From e506ea451254ab17e0bf918ca36232fec2a9b10c Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 15 Oct 2019 16:29:32 -0700 Subject: compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h In preparation for allowing architectures to define their own implementation of the READ_ONCE() macro, move the generic {READ,WRITE}_ONCE() definitions out of the unwieldy 'linux/compiler.h' file and into a new 'rwonce.h' header under 'asm-generic'. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/Kbuild | 1 + include/asm-generic/barrier.h | 2 +- include/asm-generic/rwonce.h | 101 ++++++++++++++++++++++++++++++++++++++++++ include/linux/compiler.h | 93 +------------------------------------- 4 files changed, 105 insertions(+), 92 deletions(-) create mode 100644 include/asm-generic/rwonce.h (limited to 'include') diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild index 44ec80e70518..74b0612601dd 100644 --- a/include/asm-generic/Kbuild +++ b/include/asm-generic/Kbuild @@ -45,6 +45,7 @@ mandatory-y += pci.h mandatory-y += percpu.h mandatory-y += pgalloc.h mandatory-y += preempt.h +mandatory-y += rwonce.h mandatory-y += sections.h mandatory-y += serial.h mandatory-y += shmparam.h diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 2eacaf7d62f6..8116744bb82c 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -13,7 +13,7 @@ #ifndef __ASSEMBLY__ -#include +#include #ifndef nop #define nop() asm volatile ("nop") diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h new file mode 100644 index 000000000000..87584379da43 --- /dev/null +++ b/include/asm-generic/rwonce.h @@ -0,0 +1,101 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Prevent the compiler from merging or refetching reads or writes. The + * compiler is also forbidden from reordering successive instances of + * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some + * particular ordering. One way to make the compiler aware of ordering is to + * put the two invocations of READ_ONCE or WRITE_ONCE in different C + * statements. + * + * These two macros will also work on aggregate data types like structs or + * unions. + * + * Their two major use cases are: (1) Mediating communication between + * process-level code and irq/NMI handlers, all running on the same CPU, + * and (2) Ensuring that the compiler does not fold, spindle, or otherwise + * mutilate accesses that either do not require ordering or that interact + * with an explicit memory barrier or atomic instruction that provides the + * required ordering. + */ +#ifndef __ASM_GENERIC_RWONCE_H +#define __ASM_GENERIC_RWONCE_H + +#ifndef __ASSEMBLY__ + +#include +#include +#include + +#include + +/* + * Yes, this permits 64-bit accesses on 32-bit architectures. These will + * actually be atomic in some cases (namely Armv7 + LPAE), but for others we + * rely on the access being split into 2x32-bit accesses for a 32-bit quantity + * (e.g. a virtual address) and a strong prevailing wind. + */ +#define compiletime_assert_rwonce_type(t) \ + compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \ + "Unsupported access size for {READ,WRITE}_ONCE().") + +/* + * Use __READ_ONCE() instead of READ_ONCE() if you do not require any + * atomicity or dependency ordering guarantees. Note that this may result + * in tears! + */ +#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) + +#define __READ_ONCE_SCALAR(x) \ +({ \ + __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \ + smp_read_barrier_depends(); \ + (typeof(x))__x; \ +}) + +#define READ_ONCE(x) \ +({ \ + compiletime_assert_rwonce_type(x); \ + __READ_ONCE_SCALAR(x); \ +}) + +#define __WRITE_ONCE(x, val) \ +do { \ + *(volatile typeof(x) *)&(x) = (val); \ +} while (0) + +#define WRITE_ONCE(x, val) \ +do { \ + compiletime_assert_rwonce_type(x); \ + __WRITE_ONCE(x, val); \ +} while (0) + +static __no_sanitize_or_inline +unsigned long __read_once_word_nocheck(const void *addr) +{ + return __READ_ONCE(*(unsigned long *)addr); +} + +/* + * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a + * word from memory atomically but without telling KASAN/KCSAN. This is + * usually used by unwinding code when walking the stack of a running process. + */ +#define READ_ONCE_NOCHECK(x) \ +({ \ + unsigned long __x; \ + compiletime_assert(sizeof(x) == sizeof(__x), \ + "Unsupported access size for READ_ONCE_NOCHECK()."); \ + __x = __read_once_word_nocheck(&(x)); \ + smp_read_barrier_depends(); \ + (typeof(x))__x; \ +}) + +static __no_kasan_or_inline +unsigned long read_word_at_a_time(const void *addr) +{ + kasan_check_read(addr, 1); + return *(unsigned long *)addr; +} + +#endif /* __ASSEMBLY__ */ +#endif /* __ASM_GENERIC_RWONCE_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 204e76856435..f075a3df4fe2 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -230,28 +230,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) #endif -/* - * Prevent the compiler from merging or refetching reads or writes. The - * compiler is also forbidden from reordering successive instances of - * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some - * particular ordering. One way to make the compiler aware of ordering is to - * put the two invocations of READ_ONCE or WRITE_ONCE in different C - * statements. - * - * These two macros will also work on aggregate data types like structs or - * unions. - * - * Their two major use cases are: (1) Mediating communication between - * process-level code and irq/NMI handlers, all running on the same CPU, - * and (2) Ensuring that the compiler does not fold, spindle, or otherwise - * mutilate accesses that either do not require ordering or that interact - * with an explicit memory barrier or atomic instruction that provides the - * required ordering. - */ -#include -#include -#include - /** * data_race - mark an expression as containing intentional data races * @@ -272,65 +250,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, __v; \ }) -/* - * Use __READ_ONCE() instead of READ_ONCE() if you do not require any - * atomicity or dependency ordering guarantees. Note that this may result - * in tears! - */ -#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) - -#define __READ_ONCE_SCALAR(x) \ -({ \ - __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ -}) - -#define READ_ONCE(x) \ -({ \ - compiletime_assert_rwonce_type(x); \ - __READ_ONCE_SCALAR(x); \ -}) - -#define __WRITE_ONCE(x, val) \ -do { \ - *(volatile typeof(x) *)&(x) = (val); \ -} while (0) - -#define WRITE_ONCE(x, val) \ -do { \ - compiletime_assert_rwonce_type(x); \ - __WRITE_ONCE(x, val); \ -} while (0) - -static __no_sanitize_or_inline -unsigned long __read_once_word_nocheck(const void *addr) -{ - return __READ_ONCE(*(unsigned long *)addr); -} - -/* - * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a - * word from memory atomically but without telling KASAN/KCSAN. This is - * usually used by unwinding code when walking the stack of a running process. - */ -#define READ_ONCE_NOCHECK(x) \ -({ \ - unsigned long __x; \ - compiletime_assert(sizeof(x) == sizeof(__x), \ - "Unsupported access size for READ_ONCE_NOCHECK()."); \ - __x = __read_once_word_nocheck(&(x)); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ -}) - -static __no_kasan_or_inline -unsigned long read_word_at_a_time(const void *addr) -{ - kasan_check_read(addr, 1); - return *(unsigned long *)addr; -} - #endif /* __KERNEL__ */ /* @@ -395,16 +314,6 @@ static inline void *offset_to_ptr(const int *off) compiletime_assert(__native_word(t), \ "Need native word sized stores/loads for atomicity.") -/* - * Yes, this permits 64-bit accesses on 32-bit architectures. These will - * actually be atomic in some cases (namely Armv7 + LPAE), but for others we - * rely on the access being split into 2x32-bit accesses for a 32-bit quantity - * (e.g. a virtual address) and a strong prevailing wind. - */ -#define compiletime_assert_rwonce_type(t) \ - compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \ - "Unsupported access size for {READ,WRITE}_ONCE().") - /* &a[0] degrades to a pointer: a different type from an array */ #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) @@ -414,4 +323,6 @@ static inline void *offset_to_ptr(const int *off) */ #define prevent_tail_call_optimization() mb() +#include + #endif /* __LINUX_COMPILER_H */ -- cgit v1.2.3 From b78b331a3f5c0773171dadd6bbfa2a2242b45604 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 15 Oct 2019 17:30:47 -0700 Subject: asm/rwonce: Allow __READ_ONCE to be overridden by the architecture The meat and potatoes of READ_ONCE() is defined by the __READ_ONCE() macro, which uses a volatile casts in an attempt to avoid tearing of byte, halfword, word and double-word accesses. Allow this to be overridden by the architecture code in the case that things like memory barriers are also required. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/rwonce.