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aliasing-test.c

/*
 * Exercise /dev/mem mmap cases that have been troublesome in the past
 *
 * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
 *    Bjorn Helgaas <bjorn.helgaas@hp.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

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

int sum;

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;
}

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, 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 rc;
}

char buf[1024];

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) {
            perror("write");
            return -1;
      }

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

      close(fd);
      return size;
}

int scan_rom(char *path, char *file)
{
      struct dirent **namelist;
      char *name, *path2;
      int i, n, r, rc, 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 ocurred.  The
                   * important thing is that no MCA happened.
                   */
                  if (rc > 0)
                        fprintf(stderr, "PASS: %s read %ld 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 rc;
}

int main()
{
      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);
}

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