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* [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
@ 2021-06-02 23:52 ` Peter Collingbourne
  0 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Currently we can end up touching PROT_MTE user pages twice on fault
and once on unmap. On fault, with KASAN disabled we first clear data
and then set tags to 0, and with KASAN enabled we simultaneously
clear data and set tags to the KASAN random tag, and then set tags
again to 0. On unmap, we poison the page by setting tags, but this
is less likely to find a bug than poisoning kernel pages.

This patch series fixes these inefficiencies by only touching the pages
once on fault using the DC GZVA instruction to clear both data and
tags, and avoiding poisoning user pages on free.

Peter Collingbourne (4):
  mm: arch: remove indirection level in
    alloc_zeroed_user_highpage_movable()
  kasan: use separate (un)poison implementation for integrated init
  arm64: mte: handle tags zeroing at page allocation time
  kasan: disable freed user page poisoning with HW tags

 arch/alpha/include/asm/page.h   |  6 +--
 arch/arm64/include/asm/mte.h    |  4 ++
 arch/arm64/include/asm/page.h   | 10 +++--
 arch/arm64/lib/mte.S            | 20 ++++++++++
 arch/arm64/mm/fault.c           | 26 +++++++++++++
 arch/arm64/mm/proc.S            | 10 +++--
 arch/ia64/include/asm/page.h    |  6 +--
 arch/m68k/include/asm/page_no.h |  6 +--
 arch/s390/include/asm/page.h    |  6 +--
 arch/x86/include/asm/page.h     |  6 +--
 include/linux/gfp.h             | 18 +++++++--
 include/linux/highmem.h         | 43 ++++++++-------------
 include/linux/kasan.h           | 64 +++++++++++++++++++-------------
 include/linux/page-flags.h      |  9 +++++
 include/trace/events/mmflags.h  |  9 ++++-
 mm/kasan/common.c               |  4 +-
 mm/kasan/hw_tags.c              | 32 ++++++++++++++++
 mm/mempool.c                    |  6 ++-
 mm/page_alloc.c                 | 66 +++++++++++++++++++--------------
 19 files changed, 242 insertions(+), 109 deletions(-)

-- 
2.32.0.rc1.229.g3e70b5a671-goog



^ permalink raw reply	[flat|nested] 18+ messages in thread
* [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
@ 2021-06-02 23:52 ` Peter Collingbourne
  0 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Currently we can end up touching PROT_MTE user pages twice on fault
and once on unmap. On fault, with KASAN disabled we first clear data
and then set tags to 0, and with KASAN enabled we simultaneously
clear data and set tags to the KASAN random tag, and then set tags
again to 0. On unmap, we poison the page by setting tags, but this
is less likely to find a bug than poisoning kernel pages.

This patch series fixes these inefficiencies by only touching the pages
once on fault using the DC GZVA instruction to clear both data and
tags, and avoiding poisoning user pages on free.

Peter Collingbourne (4):
  mm: arch: remove indirection level in
    alloc_zeroed_user_highpage_movable()
  kasan: use separate (un)poison implementation for integrated init
  arm64: mte: handle tags zeroing at page allocation time
  kasan: disable freed user page poisoning with HW tags

 arch/alpha/include/asm/page.h   |  6 +--
 arch/arm64/include/asm/mte.h    |  4 ++
 arch/arm64/include/asm/page.h   | 10 +++--
 arch/arm64/lib/mte.S            | 20 ++++++++++
 arch/arm64/mm/fault.c           | 26 +++++++++++++
 arch/arm64/mm/proc.S            | 10 +++--
 arch/ia64/include/asm/page.h    |  6 +--
 arch/m68k/include/asm/page_no.h |  6 +--
 arch/s390/include/asm/page.h    |  6 +--
 arch/x86/include/asm/page.h     |  6 +--
 include/linux/gfp.h             | 18 +++++++--
 include/linux/highmem.h         | 43 ++++++++-------------
 include/linux/kasan.h           | 64 +++++++++++++++++++-------------
 include/linux/page-flags.h      |  9 +++++
 include/trace/events/mmflags.h  |  9 ++++-
 mm/kasan/common.c               |  4 +-
 mm/kasan/hw_tags.c              | 32 ++++++++++++++++
 mm/mempool.c                    |  6 ++-
 mm/page_alloc.c                 | 66 +++++++++++++++++++--------------
 19 files changed, 242 insertions(+), 109 deletions(-)

-- 
2.32.0.rc1.229.g3e70b5a671-goog


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^ permalink raw reply	[flat|nested] 18+ messages in thread
* [PATCH v6 1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()
  2021-06-02 23:52 ` Peter Collingbourne
@ 2021-06-02 23:52   ` Peter Collingbourne
  -1 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

In an upcoming change we would like to add a flag to
GFP_HIGHUSER_MOVABLE so that it would no longer be an OR
of GFP_HIGHUSER and __GFP_MOVABLE. This poses a problem for
alloc_zeroed_user_highpage_movable() which passes __GFP_MOVABLE
into an arch-specific __alloc_zeroed_user_highpage() hook which ORs
in GFP_HIGHUSER.

Since __alloc_zeroed_user_highpage() is only ever called from
alloc_zeroed_user_highpage_movable(), we can remove one level
of indirection here. Remove __alloc_zeroed_user_highpage(),
make alloc_zeroed_user_highpage_movable() the hook, and use
GFP_HIGHUSER_MOVABLE in the hook implementations so that they will
pick up the new flag that we are going to add.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ic6361c657b2cdcd896adbe0cf7cb5a7fbb1ed7bf
---
v6:
- fix intermediate build error on arm64

v5:
- fix s390 build error

 arch/alpha/include/asm/page.h   |  6 +++---
 arch/arm64/include/asm/page.h   |  6 +++---
 arch/ia64/include/asm/page.h    |  6 +++---
 arch/m68k/include/asm/page_no.h |  6 +++---
 arch/s390/include/asm/page.h    |  6 +++---
 arch/x86/include/asm/page.h     |  6 +++---
 include/linux/highmem.h         | 35 ++++++++-------------------------
 7 files changed, 26 insertions(+), 45 deletions(-)

diff --git a/arch/alpha/include/asm/page.h b/arch/alpha/include/asm/page.h
index 268f99b4602b..18f48a6f2ff6 100644
--- a/arch/alpha/include/asm/page.h
+++ b/arch/alpha/include/asm/page.h
@@ -17,9 +17,9 @@
 extern void clear_page(void *page);
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vmaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vmaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 extern void copy_page(void * _to, void * _from);
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 012cffc574e8..e1fc0f60e79f 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -28,9 +28,9 @@ void copy_user_highpage(struct page *to, struct page *from,
 void copy_highpage(struct page *to, struct page *from);
 #define __HAVE_ARCH_COPY_HIGHPAGE
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
diff --git a/arch/ia64/include/asm/page.h b/arch/ia64/include/asm/page.h
index f4dc81fa7146..1b990466d540 100644
--- a/arch/ia64/include/asm/page.h
+++ b/arch/ia64/include/asm/page.h
@@ -82,16 +82,16 @@ do {						\
 } while (0)
 
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr)		\
+#define alloc_zeroed_user_highpage_movable(vma, vaddr)			\
 ({									\
 	struct page *page = alloc_page_vma(				\
-		GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr);	\
+		GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr);		\
 	if (page)							\
  		flush_dcache_page(page);				\
 	page;								\
 })
 
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
 
diff --git a/arch/m68k/include/asm/page_no.h b/arch/m68k/include/asm/page_no.h
index 8d0f862ee9d7..c9d0d84158a4 100644
--- a/arch/m68k/include/asm/page_no.h
+++ b/arch/m68k/include/asm/page_no.h
@@ -13,9 +13,9 @@ extern unsigned long memory_end;
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #define __pa(vaddr)		((unsigned long)(vaddr))
 #define __va(paddr)		((void *)((unsigned long)(paddr)))
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index cc98f9b78fd4..479dc76e0eca 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -68,9 +68,9 @@ static inline void copy_page(void *to, void *from)
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 /*
  * These are used to make use of C type-checking..
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 7555b48803a8..4d5810c8fab7 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -34,9 +34,9 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
 	copy_page(to, from);
 }
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #ifndef __pa
 #define __pa(x)		__phys_addr((unsigned long)(x))
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 832b49b50c7b..54d0643b8fcf 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -152,28 +152,24 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
 }
 #endif
 
-#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 /**
- * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
- * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
+ * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
  * @vma: The VMA the page is to be allocated for
  * @vaddr: The virtual address the page will be inserted into
  *
- * This function will allocate a page for a VMA but the caller is expected
- * to specify via movableflags whether the page will be movable in the
- * future or not
+ * This function will allocate a page for a VMA that the caller knows will
+ * be able to migrate in the future using move_pages() or reclaimed
  *
  * An architecture may override this function by defining
- * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
+ * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE and providing their own
  * implementation.
  */
 static inline struct page *
-__alloc_zeroed_user_highpage(gfp_t movableflags,
-			struct vm_area_struct *vma,
-			unsigned long vaddr)
+alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+				   unsigned long vaddr)
 {
-	struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
-			vma, vaddr);
+	struct page *page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 
 	if (page)
 		clear_user_highpage(page, vaddr);
@@ -182,21 +178,6 @@ __alloc_zeroed_user_highpage(gfp_t movableflags,
 }
 #endif
 
-/**
- * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
- * @vma: The VMA the page is to be allocated for
- * @vaddr: The virtual address the page will be inserted into
- *
- * This function will allocate a page for a VMA that the caller knows will
- * be able to migrate in the future using move_pages() or reclaimed
- */
-static inline struct page *
-alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
-					unsigned long vaddr)
-{
-	return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
-}
-
 static inline void clear_highpage(struct page *page)
 {
 	void *kaddr = kmap_atomic(page);
-- 
2.32.0.rc1.229.g3e70b5a671-goog



^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()
@ 2021-06-02 23:52   ` Peter Collingbourne
  0 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

In an upcoming change we would like to add a flag to
GFP_HIGHUSER_MOVABLE so that it would no longer be an OR
of GFP_HIGHUSER and __GFP_MOVABLE. This poses a problem for
alloc_zeroed_user_highpage_movable() which passes __GFP_MOVABLE
into an arch-specific __alloc_zeroed_user_highpage() hook which ORs
in GFP_HIGHUSER.

