cregit-Linux how code gets into the kernel

Release 4.13 kernel/memremap.c

Directory: kernel
/*
 * 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/radix-tree.h>
#include <linux/memremap.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/pfn_t.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/memory_hotplug.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); }

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#endif #ifndef arch_memremap_wb
static void *arch_memremap_wb(resource_size_t offset, unsigned long size) { return (__force void *)ioremap_cache(offset, size); }

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#endif
static void *try_ram_remap(resource_size_t offset, size_t size) { 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))) return __va(offset); return NULL; /* fallback to arch_memremap_wb */ }

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Dan J Williams3571.43%133.33%
Ard Biesheuvel1428.57%266.67%
Total49100.00%3100.00%

/** * memremap() - remap an iomem_resource as cacheable memory * @offset: iomem resource start address * @size: size of remap * @flags: any of MEMREMAP_WB, MEMREMAP_WT and MEMREMAP_WC * * 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); 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; }

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Dan J Williams15280.85%233.33%
Brian Starkey3116.49%233.33%
Toshi Kani42.13%116.67%
Ard Biesheuvel10.53%116.67%
Total188100.00%6100.00%

EXPORT_SYMBOL(memremap);
void memunmap(void *addr) { if (is_vmalloc_addr(addr)) iounmap((void __iomem *) addr); }

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Dan J Williams26100.00%1100.00%
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EXPORT_SYMBOL(memunmap);
static void devm_memremap_release(struct device *dev, void *res) { memunmap(*(void **)res); }

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Christoph Hellwig2076.92%150.00%
Toshi Kani623.08%150.00%
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static int devm_memremap_match(struct device *dev, void *res, void *match_data) { return *(void **)res == match_data; }

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Christoph Hellwig30100.00%1100.00%
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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; }

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Christoph Hellwig8881.48%125.00%
Dan J Williams1110.19%250.00%
Toshi Kani98.33%125.00%
Total108100.00%4100.00%

EXPORT_SYMBOL(devm_memremap);
void devm_memunmap(struct device *dev, void *addr) { WARN_ON(devres_release(dev, devm_memremap_release, devm_memremap_match, addr)); }

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Christoph Hellwig2796.43%150.00%
Dan J Williams13.57%150.00%
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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) #define SECTION_SIZE (1UL << PA_SECTION_SHIFT) struct page_map { struct resource res; struct percpu_ref *ref; struct dev_pagemap pgmap; struct vmem_altmap altmap; };
static void pgmap_radix_release(struct resource *res) { resource_size_t key, align_start, align_size, align_end; align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(resource_size(res), SECTION_SIZE); align_end = align_start + align_size - 1; mutex_lock(&pgmap_lock); for (key = res->start; key <= res->end; key += SECTION_SIZE) radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT); mutex_unlock(&pgmap_lock); }

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Dan J Williams93100.00%2100.00%
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static unsigned long pfn_first(struct page_map *page_map) { struct dev_pagemap *pgmap = &page_map->pgmap; const struct resource *res = &page_map->res; struct vmem_altmap *altmap = pgmap->altmap; unsigned long pfn; pfn = res->start >> PAGE_SHIFT; if (altmap) pfn += vmem_altmap_offset(altmap); return pfn; }

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static unsigned long pfn_end(struct page_map *page_map) { const struct resource *res = &page_map->res; return (res->start + resource_size(res)) >> PAGE_SHIFT; }

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Dan J Williams37100.00%1100.00%
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#define for_each_device_pfn(pfn, map) \ for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
static void devm_memremap_pages_release(struct device *dev, void *data) { struct page_map *page_map = data; struct resource *res = &page_map->res; resource_size_t align_start, align_size; struct dev_pagemap *pgmap = &page_map->pgmap; unsigned long pfn; for_each_device_pfn(pfn, page_map) put_page(pfn_to_page(pfn)); if (percpu_ref_tryget_live(pgmap->ref)) { dev_WARN(dev, "%s: page mapping is still live!\n", __func__); percpu_ref_put(pgmap->ref); } /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(resource_size(res), SECTION_SIZE); mem_hotplug_begin(); arch_remove_memory(align_start, align_size); mem_hotplug_done(); untrack_pfn(NULL, PHYS_PFN(align_start), align_size); pgmap_radix_release(res); dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc, "%s: failed to free all reserved pages\n", __func__); }

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Dan J Williams13782.04%787.50%
Christoph Hellwig3017.96%112.50%
Total167100.00%8100.00%

/* assumes rcu_read_lock() held at entry */
struct dev_pagemap *find_dev_pagemap(resource_size_t phys) { struct page_map *page_map; WARN_ON_ONCE(!rcu_read_lock_held()); page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT); return page_map ? &page_map->pgmap : NULL; }

