From 1e240e8d4a7d92232b6214e02a0a4197a53afd6c Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 26 Jun 2019 14:27:08 +0200 Subject: [PATCH] memremap: move dev_pagemap callbacks into a separate structure The dev_pagemap is a growing too many callbacks. Move them into a separate ops structure so that they are not duplicated for multiple instances, and an attacker can't easily overwrite them. Signed-off-by: Christoph Hellwig Reviewed-by: Logan Gunthorpe Reviewed-by: Jason Gunthorpe Reviewed-by: Dan Williams Tested-by: Dan Williams Signed-off-by: Jason Gunthorpe --- drivers/dax/device.c | 11 ++++++---- drivers/dax/pmem/core.c | 2 +- drivers/nvdimm/pmem.c | 19 +++++++++------- drivers/pci/p2pdma.c | 8 +++++-- include/linux/memremap.h | 36 +++++++++++++++++-------------- kernel/memremap.c | 18 ++++++++-------- mm/hmm.c | 10 ++++++--- tools/testing/nvdimm/test/iomap.c | 7 +++--- 8 files changed, 65 insertions(+), 46 deletions(-) diff --git a/drivers/dax/device.c b/drivers/dax/device.c index 79014baa782d..f390083a64d7 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -36,9 +36,8 @@ static void dev_dax_percpu_exit(struct percpu_ref *ref) percpu_ref_exit(ref); } -static void dev_dax_percpu_kill(struct percpu_ref *data) +static void dev_dax_percpu_kill(struct percpu_ref *ref) { - struct percpu_ref *ref = data; struct dev_dax *dev_dax = ref_to_dev_dax(ref); dev_dbg(&dev_dax->dev, "%s\n", __func__); @@ -442,6 +441,11 @@ static void dev_dax_kill(void *dev_dax) kill_dev_dax(dev_dax); } +static const struct dev_pagemap_ops dev_dax_pagemap_ops = { + .kill = dev_dax_percpu_kill, + .cleanup = dev_dax_percpu_exit, +}; + int dev_dax_probe(struct device *dev) { struct dev_dax *dev_dax = to_dev_dax(dev); @@ -466,9 +470,8 @@ int dev_dax_probe(struct device *dev) return rc; dev_dax->pgmap.ref = &dev_dax->ref; - dev_dax->pgmap.kill = dev_dax_percpu_kill; - dev_dax->pgmap.cleanup = dev_dax_percpu_exit; dev_dax->pgmap.type = MEMORY_DEVICE_DEVDAX; + dev_dax->pgmap.ops = &dev_dax_pagemap_ops; addr = devm_memremap_pages(dev, &dev_dax->pgmap); if (IS_ERR(addr)) return PTR_ERR(addr); diff --git a/drivers/dax/pmem/core.c b/drivers/dax/pmem/core.c index f9f51786d556..6eb6dfdf19bf 100644 --- a/drivers/dax/pmem/core.c +++ b/drivers/dax/pmem/core.c @@ -16,7 +16,7 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys) struct dev_dax *dev_dax; struct nd_namespace_io *nsio; struct dax_region *dax_region; - struct dev_pagemap pgmap = { 0 }; + struct dev_pagemap pgmap = { }; struct nd_namespace_common *ndns; struct nd_dax *nd_dax = to_nd_dax(dev); struct nd_pfn *nd_pfn = &nd_dax->nd_pfn; diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 24d7fe7c74ed..c2449af2b388 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -303,7 +303,7 @@ static const struct attribute_group *pmem_attribute_groups[] = { NULL, }; -static void __pmem_release_queue(struct percpu_ref *ref) +static void pmem_pagemap_cleanup(struct percpu_ref *ref) { struct request_queue *q; @@ -313,10 +313,10 @@ static void __pmem_release_queue(struct percpu_ref *ref) static void pmem_release_queue(void *ref) { - __pmem_release_queue(ref); + pmem_pagemap_cleanup(ref); } -static void pmem_freeze_queue(struct percpu_ref *ref) +static void pmem_pagemap_kill(struct percpu_ref *ref) { struct request_queue *q; @@ -339,19 +339,24 @@ static void pmem_release_pgmap_ops(void *__pgmap) dev_pagemap_put_ops(); } -static void fsdax_pagefree(struct page *page, void *data) +static void pmem_pagemap_page_free(struct page *page, void *data) { wake_up_var(&page->_refcount); } +static const struct dev_pagemap_ops fsdax_pagemap_ops = { + .page_free = pmem_pagemap_page_free, + .kill = pmem_pagemap_kill, + .cleanup = pmem_pagemap_cleanup, +}; + static int setup_pagemap_fsdax(struct device *dev, struct dev_pagemap *pgmap) { dev_pagemap_get_ops(); if (devm_add_action_or_reset(dev, pmem_release_pgmap_ops, pgmap)) return -ENOMEM; pgmap->type = MEMORY_DEVICE_FS_DAX; - pgmap->page_free = fsdax_pagefree; - + pgmap->ops = &fsdax_pagemap_ops; return 0; } @@ -409,8 +414,6 @@ static int pmem_attach_disk(struct device *dev, pmem->pfn_flags = PFN_DEV; pmem->pgmap.ref = &q->q_usage_counter; - pmem->pgmap.kill = pmem_freeze_queue; - pmem->pgmap.cleanup = __pmem_release_queue; if (is_nd_pfn(dev)) { if (setup_pagemap_fsdax(dev, &pmem->pgmap)) return -ENOMEM; diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index a4994aa3acc0..fb039259d463 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -153,6 +153,11 @@ static int pci_p2pdma_setup(struct pci_dev *pdev) return error; } +static const struct dev_pagemap_ops pci_p2pdma_pagemap_ops = { + .kill = pci_p2pdma_percpu_kill, + .cleanup = pci_p2pdma_percpu_cleanup, +}; + /** * pci_p2pdma_add_resource - add memory for use as p2p memory * @pdev: the device to add the memory to @@ -208,8 +213,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, pgmap->type = MEMORY_DEVICE_PCI_P2PDMA; pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) - pci_resource_start(pdev, bar); - pgmap->kill = pci_p2pdma_percpu_kill; - pgmap->cleanup = pci_p2pdma_percpu_cleanup; + pgmap->ops = &pci_p2pdma_pagemap_ops; addr = devm_memremap_pages(&pdev->dev, pgmap); if (IS_ERR(addr)) { diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 0c86f2c5ac9c..919755f48c7e 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -63,41 +63,45 @@ enum memory_type { MEMORY_DEVICE_PCI_P2PDMA, }; -/* - * Additional notes about MEMORY_DEVICE_PRIVATE may be found in - * include/linux/hmm.h and Documentation/vm/hmm.rst. There is also a brief - * explanation in include/linux/memory_hotplug.h. - * - * The page_free() callback is called once the page refcount reaches 1 - * (ZONE_DEVICE pages never reach 0 refcount unless there is a refcount bug. - * This allows the device driver to implement its own memory management.) - */ -typedef void (*dev_page_free_t)(struct page *page, void *data); +struct dev_pagemap_ops { + /* + * Called once the page refcount reaches 1. (ZONE_DEVICE pages never + * reach 0 refcount unless there is a refcount bug. This allows the + * device driver to implement its own memory management.) + */ + void (*page_free)(struct page *page, void *data); + + /* + * Transition the refcount in struct dev_pagemap to the dead state. + */ + void (*kill)(struct percpu_ref *ref); + + /* + * Wait for refcount in struct dev_pagemap to be idle and reap it. + */ + void (*cleanup)(struct percpu_ref *ref); +}; /** * struct dev_pagemap - metadata for ZONE_DEVICE mappings - * @page_free: free page callback when page refcount reaches 1 * @altmap: pre-allocated/reserved memory for vmemmap allocations * @res: physical address range covered by @ref * @ref: reference count that pins the devm_memremap_pages() mapping - * @kill: callback to transition @ref to the dead state - * @cleanup: callback to wait for @ref to be idle and reap it * @dev: host device of the mapping for debug * @data: private data pointer for page_free() * @type: memory type: see MEMORY_* in memory_hotplug.h + * @ops: method table */ struct