From 9b2c282b348dfe966bbba967dc7a45ce817cce50 Mon Sep 17 00:00:00 2001 From: Tom Rini Date: Mon, 29 Feb 2016 11:34:15 -0500 Subject: [PATCH] compiler*.h: sync include/linux/compiler*.h with Linux 4.5-rc6 Copy these from Linux v4.5-rc6 tag. This is needed so that we can keep up with newer gcc versions. Note that we don't have the uapi/ hierarchy from the kernel so continue to use Signed-off-by: Tom Rini --- include/linux/compiler-gcc.h | 266 ++++++++++++++++++++++++++++++++++------ include/linux/compiler-gcc3.h | 21 ---- include/linux/compiler-gcc4.h | 63 ---------- include/linux/compiler-intel.h | 45 +++++++ include/linux/compiler.h | 270 +++++++++++++++++++++++++++++++++++++++-- 5 files changed, 534 insertions(+), 131 deletions(-) delete mode 100644 include/linux/compiler-gcc3.h delete mode 100644 include/linux/compiler-gcc4.h create mode 100644 include/linux/compiler-intel.h diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 9896e54..22ab246 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -5,11 +5,28 @@ /* * Common definitions for all gcc versions go here. */ - +#define GCC_VERSION (__GNUC__ * 10000 \ + + __GNUC_MINOR__ * 100 \ + + __GNUC_PATCHLEVEL__) /* Optimization barrier */ + /* The "volatile" is due to gcc bugs */ #define barrier() __asm__ __volatile__("": : :"memory") +/* + * This version is i.e. to prevent dead stores elimination on @ptr + * where gcc and llvm may behave differently when otherwise using + * normal barrier(): while gcc behavior gets along with a normal + * barrier(), llvm needs an explicit input variable to be assumed + * clobbered. The issue is as follows: while the inline asm might + * access any memory it wants, the compiler could have fit all of + * @ptr into memory registers instead, and since @ptr never escaped + * from that, it proofed that the inline asm wasn't touching any of + * it. This version works well with both compilers, i.e. we're telling + * the compiler that the inline asm absolutely may see the contents + * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 + */ +#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") /* * This macro obfuscates arithmetic on a variable address so that gcc @@ -29,41 +46,63 @@ * the inline assembly constraint from =g to =r, in this particular * case either is valid. */ -#define RELOC_HIDE(ptr, off) \ - ({ unsigned long __ptr; \ - __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ - (typeof(ptr)) (__ptr + (off)); }) +#define RELOC_HIDE(ptr, off) \ +({ \ + unsigned long __ptr; \ + __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ + (typeof(ptr)) (__ptr + (off)); \ +}) + +/* Make the optimizer believe the variable can be manipulated arbitrarily. */ +#define OPTIMIZER_HIDE_VAR(var) \ + __asm__ ("" : "=r" (var) : "0" (var)) +#ifdef __CHECKER__ +#define __must_be_array(a) 0 +#else /* &a[0] degrades to a pointer: a different type from an array */ -#define __must_be_array(a) \ - BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0]))) +#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) +#endif /* * Force always-inline if the user requests it so via the .config, * or if gcc is too old: */ -#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ +#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) -# define inline inline __attribute__((always_inline)) -# define __inline__ __inline__ __attribute__((always_inline)) -# define __inline __inline __attribute__((always_inline)) +#define inline inline __attribute__((always_inline)) notrace +#define __inline__ __inline__ __attribute__((always_inline)) notrace +#define __inline __inline __attribute__((always_inline)) notrace +#else +/* A lot of inline functions can cause havoc with function tracing */ +#define inline inline notrace +#define __inline__ __inline__ notrace +#define __inline __inline notrace #endif -#define __deprecated __attribute__((deprecated)) -#ifndef __packed -# define __packed __attribute__((packed)) -#endif -#define __weak __attribute__((weak)) +#define __always_inline inline __attribute__((always_inline)) +#define noinline __attribute__((noinline)) + +#define __deprecated __attribute__((deprecated)) +#define __packed __attribute__((packed)) +#define __weak __attribute__((weak)) +#define __alias(symbol) __attribute__((alias(#symbol))) /* - * it doesn't make sense on ARM (currently the only user of __naked) to trace - * naked functions because then mcount is called without stack and frame