[PATCH 4/4] arm64/mm: Drop vm_fault_t argument from __do_page_fault()

From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	James Morse <james.morse@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 4/4] arm64/mm: Drop vm_fault_t argument from __do_page_fault()
Date: Wed, 29 May 2019 18:04:45 +0530	[thread overview]
Message-ID: <1559133285-27986-5-git-send-email-anshuman.khandual@arm.com> (raw)
In-Reply-To: <1559133285-27986-1-git-send-email-anshuman.khandual@arm.com>

__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

