaddr &&
- (enabler->values & ENABLE_VAL_BIT_MASK) == bit)
+ list_for_each_entry(enabler, &mm->enablers, mm_enablers_link) {
+ if (enabler->addr == uaddr && ENABLE_BIT(enabler) == bit)
return true;
}
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;
+ struct user_event_mm *mm;
int attempt;
+ lockdep_assert_held(&event_mutex);
+
+ /*
+ * We need to build a one-shot list of all the mms that have an
+ * enabler for the user_event passed in. This list is only valid
+ * while holding the event_mutex. The only reason for this is due
+ * to the global mm list being RCU protected and we use methods
+ * which can wait (mmap_read_lock and pin_user_pages_remote).
+ *
+ * NOTE: user_event_mm_get_all() increments the ref count of each
+ * mm that is added to the list to prevent removal timing windows.
+ * We must always put each mm after they are used, which may wait.
+ */
+ mm = user_event_mm_get_all(user);
+
while (mm) {
next = mm->next;
mmap_read_lock(mm->mm);
- rcu_read_lock();
- list_for_each_entry_rcu(enabler, &mm->enablers, link) {
+ list_for_each_entry(enabler, &mm->enablers, mm_enablers_link) {
if (enabler->event == user) {
attempt = 0;
user_event_enabler_write(mm, enabler, true, &attempt);
}
}
- rcu_read_unlock();
mmap_read_unlock(mm->mm);
user_event_mm_put(mm);
mm = next;
enabler->values = orig->values & ENABLE_VAL_DUP_MASK;
refcount_inc(&enabler->event->refcnt);
- list_add_rcu(&enabler->link, &mm->enablers);
+
+ /* Enablers not exposed yet, RCU not required */
+ list_add(&enabler->mm_enablers_link, &mm->enablers);
return true;
}
struct user_event_mm *mm;
/*
+ * We use the mm->next field to build a one-shot list from the global
+ * RCU protected list. To build this list the event_mutex must be held.
+ * This lets us build a list without requiring allocs that could fail
+ * when user based events are most wanted for diagnostics.
+ */
+ lockdep_assert_held(&event_mutex);
+
+ /*
* 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
*/
rcu_read_lock();
- list_for_each_entry_rcu(mm, &user_event_mms, link)
- list_for_each_entry_rcu(enabler, &mm->enablers, link)
+ list_for_each_entry_rcu(mm, &user_event_mms, mms_link) {
+ list_for_each_entry_rcu(enabler, &mm->enablers, 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)
+static struct user_event_mm *user_event_mm_alloc(struct task_struct *t)
{
struct user_event_mm *user_mm;
- unsigned long flags;
user_mm = kzalloc(sizeof(*user_mm), GFP_KERNEL_ACCOUNT);
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
return user_mm;
}
+static void user_event_mm_attach(struct user_event_mm *user_mm, struct task_struct *t)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&user_event_mms_lock, flags);
+ list_add_rcu(&user_mm->mms_link, &user_event_mms);
+ spin_unlock_irqrestore(&user_event_mms_lock, flags);
+
+ t->user_event_mm = 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);
+ user_mm = user_event_mm_alloc(current);
if (!user_mm)
goto error;
+
+ user_event_mm_attach(user_mm, current);
inc:
refcount_inc(&user_mm->refcnt);
error:
{
struct user_event_enabler *enabler, *next;
- list_for_each_entry_safe(enabler, next, &mm->enablers, link)
+ list_for_each_entry_safe(enabler, next, &mm->enablers, mm_enablers_link)
user_event_enabler_destroy(enabler);
mmdrop(mm->mm);
/* 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);
+ list_del_rcu(&mm->mms_link);
spin_unlock_irqrestore(&user_event_mms_lock, flags);
/*
void user_event_mm_dup(struct task_struct *t, struct user_event_mm *old_mm)
{
- struct user_event_mm *mm = user_event_mm_create(t);
+ struct user_event_mm *mm = user_event_mm_alloc(t);
struct user_event_enabler *enabler;
if (!mm)
rcu_read_lock();
- list_for_each_entry_rcu(enabler, &old_mm->enablers, link)
+ list_for_each_entry_rcu(enabler, &old_mm->enablers, mm_enablers_link) {
if (!user_event_enabler_dup(enabler, mm))
goto error;
+ }
rcu_read_unlock();
+ user_event_mm_attach(mm, t);
return;
error:
rcu_read_unlock();
- user_event_mm_remove(t);
+ user_event_mm_destroy(mm);
}
static bool current_user_event_enabler_exists(unsigned long uaddr,
*/
if (!*write_result) {
refcount_inc(&enabler->event->refcnt);
- list_add_rcu(&enabler->link, &user_mm->enablers);
+ list_add_rcu(&enabler->mm_enablers_link, &user_mm->enablers);
}
mutex_unlock(&event_mutex);
struct user_event_validator *validator, *next;
struct list_head *head = &user->validators;
- list_for_each_entry_safe(validator, next, head, link) {
- list_del(&validator->link);
+ list_for_each_entry_safe(validator, next, head, user_event_link) {
+ list_del(&validator->user_event_link);
kfree(validator);
}
}
validator->offset = offset;
/* Want sequential access when validating */
- list_add_tail(&validator->link, &user->validators);
+ list_add_tail(&validator->user_event_link, &user->validators);
add_field:
field->type = type;
void *pos, *end = data + len;
u32 loc, offset, size;
- list_for_each_entry(validator, head, link) {
+ list_for_each_entry(validator, head, user_event_link) {
pos = data + validator->offset;
/* Already done min_size check, no bounds check here */
*/
mutex_lock(&event_mutex);
- list_for_each_entry_safe(enabler, next, &mm->enablers, link)
+ list_for_each_entry_safe(enabler, next, &mm->enablers, mm_enablers_link) {
if (enabler->addr == reg.disable_addr &&
- (enabler->values & ENABLE_VAL_BIT_MASK) == reg.disable_bit) {
+ ENABLE_BIT(enabler) == reg.disable_bit) {
set_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler));
if (!test_bit(ENABLE_VAL_FAULTING_BIT, ENABLE_BITOPS(enabler)))
/* Removed at least one */
ret = 0;
}
+ }
mutex_unlock(&event_mutex);
projects / platform / kernel / linux-starfive.git / blobdiff