From 95f5c80050ad723163aa80dc8bffd48ef4afc6d5 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 27 Jan 2016 10:50:19 +0100 Subject: [PATCH] arm64: allow vmalloc regions to be set with set_memory_* The range of set_memory_* is currently restricted to the module address range because of difficulties in breaking down larger block sizes. vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the function ranges and add a comment explaining why the range is restricted the way it is. Suggested-by: Laura Abbott Acked-by: Mark Rutland Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon --- arch/arm64/mm/pageattr.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index cf6240741134..0795c3a36d8f 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -44,6 +45,7 @@ static int change_memory_common(unsigned long addr, int numpages, unsigned long end = start + size; int ret; struct page_change_data data; + struct vm_struct *area; if (!PAGE_ALIGNED(addr)) { start &= PAGE_MASK; @@ -51,10 +53,23 @@ static int change_memory_common(unsigned long addr, int numpages, WARN_ON_ONCE(1); } - if (start < MODULES_VADDR || start >= MODULES_END) - return -EINVAL; - - if (end < MODULES_VADDR || end >= MODULES_END) + /* + * Kernel VA mappings are always live, and splitting live section + * mappings into page mappings may cause TLB conflicts. This means + * we have to ensure that changing the permission bits of the range + * we are operating on does not result in such splitting. + * + * Let's restrict ourselves to mappings created by vmalloc (or vmap). + * Those are guaranteed to consist entirely of page mappings, and + * splitting is never needed. + * + * So check whether the [addr, addr + size) interval is entirely + * covered by precisely one VM area that has the VM_ALLOC flag set. + */ + area = find_vm_area((void *)addr); + if (!area || + end > (unsigned long)area->addr + area->size || + !(area->flags & VM_ALLOC)) return -EINVAL; if (!numpages)