[PATCH v2 1/2] kasan: support instrumented bitops combined with generic bitops
Daniel Axtens
dja at axtens.net
Tue Oct 29 00:56:11 AEDT 2019
Hi all,
Would it be possible to get an Ack from a KASAN maintainter? mpe is
happy to take this through powerpc but would like an ack first.
Regards,
Daniel
>> Currently bitops-instrumented.h assumes that the architecture provides
>> atomic, non-atomic and locking bitops (e.g. both set_bit and __set_bit).
>> This is true on x86 and s390, but is not always true: there is a
>> generic bitops/non-atomic.h header that provides generic non-atomic
>> operations, and also a generic bitops/lock.h for locking operations.
>>
>> powerpc uses the generic non-atomic version, so it does not have it's
>> own e.g. __set_bit that could be renamed arch___set_bit.
>>
>> Split up bitops-instrumented.h to mirror the atomic/non-atomic/lock
>> split. This allows arches to only include the headers where they
>> have arch-specific versions to rename. Update x86 and s390.
>
> This patch should not cause any functional change on either arch.
>
> To verify, I have compiled kernels with and without these. With the
> appropriate setting of environment variables and the general assorted
> mucking around required for reproducible builds, I have tested:
>
> - s390, without kasan - byte-for-byte identical vmlinux before and after
> - x86, without kasan - byte-for-byte identical vmlinux before and after
>
> - s390, inline kasan - byte-for-byte identical vmlinux before and after
>
> - x86, inline kasan - 3 functions in drivers/rtc/dev.o are reordered,
> build-id and __ex_table differ, rest is unchanged
>
> The kernels were based on defconfigs. I disabled debug info (as that
> obviously changes with code being rearranged) and initrd support (as the
> cpio wrapper doesn't seem to take KBUILD_BUILD_TIMESTAMP but the current
> time, and that screws things up).
>
> I wouldn't read too much in to the weird result on x86 with inline
> kasan: the code I moved about is compiled even without KASAN enabled.
>
> Regards,
> Daniel
>
>
>>
>> (The generic operations are automatically instrumented because they're
>> written in C, not asm.)
>>
>> Suggested-by: Christophe Leroy <christophe.leroy at c-s.fr>
>> Reviewed-by: Christophe Leroy <christophe.leroy at c-s.fr>
>> Signed-off-by: Daniel Axtens <dja at axtens.net>
>> ---
>> Documentation/core-api/kernel-api.rst | 17 +-
>> arch/s390/include/asm/bitops.h | 4 +-
>> arch/x86/include/asm/bitops.h | 4 +-
>> include/asm-generic/bitops-instrumented.h | 263 ------------------
>> .../asm-generic/bitops/instrumented-atomic.h | 100 +++++++
>> .../asm-generic/bitops/instrumented-lock.h | 81 ++++++
>> .../bitops/instrumented-non-atomic.h | 114 ++++++++
>> 7 files changed, 317 insertions(+), 266 deletions(-)
>> delete mode 100644 include/asm-generic/bitops-instrumented.h
>> create mode 100644 include/asm-generic/bitops/instrumented-atomic.h
>> create mode 100644 include/asm-generic/bitops/instrumented-lock.h
>> create mode 100644 include/asm-generic/bitops/instrumented-non-atomic.h
>>
>> diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst
>> index 08af5caf036d..2e21248277e3 100644
>> --- a/Documentation/core-api/kernel-api.rst
>> +++ b/Documentation/core-api/kernel-api.rst
>> @@ -54,7 +54,22 @@ The Linux kernel provides more basic utility functions.
>> Bit Operations
>> --------------
>>
>> -.. kernel-doc:: include/asm-generic/bitops-instrumented.h
>> +Atomic Operations
>> +~~~~~~~~~~~~~~~~~
>> +
>> +.. kernel-doc:: include/asm-generic/bitops/instrumented-atomic.h
>> + :internal:
>> +
>> +Non-atomic Operations
>> +~~~~~~~~~~~~~~~~~~~~~
>> +
>> +.. kernel-doc:: include/asm-generic/bitops/instrumented-non-atomic.h
>> + :internal:
>> +
>> +Locking Operations
>> +~~~~~~~~~~~~~~~~~~
>> +
>> +.. kernel-doc:: include/asm-generic/bitops/instrumented-lock.h
>> :internal:
>>
>> Bitmap Operations
>> diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
>> index b8833ac983fa..0ceb12593a68 100644
>> --- a/arch/s390/include/asm/bitops.h
>> +++ b/arch/s390/include/asm/bitops.h
>> @@ -241,7 +241,9 @@ static inline void arch___clear_bit_unlock(unsigned long nr,
>> arch___clear_bit(nr, ptr);
>> }
>>
>> -#include <asm-generic/bitops-instrumented.h>
>> +#include <asm-generic/bitops/instrumented-atomic.h>
>> +#include <asm-generic/bitops/instrumented-non-atomic.h>
>> +#include <asm-generic/bitops/instrumented-lock.h>
>>
>> /*
>> * Functions which use MSB0 bit numbering.
>> diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
>> index ba15d53c1ca7..4a2e2432238f 100644
>> --- a/arch/x86/include/asm/bitops.h
>> +++ b/arch/x86/include/asm/bitops.h
>> @@ -389,7 +389,9 @@ static __always_inline int fls64(__u64 x)
>>
>> #include <asm-generic/bitops/const_hweight.h>
>>
>> -#include <asm-generic/bitops-instrumented.h>
>> +#include <asm-generic/bitops/instrumented-atomic.h>
>> +#include <asm-generic/bitops/instrumented-non-atomic.h>
>> +#include <asm-generic/bitops/instrumented-lock.h>
>>
>> #include <asm-generic/bitops/le.h>
>>
>> diff --git a/include/asm-generic/bitops-instrumented.h b/include/asm-generic/bitops-instrumented.h
>> deleted file mode 100644
>> index ddd1c6d9d8db..000000000000
>> --- a/include/asm-generic/bitops-instrumented.h
>> +++ /dev/null
>> @@ -1,263 +0,0 @@
>> -/* SPDX-License-Identifier: GPL-2.0 */
>> -
>> -/*
>> - * This file provides wrappers with sanitizer instrumentation for bit
>> - * operations.
>> - *
>> - * To use this functionality, an arch's bitops.h file needs to define each of
>> - * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
>> - * arch___set_bit(), etc.).
>> - */
>> -#ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_H
>> -#define _ASM_GENERIC_BITOPS_INSTRUMENTED_H
>> -
>> -#include <linux/kasan-checks.h>
>> -
>> -/**
>> - * set_bit - Atomically set a bit in memory
>> - * @nr: the bit to set
>> - * @addr: the address to start counting from
>> - *
>> - * This is a relaxed atomic operation (no implied memory barriers).
>> - *
>> - * Note that @nr may be almost arbitrarily large; this function is not
>> - * restricted to acting on a single-word quantity.
>> - */
>> -static inline void set_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch_set_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * __set_bit - Set a bit in memory
>> - * @nr: the bit to set
>> - * @addr: the address to start counting from
>> - *
>> - * Unlike set_bit(), this function is non-atomic. If it is called on the same
>> - * region of memory concurrently, the effect may be that only one operation
>> - * succeeds.
>> - */
>> -static inline void __set_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch___set_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * clear_bit - Clears a bit in memory
>> - * @nr: Bit to clear
>> - * @addr: Address to start counting from
>> - *
>> - * This is a relaxed atomic operation (no implied memory barriers).
>> - */
>> -static inline void clear_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch_clear_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * __clear_bit - Clears a bit in memory
>> - * @nr: the bit to clear
>> - * @addr: the address to start counting from
>> - *
>> - * Unlike clear_bit(), this function is non-atomic. If it is called on the same
>> - * region of memory concurrently, the effect may be that only one operation
>> - * succeeds.
>> - */
>> -static inline void __clear_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch___clear_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * clear_bit_unlock - Clear a bit in memory, for unlock
>> - * @nr: the bit to set
>> - * @addr: the address to start counting from
>> - *
>> - * This operation is atomic and provides release barrier semantics.
>> - */
>> -static inline void clear_bit_unlock(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch_clear_bit_unlock(nr, addr);
>> -}
>> -
>> -/**
>> - * __clear_bit_unlock - Clears a bit in memory
>> - * @nr: Bit to clear
>> - * @addr: Address to start counting from
>> - *
>> - * This is a non-atomic operation but implies a release barrier before the
>> - * memory operation. It can be used for an unlock if no other CPUs can
>> - * concurrently modify other bits in the word.