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Dan J Williams44100.00%1100.00%
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/** * devm_memremap_pages - remap and provide memmap backing for the given resource * @dev: hosting device for @res * @res: "host memory" address range * @ref: a live per-cpu reference count * @altmap: optional descriptor for allocating the memmap from @res * * Notes: * 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time * (or devm release event). The expected order of events is that @ref has * been through percpu_ref_kill() before devm_memremap_pages_release(). The * wait for the completion of all references being dropped and * percpu_ref_exit() must occur after devm_memremap_pages_release(). * * 2/ @res is expected to be a host memory range that could feasibly be * treated as a "System RAM" range, i.e. not a device mmio range, but * this is not enforced. */
void *devm_memremap_pages(struct device *dev, struct resource *res, struct percpu_ref *ref, struct vmem_altmap *altmap) { resource_size_t key, align_start, align_size, align_end; pgprot_t pgprot = PAGE_KERNEL; struct dev_pagemap *pgmap; struct page_map *page_map; int error, nid, is_ram; unsigned long pfn; align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; is_ram = region_intersects(align_start, align_size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); if (is_ram == REGION_MIXED) { WARN_ONCE(1, "%s attempted on mixed region %pr\n", __func__, res); return ERR_PTR(-ENXIO); } if (is_ram == REGION_INTERSECTS) return __va(res->start); if (!ref) return ERR_PTR(-EINVAL); page_map = devres_alloc_node(devm_memremap_pages_release, sizeof(*page_map), GFP_KERNEL, dev_to_node(dev)); if (!page_map) return ERR_PTR(-ENOMEM); pgmap = &page_map->pgmap; memcpy(&page_map->res, res, sizeof(*res)); pgmap->dev = dev; if (altmap) { memcpy(&page_map->altmap, altmap, sizeof(*altmap)); pgmap->altmap = &page_map->altmap; } pgmap->ref = ref; pgmap->res = &page_map->res; mutex_lock(&pgmap_lock); error = 0; align_end = align_start + align_size - 1; for (key = align_start; key <= align_end; key += SECTION_SIZE) { struct dev_pagemap *dup; rcu_read_lock(); dup = find_dev_pagemap(key); rcu_read_unlock(); if (dup) { dev_err(dev, "%s: %pr collides with mapping for %s\n", __func__, res, dev_name(dup->dev)); error = -EBUSY; break; } error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT, page_map); if (error) { dev_err(dev, "%s: failed: %d\n", __func__, error); break; } } mutex_unlock(&pgmap_lock); if (error) goto err_radix; nid = dev_to_node(dev); if (nid < 0) nid = numa_mem_id(); error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0, align_size); if (error) goto err_pfn_remap; mem_hotplug_begin(); error = arch_add_memory(nid, align_start, align_size, false); if (!error) move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], align_start >> PAGE_SHIFT, align_size >> PAGE_SHIFT); mem_hotplug_done(); if (error) goto err_add_memory; for_each_device_pfn(pfn, page_map) { struct page *page = pfn_to_page(pfn); /* * ZONE_DEVICE pages union ->lru with a ->pgmap back * pointer. It is a bug if a ZONE_DEVICE page is ever * freed or placed on a driver-private list. Seed the * storage with LIST_POISON* values. */ list_del(&page->lru); page->pgmap = pgmap; percpu_ref_get(ref); } devres_add(dev, page_map); return __va(res->start); err_add_memory: untrack_pfn(NULL, PHYS_PFN(align_start), align_size); err_pfn_remap: err_radix: pgmap_radix_release(res); devres_free(page_map); return ERR_PTR(error); }

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Dan J Williams39869.22%1173.33%
Christoph Hellwig14625.39%16.67%
Michal Hocko284.87%213.33%
Linus Torvalds30.52%16.67%
Total575100.00%15100.00%

EXPORT_SYMBOL(devm_memremap_pages);
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) { /* number of pfns from base where pfn_to_page() is valid */ return altmap->reserve + altmap->free; }

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void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) { altmap->alloc -= nr_pfns; }

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struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start) { /* * 'memmap_start' is the virtual address for the first "struct * page" in this range of the vmemmap array. In the case of * CONFIG_SPARSEMEM_VMEMMAP a page_to_pfn conversion is simple * pointer arithmetic, so we can perform this to_vmem_altmap() * conversion without concern for the initialization state of * the struct page fields. */ struct page *page = (struct page *) memmap_start; struct dev_pagemap *pgmap; /* * Unconditionally retrieve a dev_pagemap associated with the * given physical address, this is only for use in the * arch_{add|remove}_memory() for setting up and tearing down * the memmap. */ rcu_read_lock(); pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page))); rcu_read_unlock(); return pgmap ? pgmap->altmap : NULL; }

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Andreas Ziegler23.45%150.00%
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#endif /* CONFIG_ZONE_DEVICE */

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Dan J Williams120670.44%1655.17%
Christoph Hellwig37521.90%26.90%
Ard Biesheuvel472.75%26.90%
Brian Starkey321.87%26.90%
Michal Hocko281.64%26.90%
Toshi Kani191.11%310.34%
Linus Torvalds30.18%13.45%
Andreas Ziegler20.12%13.45%
Total1712100.00%29100.00%
Directory: kernel
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