diff mbox

[v2,3/4] arch: introduce memremap()

Message ID 20150530185935.32590.95416.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive)
State Superseded
Headers show

Commit Message

Dan Williams May 30, 2015, 6:59 p.m. UTC 
Many existing users of ioremap_cache() and some select ioremap_nocache()
users 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
ioremep().

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/arm64/kernel/efi.c              |    4 ++--
 arch/arm64/kernel/smp_spin_table.c   |   10 +++++----
 arch/x86/kernel/crash_dump_64.c      |    6 +++---
 arch/x86/kernel/kdebugfs.c           |    8 ++++----
 arch/x86/kernel/ksysfs.c             |   28 +++++++++++++-------------
 arch/x86/mm/ioremap.c                |   10 ++++-----
 drivers/acpi/apei/einj.c             |    8 ++++----
 drivers/acpi/apei/erst.c             |   14 +++++++------
 drivers/block/pmem.c                 |    6 +++---
 drivers/firmware/google/memconsole.c |    4 ++--
 include/linux/device.h               |    5 +++++
 include/linux/io.h                   |   36 ++++++++++++++++++++++++++++++++++
 12 files changed, 89 insertions(+), 50 deletions(-)

Comments

Arnd Bergmann May 30, 2015, 9 p.m. UTC | #1 
On Saturday 30 May 2015, Dan Williams wrote:
> 
> +/*
> + * 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.
> + */
> +
> +static inline void *memremap(resource_size_t offset, size_t size)
> +{
> +       return (void __force *) ioremap(offset, size);
> +}
> +
> +static inline void *memremap_nocache(resource_size_t offset, size_t size)
> +{
> +       return (void __force *) ioremap_nocache(offset, size);
> +}
> +
> +static inline void *memremap_cache(resource_size_t offset, size_t size)
> +{
> +       return (void __force *) ioremap_cache(offset, size);
> +}
> +

There are architectures on which the result of ioremap is not necessarily
a pointer, but instead indicates that the access is to be done through
some other indirect access, or require special instructions. I think implementing
the memremap() interfaces is generally helpful, but don't rely on the
ioremap implementation.

Adding both cached an uncached versions is also dangerous, because you
typically get either undefined behavior or a system checkstop when a
single page is mapped both cached and uncached at the same time. This
means that doing memremap() or memremap_nocache() on something that
may be part of the linear kernel mapping is a bug, and we should probably
check for that here.

We can probably avoid having both memremap() and memremap_nocache(),
as all architectures define ioremap() and ioremap_nocache() to be the
same thing.
	
	Arnd
Dan Williams May 30, 2015, 9:39 p.m. UTC | #2 
On Sat, May 30, 2015 at 2:00 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Saturday 30 May 2015, Dan Williams wrote:
>>
>> +/*
>> + * 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.
>> + */
>> +
>> +static inline void *memremap(resource_size_t offset, size_t size)
>> +{
>> +       return (void __force *) ioremap(offset, size);
>> +}
>> +
>> +static inline void *memremap_nocache(resource_size_t offset, size_t size)
>> +{
>> +       return (void __force *) ioremap_nocache(offset, size);
>> +}
>> +
>> +static inline void *memremap_cache(resource_size_t offset, size_t size)
>> +{
>> +       return (void __force *) ioremap_cache(offset, size);
>> +}
>> +
>
> There are architectures on which the result of ioremap is not necessarily
> a pointer, but instead indicates that the access is to be done through
> some other indirect access, or require special instructions. I think implementing
> the memremap() interfaces is generally helpful, but don't rely on the
> ioremap implementation.

Is it enough to detect the archs where ioremap() does return an
otherwise usable pointer and set ARCH_HAS_MEMREMAP, in the first take
of this introduction?  Regardless, it seems that drivers should have
Kconfig dependency checks for archs where ioremap can not be used in
this manner.