>> - */
>> -static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch___clear_bit_unlock(nr, addr);
>> -}
>> -
>> -/**
>> - * change_bit - Toggle a bit in memory
>> - * @nr: Bit to change
>> - * @addr: Address to start counting from
>> - *
>> - * This is a relaxed atomic operation (no implied memory barriers).
>> - *
>> - * Note that @nr may be almost arbitrarily large; this function is not
>> - * restricted to acting on a single-word quantity.
>> - */
>> -static inline void change_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch_change_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * __change_bit - Toggle a bit in memory
>> - * @nr: the bit to change
>> - * @addr: the address to start counting from
>> - *
>> - * Unlike change_bit(), this function is non-atomic. If it is called on the same
>> - * region of memory concurrently, the effect may be that only one operation
>> - * succeeds.
>> - */
>> -static inline void __change_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - arch___change_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * test_and_set_bit - Set a bit and return its old value
>> - * @nr: Bit to set
>> - * @addr: Address to count from
>> - *
>> - * This is an atomic fully-ordered operation (implied full memory barrier).
>> - */
>> -static inline bool test_and_set_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch_test_and_set_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * __test_and_set_bit - Set a bit and return its old value
>> - * @nr: Bit to set
>> - * @addr: Address to count from
>> - *
>> - * This operation is non-atomic. If two instances of this operation race, one
>> - * can appear to succeed but actually fail.
>> - */
>> -static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch___test_and_set_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * test_and_set_bit_lock - Set a bit and return its old value, for lock
>> - * @nr: Bit to set
>> - * @addr: Address to count from
>> - *
>> - * This operation is atomic and provides acquire barrier semantics if
>> - * the returned value is 0.
>> - * It can be used to implement bit locks.
>> - */
>> -static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch_test_and_set_bit_lock(nr, addr);
>> -}
>> -
>> -/**
>> - * test_and_clear_bit - Clear a bit and return its old value
>> - * @nr: Bit to clear
>> - * @addr: Address to count from
>> - *
>> - * This is an atomic fully-ordered operation (implied full memory barrier).
>> - */
>> -static inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch_test_and_clear_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * __test_and_clear_bit - Clear a bit and return its old value
>> - * @nr: Bit to clear
>> - * @addr: Address to count from
>> - *
>> - * This operation is non-atomic. If two instances of this operation race, one
>> - * can appear to succeed but actually fail.
>> - */
>> -static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch___test_and_clear_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * test_and_change_bit - Change a bit and return its old value
>> - * @nr: Bit to change
>> - * @addr: Address to count from
>> - *
>> - * This is an atomic fully-ordered operation (implied full memory barrier).
>> - */
>> -static inline bool test_and_change_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch_test_and_change_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * __test_and_change_bit - Change a bit and return its old value
>> - * @nr: Bit to change
>> - * @addr: Address to count from
>> - *
>> - * This operation is non-atomic. If two instances of this operation race, one
>> - * can appear to succeed but actually fail.
>> - */
>> -static inline bool __test_and_change_bit(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch___test_and_change_bit(nr, addr);
>> -}
>> -
>> -/**
>> - * test_bit - Determine whether a bit is set
>> - * @nr: bit number to test
>> - * @addr: Address to start counting from
>> - */
>> -static inline bool test_bit(long nr, const volatile unsigned long *addr)
>> -{
>> - kasan_check_read(addr + BIT_WORD(nr), sizeof(long));
>> - return arch_test_bit(nr, addr);
>> -}
>> -
>> -#if defined(arch_clear_bit_unlock_is_negative_byte)
>> -/**
>> - * clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
>> - * byte is negative, for unlock.
>> - * @nr: the bit to clear
>> - * @addr: the address to start counting from
>> - *
>> - * This operation is atomic and provides release barrier semantics.
>> - *
>> - * This is a bit of a one-trick-pony for the filemap code, which clears
>> - * PG_locked and tests PG_waiters,
>> - */
>> -static inline bool
>> -clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr)
>> -{
>> - kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> - return arch_clear_bit_unlock_is_negative_byte(nr, addr);
>> -}
>> -/* Let everybody know we have it. */
>> -#define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte
>> -#endif
>> -
>> -#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_H */
>> diff --git a/include/asm-generic/bitops/instrumented-atomic.h b/include/asm-generic/bitops/instrumented-atomic.h
>> new file mode 100644
>> index 000000000000..18ce3c9e8eec
>> --- /dev/null
>> +++ b/include/asm-generic/bitops/instrumented-atomic.h
>> @@ -0,0 +1,100 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +/*
>> + * This file provides wrappers with sanitizer instrumentation for atomic bit
>> + * operations.
