diff options
Diffstat (limited to 'kernel/memremap.c')
| -rw-r--r-- | kernel/memremap.c | 406 |
1 files changed, 406 insertions, 0 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c new file mode 100644 index 000000000..331baad8e --- /dev/null +++ b/kernel/memremap.c @@ -0,0 +1,406 @@ +/* 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> +#include <linux/pfn_t.h> +#include <linux/io.h> +#include <linux/kasan.h> +#include <linux/mm.h> +#include <linux/memory_hotplug.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/wait_bit.h> + +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) + +static unsigned long order_at(struct resource *res, unsigned long pgoff) +{ + unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff; + unsigned long nr_pages, mask; + + nr_pages = PHYS_PFN(resource_size(res)); + if (nr_pages == pgoff) + return ULONG_MAX; + + /* + * What is the largest aligned power-of-2 range available from + * this resource pgoff to the end of the resource range, + * considering the alignment of the current pgoff? + */ + mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff); + if (!mask) + return ULONG_MAX; + + return find_first_bit(&mask, BITS_PER_LONG); +} + +#define foreach_order_pgoff(res, order, pgoff) \ + for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \ + pgoff += 1UL << order, order = order_at((res), pgoff)) + +#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) +vm_fault_t device_private_entry_fault(struct vm_area_struct *vma, + unsigned long addr, + swp_entry_t entry, + unsigned int flags, + pmd_t *pmdp) +{ + struct page *page = device_private_entry_to_page(entry); + + /* + * The page_fault() callback must migrate page back to system memory + * so that CPU can access it. This might fail for various reasons + * (device issue, device was unsafely unplugged, ...). When such + * error conditions happen, the callback must return VM_FAULT_SIGBUS. + * + * Note that because memory cgroup charges are accounted to the device + * memory, this should never fail because of memory restrictions (but + * allocation of regular system page might still fail because we are + * out of memory). + * + * There is a more in-depth description of what that callback can and + * cannot do, in include/linux/memremap.h + */ + return page->pgmap->page_fault(vma, addr, page, flags, pmdp); +} +EXPORT_SYMBOL(device_private_entry_fault); +#endif /* CONFIG_DEVICE_PRIVATE */ + +static void pgmap_radix_release(struct resource *res, unsigned long end_pgoff) +{ + unsigned long pgoff, order; + + mutex_lock(&pgmap_lock); + foreach_order_pgoff(res, order, pgoff) { + if (pgoff >= end_pgoff) + break; + radix_tree_delete(&pgmap_radix, PHYS_PFN(res->start) + pgoff); + } + mutex_unlock(&pgmap_lock); + + synchronize_rcu(); +} + +static unsigned long pfn_first(struct dev_pagemap *pgmap) +{ + const struct resource *res = &pgmap->res; + struct vmem_altmap *altmap = &pgmap->altmap; + unsigned long pfn; + + pfn = res->start >> PAGE_SHIFT; + if (pgmap->altmap_valid) + pfn += vmem_altmap_offset(altmap); + return pfn; +} + +static unsigned long pfn_end(struct dev_pagemap *pgmap) +{ + const struct resource *res = &pgmap->res; + + return (res->start + resource_size(res)) >> PAGE_SHIFT; +} + +static unsigned long pfn_next(unsigned long pfn) +{ + if (pfn % 1024 == 0) + cond_resched(); + return pfn + 1; +} + +#define for_each_device_pfn(pfn, map) \ + for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn)) + +static void devm_memremap_pages_release(void *data) +{ + struct dev_pagemap *pgmap = data; + struct device *dev = pgmap->dev; + struct resource *res = &pgmap->res; + resource_size_t align_start, align_size; + struct page *first_page; + unsigned long pfn; + int nid; + + pgmap->kill(pgmap->ref); + for_each_device_pfn(pfn, pgmap) + put_page(pfn_to_page(pfn)); + + /* pages are dead and unused, undo the arch mapping */ + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) + - align_start; + + /* make sure to access a memmap that was actually initialized */ + first_page = pfn_to_page(pfn_first(pgmap)); + + nid = page_to_nid(first_page); + + mem_hotplug_begin(); + if (pgmap->type == MEMORY_DEVICE_PRIVATE) { + pfn = align_start >> PAGE_SHIFT; + __remove_pages(pfn, align_size >> PAGE_SHIFT, NULL); + } else { + arch_remove_memory(nid, align_start, align_size, + pgmap->altmap_valid ? &pgmap->altmap : NULL); + kasan_remove_zero_shadow(__va(align_start), align_size); + } + mem_hotplug_done(); + + untrack_pfn(NULL, PHYS_PFN(align_start), align_size); + pgmap_radix_release(res, -1); + dev_WARN_ONCE(dev, pgmap->altmap.alloc, + "%s: failed to free all reserved pages\n", __func__); +} + +/** + * devm_memremap_pages - remap and provide memmap backing for the given resource + * @dev: hosting device for @res + * @pgmap: pointer to a struct dev_pagemap + * + * Notes: + * 1/ At a minimum the res, ref and type members of @pgmap must be initialized + * by the caller before passing it to this function + * + * 2/ The altmap field may optionally be initialized, in which case altmap_valid + * must be set to true + * + * 3/ pgmap->ref must be 'live' on entry and will be killed at + * devm_memremap_pages_release() time, or if this routine fails. + * + * 4/ 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 dev_pagemap *pgmap) +{ + resource_size_t