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Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c46
1 files changed, 43 insertions, 3 deletions
diff --git a/mm/memory.c b/mm/memory.c
index feff48e1465a..8079c181efff 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4834,28 +4834,68 @@ out:
return ret;
}
+/**
+ * generic_access_phys - generic implementation for iomem mmap access
+ * @vma: the vma to access
+ * @addr: userspace addres, not relative offset within @vma
+ * @buf: buffer to read/write
+ * @len: length of transfer
+ * @write: set to FOLL_WRITE when writing, otherwise reading
+ *
+ * This is a generic implementation for &vm_operations_struct.access for an
+ * iomem mapping. This callback is used by access_process_vm() when the @vma is
+ * not page based.
+ */
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
resource_size_t phys_addr;
unsigned long prot = 0;
void __iomem *maddr;
- int offset = addr & (PAGE_SIZE-1);
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+ int offset = offset_in_page(addr);
+ int ret = -EINVAL;
+
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ return -EINVAL;
+
+retry:
+ if (follow_pte(vma->vm_mm, addr, NULL, &ptep, NULL, &ptl))
+ return -EINVAL;
+ pte = *ptep;
+ pte_unmap_unlock(ptep, ptl);
- if (follow_phys(vma, addr, write, &prot, &phys_addr))
+ prot = pgprot_val(pte_pgprot(pte));
+ phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
+
+ if ((write & FOLL_WRITE) && !pte_write(pte))
return -EINVAL;
maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
if (!maddr)
return -ENOMEM;
+ if (follow_pte(vma->vm_mm, addr, NULL, &ptep, NULL, &ptl))
+ goto out_unmap;
+
+ if (!pte_same(pte, *ptep)) {
+ pte_unmap_unlock(ptep, ptl);
+ iounmap(maddr);
+
+ goto retry;
+ }
+
if (write)
memcpy_toio(maddr + offset, buf, len);
else
memcpy_fromio(buf, maddr + offset, len);
+ ret = len;
+ pte_unmap_unlock(ptep, ptl);
+out_unmap:
iounmap(maddr);
- return len;
+ return ret;
}
EXPORT_SYMBOL_GPL(generic_access_phys);
#endif