>> + *
>> + * To use this functionality, an arch's bitops.h file needs to define each of
>> + * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
>> + * arch___set_bit(), etc.).
>> + */
>> +#ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H
>> +#define _ASM_GENERIC_BITOPS_INSTRUMENTED_ATOMIC_H
>> +
>> +#include <linux/kasan-checks.h>
>> +
>> +/**
>> + * set_bit - Atomically set a bit in memory
>> + * @nr: the bit to set
>> + * @addr: the address to start counting from
>> + *
>> + * This is a relaxed atomic operation (no implied memory barriers).
>> + *
>> + * Note that @nr may be almost arbitrarily large; this function is not
>> + * restricted to acting on a single-word quantity.
>> + */
>> +static inline void set_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch_set_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * clear_bit - Clears a bit in memory
>> + * @nr: Bit to clear
>> + * @addr: Address to start counting from
>> + *
>> + * This is a relaxed atomic operation (no implied memory barriers).
>> + */
>> +static inline void clear_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch_clear_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * change_bit - Toggle a bit in memory
>> + * @nr: Bit to change
>> + * @addr: Address to start counting from
>> + *
>> + * This is a relaxed atomic operation (no implied memory barriers).
>> + *
>> + * Note that @nr may be almost arbitrarily large; this function is not
>> + * restricted to acting on a single-word quantity.
>> + */
>> +static inline void change_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch_change_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * test_and_set_bit - Set a bit and return its old value
>> + * @nr: Bit to set
>> + * @addr: Address to count from
>> + *
>> + * This is an atomic fully-ordered operation (implied full memory barrier).
>> + */
>> +static inline bool test_and_set_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch_test_and_set_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * test_and_clear_bit - Clear a bit and return its old value
>> + * @nr: Bit to clear
>> + * @addr: Address to count from
>> + *
>> + * This is an atomic fully-ordered operation (implied full memory barrier).
>> + */
>> +static inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch_test_and_clear_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * test_and_change_bit - Change a bit and return its old value
>> + * @nr: Bit to change
>> + * @addr: Address to count from
>> + *
>> + * This is an atomic fully-ordered operation (implied full memory barrier).
>> + */
>> +static inline bool test_and_change_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch_test_and_change_bit(nr, addr);
>> +}
>> +
>> +#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */
>> diff --git a/include/asm-generic/bitops/instrumented-lock.h b/include/asm-generic/bitops/instrumented-lock.h
>> new file mode 100644
>> index 000000000000..ec53fdeea9ec
>> --- /dev/null
>> +++ b/include/asm-generic/bitops/instrumented-lock.h
>> @@ -0,0 +1,81 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +/*
>> + * This file provides wrappers with sanitizer instrumentation for bit
>> + * locking operations.
>> + *
>> + * To use this functionality, an arch's bitops.h file needs to define each of
>> + * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
>> + * arch___set_bit(), etc.).
>> + */
>> +#ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H
>> +#define _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H
>> +
>> +#include <linux/kasan-checks.h>
>> +
>> +/**
>> + * clear_bit_unlock - Clear a bit in memory, for unlock
>> + * @nr: the bit to set
>> + * @addr: the address to start counting from
>> + *
>> + * This operation is atomic and provides release barrier semantics.
>> + */
>> +static inline void clear_bit_unlock(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch_clear_bit_unlock(nr, addr);
>> +}
>> +
>> +/**
>> + * __clear_bit_unlock - Clears a bit in memory
>> + * @nr: Bit to clear
>> + * @addr: Address to start counting from
>> + *
>> + * This is a non-atomic operation but implies a release barrier before the
>> + * memory operation. It can be used for an unlock if no other CPUs can
>> + * concurrently modify other bits in the word.
>> + */
>> +static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch___clear_bit_unlock(nr, addr);
>> +}
>> +
>> +/**
>> + * test_and_set_bit_lock - Set a bit and return its old value, for lock
>> + * @nr: Bit to set
>> + * @addr: Address to count from
>> + *
>> + * This operation is atomic and provides acquire barrier semantics if
>> + * the returned value is 0.
