[v2,3/7] mm/gup: remove vmas parameter from get_user_pages_remote()

Commit Message

Lorenzo Stoakes April 15, 2023, 9:08 a.m. UTC

The only instances of get_user_pages_remote() invocations which used the
vmas parameter were for a single page which can instead simply look up the
VMA directly. In particular:-

- __update_ref_ctr() looked up the VMA but did nothing with it so we simply
  remove it.

- __access_remote_vm() was already using vma_lookup() when the original
  lookup failed so by doing the lookup directly this also de-duplicates the
  code.

This forms part of a broader set of patches intended to eliminate the vmas
parameter altogether.

Signed-off-by: Lorenzo Stoakes <[e-mail]>
---
 arch/arm64/kernel/mte.c   |  7 ++++---
 arch/s390/kvm/interrupt.c |  2 +-
 fs/exec.c                 |  2 +-
 include/linux/mm.h        |  2 +-
 kernel/events/uprobes.c   | 12 +++++++-----
 mm/gup.c                  | 12 ++++--------
 mm/memory.c               |  9 +++++----
 mm/rmap.c                 |  2 +-
 security/tomoyo/domain.c  |  2 +-
 virt/kvm/async_pf.c       |  3 +--
 10 files changed, 26 insertions(+), 27 deletions(-)

Comments

Tetsuo Handa April 15, 2023, 9:52 a.m. UTC | #1

On 2023/04/15 18:08, Lorenzo Stoakes wrote:
> @@ -475,10 +474,14 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
>  		gup_flags |= FOLL_SPLIT_PMD;
>  	/* Read the page with vaddr into memory */
>  	ret = get_user_pages_remote(mm, vaddr, 1, gup_flags,
> -				    &old_page, &vma, NULL);
> +				    &old_page, NULL);
>  	if (ret <= 0)
>  		return ret;
>  
> +	vma = vma_lookup(mm, vaddr);
> +	if (!vma)
> +		goto put_old;
> +
>  	ret = verify_opcode(old_page, vaddr, &opcode);
>  	if (ret <= 0)
>  		goto put_old;

This conversion looks wrong.
This causes returning a positive number when vma_lookup() returned NULL.

  * Return 0 (success) or a negative errno.

Patch

diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index f5bcb0dc6267..d43a744d7919 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -419,7 +419,6 @@  long get_mte_ctrl(struct task_struct *task)
 static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
 				struct iovec *kiov, unsigned int gup_flags)
 {
-	struct vm_area_struct *vma;
 	void __user *buf = kiov->iov_base;
 	size_t len = kiov->iov_len;
 	int ret;
@@ -432,12 +431,13 @@  static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
 		return -EIO;
 
 	while (len) {
+		struct vm_area_struct *vma;
 		unsigned long tags, offset;
 		void *maddr;
 		struct page *page = NULL;
 
 		ret = get_user_pages_remote(mm, addr, 1, gup_flags, &page,
-					    &vma, NULL);
+					    NULL);
 		if (ret <= 0)
 			break;
 
@@ -448,7 +448,8 @@  static int __access_remote_tags(struct mm_struct *mm, unsigned long addr,
 		 * would cause the existing tags to be cleared if the page
 		 * was never mapped with PROT_MTE.
 		 */
-		if (!(vma->vm_flags & VM_MTE)) {
+		vma = vma_lookup(mm, addr);
+		if (!vma || !(vma->vm_flags & VM_MTE)) {
 			ret = -EOPNOTSUPP;
 			put_page(page);
 			break;
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 9250fde1f97d..c19d0cb7d2f2 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2777,7 +2777,7 @@  static struct page *get_map_page(struct kvm *kvm, u64 uaddr)
 
 	mmap_read_lock(kvm->mm);
 	get_user_pages_remote(kvm->mm, uaddr, 1, FOLL_WRITE,
-			      &page, NULL, NULL);
+			      &page, NULL);
 	mmap_read_unlock(kvm->mm);
 	return page;
 }
diff --git a/fs/exec.c b/fs/exec.c
index 87cf3a2f0e9a..d8d48ee15aac 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -219,7 +219,7 @@  static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 	 */
 	mmap_read_lock(bprm->mm);
 	ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
-			&page, NULL, NULL);
+			&page, NULL);
 	mmap_read_unlock(bprm->mm);
 	if (ret <= 0)
 		return NULL;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ec9875c59f6d..1bfe73a2b6d3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2374,7 +2374,7 @@  extern int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
 long get_user_pages_remote(struct mm_struct *mm,
 			    unsigned long start, unsigned long nr_pages,
 			    unsigned int gup_flags, struct page **pages,
-			    struct vm_area_struct **vmas, int *locked);
+			    int *locked);
 long pin_user_pages_remote(struct mm_struct *mm,
 			   unsigned long start, unsigned long nr_pages,
 			   unsigned int gup_flags, struct page **pages,
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 59887c69d54c..b21993cd2dcc 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -365,7 +365,6 @@  __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
 {
 	void *kaddr;
 	struct page *page;
-	struct vm_area_struct *vma;
 	int ret;
 	short *ptr;
 
@@ -373,7 +372,7 @@  __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
 		return -EINVAL;
 
 	ret = get_user_pages_remote(mm, vaddr, 1,
-			FOLL_WRITE, &page, &vma, NULL);
+				    FOLL_WRITE, &page, NULL);
 	if (unlikely(ret <= 0)) {
 		/*
 		 * We are asking for 1 page. If get_user_pages_remote() fails,
@@ -475,10 +474,14 @@  int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 		gup_flags |= FOLL_SPLIT_PMD;
 	/* Read the page with vaddr into memory */
 	ret = get_user_pages_remote(mm, vaddr, 1, gup_flags,
-				    &old_page, &vma, NULL);
+				    &old_page, NULL);
 	if (ret <= 0)
 		return ret;
 