pointer - * being set up and there is no chance to restore the lr register to the value - * before mcount was called. + * it doesn't make sense on ARM (currently the only user of __naked) + * to trace naked functions because then mcount is called without + * stack and frame pointer being set up and there is no chance to + * restore the lr register to the value before mcount was called. + * + * The asm() bodies of naked functions often depend on standard calling + * conventions, therefore they must be noinline and noclone. + * + * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. + * See GCC PR44290. */ -#define __naked __attribute__((naked)) notrace +#define __naked __attribute__((naked)) noinline __noclone notrace -#define __noreturn __attribute__((noreturn)) +#define __noreturn __attribute__((noreturn)) /* * From the GCC manual: @@ -75,19 +114,170 @@ * would be. * [...] */ -#ifndef __pure -# define __pure __attribute__((pure)) -#endif -#ifndef __aligned -# define __aligned(x) __attribute__((aligned(x))) -#endif -#define __printf(a,b) __attribute__((format(printf,a,b))) -#define noinline __attribute__((noinline)) -#define __attribute_const__ __attribute__((__const__)) -#define __maybe_unused __attribute__((unused)) -#define __always_unused __attribute__((unused)) - -#define __gcc_header(x) #x -#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) -#define gcc_header(x) _gcc_header(x) -#include gcc_header(__GNUC__) +#define __pure __attribute__((pure)) +#define __aligned(x) __attribute__((aligned(x))) +#define __printf(a, b) __attribute__((format(printf, a, b))) +#define __scanf(a, b) __attribute__((format(scanf, a, b))) +#define __attribute_const__ __attribute__((__const__)) +#define __maybe_unused __attribute__((unused)) +#define __always_unused __attribute__((unused)) + +/* gcc version specific checks */ + +#if GCC_VERSION < 30200 +# error Sorry, your compiler is too old - please upgrade it. +#endif + +#if GCC_VERSION < 30300 +# define __used __attribute__((__unused__)) +#else +# define __used __attribute__((__used__)) +#endif + +#ifdef CONFIG_GCOV_KERNEL +# if GCC_VERSION < 30400 +# error "GCOV profiling support for gcc versions below 3.4 not included" +# endif /* __GNUC_MINOR__ */ +#endif /* CONFIG_GCOV_KERNEL */ + +#if GCC_VERSION >= 30400 +#define __must_check __attribute__((warn_unused_result)) +#endif + +#if GCC_VERSION >= 40000 + +/* GCC 4.1.[01] miscompiles __weak */ +#ifdef __KERNEL__ +# if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 +# error Your version of gcc miscompiles the __weak directive +# endif +#endif + +#define __used __attribute__((__used__)) +#define __compiler_offsetof(a, b) \ + __builtin_offsetof(a, b) + +#if GCC_VERSION >= 40100 && GCC_VERSION < 40600 +# define __compiletime_object_size(obj) __builtin_object_size(obj, 0) +#endif + +#if GCC_VERSION >= 40300 +/* Mark functions as cold. gcc will assume any path leading to a call + * to them will be unlikely. This means a lot of manual unlikely()s + * are unnecessary now for any paths leading to the usual suspects + * like BUG(), printk(), panic() etc. [but let's keep them for now for + * older compilers] + * + * Early snapshots of gcc 4.3 don't support this and we can't detect this + * in the preprocessor, but we can live with this because they're unreleased. + * Maketime probing would be overkill here. + * + * gcc also has a __attribute__((__hot__)) to move hot functions into + * a special section, but I don't see any sense in this right now in + * the kernel context + */ +#define __cold __attribute__((__cold__)) + +#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) + +#ifndef __CHECKER__ +# define __compiletime_warning(message) __attribute__((warning(message))) +# define __compiletime_error(message) __attribute__((error(message))) +#endif /* __CHECKER__ */ +#endif /* GCC_VERSION >= 40300 */ + +#if GCC_VERSION >= 40500 +/* + * Mark a position in code as unreachable. This can be used to + * suppress control flow warnings after asm blocks that transfer + * control elsewhere. + * + * Early snapshots of gcc 4.5 don't support this and we can't detect + * this in the preprocessor, but we can live with this because they're + * unreleased. Really, we need to have autoconf for the kernel. + */ +#define unreachable() __builtin_unreachable() + +/* Mark a function definition as prohibited from being cloned. */ +#define __noclone __attribute__((__noclone__)) + +#endif /* GCC_VERSION >= 40500 */ + +#if GCC_VERSION >= 40600 +/* + * When used with Link Time Optimization, gcc can optimize away C functions or + * variables which are referenced only from assembly code. __visible tells the + * optimizer that something else uses this function or variable, thus preventing + * this. + */ +#define __visible __attribute__((externally_visible)) +#endif + + +#if GCC_VERSION >= 40900 && !defined(__CHECKER__) +/* + * __assume_aligned(n, k): Tell the optimizer that the returned + * pointer can be assumed to be k modulo n. The second argument is + * optional (default 0), so we use a variadic macro to make the + * shorthand. + * + * Beware: Do not apply this to functions which may return + * ERR_PTRs. Also, it is probably unwise to apply it to functions + * returning extra information in the low bits (but in that case the + * compiler should see some alignment anyway, when the return value is + * massaged by 'flags = ptr & 3; ptr &= ~3;'). + */ +#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) +#endif + +/* + * GCC 'asm goto' miscompiles certain code sequences: + * + * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 + * + * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. + * + * (asm goto is automatically volatile - the naming reflects this.) + */ +#define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) + +#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP +#if GCC_VERSION >= 40400 +#define __HAVE_BUILTIN_BSWAP32__ +#define __HAVE_BUILTIN_BSWAP64__ +#endif +#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600) +#define __HAVE_BUILTIN_BSWAP16__ +#endif +#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ + +#if GCC_VERSION >= 50000 +#define KASAN_ABI_VERSION 4 +#elif GCC_VERSION >= 40902 +#define KASAN_ABI_VERSION 3 +#endif + +#if GCC_VERSION >= 40902 +/* + * Tell the compiler that address safety instrumentation (KASAN) + * should not be applied to that function. + * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 + */ +#define __no_sanitize_address __attribute__((no_sanitize_address)) +#endif + +#endif /* gcc version >= 40000 specific checks */ + +#if !defined(__noclone) +#define __noclone /* not needed */ +#endif + +#if !defined(__no_sanitize_address) +#define __no_sanitize_address +#endif + +/* + * A trick to suppress uninitialized variable warning without generating any + * code + */ +#define uninitialized_var(x) x = x diff --git a/include/linux/compiler-gcc3.h b/include/linux/compiler-gcc3.h deleted file mode 100644 index 2befe65..0000000 --- a/include/linux/compiler-gcc3.h +++ /dev/null @@ -1,21 +0,0 @@ -#ifndef __LINUX_COMPILER_H -#error "Please don't include directly, include instead." -#endif - -#if __GNUC_MINOR__ >= 3 -# define __used __attribute__((__used__)) -#else -# define __used __attribute__((__unused__)) -#endif - -#if __GNUC_MINOR__ >= 4 -#define __must_check __attribute__((warn_unused_result)) -#endif - -/* - * A trick to suppress uninitialized variable warning without generating any - * code - */ -#define uninitialized_var(x) x = x - -#define __always_inline inline __attribute__((always_inline)) diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h deleted file mode 100644 index 27d11ca..0000000 --- a/include/linux/compiler-gcc4.h +++ /dev/null @@ -1,63 +0,0 @@ -#ifndef __LINUX_COMPILER_H -#error "Please don't include directly, include instead." -#endif - -/* GCC 4.1.[01] miscompiles __weak */ -#ifdef __KERNEL__ -# if __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ <= 1 -# error Your version of gcc miscompiles the __weak directive -# endif -#endif - -#define __used __attribute__((__used__)) -#define __must_check __attribute__((warn_unused_result)) -#define __compiler_offsetof(a,b) __builtin_offsetof(a,b) -#ifndef __always_inline -# define __always_inline inline __attribute__((always_inline)) -#endif - -/* - * A trick to suppress uninitialized variable warning without generating any - * code - */ -#define uninitialized_var(x) x = x - -#if __GNUC_MINOR__ >= 3 -/* Mark functions as cold. gcc will assume any path leading to a call - to them will be unlikely. This means a lot of manual unlikely()s - are unnecessary now for any paths leading to the usual suspects - like BUG(), printk(), panic() etc. [but let's keep them for now for - older compilers] - - Early snapshots of gcc 4.3 don't support this and we can't detect this - in the preprocessor, but we can live with this