> Adding both cached an uncached versions is also dangerous, because you
> typically get either undefined behavior or a system checkstop when a
> single page is mapped both cached and uncached at the same time. This
> means that doing memremap() or memremap_nocache() on something that
> may be part of the linear kernel mapping is a bug, and we should probably
> check for that here.

Part of the reason for relying on ioremap() was to borrow its internal
checks to fail attempts that try to remap ranges that are already in
the kernel linear map.  Hmm, that's a guarantee x86 ioremap gives, but
maybe that's not universal?

> We can probably avoid having both memremap() and memremap_nocache(),
> as all architectures define ioremap() and ioremap_nocache() to be the
> same thing.
>

Ok
Arnd Bergmann June 1, 2015, 2:29 p.m. UTC | #3 
On Saturday 30 May 2015 14:39:48 Dan Williams wrote:
> On Sat, May 30, 2015 at 2:00 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Saturday 30 May 2015, Dan Williams wrote:
> >>
> >> +/*
> >> + * 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.
> >> + */
> >> +
> >> +static inline void *memremap(resource_size_t offset, size_t size)
> >> +{
> >> +       return (void __force *) ioremap(offset, size);
> >> +}
> >> +
> >> +static inline void *memremap_nocache(resource_size_t offset, size_t size)
> >> +{
> >> +       return (void __force *) ioremap_nocache(offset, size);
> >> +}
> >> +
> >> +static inline void *memremap_cache(resource_size_t offset, size_t size)
> >> +{
> >> +       return (void __force *) ioremap_cache(offset, size);
> >> +}
> >> +
> >
> > There are architectures on which the result of ioremap is not necessarily
> > a pointer, but instead indicates that the access is to be done through
> > some other indirect access, or require special instructions. I think implementing
> > the memremap() interfaces is generally helpful, but don't rely on the
> > ioremap implementation.
> 
> Is it enough to detect the archs where ioremap() does return an
> otherwise usable pointer and set ARCH_HAS_MEMREMAP, in the first take
> of this introduction?  Regardless, it seems that drivers should have
> Kconfig dependency checks for archs where ioremap can not be used in
> this manner.

Yes, that should work.

> > Adding both cached an uncached versions is also dangerous, because you
> > typically get either undefined behavior or a system checkstop when a
> > single page is mapped both cached and uncached at the same time. This
> > means that doing memremap() or memremap_nocache() on something that
> > may be part of the linear kernel mapping is a bug, and we should probably
> > check for that here.
> 
> Part of the reason for relying on ioremap() was to borrow its internal
> checks to fail attempts that try to remap ranges that are already in
> the kernel linear map.  Hmm, that's a guarantee x86 ioremap gives, but
> maybe that's not universal?

I haven't seen that check elsewhere. IIRC what ioremap() guarantees on ARM
is that if there is an existing boot-time mapping (similar to x86 fixmap,
but more commonly used), we use the same flags in the new ioremap and
override the ones that are provided by the caller.

	Arnd
diff mbox

Patch

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index ab21e0d58278..b672ef33f08b 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -289,7 +289,7 @@  static int __init arm64_enable_runtime_services(void)
 	pr_info("Remapping and enabling EFI services.\n");
 
 	mapsize = memmap.map_end - memmap.map;
-	memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
+	memmap.map = memremap_cache((phys_addr_t)memmap.phys_map,
 						   mapsize);
 	if (!memmap.map) {
 		pr_err("Failed to remap EFI memory map\n");
@@ -298,7 +298,7 @@  static int __init arm64_enable_runtime_services(void)
 	memmap.map_end = memmap.map + mapsize;
 	efi.memmap = &memmap;
 
