Commit d6c4c113 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'kcsan' of... 

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

 into locking/core

Pull KCSAN updates for v5.10 from Paul E. McKenney:

 - Improve kernel messages.

 - Be more permissive with bitops races under KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=y.

 - Optimize debugfs stat counters.

 - Introduce the instrument_*read_write() annotations, to provide a
   finer description of certain ops - using KCSAN's compound instrumentation.
   Use them for atomic RNW and bitops, where appropriate.
   Doing this might find new races.
   (Depends on the compiler having tsan-compound-read-before-write=1 support.)

 - Support atomic built-ins, which will help certain architectures, such as s390.

 - Misc enhancements and smaller fixes.

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parents e705d397 cd290ec2

include/asm-generic/atomic-instrumented.h

+165 −165

File changed.

Preview size limit exceeded, changes collapsed.

include/asm-generic/bitops/instrumented-atomic.h

+3 −3
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ static inline void change_bit(long nr, volatile unsigned long *addr) 
 */

static inline bool test_and_set_bit(long nr, volatile unsigned long *addr)

{

	instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));

	instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));

	return arch_test_and_set_bit(nr, addr);

}
@@ -80,7 +80,7 @@ static inline bool test_and_set_bit(long nr, volatile unsigned long *addr) 
 */

static inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)

{

	instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));

	instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));

	return arch_test_and_clear_bit(nr, addr);

}
@@ -93,7 +93,7 @@ static inline bool test_and_clear_bit(long nr, volatile unsigned long *addr) 
 */

static inline bool test_and_change_bit(long nr, volatile unsigned long *addr)

{

	instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));

	instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));

	return arch_test_and_change_bit(nr, addr);

}

include/asm-generic/bitops/instrumented-lock.h

+1 −1
Original line number Diff line number Diff line
@@ -52,7 +52,7 @@ static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr) 
 */

static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr)

{

	instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));

	instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));

	return arch_test_and_set_bit_lock(nr, addr);

}

include/asm-generic/bitops/instrumented-non-atomic.h

+27 −3
Original line number Diff line number Diff line
@@ -58,6 +58,30 @@ static inline void __change_bit(long nr, volatile unsigned long *addr) 
	arch___change_bit(nr, addr);

}



static inline void __instrument_read_write_bitop(long nr, volatile unsigned long *addr)

{

	if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC)) {

		/*

		 * We treat non-atomic read-write bitops a little more special.

		 * Given the operations here only modify a single bit, assuming

		 * non-atomicity of the writer is sufficient may be reasonable

		 * for certain usage (and follows the permissible nature of the

		 * assume-plain-writes-atomic rule):

		 * 1. report read-modify-write races -> check read;

		 * 2. do not report races with marked readers, but do report

		 *    races with unmarked readers -> check "atomic" write.

		 */

		kcsan_check_read(addr + BIT_WORD(nr), sizeof(long));

		/*

		 * Use generic write instrumentation, in case other sanitizers

		 * or tools are enabled alongside KCSAN.

		 */

		instrument_write(addr + BIT_WORD(nr), sizeof(long));

	} else {

		instrument_read_write(addr + BIT_WORD(nr), sizeof(long));

	}

}



/**

 * __test_and_set_bit - Set a bit and return its old value

 * @nr: Bit to set
@@ -68,7 +92,7 @@ static inline void __change_bit(long nr, volatile unsigned long *addr) 
 */

static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr)

{

	instrument_write(addr + BIT_WORD(nr), sizeof(long));

	__instrument_read_write_bitop(nr, addr);

	return arch___test_and_set_bit(nr, addr);

}
@@ -82,7 +106,7 @@ static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr) 
 */

static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr)

{

	instrument_write(addr + BIT_WORD(nr), sizeof(long));

	__instrument_read_write_bitop(nr, addr);

	return arch___test_and_clear_bit(nr, addr);

}
@@ -96,7 +120,7 @@ static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr) 
 */

static inline bool __test_and_change_bit(long nr, volatile unsigned long *addr)

{

	instrument_write(addr + BIT_WORD(nr), sizeof(long));

	__instrument_read_write_bitop(nr, addr);

	return arch___test_and_change_bit(nr, addr);

}

include/linux/instrumented.h

+30 −0
Original line number Diff line number Diff line
@@ -42,6 +42,21 @@ static __always_inline void instrument_write(const volatile void *v, size_t size 
	kcsan_check_write(v, size);

}



/**

 * instrument_read_write - instrument regular read-write 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)

{

	kasan_check_write(v, size);

	kcsan_check_read_write(v, size);

}



/**

 * instrument_atomic_read - instrument atomic read access

 *
@@ -72,6 +87,21 @@ static __always_inline void instrument_atomic_write(const volatile void *v, size 
	kcsan_check_atomic_write(v, size);

}



/**

 * instrument_atomic_read_write - instrument atomic read-write 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)

{

	kasan_check_write(v, size);

	kcsan_check_atomic_read_write(v, size);

}



/**

 * instrument_copy_to_user - instrument reads of copy_to_user

 *

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