because they're unreleased. - Maketime probing would be overkill here. - - gcc also has a __attribute__((__hot__)) to move hot functions into - a special section, but I don't see any sense in this right now in - the kernel context */ -#define __cold __attribute__((__cold__)) - - -#if __GNUC_MINOR__ >= 5 -/* - * Mark a position in code as unreachable. This can be used to - * suppress control flow warnings after asm blocks that transfer - * control elsewhere. - * - * Early snapshots of gcc 4.5 don't support this and we can't detect - * this in the preprocessor, but we can live with this because they're - * unreleased. Really, we need to have autoconf for the kernel. - */ -#define unreachable() __builtin_unreachable() -#endif - -#endif - -#if __GNUC_MINOR__ > 0 -#define __compiletime_object_size(obj) __builtin_object_size(obj, 0) -#endif -#if __GNUC_MINOR__ >= 4 -#define __compiletime_warning(message) __attribute__((warning(message))) -#define __compiletime_error(message) __attribute__((error(message))) -#endif diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h new file mode 100644 index 0000000..d4c7113 --- /dev/null +++ b/include/linux/compiler-intel.h @@ -0,0 +1,45 @@ +#ifndef __LINUX_COMPILER_H +#error "Please don't include directly, include instead." +#endif + +#ifdef __ECC + +/* Some compiler specific definitions are overwritten here + * for Intel ECC compiler + */ + +#include + +/* Intel ECC compiler doesn't support gcc specific asm stmts. + * It uses intrinsics to do the equivalent things. + */ +#undef barrier +#undef barrier_data +#undef RELOC_HIDE +#undef OPTIMIZER_HIDE_VAR + +#define barrier() __memory_barrier() +#define barrier_data(ptr) barrier() + +#define RELOC_HIDE(ptr, off) \ + ({ unsigned long __ptr; \ + __ptr = (unsigned long) (ptr); \ + (typeof(ptr)) (__ptr + (off)); }) + +/* This should act as an optimization barrier on var. + * Given that this compiler does not have inline assembly, a compiler barrier + * is the best we can do. + */ +#define OPTIMIZER_HIDE_VAR(var) barrier() + +/* Intel ECC compiler doesn't support __builtin_types_compatible_p() */ +#define __must_be_array(a) 0 + +#endif + +#ifndef __HAVE_BUILTIN_BSWAP16__ +/* icc has this, but it's called _bswap16 */ +#define __HAVE_BUILTIN_BSWAP16__ +#define __builtin_bswap16 _bswap16 +#endif + diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 5be3dab..020ad16 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -5,16 +5,24 @@ #ifdef __CHECKER__ # define __user __attribute__((noderef, address_space(1))) -# define __kernel /* default address space */ +# define __kernel __attribute__((address_space(0))) # define __safe __attribute__((safe)) # define __force __attribute__((force)) # define __nocast __attribute__((nocast)) # define __iomem __attribute__((noderef, address_space(2))) +# define __must_hold(x) __attribute__((context(x,1,1))) # define __acquires(x) __attribute__((context(x,0,1))) # define __releases(x) __attribute__((context(x,1,0))) # define __acquire(x) __context__(x,1) # define __release(x) __context__(x,-1) # define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) +# define __percpu __attribute__((noderef, address_space(3))) +# define __pmem __attribute__((noderef, address_space(5))) +#ifdef CONFIG_SPARSE_RCU_POINTER +# define __rcu __attribute__((noderef, address_space(4))) +#else +# define __rcu +#endif extern void __chk_user_ptr(const volatile void __user *); extern void __chk_io_ptr(const volatile void __iomem *); #else @@ -27,20 +35,32 @@ extern void __chk_io_ptr(const volatile void __iomem *); # define __chk_user_ptr(x) (void)0 # define __chk_io_ptr(x) (void)0 # define __builtin_warning(x, y...) (1) +# define __must_hold(x) # define __acquires(x) # define __releases(x) # define __acquire(x) (void)0 # define __release(x) (void)0 # define __cond_lock(x,c) (c) +# define __percpu +# define __rcu +# define __pmem #endif +/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ +#define ___PASTE(a,b) a##b +#define __PASTE(a,b) ___PASTE(a,b) + #ifdef __KERNEL__ #ifdef __GNUC__ #include #endif +#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) +#define notrace __attribute__((hotpatch(0,0))) +#else #define notrace __attribute__((no_instrument_function)) +#endif /* Intel compiler defines __GNUC__. So we will overwrite implementations * coming from above header files here @@ -49,6 +69,13 @@ extern void __chk_io_ptr(const volatile void __iomem *); # include #endif +/* Clang compiler defines __GNUC__. So we will overwrite implementations + * coming from above header files here + */ +#ifdef __clang__ +#include +#endif + /* * Generic compiler-dependent macros required for kernel * build go below this comment. Actual compiler/compiler version @@ -117,7 +144,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); */ #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) #define __trace_if(cond) \ - if (__builtin_constant_p((cond)) ? !!