Since __alloc_zeroed_user_highpage() is only ever called from
alloc_zeroed_user_highpage_movable(), we can remove one level
of indirection here. Remove __alloc_zeroed_user_highpage(),
make alloc_zeroed_user_highpage_movable() the hook, and use
GFP_HIGHUSER_MOVABLE in the hook implementations so that they will
pick up the new flag that we are going to add.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ic6361c657b2cdcd896adbe0cf7cb5a7fbb1ed7bf
---
v6:
- fix intermediate build error on arm64

v5:
- fix s390 build error

 arch/alpha/include/asm/page.h   |  6 +++---
 arch/arm64/include/asm/page.h   |  6 +++---
 arch/ia64/include/asm/page.h    |  6 +++---
 arch/m68k/include/asm/page_no.h |  6 +++---
 arch/s390/include/asm/page.h    |  6 +++---
 arch/x86/include/asm/page.h     |  6 +++---
 include/linux/highmem.h         | 35 ++++++++-------------------------
 7 files changed, 26 insertions(+), 45 deletions(-)

diff --git a/arch/alpha/include/asm/page.h b/arch/alpha/include/asm/page.h
index 268f99b4602b..18f48a6f2ff6 100644
--- a/arch/alpha/include/asm/page.h
+++ b/arch/alpha/include/asm/page.h
@@ -17,9 +17,9 @@
 extern void clear_page(void *page);
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vmaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vmaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 extern void copy_page(void * _to, void * _from);
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 012cffc574e8..e1fc0f60e79f 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -28,9 +28,9 @@ void copy_user_highpage(struct page *to, struct page *from,
 void copy_highpage(struct page *to, struct page *from);
 #define __HAVE_ARCH_COPY_HIGHPAGE
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
diff --git a/arch/ia64/include/asm/page.h b/arch/ia64/include/asm/page.h
index f4dc81fa7146..1b990466d540 100644
--- a/arch/ia64/include/asm/page.h
+++ b/arch/ia64/include/asm/page.h
@@ -82,16 +82,16 @@ do {						\
 } while (0)
 
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr)		\
+#define alloc_zeroed_user_highpage_movable(vma, vaddr)			\
 ({									\
 	struct page *page = alloc_page_vma(				\
-		GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr);	\
+		GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr);		\
 	if (page)							\
  		flush_dcache_page(page);				\
 	page;								\
 })
 
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
 
diff --git a/arch/m68k/include/asm/page_no.h b/arch/m68k/include/asm/page_no.h
index 8d0f862ee9d7..c9d0d84158a4 100644
--- a/arch/m68k/include/asm/page_no.h
+++ b/arch/m68k/include/asm/page_no.h
@@ -13,9 +13,9 @@ extern unsigned long memory_end;
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #define __pa(vaddr)		((unsigned long)(vaddr))
 #define __va(paddr)		((void *)((unsigned long)(paddr)))
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index cc98f9b78fd4..479dc76e0eca 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -68,9 +68,9 @@ static inline void copy_page(void *to, void *from)
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 /*
  * These are used to make use of C type-checking..
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 7555b48803a8..4d5810c8fab7 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -34,9 +34,9 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
 	copy_page(to, from);
 }
 
-#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
-#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
+	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
 #ifndef __pa
 #define __pa(x)		__phys_addr((unsigned long)(x))
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 832b49b50c7b..54d0643b8fcf 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -152,28 +152,24 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
 }
 #endif
 
-#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
+#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 /**
- * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
- * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
+ * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
  * @vma: The VMA the page is to be allocated for
  * @vaddr: The virtual address the page will be inserted into
  *
- * This function will allocate a page for a VMA but the caller is expected
- * to specify via movableflags whether the page will be movable in the
- * future or not
+ * This function will allocate a page for a VMA that the caller knows will
+ * be able to migrate in the future using move_pages() or reclaimed
  *
  * An architecture may override this function by defining
- * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
+ * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE and providing their own
  * implementation.
  */
 static inline struct page *
-__alloc_zeroed_user_highpage(gfp_t movableflags,
-			struct vm_area_struct *vma,
-			unsigned long vaddr)
+alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+				   unsigned long vaddr)
 {
-	struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
-			vma, vaddr);
+	struct page *page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 
 	if (page)
 		clear_user_highpage(page, vaddr);
@@ -182,21 +178,6 @@ __alloc_zeroed_user_highpage(gfp_t movableflags,
 }
 #endif
 
-/**
- * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
- * @vma: The VMA the page is to be allocated for
- * @vaddr: The virtual address the page will be inserted into
- *
- * This function will allocate a page for a VMA that the caller knows will
- * be able to migrate in the future using move_pages() or reclaimed
- */
-static inline struct page *
-alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
-					unsigned long vaddr)
-{
-	return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
-}
-
 static inline void clear_highpage(struct page *page)
 {
 	void *kaddr = kmap_atomic(page);
-- 
2.32.0.rc1.229.g3e70b5a671-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 2/4] kasan: use separate (un)poison implementation for integrated init
  2021-06-02 23:52 ` Peter Collingbourne
@ 2021-06-02 23:52   ` Peter Collingbourne
  -1 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Currently with integrated init page_alloc.c needs to know whether
kasan_alloc_pages() will zero initialize memory, but this will start
becoming more complicated once we start adding tag initialization
support for user pages. To avoid page_alloc.c needing to know more
details of what integrated init will do, move the unpoisoning logic
for integrated init into the HW tags implementation. Currently the
logic is identical but it will diverge in subsequent patches.

For symmetry do the same for poisoning although this logic will
be unaffected by subsequent patches.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I2c550234c6c4a893c48c18ff0c6ce658c7c67056
---
v4:
- use IS_ENABLED(CONFIG_KASAN)
- add comments to kasan_alloc_pages and kasan_free_pages
- remove line break

v3:
- use BUILD_BUG()

v2:
- fix build with KASAN disabled

 include/linux/kasan.h | 64 +++++++++++++++++++++++++------------------
 mm/kasan/common.c     |  4 +--
 mm/kasan/hw_tags.c    | 22 +++++++++++++++
 mm/mempool.c          |  6 ++--
 mm/page_alloc.c       | 55 +++++++++++++++++++------------------
 5 files changed, 95 insertions(+), 56 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index b1678a61e6a7..a1c7ce5f3e4f 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -2,6 +2,7 @@
 #ifndef _LINUX_KASAN_H
 #define _LINUX_KASAN_H
 
+#include <linux/bug.h>
 #include <linux/static_key.h>
 #include <linux/types.h>
 
@@ -79,14 +80,6 @@ static inline void kasan_disable_current(void) {}
 
 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 
-#ifdef CONFIG_KASAN
-
-struct kasan_cache {
-	int alloc_meta_offset;
-	int free_meta_offset;
-	bool is_kmalloc;
-};
-
 #ifdef CONFIG_KASAN_HW_TAGS
 
 DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
@@ -101,11 +94,14 @@ static inline bool kasan_has_integrated_init(void)
 	return kasan_enabled();
 }
 
+void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags);
+void kasan_free_pages(struct page *page, unsigned int order);
+
 #else /* CONFIG_KASAN_HW_TAGS */
 
 static inline bool kasan_enabled(void)
 {
-	return true;
+	return IS_ENABLED(CONFIG_KASAN);
 }
 
 static inline bool kasan_has_integrated_init(void)
@@ -113,8 +109,30 @@ static inline bool kasan_has_integrated_init(void)
 	return false;
 }
 
+static __always_inline void kasan_alloc_pages(struct page *page,
+					      unsigned int order, gfp_t flags)
+{
+	/* Only available for integrated init. */
+	BUILD_BUG();
+}
+
+static __always_inline void kasan_free_pages(struct page *page,
+					     unsigned int order)
+{
+	/* Only available for integrated init. */
+	BUILD_BUG();
+}
+
 #endif /* CONFIG_KASAN_HW_TAGS */
 
+#ifdef CONFIG_KASAN
+
+struct kasan_cache {
+	int alloc_meta_offset;
+	int free_meta_offset;
+	bool is_kmalloc;
+};
+
 slab_flags_t __kasan_never_merge(void);
 static __always_inline slab_flags_t kasan_never_merge(void)
 {
@@ -130,20 +148,20 @@ static __always_inline void kasan_unpoison_range(const void *addr, size_t size)
 		__kasan_unpoison_range(addr, size);
 }
 
-void __kasan_alloc_pages(struct page *page, unsigned int order, bool init);
-static __always_inline void kasan_alloc_pages(struct page *page,
+void __kasan_poison_pages(struct page *page, unsigned int order, bool init);
+static __always_inline void kasan_poison_pages(struct page *page,
 						unsigned int order, bool init)
 {
 	if (kasan_enabled())
-		__kasan_alloc_pages(page, order, init);
+		__kasan_poison_pages(page, order, init);
 }
 
-void __kasan_free_pages(struct page *page, unsigned int order, bool init);
-static __always_inline void kasan_free_pages(struct page *page,
-						unsigned int order, bool init)
+void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init);
+static __always_inline void kasan_unpoison_pages(struct page *page,
+						 unsigned int order, bool init)
 {
 	if (kasan_enabled())
-		__kasan_free_pages(page, order, init);
+		__kasan_unpoison_pages(page, order, init);
 }
 
 void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
@@ -285,21 +303,15 @@ void kasan_restore_multi_shot(bool enabled);
 
 #else /* CONFIG_KASAN */
 
-static inline bool kasan_enabled(void)
-{
-	return false;
-}
-static inline bool kasan_has_integrated_init(void)
-{
-	return false;
-}
 static inline slab_flags_t kasan_never_merge(void)
 {
 	return 0;
 }
 static inline void kasan_unpoison_range(const void *address, size_t size) {}
-static inline void kasan_alloc_pages(struct page *page, unsigned int order, bool init) {}
-static inline void kasan_free_pages(struct page *page, unsigned int order, bool init) {}
+static inline void kasan_poison_pages(struct page *page, unsigned int order,
+				      bool init) {}
+static inline void kasan_unpoison_pages(struct page *page, unsigned int order,
+					bool init) {}
 static inline void kasan_cache_create(struct kmem_cache *cache,
 				      unsigned int *size,
 				      slab_flags_t *flags) {}
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 6bb87f2acd4e..0ecd293af344 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -97,7 +97,7 @@ slab_flags_t __kasan_never_merge(void)
 	return 0;
 }
 
-void __kasan_alloc_pages(struct page *page, unsigned int order, bool init)
+void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
 {
 	u8 tag;
 	unsigned long i;
@@ -111,7 +111,7 @@ void __kasan_alloc_pages(struct page *page, unsigned int order, bool init)
 	kasan_unpoison(page_address(page), PAGE_SIZE << order, init);
 }
 
-void __kasan_free_pages(struct page *page, unsigned int order, bool init)
+void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
 {
 	if (likely(!PageHighMem(page)))
 		kasan_poison(page_address(page), PAGE_SIZE << order,
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 4004388b4e4b..9d0f6f934016 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -238,6 +238,28 @@ struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 	return &alloc_meta->free_track[0];
 }
 
