aliasing-test.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Exercise /dev/mem mmap cases that have been troublesome in the past
 *
 * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
 *	Bjorn Helgaas <[email protected]>
 */

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#include <fnmatch.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <linux/pci.h>

int sum;

static int map_mem(char *path, off_t offset, size_t length, int touch)
{
	int fd, rc;
	void *addr;
	int *c;

	fd = open(path, O_RDWR);
	if (fd == -1) {
		perror(path);
		return -1;
	}

	if (fnmatch("/proc/bus/pci/*", path, 0) == 0) {
		rc = ioctl(fd, PCIIOC_MMAP_IS_MEM);
		if (rc == -1)
			perror("PCIIOC_MMAP_IS_MEM ioctl");
	}

	addr = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, offset);
	if (addr == MAP_FAILED)
		return 1;

	if (touch) {
		c = (int *) addr;
		while (c < (int *) (addr + length))
			sum += *c++;
	}

	rc = munmap(addr, length);
	if (rc == -1) {
		perror("munmap");
		return -1;
	}

	close(fd);
	return 0;
}

static int scan_tree(char *path, char *file, off_t offset, size_t length, int touch)
{
	struct dirent **namelist;
	char *name, *path2;
	int i, n, r, rc = 0, result = 0;
	struct stat buf;

	n = scandir(path, &namelist, 0, alphasort);
	if (n < 0) {
		perror("scandir");
		return -1;
	}

	for (i = 0; i < n; i++) {
		name = namelist[i]->d_name;

		if (fnmatch(".", name, 0) == 0)
			goto skip;
		if (fnmatch("..", name, 0) == 0)
			goto skip;

		path2 = malloc(strlen(path) + strlen(name) + 3);
		strcpy(path2, path);
		strcat(path2, "/");
		strcat(path2, name);

		if (fnmatch(file, name, 0) == 0) {
			rc = map_mem(path2, offset, length, touch);
			if (rc == 0)
				fprintf(stderr, "PASS: %s 0x%lx-0x%lx is %s\n", path2, offset, offset + length, touch ? "readable" : "mappable");
			else if (rc > 0)
				fprintf(stderr, "PASS: %s 0x%lx-0x%lx not mappable\n", path2, offset, offset + length);
			else {
				fprintf(stderr, "FAIL: %s 0x%lx-0x%lx not accessible\n", path2, offset, offset + length);
				return rc;
			}
		} else {
			r = lstat(path2, &buf);
			if (r == 0 && S_ISDIR(buf.st_mode)) {
				rc = scan_tree(path2, file, offset, length, touch);
				if (rc < 0)
					return rc;
			}
		}

		result |= rc;
		free(path2);

skip:
		free(namelist[i]);
	}
	free(namelist);
	return result;
}

char buf[1024];

static int read_rom(char *path)
{
	int fd, rc;
	size_t size = 0;

	fd = open(path, O_RDWR);
	if (fd == -1) {
		perror(path);
		return -1;
	}

	rc = write(fd, "1", 2);
	if (rc <= 0) {
		close(fd);
		perror("write");
		return -1;
	}

	do {
		rc = read(fd, buf, sizeof(buf));
		if (rc > 0)
			size += rc;
	} while (rc > 0);

	close(fd);
	return size;
}

static int scan_rom(char *path, char *file)
{
	struct dirent **namelist;
	char *name, *path2;
	int i, n, r, rc = 0, result = 0;
	struct stat buf;

	n = scandir(path, &namelist, 0, alphasort);
	if (n < 0) {
		perror("scandir");
		return -1;
	}

	for (i = 0; i < n; i++) {
		name = namelist[i]->d_name;

		if (fnmatch(".", name, 0) == 0)
			goto skip;
		if (fnmatch("..", name, 0) == 0)
			goto skip;

		path2 = malloc(strlen(path) + strlen(name) + 3);
		strcpy(path2, path);
		strcat(path2, "/");
		strcat(path2, name);

		if (fnmatch(file, name, 0) == 0) {
			rc = read_rom(path2);

			/*
			 * It's OK if the ROM is unreadable.  Maybe there
			 * is no ROM, or some other error occurred.  The
			 * important thing is that no MCA happened.
			 */
			if (rc > 0)
				fprintf(stderr, "PASS: %s read %d bytes\n", path2, rc);
			else {
				fprintf(stderr, "PASS: %s not readable\n", path2);
				return rc;
			}
		} else {
			r = lstat(path2, &buf);
			if (r == 0 && S_ISDIR(buf.st_mode)) {
				rc = scan_rom(path2, file);
				if (rc < 0)
					return rc;
			}
		}

		result |= rc;
		free(path2);

skip:
		free(namelist[i]);
	}
	free(namelist);
	return result;
}

int main(void)
{
	int rc;

	if (map_mem("/dev/mem", 0, 0xA0000, 1) == 0)
		fprintf(stderr, "PASS: /dev/mem 0x0-0xa0000 is readable\n");
	else
		fprintf(stderr, "FAIL: /dev/mem 0x0-0xa0000 not accessible\n");

	/*
	 * It's not safe to blindly read the VGA frame buffer.  If you know
	 * how to poke the card the right way, it should respond, but it's
	 * not safe in general.  Many machines, e.g., Intel chipsets, cover
	 * up a non-responding card by just returning -1, but others will
	 * report the failure as a machine check.
	 */
	if (map_mem("/dev/mem", 0xA0000, 0x20000, 0) == 0)
		fprintf(stderr, "PASS: /dev/mem 0xa0000-0xc0000 is mappable\n");
	else
		fprintf(stderr, "FAIL: /dev/mem 0xa0000-0xc0000 not accessible\n");

	if (map_mem("/dev/mem", 0xC0000, 0x40000, 1) == 0)
		fprintf(stderr, "PASS: /dev/mem 0xc0000-0x100000 is readable\n");
	else
		fprintf(stderr, "FAIL: /dev/mem 0xc0000-0x100000 not accessible\n");

	/*
	 * Often you can map all the individual pieces above (0-0xA0000,
	 * 0xA0000-0xC0000, and 0xC0000-0x100000), but can't map the whole
	 * thing at once.  This is because the individual pieces use different
	 * attributes, and there's no single attribute supported over the
	 * whole region.
	 */
	rc = map_mem("/dev/mem", 0, 1024*1024, 0);
	if (rc == 0)
		fprintf(stderr, "PASS: /dev/mem 0x0-0x100000 is mappable\n");
	else if (rc > 0)
		fprintf(stderr, "PASS: /dev/mem 0x0-0x100000 not mappable\n");
	else
		fprintf(stderr, "FAIL: /dev/mem 0x0-0x100000 not accessible\n");

	scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1);
	scan_tree("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0);
	scan_tree("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1);
	scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0);

	scan_rom("/sys/devices", "rom");

	scan_tree("/proc/bus/pci", "??.?", 0, 0xA0000, 1);
	scan_tree("/proc/bus/pci", "??.?", 0xA0000, 0x20000, 0);
	scan_tree("/proc/bus/pci", "??.?", 0xC0000, 0x40000, 1);
	scan_tree("/proc/bus/pci", "??.?", 0, 1024*1024, 0);

	return rc;
}