diff options
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 502 |
1 files changed, 149 insertions, 353 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 0ea6c8fcca..5e3b3c08e9 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -1,127 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef __LINUX_COMPILER_H #define __LINUX_COMPILER_H -#ifndef __ASSEMBLY__ +#include <linux/compiler_types.h> -#ifdef __CHECKER__ -# define __user __attribute__((noderef, address_space(1))) -# 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 -# define __user -# define __kernel -# define __safe -# define __force -# define __nocast -# define __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) +#ifndef __ASSEMBLY__ #ifdef __KERNEL__ -#ifdef __GNUC__ -#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 - */ -#ifdef __INTEL_COMPILER -# include <linux/compiler-intel.h> -#endif - -/* Clang compiler defines __GNUC__. So we will overwrite implementations - * coming from above header files here - */ -#ifdef __clang__ -#include <linux/compiler-clang.h> -#endif - -/* - * Generic compiler-dependent macros required for kernel - * build go below this comment. Actual compiler/compiler version - * specific implementations come from the above header files - */ - -struct ftrace_branch_data { - const char *func; - const char *file; - unsigned line; - union { - struct { - unsigned long correct; - unsigned long incorrect; - }; - struct { - unsigned long miss; - unsigned long hit; - }; - unsigned long miss_hit[2]; - }; -}; - /* * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code * to disable branch tracing on a per file basis. */ #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) -void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); +void ftrace_likely_update(struct ftrace_likely_data *f, int val, + int expect, int is_constant); #define likely_notrace(x) __builtin_expect(!!(x), 1) #define unlikely_notrace(x) __builtin_expect(!!(x), 0) -#define __branch_check__(x, expect) ({ \ - int ______r; \ - static struct ftrace_branch_data \ - __attribute__((__aligned__(4))) \ - __attribute__((section("_ftrace_annotated_branch"))) \ +#define __branch_check__(x, expect, is_constant) ({ \ + long ______r; \ + static struct ftrace_likely_data \ + __aligned(4) \ + __section(_ftrace_annotated_branch) \ ______f = { \ - .func = __func__, \ - .file = __FILE__, \ - .line = __LINE__, \ + .data.func = __func__, \ + .data.file = __FILE__, \ + .data.line = __LINE__, \ }; \ - ______r = likely_notrace(x); \ - ftrace_likely_update(&______f, ______r, expect); \ + ______r = __builtin_expect(!!(x), expect); \ + ftrace_likely_update(&______f, ______r, \ + expect, is_constant); \ ______r; \ }) @@ -131,10 +42,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); * written by Daniel Walker. */ # ifndef likely -# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1)) +# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) # endif # ifndef unlikely -# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0)) +# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) # endif #ifdef CONFIG_PROFILE_ALL_BRANCHES @@ -142,23 +53,24 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); * "Define 'is'", Bill Clinton * "Define 'if'", Steven Rostedt */ -#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) -#define __trace_if(cond) \ - if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ - ({ \ - int ______r; \ - static struct ftrace_branch_data \ - __attribute__((__aligned__(4))) \ - __attribute__((section("_ftrace_branch"))) \ - ______f = { \ - .func = __func__, \ - .file = __FILE__, \ - .line = __LINE__, \ - }; \ - ______r = !!(cond); \ - ______f.miss_hit[______r]++; \ - ______r; \ - })) +#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) + +#define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) + +#define __trace_if_value(cond) ({ \ + static struct ftrace_branch_data \ + __aligned(4) \ + __section(_ftrace_branch) \ + __if_trace = { \ + .func = __func__, \ + .file = __FILE__, \ + .line = __LINE__, \ + }; \ + (cond) ? \ + (__if_trace.miss_hit[1]++,1) : \ + (__if_trace.miss_hit[0]++,0); \ +}) + #endif /* CONFIG_PROFILE_ALL_BRANCHES */ #else @@ -175,9 +87,76 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); # define barrier_data(ptr) barrier() #endif +/* workaround for GCC PR82365 if needed */ +#ifndef barrier_before_unreachable +# define barrier_before_unreachable() do { } while (0) +#endif + /* Unreachable code */ +#ifdef CONFIG_STACK_VALIDATION +/* + * These macros help objtool understand GCC code flow for unreachable code. + * The __COUNTER__ based labels are a hack to make each instance of the macros + * unique, to convince GCC not to merge duplicate inline asm statements. + */ +#define annotate_reachable() ({ \ + asm volatile("%c0:\n\t" \ + ".pushsection .discard.reachable\n\t" \ + ".long %c0b - .