+void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
+{
+	/*
+	 * This condition should match the one in post_alloc_hook() in
+	 * page_alloc.c.
+	 */
+	bool init = !want_init_on_free() && want_init_on_alloc(flags);
+
+	kasan_unpoison_pages(page, order, init);
+}
+
+void kasan_free_pages(struct page *page, unsigned int order)
+{
+	/*
+	 * This condition should match the one in free_pages_prepare() in
+	 * page_alloc.c.
+	 */
+	bool init = want_init_on_free();
+
+	kasan_poison_pages(page, order, init);
+}
+
 #if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 
 void kasan_set_tagging_report_once(bool state)
diff --git a/mm/mempool.c b/mm/mempool.c
index a258cf4de575..0b8afbec3e35 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -106,7 +106,8 @@ static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
 	if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
 		kasan_slab_free_mempool(element);
 	else if (pool->alloc == mempool_alloc_pages)
-		kasan_free_pages(element, (unsigned long)pool->pool_data, false);
+		kasan_poison_pages(element, (unsigned long)pool->pool_data,
+				   false);
 }
 
 static void kasan_unpoison_element(mempool_t *pool, void *element)
@@ -114,7 +115,8 @@ static void kasan_unpoison_element(mempool_t *pool, void *element)
 	if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
 		kasan_unpoison_range(element, __ksize(element));
 	else if (pool->alloc == mempool_alloc_pages)
-		kasan_alloc_pages(element, (unsigned long)pool->pool_data, false);
+		kasan_unpoison_pages(element, (unsigned long)pool->pool_data,
+				     false);
 }
 
 static __always_inline void add_element(mempool_t *pool, void *element)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index aaa1655cf682..4fddb7cac3c6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -382,7 +382,7 @@ int page_group_by_mobility_disabled __read_mostly;
 static DEFINE_STATIC_KEY_TRUE(deferred_pages);
 
 /*
- * Calling kasan_free_pages() only after deferred memory initialization
+ * Calling kasan_poison_pages() only after deferred memory initialization
  * has completed. Poisoning pages during deferred memory init will greatly
  * lengthen the process and cause problem in large memory systems as the
  * deferred pages initialization is done with interrupt disabled.
@@ -394,15 +394,11 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages);
  * on-demand allocation and then freed again before the deferred pages
  * initialization is done, but this is not likely to happen.
  */
-static inline void kasan_free_nondeferred_pages(struct page *page, int order,
-						bool init, fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
 {
-	if (static_branch_unlikely(&deferred_pages))
-		return;
-	if (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-			(fpi_flags & FPI_SKIP_KASAN_POISON))
-		return;
-	kasan_free_pages(page, order, init);
+	return static_branch_unlikely(&deferred_pages) ||
+	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+		(fpi_flags & FPI_SKIP_KASAN_POISON));
 }
 
 /* Returns true if the struct page for the pfn is uninitialised */
@@ -453,13 +449,10 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 	return false;
 }
 #else
-static inline void kasan_free_nondeferred_pages(struct page *page, int order,
-						bool init, fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
 {
-	if (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-			(fpi_flags & FPI_SKIP_KASAN_POISON))
-		return;
-	kasan_free_pages(page, order, init);
+	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+		(fpi_flags & FPI_SKIP_KASAN_POISON));
 }
 
 static inline bool early_page_uninitialised(unsigned long pfn)
@@ -1245,7 +1238,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 			unsigned int order, bool check_free, fpi_t fpi_flags)
 {
 	int bad = 0;
-	bool init;
+	bool skip_kasan_poison = should_skip_kasan_poison(fpi_flags);
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
@@ -1314,10 +1307,17 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	 * With hardware tag-based KASAN, memory tags must be set before the
 	 * page becomes unavailable via debug_pagealloc or arch_free_page.
 	 */
-	init = want_init_on_free();
-	if (init && !kasan_has_integrated_init())
-		kernel_init_free_pages(page, 1 << order);
-	kasan_free_nondeferred_pages(page, order, init, fpi_flags);
+	if (kasan_has_integrated_init()) {
+		if (!skip_kasan_poison)
+			kasan_free_pages(page, order);
+	} else {
+		bool init = want_init_on_free();
+
+		if (init)
+			kernel_init_free_pages(page, 1 << order);
+		if (!skip_kasan_poison)
+			kasan_poison_pages(page, order, init);
+	}
 
 	/*
 	 * arch_free_page() can make the page's contents inaccessible.  s390
@@ -2324,8 +2324,6 @@ static bool check_new_pages(struct page *page, unsigned int order)
 inline void post_alloc_hook(struct page *page, unsigned int order,
 				gfp_t gfp_flags)
 {
-	bool init;
-
 	set_page_private(page, 0);
 	set_page_refcounted(page);
 
@@ -2344,10 +2342,15 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 	 * kasan_alloc_pages and kernel_init_free_pages must be
 	 * kept together to avoid discrepancies in behavior.
 	 */
-	init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
-	kasan_alloc_pages(page, order, init);
-	if (init && !kasan_has_integrated_init())
-		kernel_init_free_pages(page, 1 << order);
+	if (kasan_has_integrated_init()) {
+		kasan_alloc_pages(page, order, gfp_flags);
+	} else {
+		bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
+
+		kasan_unpoison_pages(page, order, init);
+		if (init)
+			kernel_init_free_pages(page, 1 << order);
+	}
 
 	set_page_owner(page, order, gfp_flags);
 }
-- 
2.32.0.rc1.229.g3e70b5a671-goog



^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 2/4] kasan: use separate (un)poison implementation for integrated init
@ 2021-06-02 23:52   ` Peter Collingbourne
  0 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Currently with integrated init page_alloc.c needs to know whether
kasan_alloc_pages() will zero initialize memory, but this will start
becoming more complicated once we start adding tag initialization
support for user pages. To avoid page_alloc.c needing to know more
details of what integrated init will do, move the unpoisoning logic
for integrated init into the HW tags implementation. Currently the
logic is identical but it will diverge in subsequent patches.

For symmetry do the same for poisoning although this logic will
be unaffected by subsequent patches.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I2c550234c6c4a893c48c18ff0c6ce658c7c67056
---
v4:
- use IS_ENABLED(CONFIG_KASAN)
- add comments to kasan_alloc_pages and kasan_free_pages
- remove line break

v3:
- use BUILD_BUG()

v2:
- fix build with KASAN disabled

 include/linux/kasan.h | 64 +++++++++++++++++++++++++------------------
 mm/kasan/common.c     |  4 +--
 mm/kasan/hw_tags.c    | 22 +++++++++++++++
 mm/mempool.c          |  6 ++--
 mm/page_alloc.c       | 55 +++++++++++++++++++------------------
 5 files changed, 95 insertions(+), 56 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index b1678a61e6a7..a1c7ce5f3e4f 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -2,6 +2,7 @@
 #ifndef _LINUX_KASAN_H
 #define _LINUX_KASAN_H
 
+#include <linux/bug.h>
 #include <linux/static_key.h>
 #include <linux/types.h>
 
@@ -79,14 +80,6 @@ static inline void kasan_disable_current(void) {}
 
 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 
-#ifdef CONFIG_KASAN
-
-struct kasan_cache {
-	int alloc_meta_offset;
-	int free_meta_offset;
-	bool is_kmalloc;
-};
-
 #ifdef CONFIG_KASAN_HW_TAGS
 
 DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
@@ -101,11 +94,14 @@ static inline bool kasan_has_integrated_init(void)
 	return kasan_enabled();
 }
 
+void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags);
+void kasan_free_pages(struct page *page, unsigned int order);
+
 #else /* CONFIG_KASAN_HW_TAGS */
 
 static inline bool kasan_enabled(void)
 {
-	return true;
+	return IS_ENABLED(CONFIG_KASAN);
 }
 
 static inline bool kasan_has_integrated_init(void)
@@ -113,8 +109,30 @@ static inline bool kasan_has_integrated_init(void)
 	return false;
 }
 
+static __always_inline void kasan_alloc_pages(struct page *page,
+					      unsigned int order, gfp_t flags)
+{
+	/* Only available for integrated init. */
+	BUILD_BUG();
+}
+
+static __always_inline void kasan_free_pages(struct page *page,
+					     unsigned int order)
+{
+	/* Only available for integrated init. */
+	BUILD_BUG();
+}
+
 #endif /* CONFIG_KASAN_HW_TAGS */
 
+#ifdef CONFIG_KASAN
+
+struct kasan_cache {
+	int alloc_meta_offset;
+	int free_meta_offset;
+	bool is_kmalloc;
+};
+
 slab_flags_t __kasan_never_merge(void);
 static __always_inline slab_flags_t kasan_never_merge(void)
 {
@@ -130,20 +148,20 @@ static __always_inline void kasan_unpoison_range(const void *addr, size_t size)
 		__kasan_unpoison_range(addr, size);
 }
 
-void __kasan_alloc_pages(struct page *page, unsigned int order, bool init);
-static __always_inline void kasan_alloc_pages(struct page *page,
+void __kasan_poison_pages(struct page *page, unsigned int order, bool init);
+static __always_inline void kasan_poison_pages(struct page *page,
 						unsigned int order, bool init)
 {
 	if (kasan_enabled())
-		__kasan_alloc_pages(page, order, init);
+		__kasan_poison_pages(page, order, init);
 }
 
-void __kasan_free_pages(struct page *page, unsigned int order, bool init);
-static __always_inline void kasan_free_pages(struct page *page,
-						unsigned int order, bool init)
+void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init);
+static __always_inline void kasan_unpoison_pages(struct page *page,
+						 unsigned int order, bool init)
 {
 	if (kasan_enabled())
-		__kasan_free_pages(page, order, init);
+		__kasan_unpoison_pages(page, order, init);
 }
 
 void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
@@ -285,21 +303,15 @@ void kasan_restore_multi_shot(bool enabled);
 
 #else /* CONFIG_KASAN */
 
-static inline bool kasan_enabled(void)
-{
-	return false;
-}
-static inline bool kasan_has_integrated_init(void)
-{
-	return false;
-}
 static inline slab_flags_t kasan_never_merge(void)
 {
 	return 0;
 }
 static inline void kasan_unpoison_range(const void *address, size_t size) {}
-static inline void kasan_alloc_pages(struct page *page, unsigned int order, bool init) {}
-static inline void kasan_free_pages(struct page *page, unsigned int order, bool init) {}
+static inline void kasan_poison_pages(struct page *page, unsigned int order,
+				      bool init) {}
+static inline void kasan_unpoison_pages(struct page *page, unsigned int order,
+					bool init) {}
 static inline void kasan_cache_create(struct kmem_cache *cache,
 				      unsigned int *size,
 				      slab_flags_t *flags) {}
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 6bb87f2acd4e..0ecd293af344 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -97,7 +97,7 @@ slab_flags_t __kasan_never_merge(void)
 	return 0;
 }
 
-void __kasan_alloc_pages(struct page *page, unsigned int order, bool init)
+void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
 {
 	u8 tag;
 	unsigned long i;
@@ -111,7 +111,7 @@ void __kasan_alloc_pages(struct page *page, unsigned int order, bool init)
 	kasan_unpoison(page_address(page), PAGE_SIZE << order, init);
 }
 
-void __kasan_free_pages(struct page *page, unsigned int order, bool init)
+void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
 {
 	if (likely(!PageHighMem(page)))
 		kasan_poison(page_address(page), PAGE_SIZE << order,
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 4004388b4e4b..9d0f6f934016 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -238,6 +238,28 @@ struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
 	return &alloc_meta->free_track[0];
 }
 
