diff options
| -rw-r--r-- | include/linux/instrumented.h | 63 | ||||
| -rw-r--r-- | kernel/kcsan/core.c | 17 |
2 files changed, 39 insertions, 41 deletions
diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h index 501fa8486749..1b608e00290a 100644 --- a/include/linux/instrumented.h +++ b/include/linux/instrumented.h @@ -15,12 +15,11 @@ /** * instrument_read - instrument regular read access + * @v: address of access + * @size: size of access * * Instrument a regular read access. The instrumentation should be inserted * before the actual read happens. - * - * @ptr address of access - * @size size of access */ static __always_inline void instrument_read(const volatile void *v, size_t size) { @@ -30,12 +29,11 @@ static __always_inline void instrument_read(const volatile void *v, size_t size) /** * instrument_write - instrument regular write access + * @v: address of access + * @size: size of access * * Instrument a regular write access. The instrumentation should be inserted * before the actual write happens. - * - * @ptr address of access - * @size size of access */ static __always_inline void instrument_write(const volatile void *v, size_t size) { @@ -45,12 +43,11 @@ static __always_inline void instrument_write(const volatile void *v, size_t size /** * instrument_read_write - instrument regular read-write access + * @v: address of access + * @size: size of access * * Instrument a regular write access. The instrumentation should be inserted * before the actual write happens. - * - * @ptr address of access - * @size size of access */ static __always_inline void instrument_read_write(const volatile void *v, size_t size) { @@ -60,12 +57,11 @@ static __always_inline void instrument_read_write(const volatile void *v, size_t /** * instrument_atomic_read - instrument atomic read access + * @v: address of access + * @size: size of access * * Instrument an atomic read access. The instrumentation should be inserted * before the actual read happens. - * - * @ptr address of access - * @size size of access */ static __always_inline void instrument_atomic_read(const volatile void *v, size_t size) { @@ -75,12 +71,11 @@ static __always_inline void instrument_atomic_read(const volatile void *v, size_ /** * instrument_atomic_write - instrument atomic write access + * @v: address of access + * @size: size of access * * Instrument an atomic write access. The instrumentation should be inserted * before the actual write happens. - * - * @ptr address of access - * @size size of access */ static __always_inline void instrument_atomic_write(const volatile void *v, size_t size) { @@ -90,12 +85,11 @@ static __always_inline void instrument_atomic_write(const volatile void *v, size /** * instrument_atomic_read_write - instrument atomic read-write access + * @v: address of access + * @size: size of access * * Instrument an atomic read-write access. The instrumentation should be * inserted before the actual write happens. - * - * @ptr address of access - * @size size of access */ static __always_inline void instrument_atomic_read_write(const volatile void *v, size_t size) { @@ -105,13 +99,12 @@ static __always_inline void instrument_atomic_read_write(const volatile void *v, /** * instrument_copy_to_user - instrument reads of copy_to_user + * @to: destination address + * @from: source address + * @n: number of bytes to copy * * Instrument reads from kernel memory, that are due to copy_to_user (and * variants). The instrumentation must be inserted before the accesses. - * - * @to destination address - * @from source address - * @n number of bytes to copy */ static __always_inline void instrument_copy_to_user(void __user *to, const void *from, unsigned long n) @@ -123,13 +116,12 @@ instrument_copy_to_user(void __user *to, const void *from, unsigned long n) /** * instrument_copy_from_user_before - add instrumentation before copy_from_user + * @to: destination address + * @from: source address + * @n: number of bytes to copy * * Instrument writes to kernel memory, that are due to copy_from_user (and * variants). The instrumentation should be inserted before the accesses. - * - * @to destination address - * @from source address - * @n number of bytes to copy */ static __always_inline void instrument_copy_from_user_before(const void *to, const void __user *from, unsigned long n) @@ -140,14 +132,13 @@ instrument_copy_from_user_before(const void *to, const void __user *from, unsign /** * instrument_copy_from_user_after - add instrumentation after copy_from_user + * @to: destination address + * @from: source address + * @n: number of bytes to copy + * @left: number of bytes not copied (as returned by copy_from_user) * * Instrument writes to kernel memory, that are due to copy_from_user (and * variants). The instrumentation should be inserted after the accesses. - * - * @to destination address - * @from source address - * @n number of bytes to copy - * @left number of bytes not copied (as returned by copy_from_user) */ static __always_inline void instrument_copy_from_user_after(const void *to, const void __user *from, @@ -158,12 +149,11 @@ instrument_copy_from_user_after(const void *to, const void __user *from, /** * instrument_get_user() - add instrumentation to get_user()-like macros + * @to: destination variable, may not be address-taken * * get_user() and friends are fragile, so it may depend on the implementation * whether the instrumentation happens before or after the data is copied from * the userspace. - * - * @to destination variable, may not be address-taken */ #define instrument_get_user(to) \ ({ \ @@ -175,14 +165,13 @@ instrument_copy_from_user_after(const void *to, const void __user *from, /** * instrument_put_user() - add instrumentation to put_user()-like macros + * @from: source address + * @ptr: userspace pointer to copy to + * @size: number of bytes to copy * * put_user() and friends are fragile, so it may depend on the implementation * whether the instrumentation happens before or after the data is copied from * the userspace. - * - * @from source address - * @ptr userspace pointer to copy to - * @size number of bytes to copy */ #define instrument_put_user(from, ptr, size) \ ({ \ diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index 54d077e1a2dc..5a60cc52adc0 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -337,11 +337,20 @@ static void delay_access(int type) */ static __always_inline u64 read_instrumented_memory(const volatile void *ptr, size_t size) { + /* + * In the below we don't necessarily need the read of the location to + * be atomic, and we don't use READ_ONCE(), since all we need for race + * detection is to observe 2 different values. + * + * Furthermore, on certain architectures (such as arm64), READ_ONCE() + * may turn into more complex instructions than a plain load that cannot + * do unaligned accesses. + */ switch (size) { - case 1: return READ_ONCE(*(const u8 *)ptr); - case 2: return READ_ONCE(*(const u16 *)ptr); - case 4: return READ_ONCE(*(const u32 *)ptr); - case 8: return READ_ONCE(*(const u64 *)ptr); + case 1: return *(const volatile u8 *)ptr; + case 2: return *(const volatile u16 *)ptr; + case 4: return *(const volatile u32 *)ptr; + case 8: return *(const volatile u64 *)ptr; default: return 0; /* Ignore; we do not diff the values. */ } } |