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/* ----------------------------------------------------------------------- *
*
* Copyright 2010 Intel Corporation; author: H. Peter Anvin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston MA 02110-1301, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* memdiskfind.c
*
* Simple utility to search for a MEMDISK instance and output the parameters
* needed to use the "phram" driver in Linux to map it.
*/
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "../memdisk/mstructs.h"
#define MBFT_MIN_LENGTH (36+4+26)
static bool valid_mbft(const struct mBFT *mbft, size_t space)
{
uint8_t csum;
size_t i;
if (memcmp(mbft->acpi.signature, "mBFT", 4))
return false;
if (mbft->acpi.length < MBFT_MIN_LENGTH)
return false;
if (mbft->acpi.length > space)
return false;
if ((size_t)mbft->acpi.length != (size_t)mbft->mdi.bytes + 36+4)
return false;
csum = 0;
for (i = 0; i < mbft->acpi.length; i++)
csum += ((const uint8_t *)mbft)[i];
if (csum)
return false;
return true;
}
static void output_params(const struct mBFT *mbft)
{
int sector_shift = mbft->mdi.sector_shift;
if (!sector_shift)
sector_shift = 9;
printf("%#x,%#x\n",
mbft->mdi.diskbuf, mbft->mdi.disksize << sector_shift);
}
static size_t memlimit(void)
{
char txtline[256], user[256];
size_t maxram = 0;
unsigned long long start, end;
FILE *iomem;
iomem = fopen("/proc/iomem", "r");
if (!iomem)
return 0;
while (fgets(txtline, sizeof txtline, iomem) != NULL) {
if (sscanf(txtline, "%llx-%llx : %[^\n]", &start, &end, user) != 3)
continue;
if (strcmp(user, "System RAM"))
continue;
if (start >= 0xa0000)
continue;
maxram = (end >= 0xa0000) ? 0xa0000 : end+1;
}
fclose(iomem);
return maxram;
}
static inline size_t get_page_size(void)
{
#ifdef _SC_PAGESIZE
return sysconf(_SC_PAGESIZE);
#else
/* klibc, for one, doesn't have sysconf() due to excessive multiplex */
return getpagesize();
#endif
}
int main(int argc, char *argv[])
{
const char *map;
int memfd;
size_t fbm;
const char *ptr, *end;
size_t page = get_page_size();
size_t mapbase, maplen;
int err = 1;
(void)argc;
mapbase = memlimit() & ~(page - 1);
if (!mapbase)
return 2;
memfd = open("/dev/mem", O_RDONLY);
if (memfd < 0) {
fprintf(stderr, "%s: cannot open /dev/mem: %s\n",
argv[0], strerror(errno));
return 2;
}
map = mmap(NULL, page, PROT_READ, MAP_SHARED, memfd, 0);
if (map == MAP_FAILED) {
fprintf(stderr, "%s: cannot map page 0: %s\n",
argv[0], strerror(errno));
return 2;
}
fbm = *(uint16_t *)(map + 0x413) << 10;
if (fbm < mapbase)
fbm = mapbase;
munmap((void *)map, page);
if (fbm < 64*1024 || fbm >= 640*1024)
return 1;
maplen = 0xa0000 - mapbase;
map = mmap(NULL, maplen, PROT_READ, MAP_SHARED, memfd, mapbase);
if (map == MAP_FAILED) {
fprintf(stderr, "%s: cannot map base memory: %s\n",
argv[0], strerror(errno));
return 2;
}
ptr = map + (fbm - mapbase);
end = map + (0xa0000 - mapbase);
while (ptr < end) {
if (valid_mbft((const struct mBFT *)ptr, end-ptr)) {
output_params((const struct mBFT *)ptr);
err = 0;
break;
}
ptr += 16;
}
munmap((void *)map, maplen);
return err;
}
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