+void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
+{
+	/*
+	 * This condition should match the one in post_alloc_hook() in
+	 * page_alloc.c.
+	 */
+	bool init = !want_init_on_free() && want_init_on_alloc(flags);
+
+	kasan_unpoison_pages(page, order, init);
+}
+
+void kasan_free_pages(struct page *page, unsigned int order)
+{
+	/*
+	 * This condition should match the one in free_pages_prepare() in
+	 * page_alloc.c.
+	 */
+	bool init = want_init_on_free();
+
+	kasan_poison_pages(page, order, init);
+}
+
 #if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 
 void kasan_set_tagging_report_once(bool state)
diff --git a/mm/mempool.c b/mm/mempool.c
index a258cf4de575..0b8afbec3e35 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -106,7 +106,8 @@ static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
 	if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
 		kasan_slab_free_mempool(element);
 	else if (pool->alloc == mempool_alloc_pages)
-		kasan_free_pages(element, (unsigned long)pool->pool_data, false);
+		kasan_poison_pages(element, (unsigned long)pool->pool_data,
+				   false);
 }
 
 static void kasan_unpoison_element(mempool_t *pool, void *element)
@@ -114,7 +115,8 @@ static void kasan_unpoison_element(mempool_t *pool, void *element)
 	if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
 		kasan_unpoison_range(element, __ksize(element));
 	else if (pool->alloc == mempool_alloc_pages)
-		kasan_alloc_pages(element, (unsigned long)pool->pool_data, false);
+		kasan_unpoison_pages(element, (unsigned long)pool->pool_data,
+				     false);
 }
 
 static __always_inline void add_element(mempool_t *pool, void *element)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index aaa1655cf682..4fddb7cac3c6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -382,7 +382,7 @@ int page_group_by_mobility_disabled __read_mostly;
 static DEFINE_STATIC_KEY_TRUE(deferred_pages);
 
 /*
- * Calling kasan_free_pages() only after deferred memory initialization
+ * Calling kasan_poison_pages() only after deferred memory initialization
  * has completed. Poisoning pages during deferred memory init will greatly
  * lengthen the process and cause problem in large memory systems as the
  * deferred pages initialization is done with interrupt disabled.
@@ -394,15 +394,11 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages);
  * on-demand allocation and then freed again before the deferred pages
  * initialization is done, but this is not likely to happen.
  */
-static inline void kasan_free_nondeferred_pages(struct page *page, int order,
-						bool init, fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
 {
-	if (static_branch_unlikely(&deferred_pages))
-		return;
-	if (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-			(fpi_flags & FPI_SKIP_KASAN_POISON))
-		return;
-	kasan_free_pages(page, order, init);
+	return static_branch_unlikely(&deferred_pages) ||
+	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+		(fpi_flags & FPI_SKIP_KASAN_POISON));
 }
 
 /* Returns true if the struct page for the pfn is uninitialised */
@@ -453,13 +449,10 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 	return false;
 }
 #else
-static inline void kasan_free_nondeferred_pages(struct page *page, int order,
-						bool init, fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
 {
-	if (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-			(fpi_flags & FPI_SKIP_KASAN_POISON))
-		return;
-	kasan_free_pages(page, order, init);
+	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+		(fpi_flags & FPI_SKIP_KASAN_POISON));
 }
 
 static inline bool early_page_uninitialised(unsigned long pfn)
@@ -1245,7 +1238,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 			unsigned int order, bool check_free, fpi_t fpi_flags)
 {
 	int bad = 0;
-	bool init;
+	bool skip_kasan_poison = should_skip_kasan_poison(fpi_flags);
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
@@ -1314,10 +1307,17 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	 * With hardware tag-based KASAN, memory tags must be set before the
 	 * page becomes unavailable via debug_pagealloc or arch_free_page.
 	 */
-	init = want_init_on_free();
-	if (init && !kasan_has_integrated_init())
-		kernel_init_free_pages(page, 1 << order);
-	kasan_free_nondeferred_pages(page, order, init, fpi_flags);
+	if (kasan_has_integrated_init()) {
+		if (!skip_kasan_poison)
+			kasan_free_pages(page, order);
+	} else {
+		bool init = want_init_on_free();
+
+		if (init)
+			kernel_init_free_pages(page, 1 << order);
+		if (!skip_kasan_poison)
+			kasan_poison_pages(page, order, init);
+	}
 
 	/*
 	 * arch_free_page() can make the page's contents inaccessible.  s390
@@ -2324,8 +2324,6 @@ static bool check_new_pages(struct page *page, unsigned int order)
 inline void post_alloc_hook(struct page *page, unsigned int order,
 				gfp_t gfp_flags)
 {
-	bool init;
-
 	set_page_private(page, 0);
 	set_page_refcounted(page);
 
@@ -2344,10 +2342,15 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 	 * kasan_alloc_pages and kernel_init_free_pages must be
 	 * kept together to avoid discrepancies in behavior.
 	 */
-	init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
-	kasan_alloc_pages(page, order, init);
-	if (init && !kasan_has_integrated_init())
-		kernel_init_free_pages(page, 1 << order);
+	if (kasan_has_integrated_init()) {
+		kasan_alloc_pages(page, order, gfp_flags);
+	} else {
+		bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
+
+		kasan_unpoison_pages(page, order, init);
+		if (init)
+			kernel_init_free_pages(page, 1 << order);
+	}
 
 	set_page_owner(page, order, gfp_flags);
 }
-- 
2.32.0.rc1.229.g3e70b5a671-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 3/4] arm64: mte: handle tags zeroing at page allocation time
  2021-06-02 23:52 ` Peter Collingbourne
@ 2021-06-02 23:52   ` Peter Collingbourne
  -1 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Currently, on an anonymous page fault, the kernel allocates a zeroed
page and maps it in user space. If the mapping is tagged (PROT_MTE),
set_pte_at() additionally clears the tags. It is, however, more
efficient to clear the tags at the same time as zeroing the data on
allocation. To avoid clearing the tags on any page (which may not be
mapped as tagged), only do this if the vma flags contain VM_MTE. This
requires introducing a new GFP flag that is used to determine whether
to clear the tags.

The DC GZVA instruction with a 0 top byte (and 0 tag) requires
top-byte-ignore. Set the TCR_EL1.{TBI1,TBID1} bits irrespective of
whether KASAN_HW is enabled.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://linux-review.googlesource.com/id/Id46dc94e30fe11474f7e54f5d65e7658dbdddb26
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
---
v2:
- remove want_zero_tags_on_free()

 arch/arm64/include/asm/mte.h  |  4 ++++
 arch/arm64/include/asm/page.h |  8 ++++++--
 arch/arm64/lib/mte.S          | 20 ++++++++++++++++++++
 arch/arm64/mm/fault.c         | 26 ++++++++++++++++++++++++++
 arch/arm64/mm/proc.S          | 10 +++++++---
 include/linux/gfp.h           |  9 +++++++--
 include/linux/highmem.h       |  8 ++++++++
 mm/kasan/hw_tags.c            |  9 ++++++++-
 mm/page_alloc.c               | 13 ++++++++++---
 9 files changed, 96 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index bc88a1ced0d7..67bf259ae768 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -37,6 +37,7 @@ void mte_free_tag_storage(char *storage);
 /* track which pages have valid allocation tags */
 #define PG_mte_tagged	PG_arch_2
 
+void mte_zero_clear_page_tags(void *addr);
 void mte_sync_tags(pte_t *ptep, pte_t pte);
 void mte_copy_page_tags(void *kto, const void *kfrom);
 void mte_thread_init_user(void);
@@ -53,6 +54,9 @@ int mte_ptrace_copy_tags(struct task_struct *child, long request,
 /* unused if !CONFIG_ARM64_MTE, silence the compiler */
 #define PG_mte_tagged	0
 
+static inline void mte_zero_clear_page_tags(void *addr)
+{
+}
 static inline void mte_sync_tags(pte_t *ptep, pte_t pte)
 {
 }
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index e1fc0f60e79f..ed1b9dcf12b2 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -13,6 +13,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/personality.h> /* for READ_IMPLIES_EXEC */
+#include <linux/types.h> /* for gfp_t */
 #include <asm/pgtable-types.h>
 
 struct page;
@@ -28,10 +29,13 @@ void copy_user_highpage(struct page *to, struct page *from,
 void copy_highpage(struct page *to, struct page *from);
 #define __HAVE_ARCH_COPY_HIGHPAGE
 
-#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+						unsigned long vaddr);
 #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
+void tag_clear_highpage(struct page *to);
+#define __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
+
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S
index 351537c12f36..e83643b3995f 100644
--- a/arch/arm64/lib/mte.S
+++ b/arch/arm64/lib/mte.S
@@ -36,6 +36,26 @@ SYM_FUNC_START(mte_clear_page_tags)
 	ret
 SYM_FUNC_END(mte_clear_page_tags)
 
+/*
+ * Zero the page and tags at the same time
+ *
+ * Parameters:
+ *	x0 - address to the beginning of the page
+ */
+SYM_FUNC_START(mte_zero_clear_page_tags)
+	mrs	x1, dczid_el0
+	and	w1, w1, #0xf
+	mov	x2, #4
+	lsl	x1, x2, x1
+	and	x0, x0, #(1 << MTE_TAG_SHIFT) - 1	// clear the tag
+
+1:	dc	gzva, x0
+	add	x0, x0, x1
+	tst	x0, #(PAGE_SIZE - 1)
+	b.ne	1b
+	ret
+SYM_FUNC_END(mte_zero_clear_page_tags)
+
 /*
  * Copy the tags from the source page to the destination one
  *   x0 - address of the destination page
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 871c82ab0a30..180c0343d82a 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -921,3 +921,29 @@ void do_debug_exception(unsigned long addr_if_watchpoint, unsigned int esr,
 	debug_exception_exit(regs);
 }
 NOKPROBE_SYMBOL(do_debug_exception);
+
+/*
+ * Used during anonymous page fault handling.
+ */
+struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+						unsigned long vaddr)
+{
+	gfp_t flags = GFP_HIGHUSER_MOVABLE | __GFP_ZERO;
+
+	/*
+	 * If the page is mapped with PROT_MTE, initialise the tags at the
+	 * point of allocation and page zeroing as this is usually faster than
+	 * separate DC ZVA and STGM.
+	 */
+	if (vma->vm_flags & VM_MTE)
+		flags |= __GFP_ZEROTAGS;
+
+	return alloc_page_vma(flags, vma, vaddr);
+}
+
+void tag_clear_highpage(struct page *page)
+{
+	mte_zero_clear_page_tags(page_address(page));
+	page_kasan_tag_reset(page);
+	set_bit(PG_mte_tagged, &page->flags);
+}
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 97d7bcd8d4f2..48fd1df3d05a 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -46,9 +46,13 @@
 #endif
 
 #ifdef CONFIG_KASAN_HW_TAGS
-#define TCR_KASAN_HW_FLAGS SYS_TCR_EL1_TCMA1 | TCR_TBI1 | TCR_TBID1
+#define TCR_MTE_FLAGS SYS_TCR_EL1_TCMA1 | TCR_TBI1 | TCR_TBID1
 #else
-#define TCR_KASAN_HW_FLAGS 0
+/*
+ * The mte_zero_clear_page_tags() implementation uses DC GZVA, which relies on
+ * TBI being enabled at EL1.
+ */
+#define TCR_MTE_FLAGS TCR_TBI1 | TCR_TBID1
 #endif
 
