forked from mirrors/linux
f6b5f1a569
absolute_pointer() disassociates a pointer from its originating symbol type and context. Use it to prevent compiler warnings/errors such as drivers/net/ethernet/i825xx/82596.c: In function 'i82596_probe': arch/m68k/include/asm/string.h:72:25: error: '__builtin_memcpy' reading 6 bytes from a region of size 0 [-Werror=stringop-overread] Such warnings may be reported by gcc 11.x for string and memory operations on fixed addresses. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
268 lines
8.1 KiB
C
268 lines
8.1 KiB
C
/* 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 __stringify_label(n) #n
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#define __annotate_reachable(c) ({ \
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asm volatile(__stringify_label(c) ":\n\t" \
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".pushsection .discard.reachable\n\t" \
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".long " __stringify_label(c) "b - .\n\t" \
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".popsection\n\t"); \
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})
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#define annotate_reachable() __annotate_reachable(__COUNTER__)
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#define __annotate_unreachable(c) ({ \
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asm volatile(__stringify_label(c) ":\n\t" \
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".pushsection .discard.unreachable\n\t" \
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".long " __stringify_label(c) "b - .\n\t" \
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".popsection\n\t"); \
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})
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#define annotate_unreachable() __annotate_unreachable(__COUNTER__)
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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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#define absolute_pointer(val) RELOC_HIDE((void *)(val), 0)
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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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/*
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* With CONFIG_CFI_CLANG, the compiler replaces function addresses in
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* instrumented C code with jump table addresses. Architectures that
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* support CFI can define this macro to return the actual function address
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* when needed.
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*/
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#ifndef function_nocfi
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#define function_nocfi(x) (x)
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#endif
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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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