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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_COMPILER_H
#define __LINUX_COMPILER_H
#include <linux/compiler_types.h>
#ifndef __ASSEMBLY__
#ifdef __KERNEL__
/*
* 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) ({ \
long ______r; \
static struct ftrace_likely_data \
__aligned(4) \
__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, ...) 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
# define likely(x) __builtin_expect(!!(x), 1)
# define unlikely(x) __builtin_expect(!!(x), 0)
#endif
/* Optimization barrier */
#ifndef barrier
/* The "volatile" is due to gcc bugs */
# define barrier() __asm__ __volatile__("": : :"memory")
#endif
#ifndef barrier_data
/*
* 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 proved 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")
#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)
#ifdef CONFIG_DEBUG_ENTRY
/* Begin/end of an instrumentation safe region */
#define instrumentation_begin() ({ \
asm volatile("%c0:\n\t" \
".pushsection .discard.instr_begin\n\t" \
".long %c0b - .\n\t" \
".popsection\n\t" : : "i" (__COUNTER__)); \
})
/*
* Because instrumentation_{begin,end}() can nest, objtool validation considers
* _begin() a +1 and _end() a -1 and computes a sum over the instructions.
* When the value is greater than 0, we consider instrumentation allowed.
*
* There is a problem with code like:
*
* noinstr void foo()
* {
* instrumentation_begin();
* ...
* if (cond) {
* instrumentation_begin();
* ...
* instrumentation_end();
* }
* bar();
* instrumentation_end();
* }
*
* If instrumentation_end() would be an empty label, like all the other
* annotations, the inner _end(), which is at the end of a conditional block,
* would land on the instruction after the block.
*
* If we then consider the sum of the !cond path, we'll see that the call to
* bar() is with a 0-value, even though, we meant it to happen with a positive
* value.
*
* To avoid this, have _end() be a NOP instruction, this ensures it will be
* part of the condition block and does not escape.
*/
#define instrumentation_end() ({ \
asm volatile("%c0: nop\n\t" \
".pushsection .discard.instr_end\n\t" \
".long %c0b - .\n\t" \
".popsection\n\t" : : "i" (__COUNTER__)); \
})
#endif /* CONFIG_DEBUG_ENTRY */
#else
#define annotate_reachable()
#define annotate_unreachable()
#define __annotate_jump_table
#endif
#ifndef instrumentation_begin
#define instrumentation_begin() do { } while(0)
#define instrumentation_end() do { } while(0)
#endif
#ifndef ASM_UNREACHABLE
# define ASM_UNREACHABLE
#endif
#ifndef unreachable
# 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
# define RELOC_HIDE(ptr, off) \
({ unsigned long __ptr; \
__ptr = (unsigned long) (ptr); \
(typeof(ptr)) (__ptr + (off)); })
#endif
#define absolute_pointer(val) RELOC_HIDE((void *)(val), 0)
#ifndef OPTIMIZER_HIDE_VAR
/* 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. */
#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;
}
#ifdef CONFIG_KASAN
/*
* 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.
*/
# define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused
#else
# 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;
}
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 and WRITE_ONCE, but only when the compiler is aware of some
* particular ordering. One way to make the compiler aware of ordering is to
* put the two invocations of READ_ONCE or WRITE_ONCE in different C
* statements.
*
* These two macros will also work on aggregate data types like structs or
* unions. 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.
*/
#include <asm/barrier.h>
#include <linux/kasan-checks.h>
#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)); \
smp_read_barrier_depends(); /* Enforce dependency ordering from 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)
static __no_kasan_or_inline
unsigned long read_word_at_a_time(const void *addr)
{
kasan_check_read(addr, 1);
return *(unsigned long *)addr;
}
#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__ */
/*
* 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;
/**
* offset_to_ptr - convert a relative memory offset to an absolute pointer
* @off: the address of the 32-bit offset value
*/
static inline void *offset_to_ptr(const int *off)
{
return (void *)((unsigned long)off + *off);
}
#endif /* __ASSEMBLY__ */
/* Compile time object size, -1 for unknown */
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
#endif
#ifndef __compiletime_warning
# define __compiletime_warning(message)
#endif
#ifndef __compiletime_error
# define __compiletime_error(message)
#endif
#ifdef __OPTIMIZE__
# define __compiletime_assert(condition, msg, prefix, suffix) \
do { \
extern void prefix ## suffix(void) __compiletime_error(msg); \
if (!(condition)) \
prefix ## suffix(); \
} while (0)
#else
# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
#endif
#define _compiletime_assert(condition, msg, prefix, suffix) \
__compiletime_assert(condition, msg, prefix, suffix)
/**
* compiletime_assert - break build and emit msg if condition is false
* @condition: a compile-time constant condition to check
* @msg: a message to emit if condition is false
*
* In tradition of POSIX assert, this macro will break the build if the
* supplied condition is *false*, emitting the supplied error message if the
* compiler has support to do so.
*/
#define compiletime_assert(condition, msg) \
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
#define compiletime_assert_atomic_type(t) \
compiletime_assert(__native_word(t), \
"Need native word sized stores/loads for atomicity.")
/* &a[0] degrades to a pointer: a different type from an array */
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
/*
* This is needed in functions which generate the stack canary, see
* arch/x86/kernel/smpboot.c::start_secondary() for an example.
*/
#define prevent_tail_call_optimization() mb()
#endif /* __LINUX_COMPILER_H */
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