 /*
@@ -464,7 +468,7 @@ SYM_FUNC_START(__cpu_setup)
 	msr_s	SYS_TFSRE0_EL1, xzr
 
 	/* set the TCR_EL1 bits */
-	mov_q	x10, TCR_KASAN_HW_FLAGS
+	mov_q	x10, TCR_MTE_FLAGS
 	orr	tcr, tcr, x10
 1:
 #endif
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 11da8af06704..68ba237365dc 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -53,8 +53,9 @@ struct vm_area_struct;
 #define ___GFP_HARDWALL		0x100000u
 #define ___GFP_THISNODE		0x200000u
 #define ___GFP_ACCOUNT		0x400000u
+#define ___GFP_ZEROTAGS		0x800000u
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x800000u
+#define ___GFP_NOLOCKDEP	0x1000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
@@ -229,16 +230,20 @@ struct vm_area_struct;
  * %__GFP_COMP address compound page metadata.
  *
  * %__GFP_ZERO returns a zeroed page on success.
+ *
+ * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
+ * __GFP_ZERO is set.
  */
 #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)
 
 /* 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 (24 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 54d0643b8fcf..8c6e8e996c87 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -185,6 +185,14 @@ static inline void clear_highpage(struct page *page)
 	kunmap_atomic(kaddr);
 }
 
+#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
+
+static inline void tag_clear_highpage(struct page *page)
+{
+}
+
+#endif
+
 /*
  * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
  * If we pass in a head page, we can zero up to the size of the compound page.
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 9d0f6f934016..41fd5326ee0a 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -246,7 +246,14 @@ void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
 	 */
 	bool init = !want_init_on_free() && want_init_on_alloc(flags);
 
-	kasan_unpoison_pages(page, order, init);
+	if (flags & __GFP_ZEROTAGS) {
+		int i;
+
+		for (i = 0; i != 1 << order; ++i)
+			tag_clear_highpage(page + i);
+	} else {
+		kasan_unpoison_pages(page, order, init);
+	}
 }
 
 void kasan_free_pages(struct page *page, unsigned int order)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4fddb7cac3c6..13937e793fda 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1219,10 +1219,16 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
 	return ret;
 }
 
-static void kernel_init_free_pages(struct page *page, int numpages)
+static void kernel_init_free_pages(struct page *page, int numpages, bool zero_tags)
 {
 	int i;
 
+	if (zero_tags) {
+		for (i = 0; i < numpages; i++)
+			tag_clear_highpage(page + i);
+		return;
+	}
+
 	/* s390's use of memset() could override KASAN redzones. */
 	kasan_disable_current();
 	for (i = 0; i < numpages; i++) {
@@ -1314,7 +1320,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 		bool init = want_init_on_free();
 
 		if (init)
-			kernel_init_free_pages(page, 1 << order);
+			kernel_init_free_pages(page, 1 << order, false);
 		if (!skip_kasan_poison)
 			kasan_poison_pages(page, order, init);
 	}
@@ -2349,7 +2355,8 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 
 		kasan_unpoison_pages(page, order, init);
 		if (init)
-			kernel_init_free_pages(page, 1 << order);
+			kernel_init_free_pages(page, 1 << order,
+					       gfp_flags & __GFP_ZEROTAGS);
 	}
 
 	set_page_owner(page, order, gfp_flags);
-- 
2.32.0.rc1.229.g3e70b5a671-goog



^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 3/4] arm64: mte: handle tags zeroing at page allocation time
@ 2021-06-02 23:52   ` Peter Collingbourne
  0 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Currently, on an anonymous page fault, the kernel allocates a zeroed
page and maps it in user space. If the mapping is tagged (PROT_MTE),
set_pte_at() additionally clears the tags. It is, however, more
efficient to clear the tags at the same time as zeroing the data on
allocation. To avoid clearing the tags on any page (which may not be
mapped as tagged), only do this if the vma flags contain VM_MTE. This
requires introducing a new GFP flag that is used to determine whether
to clear the tags.

The DC GZVA instruction with a 0 top byte (and 0 tag) requires
top-byte-ignore. Set the TCR_EL1.{TBI1,TBID1} bits irrespective of
whether KASAN_HW is enabled.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://linux-review.googlesource.com/id/Id46dc94e30fe11474f7e54f5d65e7658dbdddb26
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
---
v2:
- remove want_zero_tags_on_free()

 arch/arm64/include/asm/mte.h  |  4 ++++
 arch/arm64/include/asm/page.h |  8 ++++++--
 arch/arm64/lib/mte.S          | 20 ++++++++++++++++++++
 arch/arm64/mm/fault.c         | 26 ++++++++++++++++++++++++++
 arch/arm64/mm/proc.S          | 10 +++++++---
 include/linux/gfp.h           |  9 +++++++--
 include/linux/highmem.h       |  8 ++++++++
 mm/kasan/hw_tags.c            |  9 ++++++++-
 mm/page_alloc.c               | 13 ++++++++++---
 9 files changed, 96 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index bc88a1ced0d7..67bf259ae768 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -37,6 +37,7 @@ void mte_free_tag_storage(char *storage);
 /* track which pages have valid allocation tags */
 #define PG_mte_tagged	PG_arch_2
 
+void mte_zero_clear_page_tags(void *addr);
 void mte_sync_tags(pte_t *ptep, pte_t pte);
 void mte_copy_page_tags(void *kto, const void *kfrom);
 void mte_thread_init_user(void);
@@ -53,6 +54,9 @@ int mte_ptrace_copy_tags(struct task_struct *child, long request,
 /* unused if !CONFIG_ARM64_MTE, silence the compiler */
 #define PG_mte_tagged	0
 
+static inline void mte_zero_clear_page_tags(void *addr)
+{
+}
 static inline void mte_sync_tags(pte_t *ptep, pte_t pte)
 {
 }
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index e1fc0f60e79f..ed1b9dcf12b2 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -13,6 +13,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/personality.h> /* for READ_IMPLIES_EXEC */
+#include <linux/types.h> /* for gfp_t */
 #include <asm/pgtable-types.h>
 
 struct page;
@@ -28,10 +29,13 @@ void copy_user_highpage(struct page *to, struct page *from,
 void copy_highpage(struct page *to, struct page *from);
 #define __HAVE_ARCH_COPY_HIGHPAGE
 
-#define alloc_zeroed_user_highpage_movable(vma, vaddr) \
-	alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, vma, vaddr)
+struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+						unsigned long vaddr);
 #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
 
+void tag_clear_highpage(struct page *to);
+#define __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
+
 #define clear_user_page(page, vaddr, pg)	clear_page(page)
 #define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 
diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S
index 351537c12f36..e83643b3995f 100644
--- a/arch/arm64/lib/mte.S
+++ b/arch/arm64/lib/mte.S
@@ -36,6 +36,26 @@ SYM_FUNC_START(mte_clear_page_tags)
 	ret
 SYM_FUNC_END(mte_clear_page_tags)
 
+/*
+ * Zero the page and tags at the same time
+ *
+ * Parameters:
+ *	x0 - address to the beginning of the page
+ */
+SYM_FUNC_START(mte_zero_clear_page_tags)
+	mrs	x1, dczid_el0
+	and	w1, w1, #0xf
+	mov	x2, #4
+	lsl	x1, x2, x1
+	and	x0, x0, #(1 << MTE_TAG_SHIFT) - 1	// clear the tag
+
+1:	dc	gzva, x0
+	add	x0, x0, x1
+	tst	x0, #(PAGE_SIZE - 1)
+	b.ne	1b
+	ret
+SYM_FUNC_END(mte_zero_clear_page_tags)
+
 /*
  * Copy the tags from the source page to the destination one
  *   x0 - address of the destination page
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 871c82ab0a30..180c0343d82a 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -921,3 +921,29 @@ void do_debug_exception(unsigned long addr_if_watchpoint, unsigned int esr,
 	debug_exception_exit(regs);
 }
 NOKPROBE_SYMBOL(do_debug_exception);
+
+/*
+ * Used during anonymous page fault handling.
+ */
+struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
+						unsigned long vaddr)
+{
+	gfp_t flags = GFP_HIGHUSER_MOVABLE | __GFP_ZERO;
+
+	/*
+	 * If the page is mapped with PROT_MTE, initialise the tags at the
+	 * point of allocation and page zeroing as this is usually faster than
+	 * separate DC ZVA and STGM.
+	 */
+	if (vma->vm_flags & VM_MTE)
+		flags |= __GFP_ZEROTAGS;
+
+	return alloc_page_vma(flags, vma, vaddr);
+}
+
+void tag_clear_highpage(struct page *page)
+{
+	mte_zero_clear_page_tags(page_address(page));
+	page_kasan_tag_reset(page);
+	set_bit(PG_mte_tagged, &page->flags);
+}
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 97d7bcd8d4f2..48fd1df3d05a 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -46,9 +46,13 @@
 #endif
 
 #ifdef CONFIG_KASAN_HW_TAGS
-#define TCR_KASAN_HW_FLAGS SYS_TCR_EL1_TCMA1 | TCR_TBI1 | TCR_TBID1
+#define TCR_MTE_FLAGS SYS_TCR_EL1_TCMA1 | TCR_TBI1 | TCR_TBID1
 #else
-#define TCR_KASAN_HW_FLAGS 0
+/*
+ * The mte_zero_clear_page_tags() implementation uses DC GZVA, which relies on
+ * TBI being enabled at EL1.
+ */
+#define TCR_MTE_FLAGS TCR_TBI1 | TCR_TBID1
 #endif
 
 /*
@@ -464,7 +468,7 @@ SYM_FUNC_START(__cpu_setup)
 	msr_s	SYS_TFSRE0_EL1, xzr
 
 	/* set the TCR_EL1 bits */
-	mov_q	x10, TCR_KASAN_HW_FLAGS
+	mov_q	x10, TCR_MTE_FLAGS
 	orr	tcr, tcr, x10
 1:
 #endif
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 11da8af06704..68ba237365dc 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -53,8 +53,9 @@ struct vm_area_struct;
 #define ___GFP_HARDWALL		0x100000u
 #define ___GFP_THISNODE		0x200000u
 #define ___GFP_ACCOUNT		0x400000u
+#define ___GFP_ZEROTAGS		0x800000u
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x800000u
+#define ___GFP_NOLOCKDEP	0x1000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
@@ -229,16 +230,20 @@ struct vm_area_struct;
  * %__GFP_COMP address compound page metadata.
  *
  * %__GFP_ZERO returns a zeroed page on success.
+ *
+ * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
+ * __GFP_ZERO is set.
  */
 #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)
 
 /* 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 (24 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 54d0643b8fcf..8c6e8e996c87 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -185,6 +185,14 @@ static inline void clear_highpage(struct page *page)
 	kunmap_atomic(kaddr);
 }
 
+#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
+
+static inline void tag_clear_highpage(struct page *page)
+{
+}
+
+#endif
+
 /*
  * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
  * If we pass in a head page, we can zero up to the size of the compound page.
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 9d0f6f934016..41fd5326ee0a 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -246,7 +246,14 @@ void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
 	 */
 	bool init = !want_init_on_free() && want_init_on_alloc(flags);
 
