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Message-ID: <20250724145313.65920-1-lorenzo.stoakes@oracle.com>
Date: Thu, 24 Jul 2025 15:53:12 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Christoph Hellwig <hch@...radead.org>,
David Hildenbrand <david@...hat.com>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] mm: remove io-mapping
This is dead code, which was used from commit b739f125e4eb ("i915: use
io_mapping_map_user") but reverted a month later by commit
0e4fe0c9f2f9 ("Revert "i915: use io_mapping_map_user"") back in 2021.
Since then nobody has used it, so remove it.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
include/linux/io-mapping.h | 231 -------------------------------------
mm/Kconfig | 4 -
mm/Makefile | 1 -
mm/io-mapping.c | 30 -----
4 files changed, 266 deletions(-)
delete mode 100644 include/linux/io-mapping.h
delete mode 100644 mm/io-mapping.c
diff --git a/include/linux/io-mapping.h b/include/linux/io-mapping.h
deleted file mode 100644
index 7376c1df9c90..000000000000
--- a/include/linux/io-mapping.h
+++ /dev/null
@@ -1,231 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright © 2008 Keith Packard <keithp@...thp.com>
- */
-
-#ifndef _LINUX_IO_MAPPING_H
-#define _LINUX_IO_MAPPING_H
-
-#include <linux/types.h>
-#include <linux/slab.h>
-#include <linux/bug.h>
-#include <linux/io.h>
-#include <linux/pgtable.h>
-#include <asm/page.h>
-
-/*
- * The io_mapping mechanism provides an abstraction for mapping
- * individual pages from an io device to the CPU in an efficient fashion.
- *
- * See Documentation/driver-api/io-mapping.rst
- */
-
-struct io_mapping {
- resource_size_t base;
- unsigned long size;
- pgprot_t prot;
- void __iomem *iomem;
-};
-
-#ifdef CONFIG_HAVE_ATOMIC_IOMAP
-
-#include <linux/pfn.h>
-#include <asm/iomap.h>
-/*
- * For small address space machines, mapping large objects
- * into the kernel virtual space isn't practical. Where
- * available, use fixmap support to dynamically map pages
- * of the object at run time.
- */
-
-static inline struct io_mapping *
-io_mapping_init_wc(struct io_mapping *iomap,
- resource_size_t base,
- unsigned long size)
-{
- pgprot_t prot;
-
- if (iomap_create_wc(base, size, &prot))
- return NULL;
-
- iomap->base = base;
- iomap->size = size;
- iomap->prot = prot;
- return iomap;
-}
-
-static inline void
-io_mapping_fini(struct io_mapping *mapping)
-{
- iomap_free(mapping->base, mapping->size);
-}
-
-/* Atomic map/unmap */
-static inline void __iomem *
-io_mapping_map_atomic_wc(struct io_mapping *mapping,
- unsigned long offset)
-{
- resource_size_t phys_addr;
-
- BUG_ON(offset >= mapping->size);
- phys_addr = mapping->base + offset;
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_disable();
- else
- migrate_disable();
- pagefault_disable();
- return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
-}
-
-static inline void
-io_mapping_unmap_atomic(void __iomem *vaddr)
-{
- kunmap_local_indexed((void __force *)vaddr);
- pagefault_enable();
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_enable();
- else
- migrate_enable();
-}
-
-static inline void __iomem *
-io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
-{
- resource_size_t phys_addr;
-
- BUG_ON(offset >= mapping->size);
- phys_addr = mapping->base + offset;
- return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
-}
-
-static inline void io_mapping_unmap_local(void __iomem *vaddr)
-{
- kunmap_local_indexed((void __force *)vaddr);
-}
-
-static inline void __iomem *
-io_mapping_map_wc(struct io_mapping *mapping,
- unsigned long offset,
- unsigned long size)
-{
- resource_size_t phys_addr;
-
- BUG_ON(offset >= mapping->size);
- phys_addr = mapping->base + offset;
-
- return ioremap_wc(phys_addr, size);
-}
-
-static inline void
-io_mapping_unmap(void __iomem *vaddr)
-{
- iounmap(vaddr);
-}
-
-#else /* HAVE_ATOMIC_IOMAP */
-
-#include <linux/uaccess.h>
-
-/* Create the io_mapping object*/
-static inline struct io_mapping *
-io_mapping_init_wc(struct io_mapping *iomap,
- resource_size_t base,
- unsigned long size)
-{
- iomap->iomem = ioremap_wc(base, size);
