Commit ae870a68 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

arm64/mm: Convert to using lock_mm_and_find_vma() 



This converts arm64 to use the new page fault helper.  It was very
straightforward, but still needed a fix for the "obvious" conversion I
initially did.  Thanks to Suren for the fix and testing.

Fixed-and-tested-by: default avatarSuren Baghdasaryan <surenb@google.com>
Unnecessary-code-removal-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eda00472

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -225,6 +225,7 @@ config ARM64 
	select IRQ_DOMAIN

	select IRQ_FORCED_THREADING

	select KASAN_VMALLOC if KASAN

	select LOCK_MM_AND_FIND_VMA

	select MODULES_USE_ELF_RELA

	select NEED_DMA_MAP_STATE

	select NEED_SG_DMA_LENGTH

arch/arm64/mm/fault.c

+8 −39
Original line number Diff line number Diff line
@@ -483,27 +483,14 @@ static void do_bad_area(unsigned long far, unsigned long esr, 
#define VM_FAULT_BADMAP		((__force vm_fault_t)0x010000)

#define VM_FAULT_BADACCESS	((__force vm_fault_t)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.

	 */
@@ -617,31 +604,15 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, 
	}

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)) {
@@ -660,9 +631,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, 
	}

	mmap_read_unlock(mm);



#ifdef CONFIG_PER_VMA_LOCK

done:

#endif

	/*

	 * Handle the "normal" (no error) case first.

	 */