1 files changed, 25 insertions, 12 deletions

diff --git a/arch/mips/mm/ioremap.c b/arch/mips/mm/ioremap.c
index 1986e09fb457..1601d90b087b 100644
--- a/arch/mips/mm/ioremap.c
+++ b/arch/mips/mm/ioremap.c
@@ -9,6 +9,7 @@
 #include <linux/export.h>
 #include <asm/addrspace.h>
 #include <asm/byteorder.h>
+#include <linux/ioport.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
@@ -98,6 +99,20 @@ static int remap_area_pages(unsigned long address, phys_addr_t phys_addr,
         return error;
 }
 
+static int __ioremap_check_ram(unsigned long start_pfn, unsigned long nr_pages,
+                               void *arg)
+{
+        unsigned long i;
+
+        for (i = 0; i < nr_pages; i++) {
+                if (pfn_valid(start_pfn + i) &&
+                    !PageReserved(pfn_to_page(start_pfn + i)))
+                        return 1;
+        }
+
+        return 0;
+}
+
 /*
  * Generic mapping function (not visible outside):
  */
@@ -116,8 +131,8 @@ static int remap_area_pages(unsigned long address, phys_addr_t phys_addr,
 
 void __iomem * __ioremap(phys_addr_t phys_addr, phys_addr_t size, unsigned long flags)
 {
+        unsigned long offset, pfn, last_pfn;
         struct vm_struct * area;
-        unsigned long offset;
         phys_addr_t last_addr;
         void * addr;
 
@@ -137,18 +152,16 @@ void __iomem * __ioremap(phys_addr_t phys_addr, phys_addr_t size, unsigned long
                 return (void __iomem *) CKSEG1ADDR(phys_addr);
 
         /*
-         * Don't allow anybody to remap normal RAM that we're using..
+         * Don't allow anybody to remap RAM that may be allocated by the page
+         * allocator, since that could lead to races & data clobbering.
          */
-        if (phys_addr < virt_to_phys(high_memory)) {
-                char *t_addr, *t_end;
-                struct page *page;
-
-                t_addr = __va(phys_addr);
-                t_end = t_addr + (size - 1);
-
-                for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
-                        if(!PageReserved(page))
-                                return NULL;
+        pfn = PFN_DOWN(phys_addr);
+        last_pfn = PFN_DOWN(last_addr);
+        if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
+                                  __ioremap_check_ram) == 1) {
+                WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
+                          &phys_addr, &last_addr);
+                return NULL;
         }
 
         /*