-	kasan_unpoison_pages(page, order, init);
+	if (flags & __GFP_ZEROTAGS) {
+		int i;
+
+		for (i = 0; i != 1 << order; ++i)
+			tag_clear_highpage(page + i);
+	} else {
+		kasan_unpoison_pages(page, order, init);
+	}
 }
 
 void kasan_free_pages(struct page *page, unsigned int order)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4fddb7cac3c6..13937e793fda 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1219,10 +1219,16 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
 	return ret;
 }
 
-static void kernel_init_free_pages(struct page *page, int numpages)
+static void kernel_init_free_pages(struct page *page, int numpages, bool zero_tags)
 {
 	int i;
 
+	if (zero_tags) {
+		for (i = 0; i < numpages; i++)
+			tag_clear_highpage(page + i);
+		return;
+	}
+
 	/* s390's use of memset() could override KASAN redzones. */
 	kasan_disable_current();
 	for (i = 0; i < numpages; i++) {
@@ -1314,7 +1320,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 		bool init = want_init_on_free();
 
 		if (init)
-			kernel_init_free_pages(page, 1 << order);
+			kernel_init_free_pages(page, 1 << order, false);
 		if (!skip_kasan_poison)
 			kasan_poison_pages(page, order, init);
 	}
@@ -2349,7 +2355,8 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 
 		kasan_unpoison_pages(page, order, init);
 		if (init)
-			kernel_init_free_pages(page, 1 << order);
+			kernel_init_free_pages(page, 1 << order,
+					       gfp_flags & __GFP_ZEROTAGS);
 	}
 
 	set_page_owner(page, order, gfp_flags);
-- 
2.32.0.rc1.229.g3e70b5a671-goog


_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 4/4] kasan: disable freed user page poisoning with HW tags
  2021-06-02 23:52 ` Peter Collingbourne
@ 2021-06-02 23:52   ` Peter Collingbourne
  -1 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Poisoning freed pages protects against kernel use-after-free. The
likelihood of such a bug involving kernel pages is significantly higher
than that for user pages. At the same time, poisoning freed pages can
impose a significant performance cost, which cannot always be justified
for user pages given the lower probability of finding a bug. Therefore,
disable freed user page poisoning when using HW tags. We identify
"user" pages via the flag set GFP_HIGHUSER_MOVABLE, which indicates
a strong likelihood of not being directly accessible to the kernel.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I716846e2de8ef179f44e835770df7e6307be96c9
---
v4:
- move flag to GFP_HIGHUSER_MOVABLE
- remove command line flag

 include/linux/gfp.h            | 13 ++++++++++---
 include/linux/page-flags.h     |  9 +++++++++
 include/trace/events/mmflags.h |  9 ++++++++-
 mm/kasan/hw_tags.c             |  3 +++
 mm/page_alloc.c                | 12 +++++++-----
 5 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 68ba237365dc..e6102dfa4faa 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -54,8 +54,9 @@ struct vm_area_struct;
 #define ___GFP_THISNODE		0x200000u
 #define ___GFP_ACCOUNT		0x400000u
 #define ___GFP_ZEROTAGS		0x800000u
+#define ___GFP_SKIP_KASAN_POISON	0x1000000u
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x1000000u
+#define ___GFP_NOLOCKDEP	0x2000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
@@ -233,17 +234,22 @@ struct vm_area_struct;
  *
  * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
  * __GFP_ZERO is set.
+ *
+ * %__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.
  */
 #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)
 
 /* 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_LOCKDEP))
+#define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**
@@ -324,7 +330,8 @@ struct vm_area_struct;
 #define GFP_DMA		__GFP_DMA
 #define GFP_DMA32	__GFP_DMA32
 #define GFP_HIGHUSER	(GFP_USER | __GFP_HIGHMEM)
-#define GFP_HIGHUSER_MOVABLE	(GFP_HIGHUSER | __GFP_MOVABLE)
+#define GFP_HIGHUSER_MOVABLE	(GFP_HIGHUSER | __GFP_MOVABLE | \
+			 __GFP_SKIP_KASAN_POISON)
 #define GFP_TRANSHUGE_LIGHT	((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
 			 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
 #define GFP_TRANSHUGE	(GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 04a34c08e0a6..40e2c5000585 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -137,6 +137,9 @@ enum pageflags {
 #endif
 #ifdef CONFIG_64BIT
 	PG_arch_2,
+#endif
+#ifdef CONFIG_KASAN_HW_TAGS
+	PG_skip_kasan_poison,
 #endif
 	__NR_PAGEFLAGS,
 
@@ -443,6 +446,12 @@ TESTCLEARFLAG(Young, young, PF_ANY)
 PAGEFLAG(Idle, idle, PF_ANY)
 #endif
 
+#ifdef CONFIG_KASAN_HW_TAGS
+PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
+#else
+PAGEFLAG_FALSE(SkipKASanPoison)
+#endif
+
 /*
  * PageReported() is used to track reported free pages within the Buddy
  * allocator. We can use the non-atomic version of the test and set
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 629c7a0eaff2..390270e00a1d 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -85,6 +85,12 @@
 #define IF_HAVE_PG_ARCH_2(flag,string)
 #endif
 
+#ifdef CONFIG_KASAN_HW_TAGS
+#define IF_HAVE_PG_SKIP_KASAN_POISON(flag,string) ,{1UL << flag, string}
+#else
+#define IF_HAVE_PG_SKIP_KASAN_POISON(flag,string)
+#endif
+
 #define __def_pageflag_names						\
 	{1UL << PG_locked,		"locked"	},		\
 	{1UL << PG_waiters,		"waiters"	},		\
@@ -112,7 +118,8 @@ IF_HAVE_PG_UNCACHED(PG_uncached,	"uncached"	)		\
 IF_HAVE_PG_HWPOISON(PG_hwpoison,	"hwpoison"	)		\
 IF_HAVE_PG_IDLE(PG_young,		"young"		)		\
 IF_HAVE_PG_IDLE(PG_idle,		"idle"		)		\
-IF_HAVE_PG_ARCH_2(PG_arch_2,		"arch_2"	)
+IF_HAVE_PG_ARCH_2(PG_arch_2,		"arch_2"	)		\
+IF_HAVE_PG_SKIP_KASAN_POISON(PG_skip_kasan_poison, "skip_kasan_poison")
 
 #define show_page_flags(flags)						\
 	(flags) ? __print_flags(flags, "|",				\
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 41fd5326ee0a..ed5e5b833d61 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -246,6 +246,9 @@ void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
 	 */
 	bool init = !want_init_on_free() && want_init_on_alloc(flags);
 
+	if (flags & __GFP_SKIP_KASAN_POISON)
+		SetPageSkipKASanPoison(page);
+
 	if (flags & __GFP_ZEROTAGS) {
 		int i;
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 13937e793fda..5ad76e540a22 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -394,11 +394,12 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages);
  * on-demand allocation and then freed again before the deferred pages
  * initialization is done, but this is not likely to happen.
  */
-static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
 {
 	return static_branch_unlikely(&deferred_pages) ||
 	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-		(fpi_flags & FPI_SKIP_KASAN_POISON));
+		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
+	       PageSkipKASanPoison(page);
 }
 
 /* Returns true if the struct page for the pfn is uninitialised */
@@ -449,10 +450,11 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 	return false;
 }
 #else
-static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
 {
 	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-		(fpi_flags & FPI_SKIP_KASAN_POISON));
+		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
+	       PageSkipKASanPoison(page);
 }
 
 static inline bool early_page_uninitialised(unsigned long pfn)
@@ -1244,7 +1246,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 			unsigned int order, bool check_free, fpi_t fpi_flags)
 {
 	int bad = 0;
-	bool skip_kasan_poison = should_skip_kasan_poison(fpi_flags);
+	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
-- 
2.32.0.rc1.229.g3e70b5a671-goog



^ permalink raw reply related	[flat|nested] 18+ messages in thread
* [PATCH v6 4/4] kasan: disable freed user page poisoning with HW tags
@ 2021-06-02 23:52   ` Peter Collingbourne
  0 siblings, 0 replies; 18+ messages in thread
From: Peter Collingbourne @ 2021-06-02 23:52 UTC (permalink / raw)
  To: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Andrew Morton, Jann Horn
  Cc: Peter Collingbourne, Evgenii Stepanov, linux-mm, linux-arm-kernel

Poisoning freed pages protects against kernel use-after-free. The
likelihood of such a bug involving kernel pages is significantly higher
than that for user pages. At the same time, poisoning freed pages can
impose a significant performance cost, which cannot always be justified
for user pages given the lower probability of finding a bug. Therefore,
disable freed user page poisoning when using HW tags. We identify
"user" pages via the flag set GFP_HIGHUSER_MOVABLE, which indicates
a strong likelihood of not being directly accessible to the kernel.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I716846e2de8ef179f44e835770df7e6307be96c9
---
v4:
- move flag to GFP_HIGHUSER_MOVABLE
- remove command line flag

 include/linux/gfp.h            | 13 ++++++++++---
 include/linux/page-flags.h     |  9 +++++++++
 include/trace/events/mmflags.h |  9 ++++++++-
 mm/kasan/hw_tags.c             |  3 +++
 mm/page_alloc.c                | 12 +++++++-----
 5 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 68ba237365dc..e6102dfa4faa 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -54,8 +54,9 @@ struct vm_area_struct;
 #define ___GFP_THISNODE		0x200000u
 #define ___GFP_ACCOUNT		0x400000u
 #define ___GFP_ZEROTAGS		0x800000u
+#define ___GFP_SKIP_KASAN_POISON	0x1000000u
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x1000000u
+#define ___GFP_NOLOCKDEP	0x2000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif
@@ -233,17 +234,22 @@ struct vm_area_struct;
  *
  * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
  * __GFP_ZERO is set.
+ *
+ * %__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.
  */
 #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)
 
 /* 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_LOCKDEP))
+#define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**
@@ -324,7 +330,8 @@ struct vm_area_struct;
 #define GFP_DMA		__GFP_DMA
 #define GFP_DMA32	__GFP_DMA32
 #define GFP_HIGHUSER	(GFP_USER | __GFP_HIGHMEM)
-#define GFP_HIGHUSER_MOVABLE	(GFP_HIGHUSER | __GFP_MOVABLE)
+#define GFP_HIGHUSER_MOVABLE	(GFP_HIGHUSER | __GFP_MOVABLE | \
+			 __GFP_SKIP_KASAN_POISON)
 #define GFP_TRANSHUGE_LIGHT	((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
 			 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
 #define GFP_TRANSHUGE	(GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 04a34c08e0a6..40e2c5000585 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -137,6 +137,9 @@ enum pageflags {
 #endif
 #ifdef CONFIG_64BIT
 	PG_arch_2,
+#endif
+#ifdef CONFIG_KASAN_HW_TAGS
+	PG_skip_kasan_poison,
 #endif
 	__NR_PAGEFLAGS,
 
@@ -443,6 +446,12 @@ TESTCLEARFLAG(Young, young, PF_ANY)
 PAGEFLAG(Idle, idle, PF_ANY)
 #endif
 
