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250 lines
7.6 KiB
250 lines
7.6 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __LINUX_COMPILER_H |
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#define __LINUX_COMPILER_H |
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#include <linux/compiler_types.h> |
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#ifndef __ASSEMBLY__ |
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#ifdef __KERNEL__ |
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/* |
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* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code |
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* to disable branch tracing on a per file basis. |
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*/ |
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#if defined(CONFIG_TRACE_BRANCH_PROFILING) \ |
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&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) |
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void ftrace_likely_update(struct ftrace_likely_data *f, int val, |
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int expect, int is_constant); |
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#define likely_notrace(x) __builtin_expect(!!(x), 1) |
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#define unlikely_notrace(x) __builtin_expect(!!(x), 0) |
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#define __branch_check__(x, expect, is_constant) ({ \ |
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long ______r; \ |
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static struct ftrace_likely_data \ |
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__aligned(4) \ |
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__section("_ftrace_annotated_branch") \ |
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______f = { \ |
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.data.func = __func__, \ |
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.data.file = __FILE__, \ |
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.data.line = __LINE__, \ |
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}; \ |
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______r = __builtin_expect(!!(x), expect); \ |
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ftrace_likely_update(&______f, ______r, \ |
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expect, is_constant); \ |
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______r; \ |
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}) |
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/* |
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* Using __builtin_constant_p(x) to ignore cases where the return |
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* value is always the same. This idea is taken from a similar patch |
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* written by Daniel Walker. |
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*/ |
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# ifndef likely |
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# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) |
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# endif |
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# ifndef unlikely |
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# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) |
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# endif |
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#ifdef CONFIG_PROFILE_ALL_BRANCHES |
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/* |
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* "Define 'is'", Bill Clinton |
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* "Define 'if'", Steven Rostedt |
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*/ |
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#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) |
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#define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) |
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#define __trace_if_value(cond) ({ \ |
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static struct ftrace_branch_data \ |
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__aligned(4) \ |
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__section("_ftrace_branch") \ |
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__if_trace = { \ |
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.func = __func__, \ |
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.file = __FILE__, \ |
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.line = __LINE__, \ |
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}; \ |
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(cond) ? \ |
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(__if_trace.miss_hit[1]++,1) : \ |
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(__if_trace.miss_hit[0]++,0); \ |
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}) |
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#endif /* CONFIG_PROFILE_ALL_BRANCHES */ |
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#else |
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# define likely(x) __builtin_expect(!!(x), 1) |
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# define unlikely(x) __builtin_expect(!!(x), 0) |
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# define likely_notrace(x) likely(x) |
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# define unlikely_notrace(x) unlikely(x) |
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#endif |
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/* Optimization barrier */ |
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#ifndef barrier |
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/* The "volatile" is due to gcc bugs */ |
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# define barrier() __asm__ __volatile__("": : :"memory") |
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#endif |
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#ifndef barrier_data |
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/* |
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* This version is i.e. to prevent dead stores elimination on @ptr |
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* where gcc and llvm may behave differently when otherwise using |
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* normal barrier(): while gcc behavior gets along with a normal |
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* barrier(), llvm needs an explicit input variable to be assumed |
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* clobbered. The issue is as follows: while the inline asm might |
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* access any memory it wants, the compiler could have fit all of |
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* @ptr into memory registers instead, and since @ptr never escaped |
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* from that, it proved that the inline asm wasn't touching any of |
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* it. This version works well with both compilers, i.e. we're telling |
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* the compiler that the inline asm absolutely may see the contents |
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* of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 |
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*/ |
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# define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") |
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#endif |
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/* workaround for GCC PR82365 if needed */ |
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#ifndef barrier_before_unreachable |
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# define barrier_before_unreachable() do { } while (0) |
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#endif |
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/* Unreachable code */ |
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#ifdef CONFIG_STACK_VALIDATION |
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/* |
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* These macros help objtool understand GCC code flow for unreachable code. |
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* The __COUNTER__ based labels are a hack to make each instance of the macros |
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* unique, to convince GCC not to merge duplicate inline asm statements. |
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*/ |
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#define annotate_reachable() ({ \ |
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asm volatile("%c0:\n\t" \ |
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".pushsection .discard.reachable\n\t" \ |
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".long %c0b - .\n\t" \ |
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".popsection\n\t" : : "i" (__COUNTER__)); \ |
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}) |
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#define annotate_unreachable() ({ \ |
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asm volatile("%c0:\n\t" \ |
