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    Subject[PATCH v8 12/18] memremap: split devm_memremap_pages() and memremap() infrastructure
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    Currently, kernel/memremap.c contains generic code for supporting
    memremap() (CONFIG_HAS_IOMEM) and devm_memremap_pages()
    (CONFIG_ZONE_DEVICE). This causes ongoing build maintenance problems as
    additions to memremap.c, especially for the ZONE_DEVICE case, need to be
    careful about being placed in ifdef guards. Remove the need for these
    ifdef guards by moving the ZONE_DEVICE support functions to their own
    compilation unit.

    Cc: Jan Kara <jack@suse.cz>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: "Jérôme Glisse" <jglisse@redhat.com>
    Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    ---
    kernel/Makefile | 3 +
    kernel/iomem.c | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++
    kernel/memremap.c | 178 +----------------------------------------------------
    3 files changed, 171 insertions(+), 177 deletions(-)
    create mode 100644 kernel/iomem.c

    diff --git a/kernel/Makefile b/kernel/Makefile
    index f85ae5dfa474..9b9241361311 100644
    --- a/kernel/Makefile
    +++ b/kernel/Makefile
    @@ -112,7 +112,8 @@ obj-$(CONFIG_JUMP_LABEL) += jump_label.o
    obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
    obj-$(CONFIG_TORTURE_TEST) += torture.o

    -obj-$(CONFIG_HAS_IOMEM) += memremap.o
    +obj-$(CONFIG_HAS_IOMEM) += iomem.o
    +obj-$(CONFIG_ZONE_DEVICE) += memremap.o