+#ifdef CONFIG_KASAN_HW_TAGS
+PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
+#else
+PAGEFLAG_FALSE(SkipKASanPoison)
+#endif
+
 /*
  * PageReported() is used to track reported free pages within the Buddy
  * allocator. We can use the non-atomic version of the test and set
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 629c7a0eaff2..390270e00a1d 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -85,6 +85,12 @@
 #define IF_HAVE_PG_ARCH_2(flag,string)
 #endif
 
+#ifdef CONFIG_KASAN_HW_TAGS
+#define IF_HAVE_PG_SKIP_KASAN_POISON(flag,string) ,{1UL << flag, string}
+#else
+#define IF_HAVE_PG_SKIP_KASAN_POISON(flag,string)
+#endif
+
 #define __def_pageflag_names						\
 	{1UL << PG_locked,		"locked"	},		\
 	{1UL << PG_waiters,		"waiters"	},		\
@@ -112,7 +118,8 @@ IF_HAVE_PG_UNCACHED(PG_uncached,	"uncached"	)		\
 IF_HAVE_PG_HWPOISON(PG_hwpoison,	"hwpoison"	)		\
 IF_HAVE_PG_IDLE(PG_young,		"young"		)		\
 IF_HAVE_PG_IDLE(PG_idle,		"idle"		)		\
-IF_HAVE_PG_ARCH_2(PG_arch_2,		"arch_2"	)
+IF_HAVE_PG_ARCH_2(PG_arch_2,		"arch_2"	)		\
+IF_HAVE_PG_SKIP_KASAN_POISON(PG_skip_kasan_poison, "skip_kasan_poison")
 
 #define show_page_flags(flags)						\
 	(flags) ? __print_flags(flags, "|",				\
diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
index 41fd5326ee0a..ed5e5b833d61 100644
--- a/mm/kasan/hw_tags.c
+++ b/mm/kasan/hw_tags.c
@@ -246,6 +246,9 @@ void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
 	 */
 	bool init = !want_init_on_free() && want_init_on_alloc(flags);
 
+	if (flags & __GFP_SKIP_KASAN_POISON)
+		SetPageSkipKASanPoison(page);
+
 	if (flags & __GFP_ZEROTAGS) {
 		int i;
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 13937e793fda..5ad76e540a22 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -394,11 +394,12 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages);
  * on-demand allocation and then freed again before the deferred pages
  * initialization is done, but this is not likely to happen.
  */
-static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
 {
 	return static_branch_unlikely(&deferred_pages) ||
 	       (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-		(fpi_flags & FPI_SKIP_KASAN_POISON));
+		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
+	       PageSkipKASanPoison(page);
 }
 
 /* Returns true if the struct page for the pfn is uninitialised */
@@ -449,10 +450,11 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 	return false;
 }
 #else
-static inline bool should_skip_kasan_poison(fpi_t fpi_flags)
+static inline bool should_skip_kasan_poison(struct page *page, fpi_t fpi_flags)
 {
 	return (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
-		(fpi_flags & FPI_SKIP_KASAN_POISON));
+		(fpi_flags & FPI_SKIP_KASAN_POISON)) ||
+	       PageSkipKASanPoison(page);
 }
 
 static inline bool early_page_uninitialised(unsigned long pfn)
@@ -1244,7 +1246,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 			unsigned int order, bool check_free, fpi_t fpi_flags)
 {
 	int bad = 0;
-	bool skip_kasan_poison = should_skip_kasan_poison(fpi_flags);
+	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
-- 
2.32.0.rc1.229.g3e70b5a671-goog


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply related	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
  2021-06-02 23:52 ` Peter Collingbourne
@ 2021-06-04  3:03   ` Andrew Morton
  -1 siblings, 0 replies; 18+ messages in thread
From: Andrew Morton @ 2021-06-04  3:03 UTC (permalink / raw)
  To: Peter Collingbourne
  Cc: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Jann Horn, Evgenii Stepanov, linux-mm,
	linux-arm-kernel

On Wed,  2 Jun 2021 16:52:26 -0700 Peter Collingbourne <pcc@google.com> wrote:

> Currently we can end up touching PROT_MTE user pages twice on fault
> and once on unmap. On fault, with KASAN disabled we first clear data
> and then set tags to 0, and with KASAN enabled we simultaneously
> clear data and set tags to the KASAN random tag, and then set tags
> again to 0. On unmap, we poison the page by setting tags, but this
> is less likely to find a bug than poisoning kernel pages.
> 
> This patch series fixes these inefficiencies by only touching the pages
> once on fault using the DC GZVA instruction to clear both data and
> tags, and avoiding poisoning user pages on free.
> 
> ...
> 
>  arch/alpha/include/asm/page.h   |  6 +--
>  arch/arm64/include/asm/mte.h    |  4 ++
>  arch/arm64/include/asm/page.h   | 10 +++--
>  arch/arm64/lib/mte.S            | 20 ++++++++++
>  arch/arm64/mm/fault.c           | 26 +++++++++++++
>  arch/arm64/mm/proc.S            | 10 +++--
>  arch/ia64/include/asm/page.h    |  6 +--
>  arch/m68k/include/asm/page_no.h |  6 +--
>  arch/s390/include/asm/page.h    |  6 +--
>  arch/x86/include/asm/page.h     |  6 +--
>  include/linux/gfp.h             | 18 +++++++--
>  include/linux/highmem.h         | 43 ++++++++-------------
>  include/linux/kasan.h           | 64 +++++++++++++++++++-------------
>  include/linux/page-flags.h      |  9 +++++
>  include/trace/events/mmflags.h  |  9 ++++-
>  mm/kasan/common.c               |  4 +-
>  mm/kasan/hw_tags.c              | 32 ++++++++++++++++
>  mm/mempool.c                    |  6 ++-
>  mm/page_alloc.c                 | 66 +++++++++++++++++++--------------
>  19 files changed, 242 insertions(+), 109 deletions(-)

This is more MMish than ARMish, but I expect it will get more exposure
in an ARM tree than in linux-next alone.

I'll grab them for now, but in the hope that they will appear in -next
via an ARM tree so I get to drop them again.



^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
@ 2021-06-04  3:03   ` Andrew Morton
  0 siblings, 0 replies; 18+ messages in thread
From: Andrew Morton @ 2021-06-04  3:03 UTC (permalink / raw)
  To: Peter Collingbourne
  Cc: Andrey Konovalov, Alexander Potapenko, Catalin Marinas,
	Vincenzo Frascino, Jann Horn, Evgenii Stepanov, linux-mm,
	linux-arm-kernel

On Wed,  2 Jun 2021 16:52:26 -0700 Peter Collingbourne <pcc@google.com> wrote:

> Currently we can end up touching PROT_MTE user pages twice on fault
> and once on unmap. On fault, with KASAN disabled we first clear data
> and then set tags to 0, and with KASAN enabled we simultaneously
> clear data and set tags to the KASAN random tag, and then set tags
> again to 0. On unmap, we poison the page by setting tags, but this
> is less likely to find a bug than poisoning kernel pages.
> 
> This patch series fixes these inefficiencies by only touching the pages
> once on fault using the DC GZVA instruction to clear both data and
> tags, and avoiding poisoning user pages on free.
> 
> ...
> 
>  arch/alpha/include/asm/page.h   |  6 +--
>  arch/arm64/include/asm/mte.h    |  4 ++
>  arch/arm64/include/asm/page.h   | 10 +++--
>  arch/arm64/lib/mte.S            | 20 ++++++++++
>  arch/arm64/mm/fault.c           | 26 +++++++++++++
>  arch/arm64/mm/proc.S            | 10 +++--
>  arch/ia64/include/asm/page.h    |  6 +--
>  arch/m68k/include/asm/page_no.h |  6 +--
>  arch/s390/include/asm/page.h    |  6 +--
>  arch/x86/include/asm/page.h     |  6 +--
>  include/linux/gfp.h             | 18 +++++++--
>  include/linux/highmem.h         | 43 ++++++++-------------
>  include/linux/kasan.h           | 64 +++++++++++++++++++-------------
>  include/linux/page-flags.h      |  9 +++++
>  include/trace/events/mmflags.h  |  9 ++++-
>  mm/kasan/common.c               |  4 +-
>  mm/kasan/hw_tags.c              | 32 ++++++++++++++++
>  mm/mempool.c                    |  6 ++-
>  mm/page_alloc.c                 | 66 +++++++++++++++++++--------------
>  19 files changed, 242 insertions(+), 109 deletions(-)

This is more MMish than ARMish, but I expect it will get more exposure
in an ARM tree than in linux-next alone.

I'll grab them for now, but in the hope that they will appear in -next
via an ARM tree so I get to drop them again.


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()
  2021-06-02 23:52   ` Peter Collingbourne
@ 2021-06-04  9:45     ` Catalin Marinas
  -1 siblings, 0 replies; 18+ messages in thread
From: Catalin Marinas @ 2021-06-04  9:45 UTC (permalink / raw)
  To: Peter Collingbourne
  Cc: Andrey Konovalov, Alexander Potapenko, Vincenzo Frascino,
	Andrew Morton, Jann Horn, Evgenii Stepanov, linux-mm,
	linux-arm-kernel

On Wed, Jun 02, 2021 at 04:52:27PM -0700, Peter Collingbourne wrote:
> In an upcoming change we would like to add a flag to
> GFP_HIGHUSER_MOVABLE so that it would no longer be an OR
> of GFP_HIGHUSER and __GFP_MOVABLE. This poses a problem for
> alloc_zeroed_user_highpage_movable() which passes __GFP_MOVABLE
> into an arch-specific __alloc_zeroed_user_highpage() hook which ORs
> in GFP_HIGHUSER.
> 
> Since __alloc_zeroed_user_highpage() is only ever called from
> alloc_zeroed_user_highpage_movable(), we can remove one level
> of indirection here. Remove __alloc_zeroed_user_highpage(),
> make alloc_zeroed_user_highpage_movable() the hook, and use
> GFP_HIGHUSER_MOVABLE in the hook implementations so that they will
> pick up the new flag that we are going to add.
> 
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> Link: https://linux-review.googlesource.com/id/Ic6361c657b2cdcd896adbe0cf7cb5a7fbb1ed7bf

Acked-by: Catalin Marinas <catalin.marinas@arm.com>


^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()
@ 2021-06-04  9:45     ` Catalin Marinas
  0 siblings, 0 replies; 18+ messages in thread
From: Catalin Marinas @ 2021-06-04  9:45 UTC (permalink / raw)
  To: Peter Collingbourne
  Cc: Andrey Konovalov, Alexander Potapenko, Vincenzo Frascino,
	Andrew Morton, Jann Horn, Evgenii Stepanov, linux-mm,
	linux-arm-kernel

On Wed, Jun 02, 2021 at 04:52:27PM -0700, Peter Collingbourne wrote:
> In an upcoming change we would like to add a flag to
> GFP_HIGHUSER_MOVABLE so that it would no longer be an OR
> of GFP_HIGHUSER and __GFP_MOVABLE. This poses a problem for
> alloc_zeroed_user_highpage_movable() which passes __GFP_MOVABLE
> into an arch-specific __alloc_zeroed_user_highpage() hook which ORs
> in GFP_HIGHUSER.
> 
> Since __alloc_zeroed_user_highpage() is only ever called from
> alloc_zeroed_user_highpage_movable(), we can remove one level
> of indirection here. Remove __alloc_zeroed_user_highpage(),
> make alloc_zeroed_user_highpage_movable() the hook, and use
> GFP_HIGHUSER_MOVABLE in the hook implementations so that they will
> pick up the new flag that we are going to add.
> 
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> Link: https://linux-review.googlesource.com/id/Ic6361c657b2cdcd896adbe0cf7cb5a7fbb1ed7bf

