Commit 8b35ca3e authored by Ben Hutchings's avatar Ben Hutchings Committed by Linus Torvalds
Browse files

arm/mm: Convert to using lock_mm_and_find_vma() 



arm has an additional check for address < FIRST_USER_ADDRESS before
expanding the stack.  Since FIRST_USER_ADDRESS is defined everywhere
(generally as 0), move that check to the generic expand_downwards().

Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7267ef7b

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -125,6 +125,7 @@ config ARM 
	select HAVE_UID16

	select HAVE_VIRT_CPU_ACCOUNTING_GEN

	select IRQ_FORCED_THREADING

	select LOCK_MM_AND_FIND_VMA

	select MODULES_USE_ELF_REL

	select NEED_DMA_MAP_STATE

	select OF_EARLY_FLATTREE if OF

arch/arm/mm/fault.c

+14 −49
Original line number Diff line number Diff line
@@ -232,37 +232,11 @@ static inline bool is_permission_fault(unsigned int fsr) 
	return false;

}



static vm_fault_t __kprobes

__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags,

		unsigned long vma_flags, struct pt_regs *regs)

{

	struct vm_area_struct *vma = find_vma(mm, addr);

	if (unlikely(!vma))

		return VM_FAULT_BADMAP;



	if (unlikely(vma->vm_start > addr)) {

		if (!(vma->vm_flags & VM_GROWSDOWN))

			return VM_FAULT_BADMAP;

		if (addr < FIRST_USER_ADDRESS)

			return VM_FAULT_BADMAP;

		if (expand_stack(vma, addr))

			return VM_FAULT_BADMAP;

	}



	/*

	 * ok, we have a good vm_area for this memory access, check the

	 * permissions on the VMA allow for the fault which occurred.

	 */

	if (!(vma->vm_flags & vma_flags))

		return VM_FAULT_BADACCESS;



	return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);

}



static int __kprobes

do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	int sig, code;

	vm_fault_t fault;

	unsigned int flags = FAULT_FLAG_DEFAULT;
@@ -301,31 +275,21 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 


	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);



	/*

	 * 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->ARM_pc))

			goto no_context;

retry:

		mmap_read_lock(mm);

	} else {

		/*

		 * The above down_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->ARM_pc))

			goto no_context;

#endif

	vma = lock_mm_and_find_vma(mm, addr, regs);

	if (unlikely(!vma)) {

		fault = VM_FAULT_BADMAP;

		goto bad_area;

	}



	fault = __do_page_fault(mm, addr, flags, vm_flags, regs);

	/*

	 * ok, we have a good vm_area for this memory access, check the

	 * permissions on the VMA allow for the fault which occurred.

	 */

	if (!(vma->vm_flags & vm_flags))

		fault = VM_FAULT_BADACCESS;

	else

		fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);



	/* If we need to retry but a fatal signal is pending, handle the

	 * signal first. We do not need to release the mmap_lock because
@@ -356,6 +320,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 
	if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))

		return 0;



bad_area:

	/*

	 * If we are in kernel mode at this point, we

	 * have no context to handle this fault with.

mm/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -2036,7 +2036,7 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) 
	int error = 0;



	address &= PAGE_MASK;

	if (address < mmap_min_addr)

	if (address < mmap_min_addr || address < FIRST_USER_ADDRESS)

		return -EPERM;



	/* Enforce stack_guard_gap */