From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/mm/frame_vector.c | 44 +++++++++++++-------------------------------
1 files changed, 13 insertions(+), 31 deletions(-)
diff --git a/kernel/mm/frame_vector.c b/kernel/mm/frame_vector.c
index c431ca8..1cd81d3 100644
--- a/kernel/mm/frame_vector.c
+++ b/kernel/mm/frame_vector.c
@@ -29,7 +29,11 @@
* different type underlying the specified range of virtual addresses.
* When the function isn't able to map a single page, it returns error.
*
- * This function takes care of grabbing mmap_sem as necessary.
+ * Note that get_vaddr_frames() cannot follow VM_IO mappings. It used
+ * to be able to do that, but that could (racily) return non-refcounted
+ * pfns.
+ *
+ * This function takes care of grabbing mmap_lock as necessary.
*/
int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
unsigned int gup_flags, struct frame_vector *vec)
@@ -37,7 +41,6 @@
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int ret = 0;
- int err;
int locked;
if (nr_frames == 0)
@@ -48,7 +51,7 @@
start = untagged_addr(start);
- down_read(&mm->mmap_sem);
+ mmap_read_lock(mm);
locked = 1;
vma = find_vma_intersection(mm, start, start + 1);
if (!vma) {
@@ -72,37 +75,17 @@
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
vec->got_ref = true;
vec->is_pfns = false;
- ret = get_user_pages_locked(start, nr_frames,
+ ret = pin_user_pages_locked(start, nr_frames,
gup_flags, (struct page **)(vec->ptrs), &locked);
- goto out;
+ if (likely(ret > 0))
+ goto out;
}
- vec->got_ref = false;
- vec->is_pfns = true;
- do {
- unsigned long *nums = frame_vector_pfns(vec);
+ vec->nr_frames = 0;
- while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
- err = follow_pfn(vma, start, &nums[ret]);
- if (err) {
- if (ret == 0)
- ret = err;
- goto out;
- }
- start += PAGE_SIZE;
- ret++;
- }
- /*
- * We stop if we have enough pages or if VMA doesn't completely
- * cover the tail page.
- */
- if (ret >= nr_frames || start < vma->vm_end)
- break;
- vma = find_vma_intersection(mm, start, start + 1);
- } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
out:
if (locked)
- up_read(&mm->mmap_sem);
+ mmap_read_unlock(mm);
if (!ret)
ret = -EFAULT;
if (ret > 0)
@@ -122,7 +105,6 @@
*/
void put_vaddr_frames(struct frame_vector *vec)
{
- int i;
struct page **pages;
if (!vec->got_ref)
@@ -135,8 +117,8 @@
*/
if (WARN_ON(IS_ERR(pages)))
goto out;
- for (i = 0; i < vec->nr_frames; i++)
- put_page(pages[i]);
+
+ unpin_user_pages(pages, vec->nr_frames);
vec->got_ref = false;
out:
vec->nr_frames = 0;
--
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