cregit-Linux how code gets into the kernel

Release 4.12 include/linux/compiler.h

Directory: include/linux
#ifndef __LINUX_COMPILER_H

#define __LINUX_COMPILER_H

#ifndef __ASSEMBLY__

#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)))
#ifdef CONFIG_SPARSE_RCU_POINTER

# define __rcu		__attribute__((noderef, address_space(4)))
#else /* CONFIG_SPARSE_RCU_POINTER */

# define __rcu
#endif /* CONFIG_SPARSE_RCU_POINTER */

# define __private	__attribute__((noderef))
extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);

# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
#else /* __CHECKER__ */
# ifdef STRUCTLEAK_PLUGIN

#  define __user __attribute__((user))
# else

#  define __user
# endif

# 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 __private

# define ACCESS_PRIVATE(p, member) ((p)->member)
#endif /* __CHECKER__ */

/* 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 <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];
	};
};


struct ftrace_likely_data {
	
struct ftrace_branch_data	data;
	
unsigned long			constant;
};

/*
 * 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_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, is_constant) ({                      \
                        int ______r;                                    \
                        static struct ftrace_likely_data                \
                                __attribute__((__aligned__(4)))         \
                                __attribute__((section("_ftrace_annotated_branch"))) \
                                ______f = {                             \
                                .data.func = __func__,                  \
                                .data.file = __FILE__,                  \
                                .data.line = __LINE__,                  \
                        };                                              \
                        ______r = __builtin_expect(!!(x), expect);      \
                        ftrace_likely_update(&______f, ______r,         \
                                             expect, is_constant);      \
                        ______r;                                        \
                })

/*
 * Using __builtin_constant_p(x) to ignore cases where the return
 * value is always the same.  This idea is taken from a similar patch
 * written by Daniel Walker.
 */
# ifndef likely

#  define likely(x)	(__branch_check__(x, 1, __builtin_constant_p(x)))
# endif
# ifndef unlikely

#  define unlikely(x)	(__branch_check__(x, 0, __builtin_constant_p(x)))
# endif

#ifdef CONFIG_PROFILE_ALL_BRANCHES
/*
 * "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;                                                \
        }))
#endif /* CONFIG_PROFILE_ALL_BRANCHES */

#else

# define likely(x)	__builtin_expect(!!(x), 1)

# define unlikely(x)	__builtin_expect(!!(x), 0)
#endif

/* Optimization barrier */
#ifndef barrier

# define barrier() __memory_barrier()
#endif

#ifndef barrier_data

# define barrier_data(ptr) barrier()
#endif

/* Unreachable code */
#ifndef unreachable

# define unreachable() do { } while (1)
#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                                                  \
        __attribute__((section("___kentry" "+" #sym ), used))   \
        = (unsigned long)&sym;
#endif

#ifndef RELOC_HIDE

# define RELOC_HIDE(ptr, off)					\
  ({ unsigned long __ptr;                                 \
     __ptr = (unsigned long) (ptr);                             \
    (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 <uapi/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; }

Contributors

PersonTokensPropCommitsCommitProp
Christian Bornträger1986.36%133.33%
Andrey Ryabinin29.09%133.33%
Linus Torvalds14.55%133.33%
Total22100.00%3100.00%

#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; }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin1982.61%150.00%
Christian Bornträger417.39%150.00%
Total23100.00%2100.00%

#else
static __always_inline void __read_once_size_nocheck(const volatile void *p, void *res, int size) { __READ_ONCE_SIZE; }

Contributors

PersonTokensPropCommitsCommitProp
Andrey Ryabinin1568.18%150.00%
Christian Bornträger731.82%150.00%
Total22100.00%2100.00%

#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(); } }

Contributors

PersonTokensPropCommitsCommitProp
Christian Bornträger126100.00%2100.00%
Total126100.00%2100.00%

/* * 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(). 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 * 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; \ }) #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 #ifndef __malloc #define __malloc #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 #ifndef __latent_entropy # define __latent_entropy #endif /* * Tell gcc if a function is cold. The compiler will assume any path * directly leading to the call is unlikely. */ #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. */ #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 #endif #ifndef __compiletime_warning # define __compiletime_warning(message) #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 * 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. * * The seemingly unused variable ___typecheck_p validates that @p is * indeed a pointer type by using a pointer to typeof(*p) as the type. * Taking a pointer to typeof(*p) again is needed in case p is void *. */ #define lockless_dereference(p) \ ({ \ typeof(p) _________p1 = READ_ONCE(p); \ typeof(*(p)) *___typecheck_p __maybe_unused; \ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ (_________p1); \ }) #endif /* __LINUX_COMPILER_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds20316.75%1819.35%
Christian Bornträger19416.01%66.45%
Steven Rostedt16113.28%77.53%
Andrey Ryabinin685.61%11.08%
Andrew Morton665.45%77.53%
Rusty Russell574.70%44.30%
Daniel Santos544.46%22.15%
Arjan van de Ven433.55%44.30%
Paul E. McKenney322.64%44.30%
Peter Zijlstra312.56%33.23%
Boqun Feng292.39%11.08%
Andi Kleen262.15%33.23%
Josh Triplett231.90%33.23%
Rasmus Villemoes221.82%22.15%
Jeff Garzik171.40%11.08%
David Woodhouse161.32%22.15%
Nicholas Piggin141.16%11.08%
David Rientjes141.16%11.08%
Sam Ravnborg131.07%11.08%
Cesar Eduardo Barros120.99%11.08%
Daniel Borkmann120.99%11.08%
James Hogan110.91%11.08%
Kees Cook110.91%11.08%
David Daney110.91%11.08%
Mark Charlebois90.74%11.08%
Li Zefan90.74%11.08%
Heiko Carstens90.74%11.08%
Emese Revfy80.66%11.08%
Bart Van Assche70.58%11.08%
Witold Baryluk70.58%11.08%
Bernardo Innocenti50.41%11.08%
Robert Love40.33%11.08%
Richard Henderson20.17%11.08%
Russ Cox20.17%11.08%
Johannes Berg20.17%11.08%
Olaf Hering20.17%11.08%
Al Viro20.17%11.08%
Konrad Rzeszutek Wilk10.08%11.08%
Alexander Stein10.08%11.08%
Arnd Bergmann10.08%11.08%
Preeti U. Murthy10.08%11.08%
Total1212100.00%93100.00%
Directory: include/linux
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