cregit-Linux how code gets into the kernel

Release 4.18 tools/testing/selftests/rseq/rseq.h

/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
 * rseq.h
 *
 * (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#ifndef RSEQ_H

#define RSEQ_H

#include <stdint.h>
#include <stdbool.h>
#include <pthread.h>
#include <signal.h>
#include <sched.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <linux/rseq.h>

/*
 * Empty code injection macros, override when testing.
 * It is important to consider that the ASM injection macros need to be
 * fully reentrant (e.g. do not modify the stack).
 */
#ifndef RSEQ_INJECT_ASM

#define RSEQ_INJECT_ASM(n)
#endif

#ifndef RSEQ_INJECT_C

#define RSEQ_INJECT_C(n)
#endif

#ifndef RSEQ_INJECT_INPUT

#define RSEQ_INJECT_INPUT
#endif

#ifndef RSEQ_INJECT_CLOBBER

#define RSEQ_INJECT_CLOBBER
#endif

#ifndef RSEQ_INJECT_FAILED

#define RSEQ_INJECT_FAILED
#endif

extern __thread volatile struct rseq __rseq_abi;


#define rseq_likely(x)		__builtin_expect(!!(x), 1)

#define rseq_unlikely(x)	__builtin_expect(!!(x), 0)

#define rseq_barrier()		__asm__ __volatile__("" : : : "memory")


#define RSEQ_ACCESS_ONCE(x)	(*(__volatile__  __typeof__(x) *)&(x))

#define RSEQ_WRITE_ONCE(x, v)	__extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })

#define RSEQ_READ_ONCE(x)	RSEQ_ACCESS_ONCE(x)


#define __rseq_str_1(x)	#x

#define __rseq_str(x)		__rseq_str_1(x)


#define rseq_log(fmt, args...)						       \
	fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
                ## args, __func__)


#define rseq_bug(fmt, args...)		\
	do {                            \
                rseq_log(fmt, ##args);  \
                abort();                \
        } while (0)

#if defined(__x86_64__) || defined(__i386__)
#include <rseq-x86.h>
#elif defined(__ARMEL__)
#include <rseq-arm.h>
#elif defined(__PPC__)
#include <rseq-ppc.h>
#elif defined(__mips__)
#include <rseq-mips.h>
#else
#error unsupported target
#endif

/*
 * Register rseq for the current thread. This needs to be called once
 * by any thread which uses restartable sequences, before they start
 * using restartable sequences, to ensure restartable sequences
 * succeed. A restartable sequence executed from a non-registered
 * thread will always fail.
 */
int rseq_register_current_thread(void);

/*
 * Unregister rseq for current thread.
 */
int rseq_unregister_current_thread(void);

/*
 * Restartable sequence fallback for reading the current CPU number.
 */
int32_t rseq_fallback_current_cpu(void);

/*
 * Values returned can be either the current CPU number, -1 (rseq is
 * uninitialized), or -2 (rseq initialization has failed).
 */

static inline int32_t rseq_current_cpu_raw(void) { return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id); }

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/* * Returns a possible CPU number, which is typically the current CPU. * The returned CPU number can be used to prepare for an rseq critical * section, which will confirm whether the cpu number is indeed the * current one, and whether rseq is initialized. * * The CPU number returned by rseq_cpu_start should always be validated * by passing it to a rseq asm sequence, or by comparing it to the * return value of rseq_current_cpu_raw() if the rseq asm sequence * does not need to be invoked. */
static inline uint32_t rseq_cpu_start(void) { return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start); }

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Mathieu Desnoyers17100.00%1100.00%
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static inline uint32_t rseq_current_cpu(void) { int32_t cpu; cpu = rseq_current_cpu_raw(); if (rseq_unlikely(cpu < 0)) cpu = rseq_fallback_current_cpu(); return cpu; }

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static inline void rseq_clear_rseq_cs(void) { #ifdef __LP64__ __rseq_abi.rseq_cs.ptr = 0; #else __rseq_abi.rseq_cs.ptr.ptr32 = 0; #endif }

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Mathieu Desnoyers34100.00%1100.00%
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/* * rseq_prepare_unload() should be invoked by each thread executing a rseq * critical section at least once between their last critical section and * library unload of the library defining the rseq critical section * (struct rseq_cs). This also applies to use of rseq in code generated by * JIT: rseq_prepare_unload() should be invoked at least once by each * thread executing a rseq critical section before reclaim of the memory * holding the struct rseq_cs. */
static inline void rseq_prepare_unload(void) { rseq_clear_rseq_cs(); }

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#endif /* RSEQ_H_ */

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Mathieu Desnoyers34497.45%375.00%
Paul Burton92.55%125.00%
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