\n\t" \ + ".popsection\n\t" : : "i" (__COUNTER__)); \ +}) +#define annotate_unreachable() ({ \ + asm volatile("%c0:\n\t" \ + ".pushsection .discard.unreachable\n\t" \ + ".long %c0b - .\n\t" \ + ".popsection\n\t" : : "i" (__COUNTER__)); \ +}) +#define ASM_UNREACHABLE \ + "999:\n\t" \ + ".pushsection .discard.unreachable\n\t" \ + ".long 999b - .\n\t" \ + ".popsection\n\t" + +/* Annotate a C jump table to allow objtool to follow the code flow */ +#define __annotate_jump_table __section(.rodata..c_jump_table) + +#else +#define annotate_reachable() +#define annotate_unreachable() +#define __annotate_jump_table +#endif + +#ifndef ASM_UNREACHABLE +# define ASM_UNREACHABLE +#endif #ifndef unreachable -# define unreachable() do { } while (1) +# define unreachable() do { \ + annotate_unreachable(); \ + __builtin_unreachable(); \ +} while (0) +#endif + +/* + * KENTRY - kernel entry point + * This can be used to annotate symbols (functions or data) that are used + * without their linker symbol being referenced explicitly. For example, + * interrupt vector handlers, or functions in the kernel image that are found + * programatically. + * + * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those + * are handled in their own way (with KEEP() in linker scripts). + * + * KENTRY can be avoided if the symbols in question are marked as KEEP() in the + * linker script. For example an architecture could KEEP() its entire + * boot/exception vector code rather than annotate each function and data. + */ +#ifndef KENTRY +# define KENTRY(sym) \ + extern typeof(sym) sym; \ + static const unsigned long __kentry_##sym \ + __used \ + __section("___kentry" "+" #sym ) \ + = (unsigned long)&sym; #endif #ifndef RELOC_HIDE @@ -188,7 +167,9 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #endif #ifndef OPTIMIZER_HIDE_VAR -#define OPTIMIZER_HIDE_VAR(var) barrier() +/* Make the optimizer believe the variable can be manipulated arbitrarily. */ +#define OPTIMIZER_HIDE_VAR(var) \ + __asm__ ("" : "=r" (var) : "0" (var)) #endif /* Not-quite-unique ID. */ @@ -220,23 +201,21 @@ void __read_once_size(const volatile void *p, void *res, int size) #ifdef CONFIG_KASAN /* - * This function is not 'inline' because __no_sanitize_address confilcts + * We can't declare function '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; -} +# define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused #else -static __always_inline +# define __no_kasan_or_inline __always_inline +#endif + +static __no_kasan_or_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) { @@ -255,20 +234,21 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s /* * 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. + * 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. * - * 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. + * 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(). There's at least two memcpy()s: one for the + * __builtin_memcpy() and then one for the macro doing the copy of variable + * - '__u' allocated on the stack. * * 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 + * 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. @@ -291,6 +271,12 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s */ #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) +static __no_kasan_or_inline +unsigned long read_word_at_a_time(const void *addr) +{ + return *(unsigned long *)addr; +} + #define WRITE_ONCE(x, val) \ ({ \ union { typeof(x) __val; char __c[1]; } __u = \ @@ -299,158 +285,28 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s __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__ */ - -#ifdef __KERNEL__ -/* - * Allow us to mark functions as 'deprecated' and have gcc emit a nice - * warning for each use, in hopes of speeding the functions removal. - * Usage is: - * int __deprecated foo(void) - */ -#ifndef __deprecated -# define __deprecated /* unimplemented */ -#endif - -#ifdef MODULE -#define __deprecated_for_modules __deprecated -#else -#define __deprecated_for_modules -#endif - -#ifndef __must_check -#define __must_check -#endif - -#ifndef CONFIG_ENABLE_MUST_CHECK -#undef __must_check -#define __must_check -#endif -#ifndef CONFIG_ENABLE_WARN_DEPRECATED -#undef __deprecated -#undef __deprecated_for_modules -#define __deprecated -#define __deprecated_for_modules -#endif - -/* - * Allow us to avoid 