[v1,1/1] mseal: Add branch prediction hint.

Commit Message

Jeff Xu April 23, 2024, 7:28 p.m. UTC

From: Jeff Xu <[e-mail]>

It is unlikely that application calls mm syscall, such as mprotect,
on already sealed mappings, adding branch prediction hint.

Signed-off-by: Jeff Xu <[e-mail]>
Suggested-by: Pedro Falcato <[e-mail]>
---
 mm/madvise.c  | 2 +-
 mm/mmap.c     | 4 ++--
 mm/mprotect.c | 2 +-
 mm/mremap.c   | 4 ++--
 mm/mseal.c    | 6 +++---
 5 files changed, 9 insertions(+), 9 deletions(-)

Patch

diff --git a/mm/madvise.c b/mm/madvise.c
index f7d589534e82..ea2e4f6981e2 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1442,7 +1442,7 @@  int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
 	 * Check if the address range is sealed for do_madvise().
 	 * can_modify_mm_madv assumes we have acquired the lock on MM.
 	 */
-	if (!can_modify_mm_madv(mm, start, end, behavior)) {
+	if (unlikely(!can_modify_mm_madv(mm, start, end, behavior))) {
 		error = -EPERM;
 		goto out;
 	}
diff --git a/mm/mmap.c b/mm/mmap.c
index 4b80076c319e..6bc0b35ee1f9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2697,7 +2697,7 @@  int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
 	 * Prevent unmapping a sealed VMA.
 	 * can_modify_mm assumes we have acquired the lock on MM.
 	 */
-	if (!can_modify_mm(mm, start, end))
+	if (unlikely(!can_modify_mm(mm, start, end)))
 		return -EPERM;
 
 	 /* arch_unmap() might do unmaps itself.  */
@@ -3120,7 +3120,7 @@  int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	 * Prevent unmapping a sealed VMA.
 	 * can_modify_mm assumes we have acquired the lock on MM.
 	 */
-	if (!can_modify_mm(mm, start, end))
+	if (unlikely(!can_modify_mm(mm, start, end)))
 		return -EPERM;
 
 	arch_unmap(mm, start, end);
diff --git a/mm/mprotect.c b/mm/mprotect.c
index b30b2494bfcd..465c6cd9578c 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -748,7 +748,7 @@  static int do_mprotect_pkey(unsigned long start, size_t len,
 	 * checking if memory is sealed.
 	 * can_modify_mm assumes we have acquired the lock on MM.
 	 */
-	if (!can_modify_mm(current->mm, start, end)) {
+	if (unlikely(!can_modify_mm(current->mm, start, end))) {
 		error = -EPERM;
 		goto out;
 	}
diff --git a/mm/mremap.c b/mm/mremap.c
index d69b438dcf83..223552901f14 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -912,7 +912,7 @@  static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
 	 *
 	 * can_modify_mm assumes we have acquired the lock on MM.
 	 */
-	if (!can_modify_mm(mm, addr, addr + old_len))
+	if (unlikely(!can_modify_mm(mm, addr, addr + old_len)))
 		return -EPERM;
 
 	if (flags & MREMAP_FIXED) {
@@ -1087,7 +1087,7 @@  SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 	 * Place can_modify_mm here so we can keep the logic related to
 	 * shrink/expand together.
 	 */
-	if (!can_modify_mm(mm, addr, addr + old_len)) {
+	if (unlikely(!can_modify_mm(mm, addr, addr + old_len))) {
 		ret = -EPERM;
 		goto out;
 	}
diff --git a/mm/mseal.c b/mm/mseal.c
index daadac4b8125..bf783bba8ed0 100644
--- a/mm/mseal.c
+++ b/mm/mseal.c
@@ -32,7 +32,7 @@  static inline void set_vma_sealed(struct vm_area_struct *vma)
  */
 static bool can_modify_vma(struct vm_area_struct *vma)
 {
-	if (vma_is_sealed(vma))
+	if (unlikely(vma_is_sealed(vma)))
 		return false;
 
 	return true;
@@ -75,7 +75,7 @@  bool can_modify_mm(struct mm_struct *mm, unsigned long start, unsigned long end)
 
 	/* going through each vma to check. */
 	for_each_vma_range(vmi, vma, end) {
-		if (!can_modify_vma(vma))
+		if (unlikely(!can_modify_vma(vma)))
 			return false;
 	}
 
@@ -100,7 +100,7 @@  bool can_modify_mm_madv(struct mm_struct *mm, unsigned long start, unsigned long
 
 	/* going through each vma to check. */
 	for_each_vma_range(vmi, vma, end)
-		if (is_ro_anon(vma) && !can_modify_vma(vma))
+		if (unlikely(is_ro_anon(vma) && !can_modify_vma(vma)))
 			return false;
 
 	/* Allow by default. */