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
  2021-06-04  3:03   ` Andrew Morton
@ 2021-06-04 18:31     ` Will Deacon
  -1 siblings, 0 replies; 18+ messages in thread
From: Will Deacon @ 2021-06-04 18:31 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Peter Collingbourne, Andrey Konovalov, Alexander Potapenko,
	Catalin Marinas, Vincenzo Frascino, Jann Horn, Evgenii Stepanov,
	linux-mm, linux-arm-kernel

On Thu, Jun 03, 2021 at 08:03:08PM -0700, Andrew Morton wrote:
> On Wed,  2 Jun 2021 16:52:26 -0700 Peter Collingbourne <pcc@google.com> wrote:
> 
> > Currently we can end up touching PROT_MTE user pages twice on fault
> > and once on unmap. On fault, with KASAN disabled we first clear data
> > and then set tags to 0, and with KASAN enabled we simultaneously
> > clear data and set tags to the KASAN random tag, and then set tags
> > again to 0. On unmap, we poison the page by setting tags, but this
> > is less likely to find a bug than poisoning kernel pages.
> > 
> > This patch series fixes these inefficiencies by only touching the pages
> > once on fault using the DC GZVA instruction to clear both data and
> > tags, and avoiding poisoning user pages on free.
> > 
> > ...
> > 
> >  arch/alpha/include/asm/page.h   |  6 +--
> >  arch/arm64/include/asm/mte.h    |  4 ++
> >  arch/arm64/include/asm/page.h   | 10 +++--
> >  arch/arm64/lib/mte.S            | 20 ++++++++++
> >  arch/arm64/mm/fault.c           | 26 +++++++++++++
> >  arch/arm64/mm/proc.S            | 10 +++--
> >  arch/ia64/include/asm/page.h    |  6 +--
> >  arch/m68k/include/asm/page_no.h |  6 +--
> >  arch/s390/include/asm/page.h    |  6 +--
> >  arch/x86/include/asm/page.h     |  6 +--
> >  include/linux/gfp.h             | 18 +++++++--
> >  include/linux/highmem.h         | 43 ++++++++-------------
> >  include/linux/kasan.h           | 64 +++++++++++++++++++-------------
> >  include/linux/page-flags.h      |  9 +++++
> >  include/trace/events/mmflags.h  |  9 ++++-
> >  mm/kasan/common.c               |  4 +-
> >  mm/kasan/hw_tags.c              | 32 ++++++++++++++++
> >  mm/mempool.c                    |  6 ++-
> >  mm/page_alloc.c                 | 66 +++++++++++++++++++--------------
> >  19 files changed, 242 insertions(+), 109 deletions(-)
> 
> This is more MMish than ARMish, but I expect it will get more exposure
> in an ARM tree than in linux-next alone.
> 
> I'll grab them for now, but in the hope that they will appear in -next
> via an ARM tree so I get to drop them again.

Sure thing, I'll queue this in a sec...

Peter -- please cc me on patches touching arch/arm64 in future, that way I
won't miss anything (or at least, you can yell at me if I do!).

Cheers,

Will


^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
@ 2021-06-04 18:31     ` Will Deacon
  0 siblings, 0 replies; 18+ messages in thread
From: Will Deacon @ 2021-06-04 18:31 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Peter Collingbourne, Andrey Konovalov, Alexander Potapenko,
	Catalin Marinas, Vincenzo Frascino, Jann Horn, Evgenii Stepanov,
	linux-mm, linux-arm-kernel

On Thu, Jun 03, 2021 at 08:03:08PM -0700, Andrew Morton wrote:
> On Wed,  2 Jun 2021 16:52:26 -0700 Peter Collingbourne <pcc@google.com> wrote:
> 
> > Currently we can end up touching PROT_MTE user pages twice on fault
> > and once on unmap. On fault, with KASAN disabled we first clear data
> > and then set tags to 0, and with KASAN enabled we simultaneously
> > clear data and set tags to the KASAN random tag, and then set tags
> > again to 0. On unmap, we poison the page by setting tags, but this
> > is less likely to find a bug than poisoning kernel pages.
> > 
> > This patch series fixes these inefficiencies by only touching the pages
> > once on fault using the DC GZVA instruction to clear both data and
> > tags, and avoiding poisoning user pages on free.
> > 
> > ...
> > 
> >  arch/alpha/include/asm/page.h   |  6 +--
> >  arch/arm64/include/asm/mte.h    |  4 ++
> >  arch/arm64/include/asm/page.h   | 10 +++--
> >  arch/arm64/lib/mte.S            | 20 ++++++++++
> >  arch/arm64/mm/fault.c           | 26 +++++++++++++
> >  arch/arm64/mm/proc.S            | 10 +++--
> >  arch/ia64/include/asm/page.h    |  6 +--
> >  arch/m68k/include/asm/page_no.h |  6 +--
> >  arch/s390/include/asm/page.h    |  6 +--
> >  arch/x86/include/asm/page.h     |  6 +--
> >  include/linux/gfp.h             | 18 +++++++--
> >  include/linux/highmem.h         | 43 ++++++++-------------
> >  include/linux/kasan.h           | 64 +++++++++++++++++++-------------
> >  include/linux/page-flags.h      |  9 +++++
> >  include/trace/events/mmflags.h  |  9 ++++-
> >  mm/kasan/common.c               |  4 +-
> >  mm/kasan/hw_tags.c              | 32 ++++++++++++++++
> >  mm/mempool.c                    |  6 ++-
> >  mm/page_alloc.c                 | 66 +++++++++++++++++++--------------
> >  19 files changed, 242 insertions(+), 109 deletions(-)
> 
> This is more MMish than ARMish, but I expect it will get more exposure
> in an ARM tree than in linux-next alone.
> 
> I'll grab them for now, but in the hope that they will appear in -next
> via an ARM tree so I get to drop them again.

Sure thing, I'll queue this in a sec...

Peter -- please cc me on patches touching arch/arm64 in future, that way I
won't miss anything (or at least, you can yell at me if I do!).

Cheers,

Will

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
  2021-06-02 23:52 ` Peter Collingbourne
@ 2021-06-04 19:48   ` Will Deacon
  -1 siblings, 0 replies; 18+ messages in thread
From: Will Deacon @ 2021-06-04 19:48 UTC (permalink / raw)
  To: Andrew Morton, Vincenzo Frascino, Alexander Potapenko,
	Peter Collingbourne, Andrey Konovalov, Jann Horn,
	Catalin Marinas
  Cc: kernel-team, Will Deacon, Evgenii Stepanov, linux-arm-kernel, linux-mm

On Wed, 2 Jun 2021 16:52:26 -0700, Peter Collingbourne wrote:
> Currently we can end up touching PROT_MTE user pages twice on fault
> and once on unmap. On fault, with KASAN disabled we first clear data
> and then set tags to 0, and with KASAN enabled we simultaneously
> clear data and set tags to the KASAN random tag, and then set tags
> again to 0. On unmap, we poison the page by setting tags, but this
> is less likely to find a bug than poisoning kernel pages.
> 
> [...]

Applied to arm64 (for-next/mte), thanks!

[1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()
      https://git.kernel.org/arm64/c/92638b4e1b47
[2/4] kasan: use separate (un)poison implementation for integrated init
      https://git.kernel.org/arm64/c/7a3b83537188
[3/4] arm64: mte: handle tags zeroing at page allocation time
      https://git.kernel.org/arm64/c/013bb59dbb7c
[4/4] kasan: disable freed user page poisoning with HW tags
      https://git.kernel.org/arm64/c/c275c5c6d50a

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev


^ permalink raw reply	[flat|nested] 18+ messages in thread
* Re: [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages
@ 2021-06-04 19:48   ` Will Deacon
  0 siblings, 0 replies; 18+ messages in thread
From: Will Deacon @ 2021-06-04 19:48 UTC (permalink / raw)
  To: Andrew Morton, Vincenzo Frascino, Alexander Potapenko,
	Peter Collingbourne, Andrey Konovalov, Jann Horn,
	Catalin Marinas
  Cc: kernel-team, Will Deacon, Evgenii Stepanov, linux-arm-kernel, linux-mm

On Wed, 2 Jun 2021 16:52:26 -0700, Peter Collingbourne wrote:
> Currently we can end up touching PROT_MTE user pages twice on fault
> and once on unmap. On fault, with KASAN disabled we first clear data
> and then set tags to 0, and with KASAN enabled we simultaneously
> clear data and set tags to the KASAN random tag, and then set tags
> again to 0. On unmap, we poison the page by setting tags, but this
> is less likely to find a bug than poisoning kernel pages.
> 
> [...]

Applied to arm64 (for-next/mte), thanks!

[1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable()
      https://git.kernel.org/arm64/c/92638b4e1b47
[2/4] kasan: use separate (un)poison implementation for integrated init
      https://git.kernel.org/arm64/c/7a3b83537188
[3/4] arm64: mte: handle tags zeroing at page allocation time
      https://git.kernel.org/arm64/c/013bb59dbb7c
[4/4] kasan: disable freed user page poisoning with HW tags
      https://git.kernel.org/arm64/c/c275c5c6d50a

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

^ permalink raw reply	[flat|nested] 18+ messages in thread
end of thread, other threads:[~2021-06-05  5:16 UTC | newest]

Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-02 23:52 [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages Peter Collingbourne
2021-06-02 23:52 ` Peter Collingbourne
2021-06-02 23:52 ` [PATCH v6 1/4] mm: arch: remove indirection level in alloc_zeroed_user_highpage_movable() Peter Collingbourne
2021-06-02 23:52   ` Peter Collingbourne
2021-06-04  9:45   ` Catalin Marinas
2021-06-04  9:45     ` Catalin Marinas
2021-06-02 23:52 ` [PATCH v6 2/4] kasan: use separate (un)poison implementation for integrated init Peter Collingbourne
2021-06-02 23:52   ` Peter Collingbourne
2021-06-02 23:52 ` [PATCH v6 3/4] arm64: mte: handle tags zeroing at page allocation time Peter Collingbourne
2021-06-02 23:52   ` Peter Collingbourne
2021-06-02 23:52 ` [PATCH v6 4/4] kasan: disable freed user page poisoning with HW tags Peter Collingbourne
2021-06-02 23:52   ` Peter Collingbourne
2021-06-04  3:03 ` [PATCH v6 0/4] arm64: improve efficiency of setting tags for user pages Andrew Morton
2021-06-04  3:03   ` Andrew Morton
2021-06-04 18:31   ` Will Deacon
2021-06-04 18:31     ` Will Deacon
2021-06-04 19:48 ` Will Deacon
2021-06-04 19:48   ` Will Deacon

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