(cond) : \ + if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ ({ \ int ______r; \ static struct ftrace_branch_data \ @@ -144,6 +171,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); # define barrier() __memory_barrier() #endif +#ifndef barrier_data +# define barrier_data(ptr) barrier() +#endif + /* Unreachable code */ #ifndef unreachable # define unreachable() do { } while (1) @@ -156,6 +187,135 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); (typeof(ptr)) (__ptr + (off)); }) #endif +#ifndef OPTIMIZER_HIDE_VAR +#define OPTIMIZER_HIDE_VAR(var) barrier() +#endif + +/* Not-quite-unique ID. */ +#ifndef __UNIQUE_ID +# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) +#endif + +#include + +#define __READ_ONCE_SIZE \ +({ \ + switch (size) { \ + case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ + case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ + case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ + case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ + default: \ + barrier(); \ + __builtin_memcpy((void *)res, (const void *)p, size); \ + barrier(); \ + } \ +}) + +static __always_inline +void __read_once_size(const volatile void *p, void *res, int size) +{ + __READ_ONCE_SIZE; +} + +#ifdef CONFIG_KASAN +/* + * This function is not 'inline' because __no_sanitize_address confilcts + * with inlining. Attempt to inline it may cause a build failure. + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 + * '__maybe_unused' allows us to avoid defined-but-not-used warnings. + */ +static __no_sanitize_address __maybe_unused +void __read_once_size_nocheck(const volatile void *p, void *res, int size) +{ + __READ_ONCE_SIZE; +} +#else +static __always_inline +void __read_once_size_nocheck(const volatile void *p, void *res, int size) +{ + __READ_ONCE_SIZE; +} +#endif + +static __always_inline void __write_once_size(volatile void *p, void *res, int size) +{ + switch (size) { + case 1: *(volatile __u8 *)p = *(__u8 *)res; break; + case 2: *(volatile __u16 *)p = *(__u16 *)res; break; + case 4: *(volatile __u32 *)p = *(__u32 *)res; break; + case 8: *(volatile __u64 *)p = *(__u64 *)res; break; + default: + barrier(); + __builtin_memcpy((void *)p, (const void *)res, size); + barrier(); + } +} + +/* + * Prevent the compiler from merging or refetching reads or writes. The + * compiler is also forbidden from reordering successive instances of + * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), 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, + * WRITE_ONCE or ACCESS_ONCE() in different C statements. + * + * In contrast to ACCESS_ONCE these two macros will also work on aggregate + * data types like structs or unions. If the size of the accessed data + * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) + * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a + * compile-time warning. + * + * 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. + */ + +#define __READ_ONCE(x, check) \ +({ \ + union { typeof(x) __val; char __c[1]; } __u; \ + if (check) \ + __read_once_size(&(x), __u.__c, sizeof(x)); \ + else \ + __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ + __u.__val; \ +}) +#define READ_ONCE(x) __READ_ONCE(x, 1) + +/* + * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need + * to hide memory access from KASAN. + */ +#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) + +#define WRITE_ONCE(x, val) \ +({ \ + union { typeof(x) __val; char __c[1]; } __u = \ + { .__val = (__force typeof(x)) (val) }; \ + __write_once_size(&(x), __u.__c, sizeof(x)); \ + __u.__val; \ +}) + +/** + * smp_cond_acquire() - Spin wait for cond with ACQUIRE ordering + * @cond: boolean expression to wait for + * + * Equivalent to using smp_load_acquire() on the condition variable but employs + * the control dependency of the wait to reduce the barrier on many platforms. + * + * The control dependency provides a LOAD->STORE order, the additional RMB + * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order, + * aka. ACQUIRE. + */ +#define smp_cond_acquire(cond) do { \ + while (!