ARM: add generic ioremap optimization by reusing static mappings
Now that we have all the static mappings from iotable_init() located
in the vmalloc area, it is trivial to optimize ioremap by reusing those
static mappings when the requested physical area fits in one of them,
and so in a generic way for all platforms.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Tested-by: Jamie Iles <jamie@jamieiles.com>
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index bc7d9bd..12c7ad2 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -36,12 +36,6 @@
#include <asm/mach/map.h>
#include "mm.h"
-/*
- * Used by ioremap() and iounmap() code to mark (super)section-mapped
- * I/O regions in vm_struct->flags field.
- */
-#define VM_ARM_SECTION_MAPPING 0x80000000
-
int ioremap_page(unsigned long virt, unsigned long phys,
const struct mem_type *mtype)
{
@@ -201,12 +195,6 @@
if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))
return NULL;
- /*
- * Don't allow RAM to be mapped - this causes problems with ARMv6+
- */
- if (WARN_ON(pfn_valid(pfn)))
- return NULL;
-
type = get_mem_type(mtype);
if (!type)
return NULL;
@@ -216,6 +204,34 @@
*/
size = PAGE_ALIGN(offset + size);
+ /*
+ * Try to reuse one of the static mapping whenever possible.
+ */
+ read_lock(&vmlist_lock);
+ for (area = vmlist; area; area = area->next) {
+ if (!size || (sizeof(phys_addr_t) == 4 && pfn >= 0x100000))
+ break;
+ if (!(area->flags & VM_ARM_STATIC_MAPPING))
+ continue;
+ if ((area->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))
+ continue;
+ if (__phys_to_pfn(area->phys_addr) > pfn ||
+ __pfn_to_phys(pfn) + size-1 > area->phys_addr + area->size-1)
+ continue;
+ /* we can drop the lock here as we know *area is static */
+ read_unlock(&vmlist_lock);
+ addr = (unsigned long)area->addr;
+ addr += __pfn_to_phys(pfn) - area->phys_addr;
+ return (void __iomem *) (offset + addr);
+ }
+ read_unlock(&vmlist_lock);
+
+ /*
+ * Don't allow RAM to be mapped - this causes problems with ARMv6+
+ */
+ if (WARN_ON(pfn_valid(pfn)))
+ return NULL;
+
area = get_vm_area_caller(size, VM_IOREMAP, caller);
if (!area)
return NULL;
@@ -313,26 +329,34 @@
void __iounmap(volatile void __iomem *io_addr)
{
void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
-#ifndef CONFIG_SMP
struct vm_struct *vm;
- /*
- * If this is a section based mapping we need to handle it
- * specially as the VM subsystem does not know how to handle
- * such a beast.
- */
read_lock(&vmlist_lock);
for (vm = vmlist; vm; vm = vm->next) {
- if ((vm->flags & VM_IOREMAP) && (vm->addr == addr)) {
- if (vm->flags & VM_ARM_SECTION_MAPPING) {
- unmap_area_sections((unsigned long)vm->addr,
- vm->size);
- }
+ if (vm->addr > addr)
+ break;
+ if (!(vm->flags & VM_IOREMAP))
+ continue;
+ /* If this is a static mapping we must leave it alone */
+ if ((vm->flags & VM_ARM_STATIC_MAPPING) &&
+ (vm->addr <= addr) && (vm->addr + vm->size > addr)) {
+ read_unlock(&vmlist_lock);
+ return;
+ }
+#ifndef CONFIG_SMP
+ /*
+ * If this is a section based mapping we need to handle it
+ * specially as the VM subsystem does not know how to handle
+ * such a beast.
+ */
+ if ((vm->addr == addr) &&
+ (vm->flags & VM_ARM_SECTION_MAPPING)) {
+ unmap_area_sections((unsigned long)vm->addr, vm->size);
break;
}
+#endif
}
read_unlock(&vmlist_lock);
-#endif
vunmap(addr);
}
diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
index ad7cce3..70f6d3ea 100644
--- a/arch/arm/mm/mm.h
+++ b/arch/arm/mm/mm.h
@@ -21,6 +21,20 @@
extern void __flush_dcache_page(struct address_space *mapping, struct page *page);
+/*
+ * ARM specific vm_struct->flags bits.
+ */
+
+/* (super)section-mapped I/O regions used by ioremap()/iounmap() */
+#define VM_ARM_SECTION_MAPPING 0x80000000
+
+/* permanent static mappings from iotable_init() */
+#define VM_ARM_STATIC_MAPPING 0x40000000
+
+/* mapping type (attributes) for permanent static mappings */
+#define VM_ARM_MTYPE(mt) ((mt) << 20)
+#define VM_ARM_MTYPE_MASK (0x1f << 20)
+
#endif
#ifdef CONFIG_ZONE_DMA
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index c614815..27e366a 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -749,7 +749,8 @@
vm->addr = (void *)(md->virtual & PAGE_MASK);
vm->size = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));
vm->phys_addr = __pfn_to_phys(md->pfn);
- vm->flags = VM_IOREMAP;
+ vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING;
+ vm->flags |= VM_ARM_MTYPE(md->type);
vm->caller = iotable_init;
vm_area_add_early(vm++);
}
