mseal: add branch prediction hint

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

Link: https://lkml.kernel.org/r/20240423192825.1273679-2-jeffxu@chromium.org
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Suggested-by: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Amer Al Shanawany <amer.shanawany@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jann Horn <jannh@google.com>
Cc: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Cc: Jeff Xu <jeffxu@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stephen Röttger <sroettger@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

5 files changed, 9 insertions, 9 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index bf1587b87c47..a77893462b92 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1449,7 +1449,7 @@ 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 47363e7f7ea2..057270dbe3aa 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2740,7 +2740,7 @@ 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.  */
@@ -3163,7 +3163,7 @@ 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 e0ec5bfd17ec..8c6cd8825273 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -749,7 +749,7 @@ 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 c94e96ad2095..5f96bc5ee918 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. */