diff --git a/Documentation/filesystems/mmap_prepare.rst b/Documentation/filesystems/mmap_prepare.rst index 14bb057be564..82c99c95ad85 100644 --- a/Documentation/filesystems/mmap_prepare.rst +++ b/Documentation/filesystems/mmap_prepare.rst @@ -156,5 +156,13 @@ pointer. These are: * mmap_action_simple_ioremap() - Sets up an I/O remap from a specified physical address and over a specified length. +* mmap_action_map_kernel_pages() - Maps a specified array of `struct page` + pointers in the VMA from a specific offset. + +* mmap_action_map_kernel_pages_full() - Maps a specified array of `struct + page` pointers over the entire VMA. The caller must ensure there are + sufficient entries in the page array to cover the entire range of the + described VMA. + **NOTE:** The ``action`` field should never normally be manipulated directly, rather you ought to use one of these helpers. diff --git a/include/linux/mm.h b/include/linux/mm.h index 53b21de40f87..61dff7f03554 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2905,7 +2905,7 @@ static inline bool folio_maybe_mapped_shared(struct folio *folio) * The caller must add any reference (e.g., from folio_try_get()) it might be * holding itself to the result. * - * Returns the expected folio refcount. + * Returns: the expected folio refcount. */ static inline int folio_expected_ref_count(const struct folio *folio) { @@ -4348,6 +4348,45 @@ static inline void mmap_action_simple_ioremap(struct vm_area_desc *desc, action->type = MMAP_SIMPLE_IO_REMAP; } +/** + * mmap_action_map_kernel_pages - helper for mmap_prepare hook to specify that + * @num kernel pages contained in the @pages array should be mapped to userland + * starting at virtual address @start. + * @desc: The VMA descriptor for the VMA requiring kernel pags to be mapped. + * @start: The virtual address from which to map them. + * @pages: An array of struct page pointers describing the memory to map. + * @nr_pages: The number of entries in the @pages aray. + */ +static inline void mmap_action_map_kernel_pages(struct vm_area_desc *desc, + unsigned long start, struct page **pages, + unsigned long nr_pages) +{ + struct mmap_action *action = &desc->action; + + action->type = MMAP_MAP_KERNEL_PAGES; + action->map_kernel.start = start; + action->map_kernel.pages = pages; + action->map_kernel.nr_pages = nr_pages; + action->map_kernel.pgoff = desc->pgoff; +} + +/** + * mmap_action_map_kernel_pages_full - helper for mmap_prepare hook to specify that + * kernel pages contained in the @pages array should be mapped to userland + * from @desc->start to @desc->end. + * @desc: The VMA descriptor for the VMA requiring kernel pags to be mapped. + * @pages: An array of struct page pointers describing the memory to map. + * + * The caller must ensure that @pages contains sufficient entries to cover the + * entire range described by @desc. + */ +static inline void mmap_action_map_kernel_pages_full(struct vm_area_desc *desc, + struct page **pages) +{ + mmap_action_map_kernel_pages(desc, desc->start, pages, + vma_desc_pages(desc)); +} + int mmap_action_prepare(struct vm_area_desc *desc); int mmap_action_complete(struct vm_area_struct *vma, struct mmap_action *action); @@ -4364,10 +4403,59 @@ static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm, return vma; } +/** + * range_is_subset - Is the specified inner range a subset of the outer range? + * @outer_start: The start of the outer range. + * @outer_end: The exclusive end of the outer range. + * @inner_start: The start of the inner range. + * @inner_end: The exclusive end of the inner range. + * + * Returns: %true if [inner_start, inner_end) is a subset of [outer_start, + * outer_end), otherwise %false. + */ +static inline bool range_is_subset(unsigned long outer_start, + unsigned long outer_end, + unsigned long inner_start, + unsigned long inner_end) +{ + return outer_start <= inner_start && inner_end <= outer_end; +} + +/** + * range_in_vma - is the specified [@start, @end) range a subset of the VMA? + * @vma: The VMA against which we want to check [@start, @end). + * @start: The start of the range we wish to check. + * @end: The exclusive end of the range we wish to check. + * + * Returns: %true if [@start, @end) is a subset of [@vma->vm_start, + * @vma->vm_end), %false otherwise. + */ static inline bool range_in_vma(const struct vm_area_struct *vma, unsigned long start, unsigned long end) { - return (vma && vma->vm_start <= start && end <= vma->vm_end); + if (!vma) + return false; + + return range_is_subset(vma->vm_start, vma->vm_end, start, end); +} + +/** + * range_in_vma_desc - is the specified [@start, @end) range a subset of the VMA + * described by @desc, a VMA descriptor? + * @desc: The VMA descriptor against which we want to check [@start, @end). + * @start: The start of the range we wish to check. + * @end: The exclusive end of the range we wish to check. + * + * Returns: %true if [@start, @end) is a subset of [@desc->start, @desc->end), + * %false otherwise. + */ +static inline bool range_in_vma_desc(const