-	efi.systab = (__force void *)ioremap_cache(efi_system_table,
+	efi.systab = memremap_cache(efi_system_table,
 						   sizeof(efi_system_table_t));
 	if (!efi.systab) {
 		pr_err("Failed to remap EFI System Table\n");
diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c
index 14944e5b28da..893c8586e20f 100644
--- a/arch/arm64/kernel/smp_spin_table.c
+++ b/arch/arm64/kernel/smp_spin_table.c
@@ -67,18 +67,18 @@  static int smp_spin_table_cpu_init(struct device_node *dn, unsigned int cpu)
 
 static int smp_spin_table_cpu_prepare(unsigned int cpu)
 {
-	__le64 __iomem *release_addr;
+	__le64 *release_addr;
 
 	if (!cpu_release_addr[cpu])
 		return -ENODEV;
 
 	/*
 	 * The cpu-release-addr may or may not be inside the linear mapping.
-	 * As ioremap_cache will either give us a new mapping or reuse the
+	 * As memremap_cache will either give us a new mapping or reuse the
 	 * existing linear mapping, we can use it to cover both cases. In
 	 * either case the memory will be MT_NORMAL.
 	 */
-	release_addr = ioremap_cache(cpu_release_addr[cpu],
+	release_addr = memremap_cache(cpu_release_addr[cpu],
 				     sizeof(*release_addr));
 	if (!release_addr)
 		return -ENOMEM;
@@ -91,7 +91,7 @@  static int smp_spin_table_cpu_prepare(unsigned int cpu)
 	 * the boot protocol.
 	 */
 	writeq_relaxed(__pa(secondary_holding_pen), release_addr);
-	__flush_dcache_area((__force void *)release_addr,
+	__flush_dcache_area(release_addr,
 			    sizeof(*release_addr));
 
 	/*
@@ -99,7 +99,7 @@  static int smp_spin_table_cpu_prepare(unsigned int cpu)
 	 */
 	sev();
 
-	iounmap(release_addr);
+	memunmap(release_addr);
 
 	return 0;
 }
diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index afa64adb75ee..8e04011665fd 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -31,19 +31,19 @@  ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 	if (!csize)
 		return 0;
 
-	vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
+	vaddr = memremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
 	if (!vaddr)
 		return -ENOMEM;
 
 	if (userbuf) {
 		if (copy_to_user(buf, vaddr + offset, csize)) {
-			iounmap(vaddr);
+			memunmap(vaddr);
 			return -EFAULT;
 		}
 	} else
 		memcpy(buf, vaddr + offset, csize);
 
 	set_iounmap_nonlazy();
-	iounmap(vaddr);
+	memunmap(vaddr);
 	return csize;
 }
diff --git a/arch/x86/kernel/kdebugfs.c b/arch/x86/kernel/kdebugfs.c
index dc1404bf8e4b..731b10e2814f 100644
--- a/arch/x86/kernel/kdebugfs.c
+++ b/arch/x86/kernel/kdebugfs.c
@@ -49,7 +49,7 @@  static ssize_t setup_data_read(struct file *file, char __user *user_buf,
 	pa = node->paddr + sizeof(struct setup_data) + pos;
 	pg = pfn_to_page((pa + count - 1) >> PAGE_SHIFT);
 	if (PageHighMem(pg)) {
-		p = ioremap_cache(pa, count);
+		p = memremap_cache(pa, count);
 		if (!p)
 			return -ENXIO;
 	} else
@@ -58,7 +58,7 @@  static ssize_t setup_data_read(struct file *file, char __user *user_buf,
 	remain = copy_to_user(user_buf, p, count);
 
 	if (PageHighMem(pg))
-		iounmap(p);
+		memunmap(p);
 
 	if (remain)
 		return -EFAULT;
@@ -128,7 +128,7 @@  static int __init create_setup_data_nodes(struct dentry *parent)
 
 		pg = pfn_to_page((pa_data+sizeof(*data)-1) >> PAGE_SHIFT);
 		if (PageHighMem(pg)) {
-			data = ioremap_cache(pa_data, sizeof(*data));
+			data = memremap_cache(pa_data, sizeof(*data));
 			if (!data) {
 				kfree(node);
 				error = -ENXIO;
@@ -144,7 +144,7 @@  static int __init create_setup_data_nodes(struct dentry *parent)
 		pa_data = data->next;
 