(cond)) \ + cpu_relax(); \ + smp_rmb(); /* ctrl + rmb := acquire */ \ +} while (0) + #endif /* __KERNEL__ */ #endif /* __ASSEMBLY__ */ @@ -228,7 +388,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); /* * Rather then using noinline to prevent stack consumption, use - * noinline_for_stack instead. For documentaiton reasons. + * noinline_for_stack instead. For documentation reasons. */ #define noinline_for_stack noinline @@ -270,11 +430,28 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); # define __section(S) __attribute__ ((__section__(#S))) #endif +#ifndef __visible +#define __visible +#endif + +/* + * Assume alignment of return value. + */ +#ifndef __assume_aligned +#define __assume_aligned(a, ...) +#endif + + /* Are two types/vars the same type (ignoring qualifiers)? */ #ifndef __same_type # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) #endif +/* Is this type a native word size -- useful for atomic operations */ +#ifndef __native_word +# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) +#endif + /* Compile time object size, -1 for unknown */ #ifndef __compiletime_object_size # define __compiletime_object_size(obj) -1 @@ -284,7 +461,48 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #endif #ifndef __compiletime_error # define __compiletime_error(message) +/* + * Sparse complains of variable sized arrays due to the temporary variable in + * __compiletime_assert. Unfortunately we can't just expand it out to make + * sparse see a constant array size without breaking compiletime_assert on old + * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. + */ +# ifndef __CHECKER__ +# define __compiletime_error_fallback(condition) \ + do { ((void)sizeof(char[1 - 2 * condition])); } while (0) +# endif #endif +#ifndef __compiletime_error_fallback +# define __compiletime_error_fallback(condition) do { } while (0) +#endif + +#define __compiletime_assert(condition, msg, prefix, suffix) \ + do { \ + bool __cond = !(condition); \ + extern void prefix ## suffix(void) __compiletime_error(msg); \ + if (__cond) \ + prefix ## suffix(); \ + __compiletime_error_fallback(__cond); \ + } while (0) + +#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_, __LINE__) + +#define compiletime_assert_atomic_type(t) \ + compiletime_assert(__native_word(t), \ + "Need native word sized stores/loads for atomicity.") /* * Prevent the compiler from merging or refetching accesses. The compiler @@ -293,11 +511,45 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); * to make the compiler aware of ordering is to put the two invocations of * ACCESS_ONCE() in different C statements. * - * This macro does absolutely -nothing- to prevent the CPU from reordering, - * merging, or refetching absolutely anything at any time. Its main intended - * use is to mediate communication between process-level code and irq/NMI - * handlers, all running on the same CPU. + * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE + * on a union member will work as long as the size of the member matches the + * size of the union and the size is smaller than word size. + * + * The major use cases of ACCESS_ONCE used to be (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. + * + * If possible use READ_ONCE()/WRITE_ONCE() instead. */ -#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) - +#define __ACCESS_ONCE(x) ({ \ + __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ + (volatile typeof(x) *)&(x); }) +#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) + +/** + * lockless_dereference() - safely load a pointer for later dereference + * @p: The pointer to load + * + * Similar to rcu_dereference(), but for situations where the pointed-to + * object's lifetime is managed by something other than RCU. That + * "something other" might be reference counting or simple immortality. + */ +#define lockless_dereference(p) \ +({ \ + typeof(p) _________p1 = READ_ONCE(p); \ + smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ + (_________p1); \ +}) + +/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ +#ifdef CONFIG_KPROBES +# define __kprobes __attribute__((__section__(".kprobes.text"))) +# define nokprobe_inline __always_inline +#else +# define __kprobes +# define nokprobe_inline inline +#endif #endif /* __LINUX_COMPILER_H */ -- 2.7.4