[PATCH RFC v3 05/12] kasan: refactor write/is_write arguments to flags

[Jann Horn <jannh@google.com>]

Refactor the "write"/"is_write" arguments of kasan_check_range() and
kasan_report() into "flags" arguments that can contain the flag
KASAN_TYPE_WRITE.
This prepares for a following patch that introduces a second flag.

This should hopefully not change the machine code in hotpaths - both before
and after this change, the argument is either 0 or 1 at the assembly level
depending on whether the access is a write.
Only kasan_report() should have to do a tiny bit of extra work to do a
bittest.

Signed-off-by: Jann Horn <jannh@google.com>
---
 arch/arm64/kernel/traps.c |  2 +-
 arch/arm64/mm/fault.c     |  2 +-
 include/linux/kasan.h     |  6 ++++--
 mm/kasan/common.c         |  2 +-
 mm/kasan/generic.c        | 20 ++++++++++----------
 mm/kasan/kasan.h          |  6 +++---
 mm/kasan/report.c         |  3 ++-
 mm/kasan/report_generic.c |  8 ++++----
 mm/kasan/shadow.c         | 24 ++++++++++++------------
 mm/kasan/sw_tags.c        | 20 ++++++++++----------
 10 files changed, 48 insertions(+), 45 deletions(-)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 914282016069..9f31fe3f1660 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -1069,7 +1069,7 @@ int kasan_brk_handler(struct pt_regs *regs, unsigned long esr)
 	void *addr = (void *)regs->regs[0];
 	u64 pc = regs->pc;
 
-	kasan_report(addr, size, write, pc);
+	kasan_report(addr, size, write ? KASAN_TYPE_WRITE : 0, pc);
 
 	/*
 	 * The instrumentation allows to control whether we can proceed after
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 0b52557652be..221e39869ae6 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -365,7 +365,7 @@ static void report_tag_fault(unsigned long addr, unsigned long esr,
 	 * find out access size.
 	 */
 	bool is_write = !!(esr & ESR_ELx_WNR);
-	kasan_report((void *)addr, 0, is_write, regs->pc);
+	kasan_report((void *)addr, 0, is_write ? KASAN_TYPE_WRITE : 0, regs->pc);
 }
 #else
 /* Tag faults aren't enabled without CONFIG_KASAN_HW_TAGS. */
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index bf233bde68c7..03c7ac79345d 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -33,6 +33,8 @@ typedef unsigned int __bitwise kasan_vmalloc_flags_t;
 #define KASAN_VMALLOC_PAGE_RANGE 0x1 /* Apply exsiting page range */
 #define KASAN_VMALLOC_TLB_FLUSH  0x2 /* TLB flush */
 
+#define KASAN_TYPE_WRITE 0x1
+
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 
 #include <linux/pgtable.h>
@@ -526,11 +528,11 @@ static inline void *kasan_reset_tag(const void *addr)
  * kasan_report - print a report about a bad memory access detected by KASAN
  * @addr: address of the bad access
  * @size: size of the bad access
- * @is_write: whether the bad access is a write or a read
+ * @flags: bitmask, can contain KASAN_TYPE_* flags
  * @ip: instruction pointer for the accessibility check or the bad access itself
  */
 bool kasan_report(const void *addr, size_t size,
-		bool is_write, unsigned long ip);
+		unsigned int flags, unsigned long ip);
 
 #else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
 
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index b7d05c2a6d93..1ab77ac9719c 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -571,7 +571,7 @@ void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
 bool __kasan_check_byte(const void *address, unsigned long ip)
 {
 	if (!kasan_byte_accessible(address)) {
-		kasan_report(address, 1, false, ip);
+		kasan_report(address, 1, 0, ip);
 		return false;
 	}
 	return true;
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 2b8e73f5f6a7..9efd6fbbb7c3 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -173,7 +173,7 @@ static __always_inline bool memory_is_poisoned(const void *addr, size_t size)
 }
 
 static __always_inline bool check_region_inline(const void *addr,
-						size_t size, bool write,
+						size_t size, unsigned int flags,
 						unsigned long ret_ip)
 {
 	if (!kasan_enabled())
@@ -183,21 +183,21 @@ static __always_inline bool check_region_inline(const void *addr,
 		return true;
 
 	if (unlikely(addr + size < addr))
-		return !kasan_report(addr, size, write, ret_ip);
+		return !kasan_report(addr, size, flags, ret_ip);
 
 	if (unlikely(!addr_has_metadata(addr)))
-		return !kasan_report(addr, size, write, ret_ip);
+		return !kasan_report(addr, size, flags, ret_ip);
 
 	if (likely(!memory_is_poisoned(addr, size)))
 		return true;
 