'defined but not used' warnings on functions and data, - * as well as force them to be emitted to the assembly file. - * - * As of gcc 3.4, static functions that are not marked with attribute((used)) - * may be elided from the assembly file. As of gcc 3.4, static data not so - * marked will not be elided, but this may change in a future gcc version. - * - * NOTE: Because distributions shipped with a backported unit-at-a-time - * compiler in gcc 3.3, we must define __used to be __attribute__((used)) - * for gcc >=3.3 instead of 3.4. - * - * In prior versions of gcc, such functions and data would be emitted, but - * would be warned about except with attribute((unused)). - * - * Mark functions that are referenced only in inline assembly as __used so - * the code is emitted even though it appears to be unreferenced. - */ -#ifndef __used -# define __used /* unimplemented */ -#endif - -#ifndef __maybe_unused -# define __maybe_unused /* unimplemented */ -#endif - -#ifndef __always_unused -# define __always_unused /* unimplemented */ -#endif - -#ifndef noinline -#define noinline -#endif - -/* - * Rather then using noinline to prevent stack consumption, use - * noinline_for_stack instead. For documentation reasons. - */ -#define noinline_for_stack noinline - -#ifndef __always_inline -#define __always_inline inline -#endif - #endif /* __KERNEL__ */ /* - * From the GCC manual: - * - * Many functions do not examine any values except their arguments, - * and have no effects except the return value. Basically this is - * just slightly more strict class than the `pure' attribute above, - * since function is not allowed to read global memory. - * - * Note that a function that has pointer arguments and examines the - * data pointed to must _not_ be declared `const'. Likewise, a - * function that calls a non-`const' function usually must not be - * `const'. It does not make sense for a `const' function to return - * `void'. - */ -#ifndef __attribute_const__ -# define __attribute_const__ /* unimplemented */ -#endif - -/* - * Tell gcc if a function is cold. The compiler will assume any path - * directly leading to the call is unlikely. + * Force the compiler to emit 'sym' as a symbol, so that we can reference + * it from inline assembler. Necessary in case 'sym' could be inlined + * otherwise, or eliminated entirely due to lack of references that are + * visible to the compiler. */ +#define __ADDRESSABLE(sym) \ + static void * __section(.discard.addressable) __used \ + __PASTE(__addressable_##sym, __LINE__) = (void *)&sym; -#ifndef __cold -#define __cold -#endif - -/* Simple shorthand for a section definition */ -#ifndef __section -# define __section(S) __attribute__ ((__section__(#S))) -#endif - -#ifndef __visible -#define __visible -#endif - -/* - * Assume alignment of return value. +/** + * offset_to_ptr - convert a relative memory offset to an absolute pointer + * @off: the address of the 32-bit offset 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 +static inline void *offset_to_ptr(const int *off) +{ + return (void *)((unsigned long)off + *off); +} -/* 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 +#endif /* __ASSEMBLY__ */ /* Compile time object size, -1 for unknown */ #ifndef __compiletime_object_size @@ -461,29 +317,14 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s #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 #ifdef __OPTIMIZE__ # define __compiletime_assert(condition, msg, prefix, suffix) \ do { \ - bool __cond = !(condition); \ extern void prefix ## suffix(void) __compiletime_error(msg); \ - if (__cond) \ + if (!(condition)) \ prefix ## suffix(); \ - __compiletime_error_fallback(__cond); \ } while (0) #else # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) @@ -502,58 +343,13 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * compiler has support to do so. */ #define compiletime_assert(condition, msg) \ - _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) + _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.") -/* - * Prevent the compiler from merging or refetching accesses. The compiler - * is also forbidden from reordering successive instances of ACCESS_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 - * ACCESS_ONCE() in different C statements. - * - * 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 lockless_dereference(p) \ -({ \ - typeof(p) _________p1 = READ_ONCE(p); \ - smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ - (_________p1); \ -}) +/* &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])) -/* 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 */ |