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arm64: allow vmalloc regions to be set with set_memory_*

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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 <labbott@fedoraproject.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-01-27 10:50:19 +01:00 committed by Will Deacon
parent 36f90b0a2d
commit 95f5c80050
1 changed files with 19 additions and 4 deletions
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23
arch/arm64/mm/pageattr.c
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@ -14,6 +14,7 @@
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
@ -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)