418 lines
12 KiB
C
418 lines
12 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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#endif
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/* Optimization barrier */
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#ifndef barrier
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# define barrier() __memory_barrier()
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#endif
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#ifndef barrier_data
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# define barrier_data(ptr) barrier()
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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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#ifdef CONFIG_DEBUG_ENTRY
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/* Begin/end of an instrumentation safe region */
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#define instrumentation_begin() ({ \
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asm volatile("%c0: nop\n\t" \
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".pushsection .discard.instr_begin\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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/*
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* Because instrumentation_{begin,end}() can nest, objtool validation considers
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* _begin() a +1 and _end() a -1 and computes a sum over the instructions.
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* When the value is greater than 0, we consider instrumentation allowed.
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*
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* There is a problem with code like:
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*
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* noinstr void foo()
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* {
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* instrumentation_begin();
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* ...
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* if (cond) {
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* instrumentation_begin();
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* ...
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* instrumentation_end();
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* }
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* bar();
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* instrumentation_end();
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* }
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*
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* If instrumentation_end() would be an empty label, like all the other
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* annotations, the inner _end(), which is at the end of a conditional block,
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* would land on the instruction after the block.
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*
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* If we then consider the sum of the !cond path, we'll see that the call to
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* bar() is with a 0-value, even though, we meant it to happen with a positive
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* value.
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*
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* To avoid this, have _end() be a NOP instruction, this ensures it will be
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* part of the condition block and does not escape.
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*/
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#define instrumentation_end() ({ \
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asm volatile("%c0: nop\n\t" \
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".pushsection .discard.instr_end\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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#endif /* CONFIG_DEBUG_ENTRY */
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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 instrumentation_begin
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#define instrumentation_begin() do { } while(0)
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#define instrumentation_end() do { } while(0)
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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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__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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* Prevent the compiler from merging or refetching reads or writes. The
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* compiler is also forbidden from reordering successive instances of
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* READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
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* particular ordering. One way to make the compiler aware of ordering is to
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* put the two invocations of READ_ONCE or WRITE_ONCE in different C
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* statements.
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*
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* These two macros will also work on aggregate data types like structs or
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* unions.
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*
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* Their two major use cases are: (1) Mediating communication between
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* process-level code and irq/NMI handlers, all running on the same CPU,
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* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
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* mutilate accesses that either do not require ordering or that interact
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* with an explicit memory barrier or atomic instruction that provides the
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* required ordering.
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*/
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#include <asm/barrier.h>
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#include <linux/kasan-checks.h>
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#include <linux/kcsan-checks.h>
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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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* Use __READ_ONCE() instead of READ_ONCE() if you do not require any
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* atomicity or dependency ordering guarantees. Note that this may result
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* in tears!
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*/
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#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x))
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#define __READ_ONCE_SCALAR(x) \
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({ \
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__unqual_scalar_typeof(x) __x = __READ_ONCE(x); \
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smp_read_barrier_depends(); \
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(typeof(x))__x; \
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})
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#define READ_ONCE(x) \
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({ \
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compiletime_assert_rwonce_type(x); \
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__READ_ONCE_SCALAR(x); \
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})
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#define __WRITE_ONCE(x, val) \
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do { \
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*(volatile typeof(x) *)&(x) = (val); \
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} while (0)
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#define WRITE_ONCE(x, val) \
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do { \
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compiletime_assert_rwonce_type(x); \
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__WRITE_ONCE(x, val); \
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} while (0)
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static __no_sanitize_or_inline
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unsigned long __read_once_word_nocheck(const void *addr)
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{
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return __READ_ONCE(*(unsigned long *)addr);
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}
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/*
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* Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need to load a
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* word from memory atomically but without telling KASAN/KCSAN. This is
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* usually used by unwinding code when walking the stack of a running process.
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*/
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#define READ_ONCE_NOCHECK(x) \
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({ \
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unsigned long __x; \
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compiletime_assert(sizeof(x) == sizeof(__x), \
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"Unsupported access size for READ_ONCE_NOCHECK()."); \
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__x = __read_once_word_nocheck(&(x)); \
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smp_read_barrier_depends(); \
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(typeof(x))__x; \
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})
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static __no_kasan_or_inline
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unsigned long read_word_at_a_time(const void *addr)
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{
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kasan_check_read(addr, 1);
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return *(unsigned long *)addr;
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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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__PASTE(__addressable_##sym, __LINE__) = (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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/* Compile time object size, -1 for unknown */
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#ifndef __compiletime_object_size
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# define __compiletime_object_size(obj) -1
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#endif
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#ifndef __compiletime_warning
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# define __compiletime_warning(message)
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#endif
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#ifndef __compiletime_error
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# define __compiletime_error(message)
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#endif
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#ifdef __OPTIMIZE__
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# define __compiletime_assert(condition, msg, prefix, suffix) \
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do { \
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extern void prefix ## suffix(void) __compiletime_error(msg); \
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if (!(condition)) \
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prefix ## suffix(); \
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} while (0)
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#else
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# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
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#endif
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#define _compiletime_assert(condition, msg, prefix, suffix) \
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__compiletime_assert(condition, msg, prefix, suffix)
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/**
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* compiletime_assert - break build and emit msg if condition is false
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* @condition: a compile-time constant condition to check
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* @msg: a message to emit if condition is false
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*
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* In tradition of POSIX assert, this macro will break the build if the
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* supplied condition is *false*, emitting the supplied error message if the
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* compiler has support to do so.
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*/
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#define compiletime_assert(condition, msg) \
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_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
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#define compiletime_assert_atomic_type(t) \
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compiletime_assert(__native_word(t), \
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"Need native word sized stores/loads for atomicity.")
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/*
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* Yes, this permits 64-bit accesses on 32-bit architectures. These will
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* actually be atomic in some cases (namely Armv7 + LPAE), but for others we
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* rely on the access being split into 2x32-bit accesses for a 32-bit quantity
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* (e.g. a virtual address) and a strong prevailing wind.
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*/
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#define compiletime_assert_rwonce_type(t) \
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compiletime_assert(__native_word(t) || sizeof(t) == sizeof(long long), \
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"Unsupported access size for {READ,WRITE}_ONCE().")
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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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#endif /* __LINUX_COMPILER_H */
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