include/linux/instrumentation.h

Source file repositories/reference/linux-study-clean/include/linux/instrumentation.h

File Facts

System
Linux kernel
Corpus path
include/linux/instrumentation.h
Extension
.h
Size
1898 bytes
Lines
61
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

*	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 */

Annotation

Implementation Notes