1 files changed, 61 insertions, 29 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 85cbd3cd3723..160c42d3eb8f 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -505,6 +505,35 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 }
 #endif /* CONFIG_STRICT_DEVMEM */
 
+/*
+ * Change the memory type for the physial address range in kernel identity
+ * mapping space if that range is a part of identity map.
+ */
+static int kernel_map_sync_memtype(u64 base, unsigned long size,
+                                        unsigned long flags)
+{
+        unsigned long id_sz;
+        int ret;
+
+        if (!pat_enabled || base >= __pa(high_memory))
+                return 0;
+
+        id_sz = (__pa(high_memory) < base + size) ?
+                                                __pa(high_memory) - base :
+                                                size;
+
+        ret = ioremap_change_attr((unsigned long)__va(base), id_sz, flags);
+        /*
+         * -EFAULT return means that the addr was not valid and did not have
+         * any identity mapping. That case is a success for
+         * kernel_map_sync_memtype.
+         */
+        if (ret == -EFAULT)
+                ret = 0;
+
+        return ret;
+}
+
 int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
                                 unsigned long size, pgprot_t *vma_prot)
 {
@@ -555,9 +584,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
         if (retval < 0)
                 return 0;
 
-        if (((pfn < max_low_pfn_mapped) ||
-             (pfn >= (1UL<<(32 - PAGE_SHIFT)) && pfn < max_pfn_mapped)) &&
-            ioremap_change_attr((unsigned long)__va(offset), size, flags) < 0) {
+        if (kernel_map_sync_memtype(offset, size, flags)) {
                 free_memtype(offset, offset + size);
                 printk(KERN_INFO
                 "%s:%d /dev/mem ioremap_change_attr failed %s for %Lx-%Lx\n",
@@ -601,12 +628,13 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
  * Reserved non RAM regions only and after successful reserve_memtype,
  * this func also keeps identity mapping (if any) in sync with this new prot.
  */
-static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t vma_prot)
+static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
+                                int strict_prot)
 {
         int is_ram = 0;
-        int id_sz, ret;
+        int ret;
         unsigned long flags;
-        unsigned long want_flags = (pgprot_val(vma_prot) & _PAGE_CACHE_MASK);
+        unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
 
         is_ram = pagerange_is_ram(paddr, paddr + size);
 
@@ -625,26 +653,27 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t vma_prot)
                 return ret;
 
         if (flags != want_flags) {
-                free_memtype(paddr, paddr + size);
-                printk(KERN_ERR
-                "%s:%d map pfn expected mapping type %s for %Lx-%Lx, got %s\n",
-                        current->comm, current->pid,
-                        cattr_name(want_flags),
-                        (unsigned long long)paddr,
-                        (unsigned long long)(paddr + size),
-                        cattr_name(flags));
-                return -EINVAL;
+                if (strict_prot || !is_new_memtype_allowed(want_flags, flags)) {
+                        free_memtype(paddr, paddr + size);
+                        printk(KERN_ERR "%s:%d map pfn expected mapping type %s"
+                                " for %Lx-%Lx, got %s\n",
+                                current->comm, current->pid,
+                                cattr_name(want_flags),
+                                (unsigned long long)paddr,
+                                (unsigned long long)(paddr + size),
+                                cattr_name(flags));
+                        return -EINVAL;
+                }
+                /*
+                 * We allow returning different type than the one requested in
+                 * non strict case.
+                 */
+                *vma_prot = __pgprot((pgprot_val(*vma_prot) &
+                                      (~_PAGE_CACHE_MASK)) |
+                                     flags);
         }
 
-        /* Need to keep identity mapping in sync */
-        if (paddr >= __pa(high_memory))
-                return 0;
-
-        id_sz = (__pa(high_memory) < paddr + size) ?
-                                __pa(high_memory) - paddr :
-                                size;
-
-        if (ioremap_change_attr((unsigned long)__va(paddr), id_sz, flags) < 0) {
+        if (kernel_map_sync_memtype(paddr, size, flags)) {
                 free_memtype(paddr, paddr + size);
                 printk(KERN_ERR
                         "%s:%d reserve_pfn_range ioremap_change_attr failed %s "
@@ -689,6 +718,7 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
         unsigned long vma_start = vma->vm_start;
         unsigned long vma_end = vma->vm_end;
         unsigned long vma_size = vma_end - vma_start;
+        pgprot_t pgprot;
 
         if (!pat_enabled)
                 return 0;
@@ -702,7 +732,8 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
                         WARN_ON_ONCE(1);
                         return -EINVAL;
                 }
-                return reserve_pfn_range(paddr, vma_size, __pgprot(prot));
+                pgprot = __pgprot(prot);
+                return reserve_pfn_range(paddr, vma_size, &pgprot, 1);
         }
 
         /* reserve entire vma page by page, using pfn and prot from pte */
@@ -710,7 +741,8 @@ int track_pfn_vma_copy(struct vm_area_struct *vma)
                 if (follow_phys(vma, vma_start + i, 0, &prot, &paddr))
                         continue;
 
-                retval = reserve_pfn_range(paddr, PAGE_SIZE, __pgprot(prot));
+                pgprot = __pgprot(prot);
+                retval = reserve_pfn_range(paddr, PAGE_SIZE, &pgprot, 1);
                 if (retval)
                         goto cleanup_ret;
         }
@@ -741,7 +773,7 @@ cleanup_ret:
  * Note that this function can be called with caller trying to map only a
  * subrange/page inside the vma.
  */
-int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
+int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
                         unsigned long pfn, unsigned long size)
 {
         int retval = 0;
@@ -758,14 +790,14 @@ int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t prot,
         if (is_linear_pfn_mapping(vma)) {
                 /* reserve the whole chunk starting from vm_pgoff */
                 paddr = (resource_size_t)vma->vm_pgoff << PAGE_SHIFT;
-                return reserve_pfn_range(paddr, vma_size, prot);
+                return reserve_pfn_range(paddr, vma_size, prot, 0);
         }
 
         /* reserve page by page using pfn and size */
         base_paddr = (resource_size_t)pfn << PAGE_SHIFT;
         for (i = 0; i < size; i += PAGE_SIZE) {
                 paddr = base_paddr + i;
-                retval = reserve_pfn_range(paddr, PAGE_SIZE, prot);
+                retval = reserve_pfn_range(paddr, PAGE_SIZE, prot, 0);
                 if (retval)
                         goto cleanup_ret;
         }