92281dee82
Existing users of ioremap_cache() are mapping memory that is known in advance to not have i/o side effects. These users are forced to cast away the __iomem annotation, or otherwise neglect to fix the sparse errors thrown when dereferencing pointers to this memory. Provide memremap() as a non __iomem annotated ioremap_*() in the case when ioremap is otherwise a pointer to cacheable memory. Empirically, ioremap_<cacheable-type>() call sites are seeking memory-like semantics (e.g. speculative reads, and prefetching permitted). memremap() is a break from the ioremap implementation pattern of adding a new memremap_<type>() for each mapping type and having silent compatibility fall backs. Instead, the implementation defines flags that are passed to the central memremap() and if a mapping type is not supported by an arch memremap returns NULL. We introduce a memremap prototype as a trivial wrapper of ioremap_cache() and ioremap_wt(). Later, once all ioremap_cache() and ioremap_wt() usage has been removed from drivers we teach archs to implement arch_memremap() with the ability to strictly enforce the mapping type. Cc: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
99 lines
3.1 KiB
C
99 lines
3.1 KiB
C
/*
|
|
* Copyright(c) 2015 Intel Corporation. All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of version 2 of the GNU General Public License as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*/
|
|
#include <linux/types.h>
|
|
#include <linux/io.h>
|
|
#include <linux/mm.h>
|
|
|
|
#ifndef ioremap_cache
|
|
/* temporary while we convert existing ioremap_cache users to memremap */
|
|
__weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
|
|
{
|
|
return ioremap(offset, size);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* memremap() - remap an iomem_resource as cacheable memory
|
|
* @offset: iomem resource start address
|
|
* @size: size of remap
|
|
* @flags: either MEMREMAP_WB or MEMREMAP_WT
|
|
*
|
|
* memremap() is "ioremap" for cases where it is known that the resource
|
|
* being mapped does not have i/o side effects and the __iomem
|
|
* annotation is not applicable.
|
|
*
|
|
* MEMREMAP_WB - matches the default mapping for "System RAM" on
|
|
* the architecture. This is usually a read-allocate write-back cache.
|
|
* Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
|
|
* memremap() will bypass establishing a new mapping and instead return
|
|
* a pointer into the direct map.
|
|
*
|
|
* MEMREMAP_WT - establish a mapping whereby writes either bypass the
|
|
* cache or are written through to memory and never exist in a
|
|
* cache-dirty state with respect to program visibility. Attempts to
|
|
* map "System RAM" with this mapping type will fail.
|
|
*/
|
|
void *memremap(resource_size_t offset, size_t size, unsigned long flags)
|
|
{
|
|
int is_ram = region_intersects(offset, size, "System RAM");
|
|
void *addr = NULL;
|
|
|
|
if (is_ram == REGION_MIXED) {
|
|
WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
|
|
&offset, (unsigned long) size);
|
|
return NULL;
|
|
}
|
|
|
|
/* Try all mapping types requested until one returns non-NULL */
|
|
if (flags & MEMREMAP_WB) {
|
|
flags &= ~MEMREMAP_WB;
|
|
/*
|
|
* MEMREMAP_WB is special in that it can be satisifed
|
|
* from the direct map. Some archs depend on the
|
|
* capability of memremap() to autodetect cases where
|
|
* the requested range is potentially in "System RAM"
|
|
*/
|
|
if (is_ram == REGION_INTERSECTS)
|
|
addr = __va(offset);
|
|
else
|
|
addr = ioremap_cache(offset, size);
|
|
}
|
|
|
|
/*
|
|
* If we don't have a mapping yet and more request flags are
|
|
* pending then we will be attempting to establish a new virtual
|
|
* address mapping. Enforce that this mapping is not aliasing
|
|
* "System RAM"
|
|
*/
|
|
if (!addr && is_ram == REGION_INTERSECTS && flags) {
|
|
WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
|
|
&offset, (unsigned long) size);
|
|
return NULL;
|
|
}
|
|
|
|
if (!addr && (flags & MEMREMAP_WT)) {
|
|
flags &= ~MEMREMAP_WT;
|
|
addr = ioremap_wt(offset, size);
|
|
}
|
|
|
|
return addr;
|
|
}
|
|
EXPORT_SYMBOL(memremap);
|
|
|
|
void memunmap(void *addr)
|
|
{
|
|
if (is_vmalloc_addr(addr))
|
|
iounmap((void __iomem *) addr);
|
|
}
|
|
EXPORT_SYMBOL(memunmap);
|