This adds a new header to asm-generic to allow optionally instrumenting architecture-specific asm implementations of bitops. This change includes the required change for x86 as reference and changes the kernel API doc to point to bitops-instrumented.h instead. Rationale: the functions in x86's bitops.h are no longer the kernel API functions, but instead the arch_ prefixed functions, which are then instrumented via bitops-instrumented.h. Other architectures can similarly add support for asm implementations of bitops. The documentation text was derived from x86 and existing bitops asm-generic versions: 1) references to x86 have been removed; 2) as a result, some of the text had to be reworded for clarity and consistency. Tested: using lib/test_kasan with bitops tests (pre-requisite patch). Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=198439 Signed-off-by: Marco Elver <elver@xxxxxxxxxx> --- Changes in v3: * Remove references to 'x86' in API documentation; as a result, had to reword doc text for clarify and consistency. * Remove #ifdef, since it is assumed that if asm-generic bitops implementations are used, bitops-instrumented.h is not needed. Changes in v2: * Instrument word-sized accesses, as specified by the interface. --- Documentation/core-api/kernel-api.rst | 2 +- arch/x86/include/asm/bitops.h | 189 ++++------------ include/asm-generic/bitops-instrumented.h | 263 ++++++++++++++++++++++ 3 files changed, 302 insertions(+), 152 deletions(-) create mode 100644 include/asm-generic/bitops-instrumented.h diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst index a29c99d13331..65266fa1b706 100644 --- a/Documentation/core-api/kernel-api.rst +++ b/Documentation/core-api/kernel-api.rst @@ -51,7 +51,7 @@ The Linux kernel provides more basic utility functions. Bit Operations -------------- -.. kernel-doc:: arch/x86/include/asm/bitops.h +.. kernel-doc:: include/asm-generic/bitops-instrumented.h :internal: Bitmap Operations diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 8e790ec219a5..ba15d53c1ca7 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -49,23 +49,8 @@ #define CONST_MASK_ADDR(nr, addr) WBYTE_ADDR((void *)(addr) + ((nr)>>3)) #define CONST_MASK(nr) (1 << ((nr) & 7)) -/** - * set_bit - Atomically set a bit in memory - * @nr: the bit to set - * @addr: the address to start counting from - * - * This function is atomic and may not be reordered. See __set_bit() - * if you do not require the atomic guarantees. - * - * Note: there are no guarantees that this function will not be reordered - * on non x86 architectures, so if you are writing portable code, - * make sure not to rely on its reordering guarantees. - * - * Note that @nr may be almost arbitrarily large; this function is not - * restricted to acting on a single-word quantity. - */ static __always_inline void -set_bit(long nr, volatile unsigned long *addr) +arch_set_bit(long nr, volatile unsigned long *addr) { if (IS_IMMEDIATE(nr)) { asm volatile(LOCK_PREFIX "orb %1,%0" @@ -78,32 +63,14 @@ set_bit(long nr, volatile unsigned long *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 and may be reordered. - * If it's called on the same region of memory simultaneously, the effect - * may be that only one operation succeeds. - */ -static __always_inline void __set_bit(long nr, volatile unsigned long *addr) +static __always_inline void +arch___set_bit(long nr, volatile unsigned long *addr) { asm volatile(__ASM_SIZE(bts) " %1,%0" : : ADDR, "Ir" (nr) : "memory"); } -/** - * clear_bit - Clears a bit in memory - * @nr: Bit to clear - * @addr: Address to start counting from - * - * clear_bit() is atomic and may not be reordered. However, it does - * not contain a memory barrier, so if it is used for locking purposes, - * you should call smp_mb__before_atomic() and/or smp_mb__after_atomic() - * in order to ensure changes are visible on other processors. - */ static __always_inline void -clear_bit(long nr, volatile unsigned long *addr) +arch_clear_bit(long nr, volatile unsigned long *addr) { if (IS_IMMEDIATE(nr)) { asm volatile(LOCK_PREFIX "andb %1,%0" @@ -115,26 +82,21 @@ clear_bit(long nr, volatile unsigned long *addr) } } -/* - * clear_bit_unlock - Clears a bit in memory - * @nr: Bit to clear - * @addr: Address to start counting from - * - * clear_bit() is atomic and implies release semantics before the memory - * operation. It can be used for an unlock. - */ -static __always_inline void clear_bit_unlock(long nr, volatile unsigned long *addr) +static __always_inline void +arch_clear_bit_unlock(long nr, volatile unsigned long *addr) { barrier(); - clear_bit(nr, addr); + arch_clear_bit(nr, addr); } -static __always_inline void __clear_bit(long nr, volatile unsigned long *addr) +static __always_inline void +arch___clear_bit(long nr, volatile unsigned long *addr) { asm volatile(__ASM_SIZE(btr) " %1,%0" : : ADDR, "Ir" (nr) : "memory"); } -static __always_inline bool clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr) +static __always_inline bool +arch_clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr) { bool negative; asm volatile(LOCK_PREFIX "andb %2,%1" @@ -143,48 +105,23 @@ static __always_inline bool clear_bit_unlock_is_negative_byte(long nr, volatile : "ir" ((char) ~(1 << nr)) : "memory"); return negative; } +#define arch_clear_bit_unlock_is_negative_byte \ + arch_clear_bit_unlock_is_negative_byte -// Let everybody know we have it -#define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte - -/* - * __clear_bit_unlock - Clears a bit in memory - * @nr: Bit to clear - * @addr: Address to start counting from - * - * __clear_bit() is non-atomic and implies release semantics before the memory - * operation. It can be used for an unlock if no other CPUs can concurrently - * modify other bits in the word. - */ -static __always_inline void __clear_bit_unlock(long nr, volatile