tools/testing/selftests/syscall_user_dispatch/sud_benchmark.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/syscall_user_dispatch/sud_benchmark.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/syscall_user_dispatch/sud_benchmark.c
Extension
.c
Size
4757 bytes
Lines
203
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2020 Collabora Ltd.
 *
 * Benchmark and test syscall user dispatch
 */

#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
#include <sys/sysinfo.h>
#include <sys/prctl.h>
#include <sys/syscall.h>

#ifndef PR_SET_SYSCALL_USER_DISPATCH
# define PR_SET_SYSCALL_USER_DISPATCH	59
# define PR_SYS_DISPATCH_OFF	0
# define PR_SYS_DISPATCH_ON	1
# define SYSCALL_DISPATCH_FILTER_ALLOW	0
# define SYSCALL_DISPATCH_FILTER_BLOCK	1
#endif

#ifdef __NR_syscalls
# define MAGIC_SYSCALL_1 (__NR_syscalls + 1) /* Bad Linux syscall number */
#else
# define MAGIC_SYSCALL_1 (0xff00)  /* Bad Linux syscall number */
#endif

/*
 * To test returning from a sigsys with selector blocked, the test
 * requires some per-architecture support (i.e. knowledge about the
 * signal trampoline address).  On i386, we know it is on the vdso, and
 * a small trampoline is open-coded for x86_64.  Other architectures
 * that have a trampoline in the vdso will support TEST_BLOCKED_RETURN
 * out of the box, but don't enable them until they support syscall user
 * dispatch.
 */
#if defined(__x86_64__) || defined(__i386__)
#define TEST_BLOCKED_RETURN
#endif

#ifdef __x86_64__
void* (syscall_dispatcher_start)(void);
void* (syscall_dispatcher_end)(void);
#else
unsigned long syscall_dispatcher_start = 0;
unsigned long syscall_dispatcher_end = 0;
#endif

unsigned long trapped_call_count = 0;
unsigned long native_call_count = 0;

char selector;
#define SYSCALL_BLOCK   (selector = SYSCALL_DISPATCH_FILTER_BLOCK)
#define SYSCALL_UNBLOCK (selector = SYSCALL_DISPATCH_FILTER_ALLOW)

#define CALIBRATION_STEP 100000
#define CALIBRATE_TO_SECS 5
int factor;

static double one_sysinfo_step(void)
{
	struct timespec t1, t2;
	int i;
	struct sysinfo info;

	clock_gettime(CLOCK_MONOTONIC, &t1);
	for (i = 0; i < CALIBRATION_STEP; i++)
		sysinfo(&info);
	clock_gettime(CLOCK_MONOTONIC, &t2);
	return (t2.tv_sec - t1.tv_sec) + 1.0e-9 * (t2.tv_nsec - t1.tv_nsec);
}

static void calibrate_set(void)
{
	double elapsed = 0;

	printf("Calibrating test set to last ~%d seconds...\n", CALIBRATE_TO_SECS);

	while (elapsed < 1) {
		elapsed += one_sysinfo_step();
		factor += CALIBRATE_TO_SECS;
	}

Annotation

Implementation Notes