+	vma = vma_lookup(mm, vaddr);
+	if (!vma)
+		goto put_old;
+
 	ret = verify_opcode(old_page, vaddr, &opcode);
 	if (ret <= 0)
 		goto put_old;
@@ -2027,8 +2030,7 @@  static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
 	 * but we treat this as a 'remote' access since it is
 	 * essentially a kernel access to the memory.
 	 */
-	result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page,
-			NULL, NULL);
+	result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, NULL);
 	if (result < 0)
 		return result;
 
diff --git a/mm/gup.c b/mm/gup.c
index 931c805bc32b..9440aa54c741 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2165,8 +2165,6 @@  static bool is_valid_gup_args(struct page **pages, struct vm_area_struct **vmas,
  * @pages:	array that receives pointers to the pages pinned.
  *		Should be at least nr_pages long. Or NULL, if caller
  *		only intends to ensure the pages are faulted in.
- * @vmas:	array of pointers to vmas corresponding to each page.
- *		Or NULL if the caller does not require them.
  * @locked:	pointer to lock flag indicating whether lock is held and
  *		subsequently whether VM_FAULT_RETRY functionality can be
  *		utilised. Lock must initially be held.
@@ -2181,8 +2179,6 @@  static bool is_valid_gup_args(struct page **pages, struct vm_area_struct **vmas,
  *
  * The caller is responsible for releasing returned @pages, via put_page().
  *
- * @vmas are valid only as long as mmap_lock is held.
- *
  * Must be called with mmap_lock held for read or write.
  *
  * get_user_pages_remote walks a process's page tables and takes a reference
@@ -2219,15 +2215,15 @@  static bool is_valid_gup_args(struct page **pages, struct vm_area_struct **vmas,
 long get_user_pages_remote(struct mm_struct *mm,
 		unsigned long start, unsigned long nr_pages,
 		unsigned int gup_flags, struct page **pages,
-		struct vm_area_struct **vmas, int *locked)
+		int *locked)
 {
 	int local_locked = 1;
 
-	if (!is_valid_gup_args(pages, vmas, locked, &gup_flags,
+	if (!is_valid_gup_args(pages, NULL, locked, &gup_flags,
 			       FOLL_TOUCH | FOLL_REMOTE))
 		return -EINVAL;
 
-	return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
+	return __get_user_pages_locked(mm, start, nr_pages, pages, NULL,
 				       locked ? locked : &local_locked,
 				       gup_flags);
 }
@@ -2237,7 +2233,7 @@  EXPORT_SYMBOL(get_user_pages_remote);
 long get_user_pages_remote(struct mm_struct *mm,
 			   unsigned long start, unsigned long nr_pages,
 			   unsigned int gup_flags, struct page **pages,
-			   struct vm_area_struct **vmas, int *locked)
+			   int *locked)
 {
 	return 0;
 }
diff --git a/mm/memory.c b/mm/memory.c
index 8ddb10199e8d..913e693322f2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5591,7 +5591,9 @@  int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
 		struct page *page = NULL;
 
 		ret = get_user_pages_remote(mm, addr, 1,
-				gup_flags, &page, &vma, NULL);
+				gup_flags, &page, NULL);
+		vma = vma_lookup(mm, addr);
+
 		if (ret <= 0) {
 #ifndef CONFIG_HAVE_IOREMAP_PROT
 			break;
@@ -5600,7 +5602,6 @@  int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
 			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
 			 * we can access using slightly different code.
 			 */
-			vma = vma_lookup(mm, addr);
 			if (!vma)
 				break;
 			if (vma->vm_ops && vma->vm_ops->access)
@@ -5617,11 +5618,11 @@  int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
 				bytes = PAGE_SIZE-offset;
 
 			maddr = kmap(page);
-			if (write) {
+			if (write && vma) {
 				copy_to_user_page(vma, page, addr,
 						  maddr + offset, buf, bytes);
 				set_page_dirty_lock(page);
-			} else {
+			} else if (vma) {
 				copy_from_user_page(vma, page, addr,
 						    buf, maddr + offset, bytes);
 			}
diff --git a/mm/rmap.c b/mm/rmap.c
index ba901c416785..756ea8a9bb90 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2324,7 +2324,7 @@  int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
 
 	npages = get_user_pages_remote(mm, start, npages,
 				       FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
-				       pages, NULL, NULL);
+				       pages, NULL);
 	if (npages < 0)
 		return npages;
 
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 31af29f669d2..ac20c0bdff9d 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -916,7 +916,7 @@  bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
 	 */
 	mmap_read_lock(bprm->mm);
 	ret = get_user_pages_remote(bprm->mm, pos, 1,
-				    FOLL_FORCE, &page, NULL, NULL);
+				    FOLL_FORCE, &page, NULL);
 	mmap_read_unlock(bprm->mm);
 	if (ret <= 0)
 		return false;
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 9bfe1d6f6529..e033c79d528e 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -61,8 +61,7 @@  static void async_pf_execute(struct work_struct *work)
 	 * access remotely.
 	 */
 	mmap_read_lock(mm);
-	get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, NULL,
-			&locked);
+	get_user_pages_remote(mm, addr, 1, FOLL_WRITE, NULL, &locked);
 	if (locked)
 		mmap_read_unlock(mm);