- if (!iomap->iomem)
- return NULL;
-
- iomap->base = base;
- iomap->size = size;
- iomap->prot = pgprot_writecombine(PAGE_KERNEL);
-
- return iomap;
-}
-
-static inline void
-io_mapping_fini(struct io_mapping *mapping)
-{
- iounmap(mapping->iomem);
-}
-
-/* Non-atomic map/unmap */
-static inline void __iomem *
-io_mapping_map_wc(struct io_mapping *mapping,
- unsigned long offset,
- unsigned long size)
-{
- return mapping->iomem + offset;
-}
-
-static inline void
-io_mapping_unmap(void __iomem *vaddr)
-{
-}
-
-/* Atomic map/unmap */
-static inline void __iomem *
-io_mapping_map_atomic_wc(struct io_mapping *mapping,
- unsigned long offset)
-{
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_disable();
- else
- migrate_disable();
- pagefault_disable();
- return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
-}
-
-static inline void
-io_mapping_unmap_atomic(void __iomem *vaddr)
-{
- io_mapping_unmap(vaddr);
- pagefault_enable();
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_enable();
- else
- migrate_enable();
-}
-
-static inline void __iomem *
-io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
-{
- return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
-}
-
-static inline void io_mapping_unmap_local(void __iomem *vaddr)
-{
- io_mapping_unmap(vaddr);
-}
-
-#endif /* !HAVE_ATOMIC_IOMAP */
-
-static inline struct io_mapping *
-io_mapping_create_wc(resource_size_t base,
- unsigned long size)
-{
- struct io_mapping *iomap;
-
- iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
- if (!iomap)
- return NULL;
-
- if (!io_mapping_init_wc(iomap, base, size)) {
- kfree(iomap);
- return NULL;
- }
-
- return iomap;
-}
-
-static inline void
-io_mapping_free(struct io_mapping *iomap)
-{
- io_mapping_fini(iomap);
- kfree(iomap);
-}
-
-int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
- unsigned long addr, unsigned long pfn, unsigned long size);
-
-#endif /* _LINUX_IO_MAPPING_H */
diff --git a/mm/Kconfig b/mm/Kconfig
index 0287e8d94aea..b7a47bb593d6 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1254,10 +1254,6 @@ config KMAP_LOCAL
config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
bool
-# struct io_mapping based helper. Selected by drivers that need them
-config IO_MAPPING
- bool
-
config MEMFD_CREATE
bool "Enable memfd_create() system call" if EXPERT
diff --git a/mm/Makefile b/mm/Makefile
index 690ddcf7d9a1..e4ab5ca755d1 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -142,7 +142,6 @@ obj-$(CONFIG_MEMFD_CREATE) += memfd.o
obj-$(CONFIG_MAPPING_DIRTY_HELPERS) += mapping_dirty_helpers.o
obj-$(CONFIG_PTDUMP) += ptdump.o
obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o
-obj-$(CONFIG_IO_MAPPING) += io-mapping.o
obj-$(CONFIG_HAVE_BOOTMEM_INFO_NODE) += bootmem_info.o
obj-$(CONFIG_GENERIC_IOREMAP) += ioremap.o
obj-$(CONFIG_SHRINKER_DEBUG) += shrinker_debug.o
diff --git a/mm/io-mapping.c b/mm/io-mapping.c
deleted file mode 100644
index d3586e95c12c..000000000000
--- a/mm/io-mapping.c
+++ /dev/null
@@ -1,30 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-
-#include <linux/mm.h>
-#include <linux/io-mapping.h>
-
-/**
- * io_mapping_map_user - remap an I/O mapping to userspace
- * @iomap: the source io_mapping
- * @vma: user vma to map to
- * @addr: target user address to start at
- * @pfn: physical address of kernel memory
- * @size: size of map area
- *
- * Note: this is only safe if the mm semaphore is held when called.
- */
-int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
- unsigned long addr, unsigned long pfn, unsigned long size)
-{
- vm_flags_t expected_flags = VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
-
- if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
- return -EINVAL;
-
- pgprot_t remap_prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
- (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
-
- /* We rely on prevalidation of the io-mapping to skip pfnmap tracking. */
- return remap_pfn_range_notrack(vma, addr, pfn, size, remap_prot);
-}
-EXPORT_SYMBOL_GPL(io_mapping_map_user);
--
2.50.1
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