dev_pagemap { - dev_page_free_t page_free; struct vmem_altmap altmap; bool altmap_valid; struct resource res; struct percpu_ref *ref; - void (*kill)(struct percpu_ref *ref); - void (*cleanup)(struct percpu_ref *ref); struct device *dev; void *data; enum memory_type type; u64 pci_p2pdma_bus_offset; + const struct dev_pagemap_ops *ops; }; #ifdef CONFIG_ZONE_DEVICE diff --git a/kernel/memremap.c b/kernel/memremap.c index abda62d1e5a3..0824237ef979 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -92,10 +92,10 @@ static void devm_memremap_pages_release(void *data) unsigned long pfn; int nid; - pgmap->kill(pgmap->ref); + pgmap->ops->kill(pgmap->ref); for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); - pgmap->cleanup(pgmap->ref); + pgmap->ops->cleanup(pgmap->ref); /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); @@ -128,8 +128,8 @@ static void devm_memremap_pages_release(void *data) * @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 + * 1/ At a minimum the res, ref and type and ops 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 @@ -179,7 +179,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) break; } - if (!pgmap->ref || !pgmap->kill || !pgmap->cleanup) { + if (!pgmap->ref || !pgmap->ops || !pgmap->ops->kill || + !pgmap->ops->cleanup) { WARN(1, "Missing reference count teardown definition\n"); return ERR_PTR(-EINVAL); } @@ -293,9 +294,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) err_pfn_remap: pgmap_array_delete(res); err_array: - pgmap->kill(pgmap->ref); - pgmap->cleanup(pgmap->ref); - + pgmap->ops->kill(pgmap->ref); + pgmap->ops->cleanup(pgmap->ref); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(devm_memremap_pages); @@ -388,7 +388,7 @@ void __put_devmap_managed_page(struct page *page) mem_cgroup_uncharge(page); - page->pgmap->page_free(page, page->pgmap->data); + page->pgmap->ops->page_free(page, page->pgmap->data); } else if (!count) __put_page(page); } diff --git a/mm/hmm.c b/mm/hmm.c index 48574f8485bb..583a02a16872 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -1384,6 +1384,12 @@ static void hmm_devmem_free(struct page *page, void *data) devmem->ops->free(devmem, page); } +static const struct dev_pagemap_ops hmm_pagemap_ops = { + .page_free = hmm_devmem_free, + .kill = hmm_devmem_ref_kill, + .cleanup = hmm_devmem_ref_exit, +}; + /* * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory * @@ -1438,12 +1444,10 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; devmem->pagemap.res = *devmem->resource; - devmem->pagemap.page_free = hmm_devmem_free; + devmem->pagemap.ops = &hmm_pagemap_ops; devmem->pagemap.altmap_valid = false; devmem->pagemap.ref = &devmem->ref; devmem->pagemap.data = devmem; - devmem->pagemap.kill = hmm_devmem_ref_kill; - devmem->pagemap.cleanup = hmm_devmem_ref_exit; result = devm_memremap_pages(devmem->device, &devmem->pagemap); if (IS_ERR(result)) diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c index 076df22e4bda..cf3f064a697d 100644 --- a/tools/testing/nvdimm/test/iomap.c +++ b/tools/testing/nvdimm/test/iomap.c @@ -100,9 +100,10 @@ static void nfit_test_kill(void *_pgmap) { struct dev_pagemap *pgmap = _pgmap; - WARN_ON(!pgmap || !pgmap->ref || !pgmap->kill || !pgmap->cleanup); - pgmap->kill(pgmap->ref); - pgmap->cleanup(pgmap->ref); + WARN_ON(!pgmap || !pgmap->ref || !pgmap->ops || !pgmap->ops->kill || + !pgmap->ops->cleanup); + pgmap->ops->kill(pgmap->ref); + pgmap->ops->cleanup(pgmap->ref); } void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)