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".pushsection .discard.unreachable\n\t" \ |
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".long %c0b - .\n\t" \ |
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".popsection\n\t" : : "i" (__COUNTER__)); \ |
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}) |
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#define ASM_UNREACHABLE \ |
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"999:\n\t" \ |
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".pushsection .discard.unreachable\n\t" \ |
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".long 999b - .\n\t" \ |
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".popsection\n\t" |
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/* Annotate a C jump table to allow objtool to follow the code flow */ |
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#define __annotate_jump_table __section(".rodata..c_jump_table") |
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#else |
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#define annotate_reachable() |
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#define annotate_unreachable() |
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#define __annotate_jump_table |
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#endif |
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#ifndef ASM_UNREACHABLE |
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# define ASM_UNREACHABLE |
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#endif |
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#ifndef unreachable |
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# define unreachable() do { \ |
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annotate_unreachable(); \ |
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__builtin_unreachable(); \ |
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} while (0) |
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#endif |
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/* |
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* KENTRY - kernel entry point |
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* This can be used to annotate symbols (functions or data) that are used |
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* without their linker symbol being referenced explicitly. For example, |
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* interrupt vector handlers, or functions in the kernel image that are found |
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* programatically. |
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* |
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* Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those |
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* are handled in their own way (with KEEP() in linker scripts). |
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* |
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* KENTRY can be avoided if the symbols in question are marked as KEEP() in the |
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* linker script. For example an architecture could KEEP() its entire |
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* boot/exception vector code rather than annotate each function and data. |
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*/ |
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#ifndef KENTRY |
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# define KENTRY(sym) \ |
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extern typeof(sym) sym; \ |
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static const unsigned long __kentry_##sym \ |
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__used \ |
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__attribute__((__section__("___kentry+" #sym))) \ |
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= (unsigned long)&sym; |
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#endif |
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#ifndef RELOC_HIDE |
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# define RELOC_HIDE(ptr, off) \ |
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({ unsigned long __ptr; \ |
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__ptr = (unsigned long) (ptr); \ |
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(typeof(ptr)) (__ptr + (off)); }) |
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#endif |
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#ifndef OPTIMIZER_HIDE_VAR |
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/* Make the optimizer believe the variable can be manipulated arbitrarily. */ |
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#define OPTIMIZER_HIDE_VAR(var) \ |
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__asm__ ("" : "=r" (var) : "0" (var)) |
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#endif |
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/* Not-quite-unique ID. */ |
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#ifndef __UNIQUE_ID |
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# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) |
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#endif |
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/** |
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* data_race - mark an expression as containing intentional data races |
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* |
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* This data_race() macro is useful for situations in which data races |
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* should be forgiven. One example is diagnostic code that accesses |
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* shared variables but is not a part of the core synchronization design. |
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* |
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* This macro *does not* affect normal code generation, but is a hint |
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* to tooling that data races here are to be ignored. |
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*/ |
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#define data_race(expr) \ |
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({ \ |
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__unqual_scalar_typeof(({ expr; })) __v = ({ \ |
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__kcsan_disable_current(); \ |
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expr; \ |
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}); \ |
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__kcsan_enable_current(); \ |
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__v; \ |
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}) |
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#endif /* __KERNEL__ */ |
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/* |
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* Force the compiler to emit 'sym' as a symbol, so that we can reference |
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* it from inline assembler. Necessary in case 'sym' could be inlined |
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* otherwise, or eliminated entirely due to lack of references that are |
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* visible to the compiler. |
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*/ |
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#define __ADDRESSABLE(sym) \ |
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static void * __section(".discard.addressable") __used \ |
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__UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; |
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/** |
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* offset_to_ptr - convert a relative memory offset to an absolute pointer |
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* @off: the address of the 32-bit offset value |
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*/ |
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static inline void *offset_to_ptr(const int *off) |
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{ |
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return (void *)((unsigned long)off + *off); |
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} |
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#endif /* __ASSEMBLY__ */ |
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/* &a[0] degrades to a pointer: a different type from an array */ |
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#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) |
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/* |
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* This is needed in functions which generate the stack canary, see |
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* arch/x86/kernel/smpboot.c::start_secondary() for an example. |
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*/ |
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#define prevent_tail_call_optimization() mb() |
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#include <asm/rwonce.h> |
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#endif /* __LINUX_COMPILER_H */
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