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: Suren Baghdasaryan <surenb@google.com>
Unnecessary-code-removal-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 343e1e1..92f3fff 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 6045a51..8a169bd 100644 (file)
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -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 @@ retry:
        }
        mmap_read_unlock(mm);
 
-#ifdef CONFIG_PER_VMA_LOCK
 done:
-#endif
        /*
         * Handle the "normal" (no error) case first.
         */