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kasan, page_alloc: allow skipping unpoisoning for HW_TAGS

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Add a new GFP flag __GFP_SKIP_KASAN_UNPOISON that allows skipping KASAN
poisoning for page_alloc allocations.  The flag is only effective with
HW_TAGS KASAN.

This flag will be used by vmalloc code for page_alloc allocations backing
vmalloc() mappings in a following patch.  The reason to skip KASAN
poisoning for these pages in page_alloc is because vmalloc code will be
poisoning them instead.

Also reword the comment for __GFP_SKIP_KASAN_POISON.

Link: https://lkml.kernel.org/r/35c97d77a704f6ff971dd3bfe4be95855744108e.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov
2022-03-24 18:11:26 -07:00
committed by Linus Torvalds
parent f49d9c5bb1
commit 53ae233c30
3 changed files with 38 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
include/linux/gfp.h
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@@ -55,12 +55,14 @@ struct vm_area_struct;
#define ___GFP_ACCOUNT 0x400000u
#define ___GFP_ZEROTAGS 0x800000u
#ifdef CONFIG_KASAN_HW_TAGS
#define ___GFP_SKIP_KASAN_POISON 0x1000000u
#define ___GFP_SKIP_KASAN_UNPOISON 0x1000000u
#define ___GFP_SKIP_KASAN_POISON 0x2000000u
#else
#define ___GFP_SKIP_KASAN_UNPOISON 0
#define ___GFP_SKIP_KASAN_POISON 0
#endif
#ifdef CONFIG_LOCKDEP
#define ___GFP_NOLOCKDEP 0x2000000u
#define ___GFP_NOLOCKDEP 0x4000000u
#else
#define ___GFP_NOLOCKDEP 0
#endif
@@ -241,22 +243,25 @@ struct vm_area_struct;
* intended for optimization: setting memory tags at the same time as zeroing
* memory has minimal additional performace impact.
*
* %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poisoned
* on deallocation. Typically used for userspace pages. Currently only has an
* effect in HW tags mode.
* %__GFP_SKIP_KASAN_UNPOISON makes KASAN skip unpoisoning on page allocation.
* Only effective in HW_TAGS mode.
*
* %__GFP_SKIP_KASAN_POISON makes KASAN skip poisoning on page deallocation.
* Typically, used for userspace pages. Only effective in HW_TAGS mode.
*/
#define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN)
#define __GFP_COMP ((__force gfp_t)___GFP_COMP)
#define __GFP_ZERO ((__force gfp_t)___GFP_ZERO)
#define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS)
#define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON)
#define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON)
#define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON)
/* Disable lockdep for GFP context tracking */
#define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
/* Room for N __GFP_FOO bits */
#define __GFP_BITS_SHIFT (24 + \
IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \
#define __GFP_BITS_SHIFT (24 + \
2 * IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \
IS_ENABLED(CONFIG_LOCKDEP))
#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))