-	return !kasan_report(addr, size, write, ret_ip);
+	return !kasan_report(addr, size, flags, ret_ip);
 }
 
-bool kasan_check_range(const void *addr, size_t size, bool write,
+bool kasan_check_range(const void *addr, size_t size, unsigned int flags,
 					unsigned long ret_ip)
 {
-	return check_region_inline(addr, size, write, ret_ip);
+	return check_region_inline(addr, size, flags, ret_ip);
 }
 
 bool kasan_byte_accessible(const void *addr)
@@ -252,7 +252,7 @@ EXPORT_SYMBOL(__asan_unregister_globals);
 #define DEFINE_ASAN_LOAD_STORE(size)					\
 	void __asan_load##size(void *addr)				\
 	{								\
-		check_region_inline(addr, size, false, _RET_IP_);	\
+		check_region_inline(addr, size, 0, _RET_IP_);	\
 	}								\
 	EXPORT_SYMBOL(__asan_load##size);				\
 	__alias(__asan_load##size)					\
@@ -260,7 +260,7 @@ EXPORT_SYMBOL(__asan_unregister_globals);
 	EXPORT_SYMBOL(__asan_load##size##_noabort);			\
 	void __asan_store##size(void *addr)				\
 	{								\
-		check_region_inline(addr, size, true, _RET_IP_);	\
+		check_region_inline(addr, size, KASAN_TYPE_WRITE, _RET_IP_); \
 	}								\
 	EXPORT_SYMBOL(__asan_store##size);				\
 	__alias(__asan_store##size)					\
@@ -275,7 +275,7 @@ DEFINE_ASAN_LOAD_STORE(16);
 
 void __asan_loadN(void *addr, ssize_t size)
 {
-	kasan_check_range(addr, size, false, _RET_IP_);
+	kasan_check_range(addr, size, 0, _RET_IP_);
 }
 EXPORT_SYMBOL(__asan_loadN);
 
@@ -285,7 +285,7 @@ EXPORT_SYMBOL(__asan_loadN_noabort);
 
 void __asan_storeN(void *addr, ssize_t size)
 {
-	kasan_check_range(addr, size, true, _RET_IP_);
+	kasan_check_range(addr, size, KASAN_TYPE_WRITE, _RET_IP_);
 }
 EXPORT_SYMBOL(__asan_storeN);
 
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index fc9169a54766..c833bd44e3cc 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -339,11 +339,11 @@ static __always_inline bool addr_has_metadata(const void *addr)
  * kasan_check_range - Check memory region, and report if invalid access.
  * @addr: the accessed address
  * @size: the accessed size
- * @write: true if access is a write access
+ * @flags: bitmask, can contain KASAN_TYPE_* flags
  * @ret_ip: return address
  * @return: true if access was valid, false if invalid
  */
-bool kasan_check_range(const void *addr, size_t size, bool write,
+bool kasan_check_range(const void *addr, size_t size, unsigned int flags,
 				unsigned long ret_ip);
 
 #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
@@ -379,7 +379,7 @@ static inline void kasan_print_aux_stacks(struct kmem_cache *cache, const void *
 #endif
 
 bool kasan_report(const void *addr, size_t size,
-		bool is_write, unsigned long ip);
+		unsigned int flags, unsigned long ip);
 void kasan_report_invalid_free(void *object, unsigned long ip, enum kasan_report_type type);
 
 struct slab *kasan_addr_to_slab(const void *addr);
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index e804b1e1f886..cfe00ebb98ec 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -568,13 +568,14 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_ty
  * user_access_save/restore(): kasan_report_invalid_free() cannot be called
  * from a UACCESS region, and kasan_report_async() is not used on x86.
  */
-bool kasan_report(const void *addr, size_t size, bool is_write,
+bool kasan_report(const void *addr, size_t size, unsigned int flags,
 			unsigned long ip)
 {
 	bool ret = true;
 	unsigned long ua_flags = user_access_save();
 	unsigned long irq_flags;
 	struct kasan_report_info info;
+	bool is_write = (flags & KASAN_TYPE_WRITE);
 
 	if (unlikely(report_suppressed_sw()) || unlikely(!report_enabled())) {
 		ret = false;
diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c
index f5b8e37b3805..445183e2f4d3 100644
--- a/mm/kasan/report_generic.c
+++ b/mm/kasan/report_generic.c
@@ -364,14 +364,14 @@ void kasan_print_address_stack_frame(const void *addr)
 #define DEFINE_ASAN_REPORT_LOAD(size)                     \
 void __asan_report_load##size##_noabort(void *addr) \
 {                                                         \
-	kasan_report(addr, size, false, _RET_IP_);	  \
+	kasan_report(addr, size, 0, _RET_IP_);	  \
 }                                                         \
 EXPORT_SYMBOL(__asan_report_load##size##_noabort)
 