unsigned long *addr) +static __always_inline void +arch___clear_bit_unlock(long nr, volatile unsigned long *addr) { - __clear_bit(nr, addr); + 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 and may be reordered. - * If it's called on the same region of memory simultaneously, the effect - * may be that only one operation succeeds. - */ -static __always_inline void __change_bit(long nr, volatile unsigned long *addr) +static __always_inline void +arch___change_bit(long nr, volatile unsigned long *addr) { asm volatile(__ASM_SIZE(btc) " %1,%0" : : ADDR, "Ir" (nr) : "memory"); } -/** - * change_bit - Toggle a bit in memory - * @nr: Bit to change - * @addr: Address to start counting from - * - * change_bit() is atomic and may not be reordered. - * Note that @nr may be almost arbitrarily large; this function is not - * restricted to acting on a single-word quantity. - */ -static __always_inline void change_bit(long nr, volatile unsigned long *addr) +static __always_inline void +arch_change_bit(long nr, volatile unsigned long *addr) { if (IS_IMMEDIATE(nr)) { asm volatile(LOCK_PREFIX "xorb %1,%0" @@ -196,42 +133,20 @@ static __always_inline void change_bit(long nr, volatile unsigned long *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 atomic and cannot be reordered. - * It also implies a memory barrier. - */ -static __always_inline bool test_and_set_bit(long nr, volatile unsigned long *addr) +static __always_inline bool +arch_test_and_set_bit(long nr, volatile unsigned long *addr) { return GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(bts), *addr, c, "Ir", nr); } -/** - * 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 is the same as test_and_set_bit on x86. - */ static __always_inline bool -test_and_set_bit_lock(long nr, volatile unsigned long *addr) +arch_test_and_set_bit_lock(long nr, volatile unsigned long *addr) { - return test_and_set_bit(nr, addr); + 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 and can be reordered. - * If two examples of this operation race, one can appear to succeed - * but actually fail. You must protect multiple accesses with a lock. - */ -static __always_inline bool __test_and_set_bit(long nr, volatile unsigned long *addr) +static __always_inline bool +arch___test_and_set_bit(long nr, volatile unsigned long *addr) { bool oldbit; @@ -242,28 +157,13 @@ static __always_inline bool __test_and_set_bit(long nr, volatile unsigned long * return oldbit; } -/** - * test_and_clear_bit - Clear a bit and return its old value - * @nr: Bit to clear - * @addr: Address to count from - * - * This operation is atomic and cannot be reordered. - * It also implies a memory barrier. - */ -static __always_inline bool test_and_clear_bit(long nr, volatile unsigned long *addr) +static __always_inline bool +arch_test_and_clear_bit(long nr, volatile unsigned long *addr) { return GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(btr), *addr, c, "Ir", nr); } -/** - * __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 and can be reordered. - * If two examples of this operation race, one can appear to succeed - * but actually fail. You must protect multiple accesses with a lock. - * +/* * Note: the operation is performed atomically with respect to * the local CPU, but not other CPUs. Portable code should not * rely on this behaviour. @@ -271,7 +171,8 @@ static __always_inline bool test_and_clear_bit(long nr, volatile unsigned long * * accessed from a hypervisor on the same CPU if running in a VM: don't change * this without also updating arch/x86/kernel/kvm.c */ -static __always_inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr) +static __always_inline bool +arch___test_and_clear_bit(long nr, volatile unsigned long *addr) { bool oldbit; @@ -282,8 +183,8 @@ static __always_inline bool __test_and_clear_bit(long nr, volatile unsigned long return oldbit; } -/* WARNING: non atomic and it can be reordered! */ -static __always_inline bool __test_and_change_bit(long nr, volatile unsigned long *addr) +static __always_inline bool +arch___test_and_change_bit(long nr, volatile unsigned long *addr) { bool oldbit; @@ -295,15 +196,8 @@ static __always_inline bool __test_and_change_bit(long nr, volatile unsigned lon return oldbit; } -/** - * test_and_change_bit - Change a bit and return its old value - * @nr: Bit to change - * @addr: Address to count from - * - * This operation is atomic and cannot be reordered. - * It also implies a memory barrier. - */ -static __always_inline bool test_and_change_bit(long nr, volatile unsigned long *addr) +static __always_inline bool +arch_test_and_change_bit(long nr, volatile unsigned long *addr) { return GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(btc), *addr, c, "Ir", nr); } @@ -326,16 +220,7 @@ static __always_inline bool variable_test_bit(long nr, volatile const unsigned l return oldbit; } -#if 0 /* Fool kernel-doc since it doesn't do macros yet */ -/** - * test_bit - Determine whether a bit is set - * @nr: bit number to test - * @addr: Address to start counting from - */ -static bool test_bit(int nr, const volatile unsigned long *addr); -#endif - -#define test_bit(nr, addr) \ +#define arch_test_bit(nr, addr) \ (__builtin_constant_p((nr)) \ ? constant_test_bit((nr), (addr)) \ : variable_test_bit((nr), (addr))) @@ -504,6 +389,8 @@ static __always_inline int fls64(__u64 x) #include <asm-generic/bitops/const_hweight.h> +#include <asm-generic/bitops-instrumented.h> + #include <asm-generic/bitops/le.h> #include <asm-generic/bitops/ext2-atomic-setbit.h> diff --git a/include/asm-generic/bitops-instrumented.h b/include/asm-generic/bitops-instrumented.h new file mode 100644 index 000000000000..ddd1c6d9d8db --- /dev/null +++ b/include/asm-generic/bitops-instrumented.h @@ -0,0 +1,263 @@ +/* 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 */ -- 2.22.0.rc1.257.g3120a18244-goog
