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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061/* SPDX-License-Identifier: GPL-2.0 */#ifndef __LINUX_INSTRUMENTATION_H#define __LINUX_INSTRUMENTATION_H
#ifdef CONFIG_NOINSTR_VALIDATION
#include <linux/objtool.h>#include <linux/stringify.h>
/* Begin/end of an instrumentation safe region */#define __instrumentation_begin(c) ({ \ asm volatile(__stringify(c) ": nop\n\t" \ ANNOTATE_INSTR_BEGIN(__ASM_BREF(c)) \ : : "i" (c)); \})#define instrumentation_begin() __instrumentation_begin(__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(c) ({ \ asm volatile(__stringify(c) ": nop\n\t" \ ANNOTATE_INSTR_END(__ASM_BREF(c)) \ : : "i" (c)); \})#define instrumentation_end() __instrumentation_end(__COUNTER__)#else /* !CONFIG_NOINSTR_VALIDATION */# define instrumentation_begin() do { } while(0)# define instrumentation_end() do { } while(0)#endif /* CONFIG_NOINSTR_VALIDATION */
#endif /* __LINUX_INSTRUMENTATION_H */