1 files changed, 11 insertions, 46 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index f4ab44e058b2..e5e07212126d 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -502,27 +502,14 @@ static void do_bad_area(unsigned long far, unsigned long esr,
 #define VM_FAULT_BADMAP		0x010000
 #define VM_FAULT_BADACCESS	0x020000
 
-static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
+static vm_fault_t __do_page_fault(struct mm_struct *mm,
+				  struct vm_area_struct *vma, unsigned long addr,
 				  unsigned int mm_flags, unsigned long vm_flags,
 				  struct pt_regs *regs)
 {
-	struct vm_area_struct *vma = find_vma(mm, addr);
-
-	if (unlikely(!vma))
-		return VM_FAULT_BADMAP;
-
 	/*
 	 * Ok, we have a good vm_area for this memory access, so we can handle
 	 * it.
-	 */
-	if (unlikely(vma->vm_start > addr)) {
-		if (!(vma->vm_flags & VM_GROWSDOWN))
-			return VM_FAULT_BADMAP;
-		if (expand_stack(vma, addr))
-			return VM_FAULT_BADMAP;
-	}
-
-	/*
 	 * Check that the permissions on the VMA allow for the fault which
 	 * occurred.
 	 */
@@ -554,9 +541,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 	unsigned long vm_flags;
 	unsigned int mm_flags = FAULT_FLAG_DEFAULT;
 	unsigned long addr = untagged_addr(far);
-#ifdef CONFIG_PER_VMA_LOCK
 	struct vm_area_struct *vma;
-#endif
 
 	if (kprobe_page_fault(regs, esr))
 		return 0;
@@ -614,7 +599,6 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
 
-#ifdef CONFIG_PER_VMA_LOCK
 	if (!(mm_flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
@@ -626,9 +610,9 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 		vma_end_read(vma);
 		goto lock_mmap;
 	}
-	fault = handle_mm_fault(vma, addr & PAGE_MASK,
-				mm_flags | FAULT_FLAG_VMA_LOCK, regs);
-	vma_end_read(vma);
+	fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs);
+	if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
+		vma_end_read(vma);
 
 	if (!(fault & VM_FAULT_RETRY)) {
 		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
@@ -643,32 +627,15 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 		return 0;
 	}
 lock_mmap:
-#endif /* CONFIG_PER_VMA_LOCK */
-	/*
-	 * As per x86, we may deadlock here. However, since the kernel only
-	 * validly references user space from well defined areas of the code,
-	 * we can bug out early if this is from code which shouldn't.
-	 */
-	if (!mmap_read_trylock(mm)) {
-		if (!user_mode(regs) && !search_exception_tables(regs->pc))
-			goto no_context;
+
 retry:
-		mmap_read_lock(mm);
-	} else {
-		/*
-		 * The above mmap_read_trylock() might have succeeded in which
-		 * case, we'll have missed the might_sleep() from down_read().
-		 */
-		might_sleep();
-#ifdef CONFIG_DEBUG_VM
-		if (!user_mode(regs) && !search_exception_tables(regs->pc)) {
-			mmap_read_unlock(mm);
-			goto no_context;
-		}
-#endif
+	vma = lock_mm_and_find_vma(mm, addr, regs);
+	if (unlikely(!vma)) {
+		fault = VM_FAULT_BADMAP;
+		goto done;
 	}
 
-	fault = __do_page_fault(mm, addr, mm_flags, vm_flags, regs);
+	fault = __do_page_fault(mm, vma, addr, mm_flags, vm_flags, regs);
 
 	/* Quick path to respond to signals */
 	if (fault_signal_pending(fault, regs)) {
@@ -687,9 +654,7 @@ retry:
 	}
 	mmap_read_unlock(mm);
 
-#ifdef CONFIG_PER_VMA_LOCK
 done:
-#endif
 	/*
 	 * Handle the "normal" (no error) case first.
 	 */