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authorAndrey Ryabinin <a.ryabinin@samsung.com>2015-02-13 14:40:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-13 21:21:42 -0800
commit71394fe50146202f2c8d92cf50f5ebc761acf254 (patch)
tree8c80ad354cded80e92a1594e8786e6f89a7ece2e
parentc420f167db8c799d69fe43a801c58a7f02e9d57c (diff)
mm: vmalloc: add flag preventing guard hole allocation
For instrumenting global variables KASan will shadow memory backing memory for modules. So on module loading we will need to allocate memory for shadow and map it at address in shadow that corresponds to the address allocated in module_alloc(). __vmalloc_node_range() could be used for this purpose, except it puts a guard hole after allocated area. Guard hole in shadow memory should be a problem because at some future point we might need to have a shadow memory at address occupied by guard hole. So we could fail to allocate shadow for module_alloc(). Add a new vm_struct flag 'VM_NO_GUARD' indicating that vm area doesn't have a guard hole. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/vmalloc.h9
-rw-r--r--mm/vmalloc.c6
2 files changed, 9 insertions, 6 deletions
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index b87696fdf06a..1526fe712ca0 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -16,6 +16,7 @@ struct vm_area_struct; /* vma defining user mapping in mm_types.h */
#define VM_USERMAP 0x00000008 /* suitable for remap_vmalloc_range */
#define VM_VPAGES 0x00000010 /* buffer for pages was vmalloc'ed */
#define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully initialized */
+#define VM_NO_GUARD 0x00000040 /* don't add guard page */
/* bits [20..32] reserved for arch specific ioremap internals */
/*
@@ -96,8 +97,12 @@ void vmalloc_sync_all(void);
static inline size_t get_vm_area_size(const struct vm_struct *area)
{
- /* return actual size without guard page */
- return area->size - PAGE_SIZE;
+ if (!(area->flags & VM_NO_GUARD))
+ /* return actual size without guard page */
+ return area->size - PAGE_SIZE;
+ else
+ return area->size;
+
}
extern struct vm_struct *get_vm_area(unsigned long size, unsigned long flags);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 39c338896416..2e74e99d4cfe 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1324,10 +1324,8 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
if (unlikely(!area))
return NULL;
- /*
- * We always allocate a guard page.
- */
- size += PAGE_SIZE;
+ if (!(flags & VM_NO_GUARD))
+ size += PAGE_SIZE;
va = alloc_vmap_area(size, align, start, end, node, gfp_mask);
if (IS_ERR(va)) {

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