From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Fri, 16 Jun 2023 18:58:07 +0000 (-0400)
Subject: patch 4
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=896235bcf1a8fadc3d1e51b9e2e2b9c182c89f0b;p=users%2Fjedix%2Flinux-maple.git

patch 4

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index bff5820b7cda..a243fcdf346d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -278,6 +278,7 @@ config PPC
 	select IRQ_DOMAIN
 	select IRQ_FORCED_THREADING
 	select KASAN_VMALLOC			if KASAN && MODULES
+	select LOCK_MM_AND_FIND_VMA
 	select MMU_GATHER_PAGE_SIZE
 	select MMU_GATHER_RCU_TABLE_FREE
 	select MMU_GATHER_MERGE_VMAS
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 531177a4ee08..7f73b278799e 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -515,40 +515,12 @@ lock_mmap:
 	 * we will deadlock attempting to validate the fault against the
 	 * address space.  Luckily the kernel only validly references user
 	 * space from well defined areas of code, which are listed in the
-	 * exceptions table.
-	 *
-	 * As the vast majority of faults will be valid we will only perform
-	 * the source reference check when there is a possibility of a deadlock.
-	 * Attempt to lock the address space, if we cannot we then validate the
-	 * source.  If this is invalid we can skip the address space check,
-	 * thus avoiding the deadlock.
+	 * exceptions table. lock_mm_and_find_vma() handles that logic.
 	 */
-	if (unlikely(!mmap_read_trylock(mm))) {
-		if (!is_user && !search_exception_tables(regs->nip))
-			return bad_area_nosemaphore(regs, address);
-
 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();
-	}
-
-	vma = find_vma(mm, address);
+	vma = lock_mm_and_find_vma(mm, address, regs);
 	if (unlikely(!vma))
-		return bad_area(regs, address);
-
-	if (unlikely(vma->vm_start > address)) {
-		if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
-			return bad_area(regs, address);
-
-		if (unlikely(expand_stack(vma, address)))
-			return bad_area(regs, address);
-	}
+		return bad_area_nosemaphore(regs, address);
 
 	if (unlikely(access_pkey_error(is_write, is_exec,
 				       (error_code & DSISR_KEYFAULT), vma)))