 		if (PageHighMem(pg))
-			iounmap(data);
+			memunmap(data);
 		if (error)
 			goto err_dir;
 		no++;
diff --git a/arch/x86/kernel/ksysfs.c b/arch/x86/kernel/ksysfs.c
index c2bedaea11f7..2fbc62886eae 100644
--- a/arch/x86/kernel/ksysfs.c
+++ b/arch/x86/kernel/ksysfs.c
@@ -16,8 +16,8 @@ 
 #include <linux/stat.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
+#include <linux/io.h>
 
-#include <asm/io.h>
 #include <asm/setup.h>
 
 static ssize_t version_show(struct kobject *kobj,
@@ -79,12 +79,12 @@  static int get_setup_data_paddr(int nr, u64 *paddr)
 			*paddr = pa_data;
 			return 0;
 		}
-		data = ioremap_cache(pa_data, sizeof(*data));
+		data = memremap_cache(pa_data, sizeof(*data));
 		if (!data)
 			return -ENOMEM;
 
 		pa_data = data->next;
-		iounmap(data);
+		memunmap(data);
 		i++;
 	}
 	return -EINVAL;
@@ -97,17 +97,17 @@  static int __init get_setup_data_size(int nr, size_t *size)
 	u64 pa_data = boot_params.hdr.setup_data;
 
 	while (pa_data) {
-		data = ioremap_cache(pa_data, sizeof(*data));
+		data = memremap_cache(pa_data, sizeof(*data));
 		if (!data)
 			return -ENOMEM;
 		if (nr == i) {
 			*size = data->len;
-			iounmap(data);
+			memunmap(data);
 			return 0;
 		}
 
 		pa_data = data->next;
-		iounmap(data);
+		memunmap(data);
 		i++;
 	}
 	return -EINVAL;
@@ -127,12 +127,12 @@  static ssize_t type_show(struct kobject *kobj,
 	ret = get_setup_data_paddr(nr, &paddr);
 	if (ret)
 		return ret;
-	data = ioremap_cache(paddr, sizeof(*data));
+	data = memremap_cache(paddr, sizeof(*data));
 	if (!data)
 		return -ENOMEM;
 
 	ret = sprintf(buf, "0x%x\n", data->type);
-	iounmap(data);
+	memunmap(data);
 	return ret;
 }
 
@@ -154,7 +154,7 @@  static ssize_t setup_data_data_read(struct file *fp,
 	ret = get_setup_data_paddr(nr, &paddr);
 	if (ret)
 		return ret;
-	data = ioremap_cache(paddr, sizeof(*data));
+	data = memremap_cache(paddr, sizeof(*data));
 	if (!data)
 		return -ENOMEM;
 
@@ -170,15 +170,15 @@  static ssize_t setup_data_data_read(struct file *fp,
 		goto out;
 
 	ret = count;
-	p = ioremap_cache(paddr + sizeof(*data), data->len);
+	p = memremap_cache(paddr + sizeof(*data), data->len);
 	if (!p) {
 		ret = -ENOMEM;
 		goto out;
 	}
 	memcpy(buf, p + off, count);
-	iounmap(p);
+	memunmap(p);
 out:
-	iounmap(data);
+	memunmap(data);
 	return ret;
 }
 
@@ -250,13 +250,13 @@  static int __init get_setup_data_total_num(u64 pa_data, int *nr)
 	*nr = 0;
 	while (pa_data) {
 		*nr += 1;
-		data = ioremap_cache(pa_data, sizeof(*data));
+		data = memremap_cache(pa_data, sizeof(*data));
 		if (!data) {
 			ret = -ENOMEM;
 			goto out;
 		}
 		pa_data = data->next;
-		iounmap(data);
+		memunmap(data);
 	}
 
 out:
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index cc5ccc415cc0..f48c137560df 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -414,12 +414,10 @@  void *xlate_dev_mem_ptr(phys_addr_t phys)
 	if (page_is_ram(start >> PAGE_SHIFT))
 		return __va(phys);
 