 #define DEFINE_ASAN_REPORT_STORE(size)                     \
 void __asan_report_store##size##_noabort(void *addr) \
 {                                                          \
-	kasan_report(addr, size, true, _RET_IP_);	   \
+	kasan_report(addr, size, KASAN_TYPE_WRITE, _RET_IP_);	   \
 }                                                          \
 EXPORT_SYMBOL(__asan_report_store##size##_noabort)
 
@@ -388,12 +388,12 @@ DEFINE_ASAN_REPORT_STORE(16);
 
 void __asan_report_load_n_noabort(void *addr, ssize_t size)
 {
-	kasan_report(addr, size, false, _RET_IP_);
+	kasan_report(addr, size, 0, _RET_IP_);
 }
 EXPORT_SYMBOL(__asan_report_load_n_noabort);
 
 void __asan_report_store_n_noabort(void *addr, ssize_t size)
 {
-	kasan_report(addr, size, true, _RET_IP_);
+	kasan_report(addr, size, KASAN_TYPE_WRITE, _RET_IP_);
 }
 EXPORT_SYMBOL(__asan_report_store_n_noabort);
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index d286e0a04543..a24f1225dd88 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -28,13 +28,13 @@
 
 bool __kasan_check_read(const volatile void *p, unsigned int size)
 {
-	return kasan_check_range((void *)p, size, false, _RET_IP_);
+	return kasan_check_range((void *)p, size, 0, _RET_IP_);
 }
 EXPORT_SYMBOL(__kasan_check_read);
 
 bool __kasan_check_write(const volatile void *p, unsigned int size)
 {
-	return kasan_check_range((void *)p, size, true, _RET_IP_);
+	return kasan_check_range((void *)p, size, KASAN_TYPE_WRITE, _RET_IP_);
 }
 EXPORT_SYMBOL(__kasan_check_write);
 
@@ -50,7 +50,7 @@ EXPORT_SYMBOL(__kasan_check_write);
 #undef memset
 void *memset(void *addr, int c, size_t len)
 {
-	if (!kasan_check_range(addr, len, true, _RET_IP_))
+	if (!kasan_check_range(addr, len, KASAN_TYPE_WRITE, _RET_IP_))
 		return NULL;
 
 	return __memset(addr, c, len);
@@ -60,8 +60,8 @@ void *memset(void *addr, int c, size_t len)
 #undef memmove
 void *memmove(void *dest, const void *src, size_t len)
 {
-	if (!kasan_check_range(src, len, false, _RET_IP_) ||
-	    !kasan_check_range(dest, len, true, _RET_IP_))
+	if (!kasan_check_range(src, len, 0, _RET_IP_) ||
+	    !kasan_check_range(dest, len, KASAN_TYPE_WRITE, _RET_IP_))
 		return NULL;
 
 	return __memmove(dest, src, len);
@@ -71,8 +71,8 @@ void *memmove(void *dest, const void *src, size_t len)
 #undef memcpy
 void *memcpy(void *dest, const void *src, size_t len)
 {
-	if (!kasan_check_range(src, len, false, _RET_IP_) ||
-	    !kasan_check_range(dest, len, true, _RET_IP_))
+	if (!kasan_check_range(src, len, 0, _RET_IP_) ||
+	    !kasan_check_range(dest, len, KASAN_TYPE_WRITE, _RET_IP_))
 		return NULL;
 
 	return __memcpy(dest, src, len);
@@ -81,7 +81,7 @@ void *memcpy(void *dest, const void *src, size_t len)
 
 void *__asan_memset(void *addr, int c, ssize_t len)
 {
-	if (!kasan_check_range(addr, len, true, _RET_IP_))
+	if (!kasan_check_range(addr, len, KASAN_TYPE_WRITE, _RET_IP_))
 		return NULL;
 
 	return __memset(addr, c, len);
@@ -91,8 +91,8 @@ EXPORT_SYMBOL(__asan_memset);
 #ifdef __HAVE_ARCH_MEMMOVE
 void *__asan_memmove(void *dest, const void *src, ssize_t len)
 {
-	if (!kasan_check_range(src, len, false, _RET_IP_) ||
-	    !kasan_check_range(dest, len, true, _RET_IP_))
+	if (!kasan_check_range(src, len, 0, _RET_IP_) ||
+	    !kasan_check_range(dest, len, KASAN_TYPE_WRITE, _RET_IP_))
 		return NULL;
 
