diff options
| -rw-r--r-- | arch/s390/mm/pgtable.c | 44 |
1 files changed, 27 insertions, 17 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 5c1aea97cd12..3d98ba82ea67 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -254,36 +254,46 @@ void disable_noexec(struct mm_struct *mm, struct task_struct *tsk) int s390_enable_sie(void) { struct task_struct *tsk = current; - struct mm_struct *mm; - int rc; + struct mm_struct *mm, *old_mm; - task_lock(tsk); - - rc = 0; + /* Do we have pgstes? if yes, we are done */ if (tsk->mm->context.pgstes) - goto unlock; + return 0; - rc = -EINVAL; + /* lets check if we are allowed to replace the mm */ + task_lock(tsk); if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 || - tsk->mm != tsk->active_mm || tsk->mm->ioctx_list) - goto unlock; + tsk->mm != tsk->active_mm || tsk->mm->ioctx_list) { + task_unlock(tsk); + return -EINVAL; + } + task_unlock(tsk); - tsk->mm->context.pgstes = 1; /* dirty little tricks .. */ + /* we copy the mm with pgstes enabled */ + tsk->mm->context.pgstes = 1; mm = dup_mm(tsk); tsk->mm->context.pgstes = 0; - - rc = -ENOMEM; if (!mm) - goto unlock; - mmput(tsk->mm); + return -ENOMEM; + + /* Now lets check again if somebody attached ptrace etc */ + task_lock(tsk); + if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 || + tsk->mm != tsk->active_mm || tsk->mm->ioctx_list) { + mmput(mm); + task_unlock(tsk); + return -EINVAL; + } + + /* ok, we are alone. No ptrace, no threads, etc. */ + old_mm = tsk->mm; tsk->mm = tsk->active_mm = mm; preempt_disable(); update_mm(mm, tsk); cpu_set(smp_processor_id(), mm->cpu_vm_mask); preempt_enable(); - rc = 0; -unlock: task_unlock(tsk); - return rc; + mmput(old_mm); + return 0; } EXPORT_SYMBOL_GPL(s390_enable_sie); |