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 <linux/types.h>
Signed-off-by: Tom Rini trini@konsulko.com --- include/linux/compiler-gcc.h | 259 ++++++++++++++++++++++++++++++++-------- include/linux/compiler-gcc3.h | 23 ---- include/linux/compiler-gcc4.h | 88 -------------- include/linux/compiler-gcc5.h | 65 ---------- include/linux/compiler-intel.h | 5 + include/linux/compiler.h | 178 +++++++++++++++++++++++++-- 6 files changed, 383 insertions(+), 235 deletions(-) delete mode 100644 include/linux/compiler-gcc3.h delete mode 100644 include/linux/compiler-gcc4.h delete mode 100644 include/linux/compiler-gcc5.h
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index e057bd2..22ab246 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -5,14 +5,28 @@ /* * Common definitions for all gcc versions go here. */ -#define GCC_VERSION (__GNUC__ * 10000 \ - + __GNUC_MINOR__ * 100 \ - + __GNUC_PATCHLEVEL__) - +#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 @@ -32,58 +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)) +#define OPTIMIZER_HIDE_VAR(var) \ + __asm__ ("" : "=r" (var) : "0" (var))
#ifdef __CHECKER__ -#define __must_be_array(arr) 0 +#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(__same_type((a), &(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)) notrace -# define __inline__ __inline__ __attribute__((always_inline)) notrace -# define __inline __inline __attribute__((always_inline)) notrace +#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 +#define inline inline notrace +#define __inline__ __inline__ notrace +#define __inline __inline notrace #endif
-#define __deprecated __attribute__((deprecated)) -#ifndef __packed -#define __packed __attribute__((packed)) -#endif -#ifndef __weak -#define __weak __attribute__((weak)) -#endif +#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. * - * 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. + * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. + * See GCC PR44290. */ -#define __naked __attribute__((naked)) noinline __noclone notrace +#define __naked __attribute__((naked)) noinline __noclone notrace
-#define __noreturn __attribute__((noreturn)) +#define __noreturn __attribute__((noreturn))
/* * From the GCC manual: @@ -95,34 +114,170 @@ * would be. * [...] */ -#ifndef __pure -#define __pure __attribute__((pure)) +#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 -#ifndef __aligned -#define __aligned(x) __attribute__((aligned(x))) + + +#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 -#define __printf(a, b) __attribute__((format(printf, a, b))) -#define __scanf(a, b) __attribute__((format(scanf, 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__) +/* + * 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 - -#ifndef __always_inline -#define __always_inline inline __attribute__((always_inline)) -#endif diff --git a/include/linux/compiler-gcc3.h b/include/linux/compiler-gcc3.h deleted file mode 100644 index 7d89feb..0000000 --- a/include/linux/compiler-gcc3.h +++ /dev/null @@ -1,23 +0,0 @@ -#ifndef __LINUX_COMPILER_H -#error "Please don't include <linux/compiler-gcc3.h> directly, include <linux/compiler.h> instead." -#endif - -#if GCC_VERSION < 30200 -# error Sorry, your compiler is too old - please upgrade it. -#endif - -#if GCC_VERSION >= 30300 -# define __used __attribute__((__used__)) -#else -# define __used __attribute__((__unused__)) -#endif - -#if GCC_VERSION >= 30400 -#define __must_check __attribute__((warn_unused_result)) -#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 */ diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h deleted file mode 100644 index 2507fd2..0000000 --- a/include/linux/compiler-gcc4.h +++ /dev/null @@ -1,88 +0,0 @@ -#ifndef __LINUX_COMPILER_H -#error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead." -#endif - -/* 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 __must_check __attribute__((warn_unused_result)) -#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 -/* - * Tell the optimizer that something else uses this function or variable. - */ -#define __visible __attribute__((externally_visible)) -#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. - * Fixed in GCC 4.8.2 and later versions. - * - * (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 */ diff --git a/include/linux/compiler-gcc5.h b/include/linux/compiler-gcc5.h deleted file mode 100644 index c8c5659..0000000 --- a/include/linux/compiler-gcc5.h +++ /dev/null @@ -1,65 +0,0 @@ -#ifndef __LINUX_COMPILER_H -#error "Please don't include <linux/compiler-gcc5.h> directly, include <linux/compiler.h> instead." -#endif - -#define __used __attribute__((__used__)) -#define __must_check __attribute__((warn_unused_result)) -#define __compiler_offsetof(a, b) __builtin_offsetof(a, b) - -/* 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__ */ - -/* - * 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__)) - -/* - * Tell the optimizer that something else uses this function or variable. - */ -#define __visible __attribute__((externally_visible)) - -/* - * 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 -#define __HAVE_BUILTIN_BSWAP32__ -#define __HAVE_BUILTIN_BSWAP64__ -#define __HAVE_BUILTIN_BSWAP16__ -#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h index ba147a1..d4c7113 100644 --- a/include/linux/compiler-intel.h +++ b/include/linux/compiler-intel.h @@ -13,9 +13,14 @@ /* 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); \ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index d5ad7b1..020ad16 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -17,6 +17,7 @@ # 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 @@ -42,6 +43,7 @@ extern void __chk_io_ptr(const volatile void __iomem *); # define __cond_lock(x,c) (c) # define __percpu # define __rcu +# define __pmem #endif
/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ @@ -54,7 +56,11 @@ extern void __chk_io_ptr(const volatile void __iomem *); #include <linux/compiler-gcc.h> #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 @@ -138,7 +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 \ @@ -165,6 +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) @@ -186,6 +196,126 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) #endif
+#include <linux/types.h> + +#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__ */ @@ -304,6 +434,14 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #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)) @@ -311,7 +449,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
/* Is this type a native word size -- useful for atomic operations */ #ifndef __native_word -# define __native_word(t) (sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) +# 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 */ @@ -373,12 +511,38 @@ 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) ({ \ + __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 ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) +#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