>> + * It can be used to implement bit locks.
>> + */
>> +static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch_test_and_set_bit_lock(nr, addr);
>> +}
>> +
>> +#if defined(arch_clear_bit_unlock_is_negative_byte)
>> +/**
>> + * clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
>> + * byte is negative, for unlock.
>> + * @nr: the bit to clear
>> + * @addr: the address to start counting from
>> + *
>> + * This operation is atomic and provides release barrier semantics.
>> + *
>> + * This is a bit of a one-trick-pony for the filemap code, which clears
>> + * PG_locked and tests PG_waiters,
>> + */
>> +static inline bool
>> +clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch_clear_bit_unlock_is_negative_byte(nr, addr);
>> +}
>> +/* Let everybody know we have it. */
>> +#define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte
>> +#endif
>> +
>> +#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H */
>> diff --git a/include/asm-generic/bitops/instrumented-non-atomic.h b/include/asm-generic/bitops/instrumented-non-atomic.h
>> new file mode 100644
>> index 000000000000..95ff28d128a1
>> --- /dev/null
>> +++ b/include/asm-generic/bitops/instrumented-non-atomic.h
>> @@ -0,0 +1,114 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +/*
>> + * This file provides wrappers with sanitizer instrumentation for non-atomic
>> + * bit operations.
>> + *
>> + * To use this functionality, an arch's bitops.h file needs to define each of
>> + * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
>> + * arch___set_bit(), etc.).
>> + */
>> +#ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
>> +#define _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
>> +
>> +#include <linux/kasan-checks.h>
>> +
>> +/**
>> + * __set_bit - Set a bit in memory
>> + * @nr: the bit to set
>> + * @addr: the address to start counting from
>> + *
>> + * Unlike set_bit(), this function is non-atomic. If it is called on the same
>> + * region of memory concurrently, the effect may be that only one operation
>> + * succeeds.
>> + */
>> +static inline void __set_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch___set_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * __clear_bit - Clears a bit in memory
>> + * @nr: the bit to clear
>> + * @addr: the address to start counting from
>> + *
>> + * Unlike clear_bit(), this function is non-atomic. If it is called on the same
>> + * region of memory concurrently, the effect may be that only one operation
>> + * succeeds.
>> + */
>> +static inline void __clear_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch___clear_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * __change_bit - Toggle a bit in memory
>> + * @nr: the bit to change
>> + * @addr: the address to start counting from
>> + *
>> + * Unlike change_bit(), this function is non-atomic. If it is called on the same
>> + * region of memory concurrently, the effect may be that only one operation
>> + * succeeds.
>> + */
>> +static inline void __change_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + arch___change_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * __test_and_set_bit - Set a bit and return its old value
>> + * @nr: Bit to set
>> + * @addr: Address to count from
>> + *
>> + * This operation is non-atomic. If two instances of this operation race, one
>> + * can appear to succeed but actually fail.
>> + */
>> +static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch___test_and_set_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * __test_and_clear_bit - Clear a bit and return its old value
>> + * @nr: Bit to clear
>> + * @addr: Address to count from
>> + *
>> + * This operation is non-atomic. If two instances of this operation race, one
>> + * can appear to succeed but actually fail.
>> + */
>> +static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch___test_and_clear_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * __test_and_change_bit - Change a bit and return its old value
>> + * @nr: Bit to change
>> + * @addr: Address to count from
>> + *
>> + * This operation is non-atomic. If two instances of this operation race, one
>> + * can appear to succeed but actually fail.
>> + */
>> +static inline bool __test_and_change_bit(long nr, volatile unsigned long *addr)
>> +{
>> + kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
>> + return arch___test_and_change_bit(nr, addr);
>> +}
>> +
>> +/**
>> + * test_bit - Determine whether a bit is set
>> + * @nr: bit number to test
>> + * @addr: Address to start counting from
>> + */
>> +static inline bool test_bit(long nr, const volatile unsigned long *addr)
>> +{
>> + kasan_check_read(addr + BIT_WORD(nr), sizeof(long));
>> + return arch_test_bit(nr, addr);
>> +}
>> +
>> +#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */
>> --
>> 2.20.1
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