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Subject[PATCH 4/4] arm64/mm: Drop vm_fault_t argument from __do_page_fault()
Date
__do_page_fault() is over complicated with multiple goto statements. This
cleans up code flow and while there drops the vm_fault_t argument.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
---
arch/arm64/mm/fault.c | 38 ++++++++++++++++----------------------
1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 170c71f..a53a30e 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -397,37 +397,31 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
unsigned int mm_flags, unsigned long vm_flags)
{
- struct vm_area_struct *vma;
- vm_fault_t fault;
+ struct vm_area_struct *vma = find_vma(mm, addr);

- vma = find_vma(mm, addr);
- fault = VM_FAULT_BADMAP;
if (unlikely(!vma))
- goto out;
- if (unlikely(vma->vm_start > addr))
- goto check_stack;
+ return VM_FAULT_BADMAP;

/*
- * Ok, we have a good vm_area for this memory access, so we can handle
- * it.
+ * Check if the VMA has got the required permssion with respect
+ * to the access fault here.
*/
-good_area:
+ if (!(vma->vm_flags & vm_flags))
+ return VM_FAULT_BADACCESS;
+
/*
- * Check that the permissions on the VMA allow for the fault which
- * occurred.
+ * There is a valid VMA for this access. But before proceeding
+ * make sure that it has required flags if there is an attempt
+ * to expand the stack downwards.
*/
- if (!(vma->vm_flags & vm_flags)) {
- fault = VM_FAULT_BADACCESS;
- goto out;
- }
+ 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;
+ }
return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
-
-check_stack:
- if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
- goto good_area;
-out:
- return fault;
}

static bool is_el0_instruction_abort(unsigned int esr)
--
2.7.4
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