 	return __memmove(dest, src, len);
@@ -102,8 +102,8 @@ EXPORT_SYMBOL(__asan_memmove);
 
 void *__asan_memcpy(void *dest, const void *src, ssize_t len)
 {
-	if (!kasan_check_range(src, len, false, _RET_IP_) ||
-	    !kasan_check_range(dest, len, true, _RET_IP_))
+	if (!kasan_check_range(src, len, 0, _RET_IP_) ||
+	    !kasan_check_range(dest, len, KASAN_TYPE_WRITE, _RET_IP_))
 		return NULL;
 
 	return __memcpy(dest, src, len);
diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
index c75741a74602..af77b642ede7 100644
--- a/mm/kasan/sw_tags.c
+++ b/mm/kasan/sw_tags.c
@@ -72,7 +72,7 @@ u8 kasan_random_tag(void)
 	return (u8)(state % (KASAN_TAG_MAX + 1));
 }
 
-bool kasan_check_range(const void *addr, size_t size, bool write,
+bool kasan_check_range(const void *addr, size_t size, unsigned int flags,
 			unsigned long ret_ip)
 {
 	u8 tag;
@@ -83,7 +83,7 @@ bool kasan_check_range(const void *addr, size_t size, bool write,
 		return true;
 
 	if (unlikely(addr + size < addr))
-		return !kasan_report(addr, size, write, ret_ip);
+		return !kasan_report(addr, size, flags, ret_ip);
 
 	tag = get_tag((const void *)addr);
 
@@ -109,12 +109,12 @@ bool kasan_check_range(const void *addr, size_t size, bool write,
 
 	untagged_addr = kasan_reset_tag((const void *)addr);
 	if (unlikely(!addr_has_metadata(untagged_addr)))
-		return !kasan_report(addr, size, write, ret_ip);
+		return !kasan_report(addr, size, flags, ret_ip);
 	shadow_first = kasan_mem_to_shadow(untagged_addr);
 	shadow_last = kasan_mem_to_shadow(untagged_addr + size - 1);
 	for (shadow = shadow_first; shadow <= shadow_last; shadow++) {
 		if (*shadow != tag) {
-			return !kasan_report(addr, size, write, ret_ip);
+			return !kasan_report(addr, size, flags, ret_ip);
 		}
 	}
 
@@ -137,12 +137,12 @@ bool kasan_byte_accessible(const void *addr)
 #define DEFINE_HWASAN_LOAD_STORE(size)					\
 	void __hwasan_load##size##_noabort(void *addr)			\
 	{								\
-		kasan_check_range(addr, size, false, _RET_IP_);		\
+		kasan_check_range(addr, size, 0, _RET_IP_);		\
 	}								\
 	EXPORT_SYMBOL(__hwasan_load##size##_noabort);			\
 	void __hwasan_store##size##_noabort(void *addr)			\
 	{								\
-		kasan_check_range(addr, size, true, _RET_IP_);		\
+		kasan_check_range(addr, size, KASAN_TYPE_WRITE, _RET_IP_); \
 	}								\
 	EXPORT_SYMBOL(__hwasan_store##size##_noabort)
 
@@ -154,13 +154,13 @@ DEFINE_HWASAN_LOAD_STORE(16);
 
 void __hwasan_loadN_noabort(void *addr, ssize_t size)
 {
-	kasan_check_range(addr, size, false, _RET_IP_);
+	kasan_check_range(addr, size, 0, _RET_IP_);
 }
 EXPORT_SYMBOL(__hwasan_loadN_noabort);
 
 void __hwasan_storeN_noabort(void *addr, ssize_t size)
 {
-	kasan_check_range(addr, size, true, _RET_IP_);
+	kasan_check_range(addr, size, KASAN_TYPE_WRITE, _RET_IP_);
 }
 EXPORT_SYMBOL(__hwasan_storeN_noabort);
 
@@ -173,6 +173,6 @@ EXPORT_SYMBOL(__hwasan_tag_memory);
 void kasan_tag_mismatch(void *addr, unsigned long access_info,
 			unsigned long ret_ip)
 {
-	kasan_report(addr, 1 << (access_info & 0xf), access_info & 0x10,
-		     ret_ip);
+	kasan_report(addr, 1 << (access_info & 0xf),
+		(access_info & 0x10) ? KASAN_TYPE_WRITE : 0, ret_ip);
 }

-- 
2.55.0.979.g7e5102b832-goog