-	vaddr = ioremap_cache(start, PAGE_SIZE);
-	/* Only add the offset on success and return NULL if the ioremap() failed: */
+	vaddr = memremap_cache(start, PAGE_SIZE);
 	if (vaddr)
-		vaddr += offset;
-
-	return vaddr;
+		return vaddr + offset;
+	return NULL;
 }
 
 void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
@@ -427,7 +425,7 @@  void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
 	if (page_is_ram(phys >> PAGE_SHIFT))
 		return;
 
-	iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
+	memunmap((void *) ((unsigned long)addr & PAGE_MASK));
 }
 
 static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index a095d4f858da..2ec9006cfb6c 100644
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -318,7 +318,7 @@  static int __einj_error_trigger(u64 trigger_paddr, u32 type,
 			    sizeof(*trigger_tab) - 1);
 		goto out;
 	}
-	trigger_tab = ioremap_cache(trigger_paddr, sizeof(*trigger_tab));
+	trigger_tab = memremap_cache(trigger_paddr, sizeof(*trigger_tab));
 	if (!trigger_tab) {
 		pr_err(EINJ_PFX "Failed to map trigger table!\n");
 		goto out_rel_header;
@@ -346,8 +346,8 @@  static int __einj_error_trigger(u64 trigger_paddr, u32 type,
 		       (unsigned long long)trigger_paddr + table_size - 1);
 		goto out_rel_header;
 	}
-	iounmap(trigger_tab);
-	trigger_tab = ioremap_cache(trigger_paddr, table_size);
+	memunmap(trigger_tab);
+	trigger_tab = memremap_cache(trigger_paddr, table_size);
 	if (!trigger_tab) {
 		pr_err(EINJ_PFX "Failed to map trigger table!\n");
 		goto out_rel_entry;
@@ -409,7 +409,7 @@  out_rel_header:
 	release_mem_region(trigger_paddr, sizeof(*trigger_tab));
 out:
 	if (trigger_tab)
-		iounmap(trigger_tab);
+		memunmap(trigger_tab);
 
 	return rc;
 }
diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index ed65e9c4b5b0..4f8b62404db5 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -76,7 +76,7 @@  static struct acpi_table_erst *erst_tab;
 static struct erst_erange {
 	u64 base;
 	u64 size;
-	void __iomem *vaddr;
+	void *vaddr;
 	u32 attr;
 } erst_erange;
 
@@ -279,19 +279,19 @@  static int erst_exec_move_data(struct apei_exec_context *ctx,
 	if (rc)
 		return rc;
 
-	src = ioremap(ctx->src_base + offset, ctx->var2);
+	src = memremap(ctx->src_base + offset, ctx->var2);
 	if (!src)
 		return -ENOMEM;
-	dst = ioremap(ctx->dst_base + offset, ctx->var2);
+	dst = memremap(ctx->dst_base + offset, ctx->var2);
 	if (!dst) {
-		iounmap(src);
+		memunmap(src);
 		return -ENOMEM;
 	}
 
 	memmove(dst, src, ctx->var2);
 
