Commit 022e3209 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'kcsan.2023.04.04a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu 

Pull KCSAN updates from Paul McKenney:
 "Kernel concurrency sanitizer (KCSAN) updates for v6.4

  This fixes kernel-doc warnings and also updates instrumentation from
  READ_ONCE() to volatile in order to avoid unaligned load-acquire
  instructions on arm64 in kernels built with LTO"

* tag 'kcsan.2023.04.04a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  kcsan: Avoid READ_ONCE() in read_instrumented_memory()
  instrumented.h: Fix all kernel-doc format warnings
parents 1a0beef9 8dec8807

include/linux/instrumented.h

+26 −37
Original line number Diff line number Diff line
@@ -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)			\

({								\

kernel/kcsan/core.c

+13 −4
Original line number Diff line number Diff line
@@ -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. */

	}

}