Commit ca5e8632 authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

mm/gup: remove vmas parameter from get_user_pages_remote() 

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.

We are able to perform these VMA operations as we already hold the
mmap_lock in order to be able to call get_user_pages_remote().

As part of this work we add get_user_page_vma_remote() which abstracts the
VMA lookup, error handling and decrementing the page reference count should
the VMA lookup fail.

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

[akpm@linux-foundation.org: avoid passing NULL to PTR_ERR]
Link: https://lkml.kernel.org/r/d20128c849ecdbf4dd01cc828fcec32127ed939a.1684350871.git.lstoakes@gmail.com


Signed-off-by: default avatarLorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> (for arm64)
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com> (for s390)
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 0b295316

arch/arm64/kernel/mte.c

+9 −8
Original line number Diff line number Diff line
@@ -416,10 +416,9 @@ 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;

	int err = 0;

	int write = gup_flags & FOLL_WRITE;



	if (!access_ok(buf, len))
@@ -429,14 +428,16 @@ 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;

		struct page *page = get_user_page_vma_remote(mm, addr,

							     gup_flags, &vma);



		ret = get_user_pages_remote(mm, addr, 1, gup_flags, &page,

					    &vma, NULL);

		if (ret <= 0)

		if (IS_ERR_OR_NULL(page)) {

			err = page == NULL ? -EIO : PTR_ERR(page);

			break;

		}



		/*

		 * Only copy tags if the page has been mapped as PROT_MTE
@@ -446,7 +447,7 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr, 
		 * was never mapped with PROT_MTE.

		 */

		if (!(vma->vm_flags & VM_MTE)) {

			ret = -EOPNOTSUPP;

			err = -EOPNOTSUPP;

			put_page(page);

			break;

		}
@@ -479,7 +480,7 @@ static int __access_remote_tags(struct mm_struct *mm, unsigned long addr, 
	kiov->iov_len = buf - kiov->iov_base;

	if (!kiov->iov_len) {

		/* check for error accessing the tracee's address space */

		if (ret <= 0)

		if (err)

			return -EIO;

		else

			return -EFAULT;

arch/s390/kvm/interrupt.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

}

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -220,7 +220,7 @@ 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;

include/linux/mm.h

+31 −3
Original line number Diff line number Diff line
@@ -2353,6 +2353,9 @@ static inline void unmap_shared_mapping_range(struct address_space *mapping, 
	unmap_mapping_range(mapping, holebegin, holelen, 0);

}



static inline struct vm_area_struct *vma_lookup(struct mm_struct *mm,

						unsigned long addr);



extern int access_process_vm(struct task_struct *tsk, unsigned long addr,

		void *buf, int len, unsigned int gup_flags);

extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
@@ -2363,11 +2366,36 @@ 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,

			   int *locked);



static inline struct page *get_user_page_vma_remote(struct mm_struct *mm,

						    unsigned long addr,

						    int gup_flags,

						    struct vm_area_struct **vmap)

{

	struct page *page;

	struct vm_area_struct *vma;

	int got = get_user_pages_remote(mm, addr, 1, gup_flags, &page, NULL);



	if (got < 0)

		return ERR_PTR(got);

	if (got == 0)

		return NULL;



	vma = vma_lookup(mm, addr);

	if (WARN_ON_ONCE(!vma)) {

		put_page(page);

		return ERR_PTR(-EINVAL);

	}



	*vmap = vma;

	return page;

}



long get_user_pages(unsigned long start, unsigned long nr_pages,

		    unsigned int gup_flags, struct page **pages);

long pin_user_pages(unsigned long start, unsigned long nr_pages,

kernel/events/uprobes.c

+5 −8
Original line number Diff line number Diff line
@@ -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,
@@ -474,10 +473,9 @@ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, 
	if (is_register)

		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);

	if (ret <= 0)

		return ret;

	old_page = get_user_page_vma_remote(mm, vaddr, gup_flags, &vma);

	if (IS_ERR_OR_NULL(old_page))

		return old_page ? PTR_ERR(old_page) : 0;



	ret = verify_opcode(old_page, vaddr, &opcode);

	if (ret <= 0)
@@ -2027,8 +2025,7 @@ 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;