-	iounmap(src);
-	iounmap(dst);
+	memunmap(src);
+	memunmap(dst);
 
 	return 0;
 }
@@ -1184,7 +1184,7 @@  static int __init erst_init(void)
 		goto err_unmap_reg;
 	}
 	rc = -ENOMEM;
-	erst_erange.vaddr = ioremap_cache(erst_erange.base,
+	erst_erange.vaddr = memremap_cache(erst_erange.base,
 					  erst_erange.size);
 	if (!erst_erange.vaddr)
 		goto err_release_erange;
diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c
index 095dfaadcaa5..799acff6bd7c 100644
--- a/drivers/block/pmem.c
+++ b/drivers/block/pmem.c
@@ -143,7 +143,7 @@  static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
 	 * of the CPU caches in case of a crash.
 	 */
 	err = -ENOMEM;
-	pmem->virt_addr = ioremap_wt(pmem->phys_addr, pmem->size);
+	pmem->virt_addr = memremap_wt(pmem->phys_addr, pmem->size);
 	if (!pmem->virt_addr)
 		goto out_release_region;
 
@@ -179,7 +179,7 @@  static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
 out_free_queue:
 	blk_cleanup_queue(pmem->pmem_queue);
 out_unmap:
-	iounmap(pmem->virt_addr);
+	memunmap(pmem->virt_addr);
 out_release_region:
 	release_mem_region(pmem->phys_addr, pmem->size);
 out_free_dev:
@@ -193,7 +193,7 @@  static void pmem_free(struct pmem_device *pmem)
 	del_gendisk(pmem->pmem_disk);
 	put_disk(pmem->pmem_disk);
 	blk_cleanup_queue(pmem->pmem_queue);
-	iounmap(pmem->virt_addr);
+	memunmap(pmem->virt_addr);
 	release_mem_region(pmem->phys_addr, pmem->size);
 	kfree(pmem);
 }
diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c
index 2f569aaed4c7..877433dc8297 100644
--- a/drivers/firmware/google/memconsole.c
+++ b/drivers/firmware/google/memconsole.c
@@ -52,14 +52,14 @@  static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
 	char *memconsole;
 	ssize_t ret;
 
-	memconsole = ioremap_cache(memconsole_baseaddr, memconsole_length);
+	memconsole = memremap_cache(memconsole_baseaddr, memconsole_length);
 	if (!memconsole) {
 		pr_err("memconsole: ioremap_cache failed\n");
 		return -ENOMEM;
 	}
 	ret = memory_read_from_buffer(buf, count, &pos, memconsole,
 				      memconsole_length);
-	iounmap(memconsole);
+	memunmap(memconsole);
 	return ret;
 }
 
diff --git a/include/linux/device.h b/include/linux/device.h
index 6558af90c8fe..518f49c5d596 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -638,6 +638,11 @@  extern void devm_free_pages(struct device *dev, unsigned long addr);
 
 void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
 
+static inline void *devm_memremap_resource(struct device *dev, struct resource *res)
+{
+	return (void __force *) devm_ioremap_resource(dev, res);
+}
+
 /* allows to add/remove a custom action to devres stack */
 int devm_add_action(struct device *dev, void (*action)(void *), void *data);
 void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
diff --git a/include/linux/io.h b/include/linux/io.h
index 1c9ad4c6d485..86c636ce4c43 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -122,4 +122,40 @@  static inline int arch_phys_wc_index(int handle)
 #endif
 #endif
 
+/*
+ * 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.
+ */
+
+static inline void *memremap(resource_size_t offset, size_t size)
+{
+	return (void __force *) ioremap(offset, size);
+}
+
+static inline void *memremap_nocache(resource_size_t offset, size_t size)
+{
+	return (void __force *) ioremap_nocache(offset, size);
+}
+
+static inline void *memremap_cache(resource_size_t offset, size_t size)
+{
+	return (void __force *) ioremap_cache(offset, size);
+}
+
+static inline void *memremap_wc(resource_size_t offset, size_t size)
+{
+	return (void __force *) ioremap_wc(offset, size);
+}
+
+static inline void *memremap_wt(resource_size_t offset, size_t size)
+{
+	return (void __force *) ioremap_wt(offset, size);
+}
+
+static inline void memunmap(void *addr)
+{
+	return iounmap((void __iomem __force *) addr);
+}
+
 #endif /* _LINUX_IO_H */