align_start, align_size, align_end; + struct vmem_altmap *altmap = pgmap->altmap_valid ? + &pgmap->altmap : NULL; + struct resource *res = &pgmap->res; + unsigned long pfn, pgoff, order; + pgprot_t pgprot = PAGE_KERNEL; + int error, nid, is_ram; + struct dev_pagemap *conflict_pgmap; + + if (!pgmap->ref || !pgmap->kill) + return ERR_PTR(-EINVAL); + + align_start = res->start & ~(SECTION_SIZE - 1); + align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) + - align_start; + align_end = align_start + align_size - 1; + + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); + if (conflict_pgmap) { + dev_WARN(dev, "Conflicting mapping in same section\n"); + put_dev_pagemap(conflict_pgmap); + return ERR_PTR(-ENOMEM); + } + + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); + if (conflict_pgmap) { + dev_WARN(dev, "Conflicting mapping in same section\n"); + put_dev_pagemap(conflict_pgmap); + return ERR_PTR(-ENOMEM); + } + + is_ram = region_intersects(align_start, align_size, + IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); + + if (is_ram != REGION_DISJOINT) { + WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__, + is_ram == REGION_MIXED ? "mixed" : "ram", res); + error = -ENXIO; + goto err_array; + } + + pgmap->dev = dev; + + mutex_lock(&pgmap_lock); + error = 0; + + foreach_order_pgoff(res, order, pgoff) { + error = __radix_tree_insert(&pgmap_radix, + PHYS_PFN(res->start) + pgoff, order, pgmap); + 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(); + + /* + * For device private memory we call add_pages() as we only need to + * allocate and initialize struct page for the device memory. More- + * over the device memory is un-accessible thus we do not want to + * create a linear mapping for the memory like arch_add_memory() + * would do. + * + * For all other device memory types, which are accessible by + * the CPU, we do want the linear mapping and thus use + * arch_add_memory(). + */ + if (pgmap->type == MEMORY_DEVICE_PRIVATE) { + error = add_pages(nid, align_start >> PAGE_SHIFT, + align_size >> PAGE_SHIFT, NULL, false); + } else { + error = kasan_add_zero_shadow(__va(align_start), align_size); + if (error) { + mem_hotplug_done(); + goto err_kasan; + } + + error = arch_add_memory(nid, align_start, align_size, altmap, + false); + } + + if (!error) { + struct zone *zone; + + zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE]; + move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT, + align_size >> PAGE_SHIFT, altmap); + } + + mem_hotplug_done(); + if (error) + goto err_add_memory; + + for_each_device_pfn(pfn, pgmap) { + 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(pgmap->ref); + } + + error = devm_add_action_or_reset(dev, devm_memremap_pages_release, + pgmap); + if (error) + return ERR_PTR(error); + + return __va(res->start); + + err_add_memory: + kasan_remove_zero_shadow(__va(align_start), align_size); + err_kasan: + untrack_pfn(NULL, PHYS_PFN(align_start), align_size); + err_pfn_remap: + err_radix: + pgmap_radix_release(res, pgoff); + err_array: + pgmap->kill(pgmap->ref); + return ERR_PTR(error); +} +EXPORT_SYMBOL_GPL(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; +} + +void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) +{ + altmap->alloc -= nr_pfns; +} + +/** + * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn + * @pfn: page frame number to lookup page_map + * @pgmap: optional known pgmap that already has a reference + * + * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap + * is non-NULL but does not cover @pfn the reference to it will be released. + */ +struct dev_pagemap *get_dev_pagemap(unsigned long pfn, + struct dev_pagemap *pgmap) +{ + resource_size_t phys = PFN_PHYS(pfn); + + /* + * In the cached case we're already holding a live reference. + */ + if (pgmap) { + if (phys >= pgmap->res.start && phys <= pgmap->res.end) + return pgmap; + put_dev_pagemap(pgmap); + } + + /* fall back to slow path lookup */ + rcu_read_lock(); + pgmap = radix_tree_lookup(&pgmap_radix, PHYS_PFN(phys)); + if (pgmap && !percpu_ref_tryget_live(pgmap->ref)) + pgmap = NULL; + rcu_read_unlock(); + + return pgmap; +} +EXPORT_SYMBOL_GPL(get_dev_pagemap); + +#ifdef CONFIG_DEV_PAGEMAP_OPS +DEFINE_STATIC_KEY_FALSE(devmap_managed_key); +EXPORT_SYMBOL(devmap_managed_key); +static atomic_t devmap_enable; + +/* + * Toggle the static key for ->page_free() callbacks when dev_pagemap + * pages go idle. + */ +void dev_pagemap_get_ops(void) +{ + if (atomic_inc_return(&devmap_enable) == 1) + static_branch_enable(&devmap_managed_key); +} +EXPORT_SYMBOL_GPL(dev_pagemap_get_ops); + +void dev_pagemap_put_ops(void) +{ + if (atomic_dec_and_test(&devmap_enable)) + static_branch_disable(&devmap_managed_key); +} +EXPORT_SYMBOL_GPL(dev_pagemap_put_ops); + +void __put_devmap_managed_page(struct page *page) +{ + int count = page_ref_dec_return(page); + + /* + * If refcount is 1 then page is freed and refcount is stable as nobody + * holds a reference on the page. + */ + if (count == 1) { + /* Clear Active bit in case of parallel mark_page_accessed */ + __ClearPageActive(page); + __ClearPageWaiters(page); + + mem_cgroup_uncharge(page); + + page->pgmap->page_free(page, page->pgmap->data); + } else if (!count) + __put_page(page); +} +EXPORT_SYMBOL(__put_devmap_managed_page); +#endif /* CONFIG_DEV_PAGEMAP_OPS */ |