Messages in this thread Patch in this message | | | From | Chris Wilson <> | Subject | [PATCH 1/4] mm: Export flush_vm_area() to sync the PTEs upon construction | Date | Fri, 21 Aug 2020 09:50:08 +0100 |
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The alloc_vm_area() is another method for drivers to vmap/map_kernel_range that uses apply_to_page_range() rather than the direct vmalloc walkers. This is missing the page table modification tracking, and the ability to synchronize the PTE updates afterwards. Provide flush_vm_area() for the users of alloc_vm_area() that assumes the worst and ensures that the page directories are correctly flushed upon construction.
The impact is most pronounced on x86_32 due to the delayed set_pmd().
Reported-by: Pavel Machek <pavel@ucw.cz> References: 2ba3e6947aed ("mm/vmalloc: track which page-table levels were modified") References: 86cf69f1d893 ("x86/mm/32: implement arch_sync_kernel_mappings()") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Joerg Roedel <jroedel@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Dave Airlie <airlied@redhat.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: David Vrabel <david.vrabel@citrix.com> Cc: <stable@vger.kernel.org> # v5.8+ --- include/linux/vmalloc.h | 1 + mm/vmalloc.c | 16 ++++++++++++++++ 2 files changed, 17 insertions(+)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 0221f852a7e1..a253b27df0ac 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -204,6 +204,7 @@ static inline void set_vm_flush_reset_perms(void *addr) /* Allocate/destroy a 'vmalloc' VM area. */ extern struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes); +extern void flush_vm_area(struct vm_struct *area); extern void free_vm_area(struct vm_struct *area); /* for /dev/kmem */ diff --git a/mm/vmalloc.c b/mm/vmalloc.c index b482d240f9a2..c41934486031 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3078,6 +3078,22 @@ struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes) } EXPORT_SYMBOL_GPL(alloc_vm_area); +void flush_vm_area(struct vm_struct *area) +{ + unsigned long addr = (unsigned long)area->addr; + + /* apply_to_page_range() doesn't track the damage, assume the worst */ + if (ARCH_PAGE_TABLE_SYNC_MASK & (PGTBL_PTE_MODIFIED | + PGTBL_PMD_MODIFIED | + PGTBL_PUD_MODIFIED | + PGTBL_P4D_MODIFIED | + PGTBL_PGD_MODIFIED)) + arch_sync_kernel_mappings(addr, addr + area->size); + + flush_cache_vmap(addr, area->size); +} +EXPORT_SYMBOL_GPL(flush_vm_area); + void free_vm_area(struct vm_struct *area) { struct vm_struct *ret; -- 2.20.1
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