From: Anshuman Khandual <anshuman.khandual@arm.com>
Date: Tue, 7 Apr 2020 03:03:59 +0000 (-0700)
Subject: mm/vma: append unlikely() while testing VMA access permissions
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5093c5872be3a041917828b2b53e9f981d754768;p=linux.git

mm/vma: append unlikely() while testing VMA access permissions

It is unlikely that an inaccessible VMA without required permission flags
will get a page fault.  Hence lets just append unlikely() directive to
such checks in order to improve performance while also standardizing it
across various platforms.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Link: http://lkml.kernel.org/r/1582525304-32113-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
index a6e8230b6fbfa..4e6dc68f32584 100644
--- a/arch/csky/mm/fault.c
+++ b/arch/csky/mm/fault.c
@@ -141,7 +141,7 @@ good_area:
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 	} else {
-		if (!vma_is_accessible(vma))
+		if (unlikely(!vma_is_accessible(vma)))
 			goto bad_area;
 	}
 
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index 0c4a21a685d59..3bfb5c8ac3c7a 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -125,7 +125,7 @@ good_area:
 		case 1:		/* read, present */
 			goto acc_err;
 		case 0:		/* read, not present */
-			if (!vma_is_accessible(vma))
+			if (unlikely(!vma_is_accessible(vma)))
 				goto acc_err;
 	}
 
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index fb048ba2b91d4..f8d62cd83b36c 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -142,7 +142,7 @@ good_area:
 				goto bad_area;
 			}
 		} else {
-			if (!vma_is_accessible(vma))
+			if (unlikely(!vma_is_accessible(vma)))
 				goto bad_area;
 		}
 	}