struct vm_area_desc *desc, + unsigned long start, unsigned long end) +{ + if (!desc) + return false; + + return range_is_subset(desc->start, desc->end, start, end); } #ifdef CONFIG_MMU @@ -4411,6 +4499,9 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, struct page **pages, unsigned long *num); +int map_kernel_pages_prepare(struct vm_area_desc *desc); +int map_kernel_pages_complete(struct vm_area_struct *vma, + struct mmap_action *action); int vm_map_pages(struct vm_area_struct *vma, struct page **pages, unsigned long num); int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index b702c63bf0e0..a308e2c23b82 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -815,6 +815,7 @@ enum mmap_action_type { MMAP_REMAP_PFN, /* Remap PFN range. */ MMAP_IO_REMAP_PFN, /* I/O remap PFN range. */ MMAP_SIMPLE_IO_REMAP, /* I/O remap with guardrails. */ + MMAP_MAP_KERNEL_PAGES, /* Map kernel page range from array. */ }; /* @@ -833,6 +834,12 @@ struct mmap_action { phys_addr_t start_phys_addr; unsigned long size; } simple_ioremap; + struct { + unsigned long start; + struct page **pages; + unsigned long nr_pages; + pgoff_t pgoff; + } map_kernel; }; enum mmap_action_type type; diff --git a/mm/memory.c b/mm/memory.c index c1c323512939..5d032b5293c6 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2484,13 +2484,14 @@ static int insert_pages(struct vm_area_struct *vma, unsigned long addr, int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, struct page **pages, unsigned long *num) { - const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; + const unsigned long nr_pages = *num; + const unsigned long end = addr + PAGE_SIZE * nr_pages; - if (addr < vma->vm_start || end_addr >= vma->vm_end) + if (!range_in_vma(vma, addr, end)) return -EFAULT; if (!(vma->vm_flags & VM_MIXEDMAP)) { - BUG_ON(mmap_read_trylock(vma->vm_mm)); - BUG_ON(vma->vm_flags & VM_PFNMAP); + VM_WARN_ON_ONCE(mmap_read_trylock(vma->vm_mm)); + VM_WARN_ON_ONCE(vma->vm_flags & VM_PFNMAP); vm_flags_set(vma, VM_MIXEDMAP); } /* Defer page refcount checking till we're about to map that page. */ @@ -2498,6 +2499,39 @@ int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, } EXPORT_SYMBOL(vm_insert_pages); +int map_kernel_pages_prepare(struct vm_area_desc *desc) +{ + const struct mmap_action *action = &desc->action; + const unsigned long addr = action->map_kernel.start; + unsigned long nr_pages, end; + + if (!vma_desc_test(desc, VMA_MIXEDMAP_BIT)) { + VM_WARN_ON_ONCE(mmap_read_trylock(desc->mm)); + VM_WARN_ON_ONCE(vma_desc_test(desc, VMA_PFNMAP_BIT)); + vma_desc_set_flags(desc, VMA_MIXEDMAP_BIT); + } + + nr_pages = action->map_kernel.nr_pages; + end = addr + PAGE_SIZE * nr_pages; + if (!range_in_vma_desc(desc, addr, end)) + return -EFAULT; + + return 0; +} +EXPORT_SYMBOL(map_kernel_pages_prepare); + +int map_kernel_pages_complete(struct vm_area_struct *vma, + struct mmap_action *action) +{ + unsigned long nr_pages; + + nr_pages = action->map_kernel.nr_pages; + return insert_pages(vma, action->map_kernel.start, + action->map_kernel.pages, + &nr_pages, vma->vm_page_prot); +} +EXPORT_SYMBOL(map_kernel_pages_complete); + /** * vm_insert_page - insert single page into user vma * @vma: user vma to map to diff --git a/mm/util.c b/mm/util.c index 5ae20876ef2c..f063fd4de1e8 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1448,6 +1448,8 @@ int mmap_action_prepare(struct vm_area_desc *desc) return io_remap_pfn_range_prepare(desc); case MMAP_SIMPLE_IO_REMAP: return simple_ioremap_prepare(desc); + case MMAP_MAP_KERNEL_PAGES: + return map_kernel_pages_prepare(desc); } WARN_ON_ONCE(1); @@ -1475,6 +1477,9 @@ int mmap_action_complete(struct vm_area_struct *vma, case MMAP_REMAP_PFN: err = remap_pfn_range_complete(vma, action); break; + case MMAP_MAP_KERNEL_PAGES: + err = map_kernel_pages_complete(vma, action); + break; case MMAP_IO_REMAP_PFN: case MMAP_SIMPLE_IO_REMAP: /* Should have been delegated. */ @@ -1495,6 +1500,7 @@ int mmap_action_prepare(struct vm_area_desc *desc) case MMAP_REMAP_PFN: case MMAP_IO_REMAP_PFN: case MMAP_SIMPLE_IO_REMAP: + case MMAP_MAP_KERNEL_PAGES: WARN_ON_ONCE(1); /* nommu cannot handle these. */ break; } @@ -1514,6 +1520,7 @@ int mmap_action_complete(struct vm_area_struct *vma, case MMAP_REMAP_PFN: case MMAP_IO_REMAP_PFN: case MMAP_SIMPLE_IO_REMAP: + case MMAP_MAP_KERNEL_PAGES: WARN_ON_ONCE(1); /* nommu cannot handle this. */ err = -EINVAL; diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index ecd47d0f7d17..b4864aad2db0 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -454,6 +454,7 @@ enum mmap_action_type { MMAP_REMAP_PFN, /* Remap PFN range. */ MMAP_IO_REMAP_PFN, /* I/O remap PFN range. */ MMAP_SIMPLE_IO_REMAP, /* I/O remap with guardrails. */ + MMAP_MAP_KERNEL_PAGES, /* Map kernel page range from an array. */ }; /* @@ -472,6 +473,12 @@ struct mmap_action { phys_addr_t start_phys_addr; unsigned long size; } simple_ioremap; + struct { + unsigned long start; + struct page **pages; + unsigned long nr_pages; + pgoff_t pgoff; + } map_kernel; }; enum mmap_action_type type;