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h index 87584379da43..04586b55a7c2 100644 --- a/include/asm-generic/rwonce.h +++ b/include/asm-generic/rwonce.h @@ -43,7 +43,9 @@ * atomicity or dependency ordering guarantees. Note that this may result * in tears! */ +#ifndef __READ_ONCE #define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) +#endif #define __READ_ONCE_SCALAR(x) \ ({ \ -- cgit v1.2.3 From 3c9184109e78ea2371ca8fa66d7f36986a53af98 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 30 Oct 2019 16:51:07 +0000 Subject: asm/rwonce: Remove smp_read_barrier_depends() invocation Alpha overrides __READ_ONCE() directly, so there's no need to use smp_read_barrier_depends() in the core code. This also means that __READ_ONCE() can be relied upon to provide dependency ordering. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/rwonce.h | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) (limited to 'include') diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h index 04586b55a7c2..3a7f737c77bd 100644 --- a/include/asm-generic/rwonce.h +++ b/include/asm-generic/rwonce.h @@ -40,24 +40,16 @@ /* * Use __READ_ONCE() instead of READ_ONCE() if you do not require any - * atomicity or dependency ordering guarantees. Note that this may result - * in tears! + * atomicity. Note that this may result in tears! */ #ifndef __READ_ONCE #define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x)) #endif -#define __READ_ONCE_SCALAR(x) \ -({ \ - __unqual_scalar_typeof(x) __x = __READ_ONCE(x); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ -}) - #define READ_ONCE(x) \ ({ \ compiletime_assert_rwonce_type(x); \ - __READ_ONCE_SCALAR(x); \ + __READ_ONCE(x); \ }) #define __WRITE_ONCE(x, val) \ @@ -84,12 +76,9 @@ unsigned long __read_once_word_nocheck(const void *addr) */ #define READ_ONCE_NOCHECK(x) \ ({ \ - unsigned long __x; \ - compiletime_assert(sizeof(x) == sizeof(__x), \ + compiletime_assert(sizeof(x) == sizeof(unsigned long), \ "Unsupported access size for READ_ONCE_NOCHECK()."); \ - __x = __read_once_word_nocheck(&(x)); \ - smp_read_barrier_depends(); \ - (typeof(x))__x; \ + (typeof(x))__read_once_word_nocheck(&(x)); \ }) static __no_kasan_or_inline -- cgit v1.2.3 From 002dff36acfba3476b685a09f78ffb7c452f5951 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 10 Jul 2020 14:49:40 +0100 Subject: asm/rwonce: Don't pull into 'asm-generic/rwonce.h' Now that 'smp_read_barrier_depends()' has gone the way of the Norwegian Blue, drop the inclusion of in 'asm-generic/rwonce.h'. This requires fixups to some architecture vdso headers which were previously relying on 'asm/barrier.h' coming in via 'linux/compiler.h'. Acked-by: Peter Zijlstra (Intel) Signed-off-by: Will Deacon --- arch/arm/include/asm/vdso/gettimeofday.h | 1 + arch/arm64/include/asm/vdso/compat_gettimeofday.h | 1 + arch/arm64/include/asm/vdso/gettimeofday.h | 1 + arch/riscv/include/asm/vdso/gettimeofday.h | 1 + include/asm-generic/rwonce.h | 2 -- include/linux/nospec.h | 2 ++ 6 files changed, 6 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/arch/arm/include/asm/vdso/gettimeofday.h b/arch/arm/include/asm/vdso/gettimeofday.h index 36dc18553ed8..1b207cf07697 100644 --- a/arch/arm/include/asm/vdso/gettimeofday.h +++ b/arch/arm/include/asm/vdso/gettimeofday.h @@ -7,6 +7,7 @@ #ifndef __ASSEMBLY__ +#include #include #include #include diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h index b6907ae78e53..bcf7649999a4 100644 --- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h +++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h @@ -7,6 +7,7 @@ #ifndef __ASSEMBLY__ +#include #include #include diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h index afba6ba332f8..127fa63893e2 100644 --- a/arch/arm64/include/asm/vdso/gettimeofday.h +++ b/arch/arm64/include/asm/vdso/gettimeofday.h @@ -7,6 +7,7 @@ #ifndef __ASSEMBLY__ +#include #include #define VDSO_HAS_CLOCK_GETRES 1 diff --git a/arch/riscv/include/asm/vdso/gettimeofday.h b/arch/riscv/include/asm/vdso/gettimeofday.h index c8e818688ec1..3099362d9f26 100644 --- a/arch/riscv/include/asm/vdso/gettimeofday.h +++ b/arch/riscv/include/asm/vdso/gettimeofday.h @@ -4,6 +4,7 @@ #ifndef __ASSEMBLY__ +#include #include #include #include diff --git a/include/asm-generic/rwonce.h b/include/asm-generic/rwonce.h index 3a7f737c77bd..8d0a6280e982 100644 --- a/include/asm-generic/rwonce.h +++ b/include/asm-generic/rwonce.h @@ -26,8 +26,6 @@ #include #include -#include - /* * Yes, this permits 64-bit accesses on 32-bit architectures. These will * actually be atomic in some cases (namely Armv7 + LPAE), but for others we diff --git a/include/linux/nospec.h b/include/linux/nospec.h index 0c5ef54fd416..c1e79f72cd89 100644 --- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -5,6 +5,8 @@ #ifndef _LINUX_NOSPEC_H #define _LINUX_NOSPEC_H + +#include #include struct task_struct; -- cgit v1.2.3 From 93fab07c22930c9ac4f01212fd92913c9a812f9f Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 30 Oct 2019 17:17:22 +0000 Subject: locking/barriers: Remove definitions for [smp_]read_barrier_depends() There are no remaining users of [smp_]read_barrier_depends(), so remove it from the generic implementation of 'barrier.h'. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/asm-generic/barrier.h | 17 ----------------- 1 file changed, 17 deletions(-) (limited to 'include') diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h index 8116744bb82c..fec97dc34de7 100644 --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -46,10 +46,6 @@ #define dma_wmb() wmb() #endif -#ifndef read_barrier_depends -#define read_barrier_depends() do { } while (0) -#endif - #ifndef __smp_mb #define __smp_mb() mb() #endif @@ -62,10 +58,6 @@ #define __smp_wmb() wmb() #endif -#ifndef __smp_read_barrier_depends -#define __smp_read_barrier_depends() read_barrier_depends() -#endif - #ifdef CONFIG_SMP #ifndef smp_mb @@ -80,10 +72,6 @@ #define smp_wmb() __smp_wmb() #endif -#ifndef smp_read_barrier_depends -#define smp_read_barrier_depends() __smp_read_barrier_depends() -#endif - #else /* !CONFIG_SMP */ #ifndef smp_mb @@ -98,10 +86,6 @@ #define smp_wmb() barrier() #endif -#ifndef smp_read_barrier_depends -#define smp_read_barrier_depends() do { } while (0) -#endif - #endif /* CONFIG_SMP */ #ifndef __smp_store_mb @@ -196,7 +180,6 @@ do { \ #define virt_mb() __smp_mb() #define virt_rmb() __smp_rmb() #define virt_wmb() __smp_wmb() -#define virt_read_barrier_depends() __smp_read_barrier_depends() #define virt_store_mb(var, value) __smp_store_mb(var, value) #define virt_mb__before_atomic() __smp_mb__before_atomic() #define virt_mb__after_atomic() __smp_mb__after_atomic() -- cgit v1.2.3 From c6cd2e011655aead2097273a04350f52429a1a8d Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 7 Nov 2019 14:46:59 +0000 Subject: include/linux: Remove smp_read_barrier_depends() from comments smp_read_barrier_depends() doesn't exist any more, so reword the two comments that mention it to refer to "dependency ordering" instead. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon --- include/linux/percpu-refcount.h | 2 +- include/linux/ptr_ring.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index 22d9d183950d..87d8a38bdea1 100644 --- a/include/linux/percpu-refcount.h +++ b/include/linux/percpu-refcount.h @@ -155,7 +155,7 @@ static inline bool __ref_is_percpu(struct percpu_ref *ref, * between contaminating the pointer value, meaning that * READ_ONCE() is required when fetching it. * - * The smp_read_barrier_depends() implied by READ_ONCE() pairs + * The dependency ordering from the READ_ONCE() pairs * with smp_store_release() in __percpu_ref_switch_to_percpu(). */ percpu_ptr = READ_ONCE(ref->percpu_count_ptr); diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index 417db0a79a62..808f9d3ee546 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -107,7 +107,7 @@ static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr) return -ENOSPC; /* Make sure the pointer we are storing points to a valid data. */ - /* Pairs with smp_read_barrier_depends in __ptr_ring_consume. */ + /* Pairs with the dependency ordering in __ptr_ring_consume. */ smp_wmb(); WRITE_ONCE(r->queue[r->producer++], ptr); -- cgit v1.2.3 From eb5c2d4b45e3d2d5d052ea6b8f1463976b1020d5 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 21 Jul 2020 09:54:15 +0100 Subject: compiler.h: Move compiletime_assert() macros into compiler_types.h The kernel test robot reports that moving READ_ONCE() out into its own header breaks a W=1 build for parisc, which is relying on the definition of compiletime_assert() being available: | In file included from ./arch/parisc/include/generated/asm/rwonce.h:1, | from ./include/asm-generic/barrier.h:16, | from ./arch/parisc/include/asm/barrier.h:29, | from ./arch/parisc/include/asm/atomic.h:11, | from ./include/linux/atomic.h:7, | from kernel/locking/percpu-rwsem.c:2: | ./arch/parisc/include/asm/atomic.h: In function 'atomic_read': | ./include/asm-generic/rwonce.h:36:2: error: implicit declaration of function 'compiletime_assert' [-Werror=implicit-function-declaration] | 36 | compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \ | | ^~~~~~~~~~~~~~~~~~ | ./include/asm-generic/rwonce.h:49:2: note: in expansion of macro 'compiletime_assert_rwonce_type' | 49 | compiletime_assert_rwonce_type(x); \ | | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | ./arch/parisc/include/asm/atomic.h:73:9: note: in expansion of macro 'READ_ONCE' | 73 | return READ_ONCE((v)->counter); | | ^~~~~~~~~ Move these macros into compiler_types.h, so that they are available to READ_ONCE() and friends. Link: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-July/587094.html Reported-by: kernel test robot Signed-off-by: Will Deacon --- include/linux/compiler.h | 41 ----------------------------------------- include/linux/compiler_types.h | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 41 deletions(-) (limited to 'include') diff --git a/include/linux/compiler.h b/include/linux/compiler.h index f075a3df4fe2..59f7194fdf08 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -273,47 +273,6 @@ static inline void *offset_to_ptr(const int *off) #endif /* __ASSEMBLY__ */ -/* Compile time object size, -1 for unknown */ -#ifndef __compiletime_object_size -# define __compiletime_object_size(obj) -1 -#endif -#ifndef __compiletime_warning -# define __compiletime_warning(message) -#endif -#ifndef __compiletime_error -# define __compiletime_error(message) -#endif - -#ifdef __OPTIMIZE__ -# define __compiletime_assert(condition, msg, prefix, suffix) \ - do { \ - extern void prefix ## suffix(void) __compiletime_error(msg); \ - if (!(condition)) \ - prefix ## suffix(); \ - } while (0) -#else -# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) -#endif - -#define _compiletime_assert(condition, msg, prefix, suffix) \ - __compiletime_assert(condition, msg, prefix, suffix) - -/** - * compiletime_assert - break build and emit msg if condition is false - * @condition: a compile-time constant condition to check - * @msg: a message to emit if condition is false - * - * In tradition of POSIX assert, this macro will break the build if the - * supplied condition is *false*, emitting the supplied error message if the - * compiler has support to do so. - */ -#define compiletime_assert(condition, msg) \ - _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) - -#define compiletime_assert_atomic_type(t) \ - compiletime_assert(__native_word(t), \ - "Need native word sized stores/loads for atomicity.") - /* &a[0] degrades to a pointer: a different type from an array */ #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index c3bf7710f69a..d9bbb62a3e2a 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -300,6 +300,47 @@ struct ftrace_likely_data { (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || \ sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) +/* Compile time object size, -1 for unknown */ +#ifndef __compiletime_object_size +# define __compiletime_object_size(obj) -1 +#endif +#ifndef __compiletime_warning +# define __compiletime_warning(message) +#endif +#ifndef __compiletime_error +# define __compiletime_error(message) +#endif + +#ifdef __OPTIMIZE__ +# define __compiletime_assert(condition, msg, prefix, suffix) \ + do { \ + extern void prefix ## suffix(void) __compiletime_error(msg); \ + if (!(condition)) \ + prefix ## suffix(); \ + } while (0) +#else +# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) +#endif + +#define _compiletime_assert(condition, msg, prefix, suffix) \ + __compiletime_assert(condition, msg, prefix, suffix) + +/** + * compiletime_assert - break build and emit msg if condition is false + * @condition: a compile-time constant condition to check + * @msg: a message to emit if condition is false + * + * In tradition of POSIX assert, this macro will break the build if the + * supplied condition is *false*, emitting the supplied error message if the + * compiler has support to do so. + */ +#define compiletime_assert(condition, msg) \ + _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) + +#define compiletime_assert_atomic_type(t) \ + compiletime_assert(__native_word(t), \ + "Need native word sized stores/loads for atomicity.") + /* Helpers for emitting diagnostics in pragmas. */ #ifndef __diag #define __diag(string) -- cgit v1.2.3