gpu/drm, x86, PAT: io_mapping_create_wc and resource_size_t

io_mapping_create_wc should take a resource_size_t parameter in place of
unsigned long. With unsigned long, there will be no way to map greater than 4GB
address in i386/32 bit.

On x86, greater than 4GB addresses cannot be mapped on i386 without PAE. Return
error for such a case.

Patch also adds a structure for io_mapping, that saves the base, size and
type on HAVE_ATOMIC_IOMAP archs, that can be used to verify the offset on
io_mapping_map calls.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/iomap.h

@@ -23,6 +23,9 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 
+int
+is_io_mapping_possible(resource_size_t base, unsigned long size);
+
 void *
 iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot);
 

arch/x86/mm/iomap_32.c

@@ -20,6 +20,24 @@
 #include <asm/pat.h>
 #include <linux/module.h>
 
+#ifdef CONFIG_X86_PAE
+int
+is_io_mapping_possible(resource_size_t base, unsigned long size)
+{
+	return 1;
+}
+#else
+int
+is_io_mapping_possible(resource_size_t base, unsigned long size)
+{
+	/* There is no way to map greater than 1 << 32 address without PAE */
+	if (base + size > 0x100000000ULL)
+		return 0;
+
+	return 1;
+}
+#endif
+
 /* Map 'pfn' using fixed map 'type' and protections 'prot'
  */
 void *

include/linux/io-mapping.h

@@ -30,11 +30,14 @@
  * See Documentation/io_mapping.txt
  */
 
-/* this struct isn't actually defined anywhere */
-struct io_mapping;
-
 #ifdef CONFIG_HAVE_ATOMIC_IOMAP
 
+struct io_mapping {
+	resource_size_t base;
+	unsigned long size;
+	pgprot_t prot;
+};
+
 /*
  * For small address space machines, mapping large objects
  * into the kernel virtual space isn't practical. Where
@@ -43,23 +46,40 @@ struct io_mapping;
  */
 
 static inline struct io_mapping *
-io_mapping_create_wc(unsigned long base, unsigned long size)
+io_mapping_create_wc(resource_size_t base, unsigned long size)
 {
-	return (struct io_mapping *) base;
+	struct io_mapping *iomap;
+
+	if (!is_io_mapping_possible(base, size))
+		return NULL;
+
+	iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
+	if (!iomap)
+		return NULL;
+
+	iomap->base = base;
+	iomap->size = size;
+	iomap->prot = pgprot_writecombine(__pgprot(__PAGE_KERNEL));
+	return iomap;
 }
 
 static inline void
 io_mapping_free(struct io_mapping *mapping)
 {
+	kfree(mapping);
 }
 
 /* Atomic map/unmap */
 static inline void *
 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
 {
-	offset += (unsigned long) mapping;
-	return iomap_atomic_prot_pfn(offset >> PAGE_SHIFT, KM_USER0,
-				     __pgprot(__PAGE_KERNEL_WC));
+	resource_size_t phys_addr;
+	unsigned long pfn;
+
+	BUG_ON(offset >= mapping->size);
+	phys_addr = mapping->base + offset;
+	pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
+	return iomap_atomic_prot_pfn(pfn, KM_USER0, mapping->prot);
 }
 
 static inline void
@@ -71,8 +91,9 @@ io_mapping_unmap_atomic(void *vaddr)
 static inline void *
 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
 {
-	offset += (unsigned long) mapping;
-	return ioremap_wc(offset, PAGE_SIZE);
+	BUG_ON(offset >= mapping->size);
+	resource_size_t phys_addr = mapping->base + offset;
+	return ioremap_wc(phys_addr, PAGE_SIZE);
 }
 
 static inline void
@@ -83,9 +104,12 @@ io_mapping_unmap(void *vaddr)
 
 #else
 
+/* this struct isn't actually defined anywhere */
+struct io_mapping;
+
 /* Create the io_mapping object*/
 static inline struct io_mapping *
-io_mapping_create_wc(unsigned long base, unsigned long size)
+io_mapping_create_wc(resource_size_t base, unsigned long size)
 {
 	return (struct io_mapping *) ioremap_wc(base, size);
 }