    $(obj)/configs.o: $(obj)/config_data.h

    diff --git a/kernel/iomem.c b/kernel/iomem.c
    new file mode 100644
    index 000000000000..f7525e14ebc6
    --- /dev/null
    +++ b/kernel/iomem.c
    @@ -0,0 +1,167 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +#include <linux/device.h>
    +#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
    +
    +#ifndef arch_memremap_wb
    +static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
    +{
    + return (__force void *)ioremap_cache(offset, size);
    +}
    +#endif
    +
    +#ifndef arch_memremap_can_ram_remap
    +static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
    + unsigned long flags)
    +{
    + return true;
    +}
    +#endif
    +
    +static void *try_ram_remap(resource_size_t offset, size_t size,
    + unsigned long flags)
    +{
    + unsigned long pfn = PHYS_PFN(offset);
    +
    + /* In the simple case just return the existing linear address */
    + if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) &&
    + arch_memremap_can_ram_remap(offset, size, flags))
    + return __va(offset);
    +
    + return NULL; /* fallback to arch_memremap_wb */
    +}
    +
    +/**
    + * memremap() - remap an iomem_resource as cacheable memory
    + * @offset: iomem resource start address
    + * @size: size of remap
    + * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
    + * MEMREMAP_ENC, MEMREMAP_DEC
    + *
    + * 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. In the case of multiple flags, the different
    + * mapping types will be attempted in the order listed below until one of
    + * them succeeds.
    + *
    + * 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.
    + *
    + * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
    + * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
    + * uncached. 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,
    + IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
    + void *addr = NULL;
    +
    + if (!flags)
    + return 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) {
    + /*
    + * 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 = try_ram_remap(offset, size, flags);
    + if (!addr)
    + addr = arch_memremap_wb(offset, size);
    + }
    +
    + /*
    + * If we don't have a mapping yet and other request flags are
    + * present 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 != MEMREMAP_WB) {
    + WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
    + &offset, (unsigned long) size);
    + return NULL;
    + }
    +
    + if (!addr && (flags & MEMREMAP_WT))
    + addr = ioremap_wt(offset, size);
    +
    + if (!addr && (flags & MEMREMAP_WC))
    + addr = ioremap_wc(offset, size);
    +
    + return addr;
    +}
    +EXPORT_SYMBOL(memremap);
    +
    +void memunmap(void *addr)
    +{
    + if (is_vmalloc_addr(addr))
    + iounmap((void __iomem *) addr);
    +}
    +EXPORT_SYMBOL(memunmap);
    +
    +static void devm_memremap_release(struct device *dev, void *res)
    +{
    + memunmap(*(void **)res);
    +}
    +
    +static int devm_memremap_match(struct device *dev, void *res, void *match_data)
    +{
    + return *(void **)res == match_data;
    +}
    +
    +void *devm_memremap(struct device *dev, resource_size_t offset,
    + size_t size, unsigned long flags)
    +{
    + void **ptr, *addr;
    +
    + ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
    + dev_to_node(dev));
    + if (!ptr)
    + return ERR_PTR(-ENOMEM);
    +
    + addr = memremap(offset, size, flags);
    + if (addr) {
    + *ptr = addr;
    + devres_add(dev, ptr);
    + } else {
    + devres_free(ptr);
    + return ERR_PTR(-ENXIO);
    + }
    +
    + return addr;
    +}
    +EXPORT_SYMBOL(devm_memremap);
    +
    +void devm_memunmap(struct device *dev, void *addr)
    +{
    + WARN_ON(devres_release(dev, devm_memremap_release,
    + devm_memremap_match, addr));
    +}
    +EXPORT_SYMBOL(devm_memunmap);
    diff --git a/kernel/memremap.c b/kernel/memremap.c
    index 4dd4274cabe2..52a2742f527f 100644
    --- a/kernel/memremap.c
    +++ b/kernel/memremap.c
    @@ -1,15 +1,5 @@
    -/*
    - * 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.
    - */
    +/* SPDX-License-Identifier: GPL-2.0 */
    +/* Copyright(c) 2015 Intel Corporation. All rights reserved. */
    #include <linux/radix-tree.h>
    #include <linux/device.h>
    #include <linux/types.h>
    @@ -20,169 +10,6 @@
    #include <linux/swap.h>
    #include <linux/swapops.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
    -
    -#ifndef arch_memremap_wb
    -static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
    -{
    - return (__force void *)ioremap_cache(offset, size);
    -}
    -#endif
    -
    -#ifndef arch_memremap_can_ram_remap
    -static bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
    - unsigned long flags)
    -{
    - return true;
    -}
    -#endif
    -
    -static void *try_ram_remap(resource_size_t offset, size_t size,
    - unsigned long flags)
    -{
    - unsigned long pfn = PHYS_PFN(offset);
    -
    - /* In the simple case just return the existing linear address */
    - if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)) &&
    - arch_memremap_can_ram_remap(offset, size, flags))
    - return __va(offset);
    -
    - return NULL; /* fallback to arch_memremap_wb */
    -}
    -
    -/**
    - * memremap() - remap an iomem_resource as cacheable memory
    - * @offset: iomem resource start address
    - * @size: size of remap
    - * @flags: any of MEMREMAP_WB, MEMREMAP_WT, MEMREMAP_WC,
    - * MEMREMAP_ENC, MEMREMAP_DEC
    - *
    - * 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. In the case of multiple flags, the different
    - * mapping types will be attempted in the order listed below until one of
    - * them succeeds.
    - *
    - * 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.
    - *
    - * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
    - * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
    - * uncached. 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,
    - IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
    - void *addr = NULL;
    -
    - if (!flags)
    - return 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) {
    - /*
    - * 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 = try_ram_remap(offset, size, flags);
    - if (!addr)
    - addr = arch_memremap_wb(offset, size);
    - }
    -
    - /*
    - * If we don't have a mapping yet and other request flags are
    - * present 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 != MEMREMAP_WB) {
    - WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
    - &offset, (unsigned long) size);
    - return NULL;
    - }
    -
    - if (!addr && (flags & MEMREMAP_WT))
    - addr = ioremap_wt(offset, size);
    -
    - if (!addr && (flags & MEMREMAP_WC))
    - addr = ioremap_wc(offset, size);
    -
    - return addr;
    -}
    -EXPORT_SYMBOL(memremap);
    -
    -void memunmap(void *addr)
    -{
    - if (is_vmalloc_addr(addr))
    - iounmap((void __iomem *) addr);
    -}
    -EXPORT_SYMBOL(memunmap);
    -
    -static void devm_memremap_release(struct device *dev, void *res)
    -{
    - memunmap(*(void **)res);
    -}
    -
    -static int devm_memremap_match(struct device *dev, void *res, void *match_data)
    -{
    - return *(void **)res == match_data;
    -}
    -
    -void *devm_memremap(struct device *dev, resource_size_t offset,
    - size_t size, unsigned long flags)
    -{
    - void **ptr, *addr;
    -
    - ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
    - dev_to_node(dev));
    - if (!ptr)
    - return ERR_PTR(-ENOMEM);
    -
    - addr = memremap(offset, size, flags);
    - if (addr) {
    - *ptr = addr;
    - devres_add(dev, ptr);
    - } else {
    - devres_free(ptr);
    - return ERR_PTR(-ENXIO);
    - }
    -
    - return addr;
    -}
    -EXPORT_SYMBOL(devm_memremap);
    -
    -void devm_memunmap(struct device *dev, void *addr)
    -{
    - WARN_ON(devres_release(dev, devm_memremap_release,
    - devm_memremap_match, addr));
    -}
    -EXPORT_SYMBOL(devm_memunmap);
    -
    -#ifdef CONFIG_ZONE_DEVICE
    static DEFINE_MUTEX(pgmap_lock);
    static RADIX_TREE(pgmap_radix, GFP_KERNEL);
    #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
    @@ -474,7 +301,6 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,

    return pgmap;
    }
    -#endif /* CONFIG_ZONE_DEVICE */

    #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC)
    void put_zone_device_private_or_public_page(struct page *page)
    \
     
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