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[RFC,v1,08/26] kmsan: gfp: introduce __GFP_NO_KMSAN_SHADOW

Message ID 20191018094304.37056-9-glider@google.com (mailing list archive)
State New, archived
Headers show
Series Add KernelMemorySanitizer infrastructure | expand

Commit Message

Alexander Potapenko Oct. 18, 2019, 9:42 a.m. UTC 
This flag is to be used by KMSAN runtime to mark that newly created
memory pages don't need KMSAN metadata backing them.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org

---
We can't decide what to do here:
 - do we need to conditionally define ___GFP_NO_KMSAN_SHADOW depending on
   CONFIG_KMSAN like LOCKDEP does?
 - if KMSAN is defined, and LOCKDEP is not, do we want to "compactify" the GFP
   bits?

Change-Id: If5d0352fd5711ad103328e2c185eb885e826423a
---
 include/linux/gfp.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index fb07b503dc45..b4e7963cd94b 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -44,6 +44,7 @@  struct vm_area_struct;
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
+#define ___GFP_NO_KMSAN_SHADOW  0x1000000u
 /* If the above are modified, __GFP_BITS_SHIFT may need updating */
 
 /*
@@ -212,12 +213,13 @@  struct vm_area_struct;
 #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_NO_KMSAN_SHADOW  ((__force gfp_t)___GFP_NO_KMSAN_SHADOW)
 
 /* Disable lockdep for GFP context tracking */
 #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
 
 /* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (23 + IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT (25)
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**