Add a version of remap_pfn_range that does not call track_pfn_range.
This will be used to fix horrible abuses of VM internals in the i915
driver.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
include/linux/mm.h | 2 ++
mm/memory.c | 52 ++++++++++++++++++++++++++++------------------
2 files changed, 34 insertions(+), 20 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 77e64e3eac80bd..fc3438daf5cfd8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2688,6 +2688,8 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t);
+int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, unsigned long size, pgprot_t prot);
int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
struct page **pages, unsigned long *num);
diff --git a/mm/memory.c b/mm/memory.c
index c8e35762731861..d038c13f489b78 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2266,26 +2266,17 @@ static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
return 0;
}
-/**
- * remap_pfn_range - remap kernel memory to userspace
- * @vma: user vma to map to
- * @addr: target page aligned user address to start at
- * @pfn: page frame number of kernel physical memory address
- * @size: size of mapping area
- * @prot: page protection flags for this mapping
- *
- * Note: this is only safe if the mm semaphore is held when called.
- *
- * Return: %0 on success, negative error code otherwise.
+/*
+ * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
+ * must have pre-validated the caching bits of the pgprot_t.
*/
-int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
- unsigned long pfn, unsigned long size, pgprot_t prot)
+int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, unsigned long size, pgprot_t prot)
{
pgd_t *pgd;
unsigned long next;
unsigned long end = addr + PAGE_ALIGN(size);
struct mm_struct *mm = vma->vm_mm;
- unsigned long remap_pfn = pfn;
int err;
if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
@@ -2315,10 +2306,6 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
vma->vm_pgoff = pfn;
}
- err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
- if (err)
- return -EINVAL;
-
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
BUG_ON(addr >= end);
@@ -2330,12 +2317,37 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
err = remap_p4d_range(mm, pgd, addr, next,
pfn + (addr >> PAGE_SHIFT), prot);
if (err)
- break;
+ return err;
} while (pgd++, addr = next, addr != end);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(remap_pfn_range_notrack);
+
+/**
+ * remap_pfn_range - remap kernel memory to userspace
+ * @vma: user vma to map to
+ * @addr: target page aligned user address to start at
+ * @pfn: page frame number of kernel physical memory address
+ * @size: size of mapping area
+ * @prot: page protection flags for this mapping
+ *
+ * Note: this is only safe if the mm semaphore is held when called.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+ int err;
+
+ err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
if (err)
- untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
+ return -EINVAL;
+ err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
+ if (err)
+ untrack_pfn(vma, pfn, PAGE_ALIGN(size));
return err;
}
EXPORT_SYMBOL(remap_pfn_range);
--
2.29.2
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