Stefan Reinauer (stefan.reinauer@coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2097
-gerrit
commit 2c470b25d6b5801a4ae81b960edb259484683179 Author: Stefan Reinauer stefan.reinauer@coreboot.org Date: Thu Jan 3 14:30:33 2013 -0800
cbmem utility: Use mmap instead of fseek/fread
The kernel on Ubuntu 12.04LTS does not allow to use fseek/fread to read the coreboot table at the end of memory but will instead abort cbmem with a "Bad Address" error.
Whether that is a security feature (some variation of CONFIG_STRICT_DEVMEM) or a kernel bug is not yet clear, however using mmap works nicely.
Change-Id: I796b4cd2096fcdcc65c1361ba990cd467f13877e Signed-off-by: Stefan Reinauer reinauer@google.com --- util/cbmem/cbmem.c | 208 +++++++++++++++++++++++++++++++---------------------- 1 file changed, 123 insertions(+), 85 deletions(-)
diff --git a/util/cbmem/cbmem.c b/util/cbmem/cbmem.c index 1cb7b8d..df00684 100644 --- a/util/cbmem/cbmem.c +++ b/util/cbmem/cbmem.c @@ -17,14 +17,20 @@ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
-#include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <getopt.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/mman.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0])) +#define MAP_BYTES (1024*1024)
-#include "stdlib.h" #include "boot/coreboot_tables.h"
typedef uint16_t u16; @@ -36,8 +42,12 @@ typedef uint64_t u64;
#define CBMEM_VERSION "1.0"
-/* File descriptor used to access /dev/mem */ -static FILE* fd; +/* verbose output? */ +static int verbose = 0; +#define debug(x...) if(verbose) printf(x) + +/* File handle used to access /dev/mem */ +static int fd;
/* * calculate ip checksum (16 bit quantities) on a passed in buffer. In case @@ -59,104 +69,113 @@ static u16 ipchcksum(const void *addr, unsigned size) }
/* - * Starting at 'offset' read 'size' bytes from the previously opened /dev/mem - * into the 'buffer'. - * - * Return zero on success or exit on any error. + * Functions to map / unmap physical memory into virtual address space. These + * functions always maps 1MB at a time and can only map one area at once. */ -static int readmem(void* buffer, u32 offset, int size) +static void *mapped_virtual; +static void *map_memory(u64 physical) { - if (fseek(fd, offset, SEEK_SET)) { - fprintf(stderr, "fseek failed(%d) for offset %d\n", - errno, offset); - exit(1); - } - if (fread(buffer, 1, size, fd) != size) { - fprintf(stderr, "failed (%d) to read %d bytes at 0x%x\n", - errno, size, offset); + void *v; + off_t p; + int page = getpagesize(); + + /* Mapped memory must be aligned to page size */ + p = physical & ~(page - 1); + + debug("Mapping 1MB of physical memory at %zx.\n", p); + + v = mmap(NULL, MAP_BYTES, PROT_READ, MAP_SHARED, fd, p); + + if (v == MAP_FAILED) { + fprintf(stderr, "Failed to mmap /dev/mem: %s\n", + strerror(errno)); exit(1); } - return 0; + + /* Remember what we actually mapped ... */ + mapped_virtual = v; + + /* ... but return address to the physical memory that was requested */ + v += physical & (page-1); + + return v; +} + +static void unmap_memory(void) +{ + debug("Unmapping 1MB of virtual memory at %p.\n", mapped_virtual); + munmap(mapped_virtual, MAP_BYTES); }
/* - * Try finding the timestamp table starting from the passed in memory offset. - * Could be called recursively in case a forwarding entry is found. + * Try finding the timestamp table and coreboot cbmem console starting from the + * passed in memory offset. Could be called recursively in case a forwarding + * entry is found. * * Returns pointer to a memory buffer containg the timestamp table or zero if * none found. */ -static const struct timestamp_table *find_tstamps(u64 address) + +static struct lb_cbmem_ref timestamps; +static struct lb_cbmem_ref console; + +static int parse_cbtable(u64 address) { - int i; + int i, found = 0; + void *buf; + + debug("Looking for coreboot table at %lx\n", address); + buf = map_memory(address);
/* look at every 16 bytes within 4K of the base */ + for (i = 0; i < 0x1000; i += 0x10) { - void *buf; - struct lb_header lbh; + struct lb_header *lbh; struct lb_record* lbr_p; + void *lbtable; int j;
- readmem(&lbh, address + i, sizeof(lbh)); - if (memcmp(lbh.signature, "LBIO", sizeof(lbh.signature)) || - !lbh.header_bytes || - ipchcksum(&lbh, sizeof(lbh))) + lbh = (struct lb_header *)(buf + i); + if (memcmp(lbh->signature, "LBIO", sizeof(lbh->signature)) || + !lbh->header_bytes || + ipchcksum(lbh, sizeof(*lbh))) { continue; - - /* good lb_header is found, try reading the table */ - buf = malloc(lbh.table_bytes); - if (!buf) { - fprintf(stderr, "failed to allocate %d bytes\n", - lbh.table_bytes); - exit(1); } + lbtable = buf + i + lbh->header_bytes;
- readmem(buf, address + i + lbh.header_bytes, lbh.table_bytes); - if (ipchcksum(buf, lbh.table_bytes) != - lbh.table_checksum) { - /* False positive or table corrupted... */ - free(buf); + if (ipchcksum(lbtable, lbh->table_bytes) != + lbh->table_checksum) { + debug("Signature found, but wrong checksum.\n"); continue; }
- for (j = 0; j < lbh.table_bytes; j += lbr_p->size) { + found = 1; + debug("Found!\n"); + + for (j = 0; j < lbh->table_bytes; j += lbr_p->size) { /* look for the timestamp table */ - lbr_p = (struct lb_record*) ((char *)buf + j); + lbr_p = (struct lb_record*) ((char *)lbtable + j); + debug(" coreboot table entry 0x%02x\n", lbr_p->tag); switch (lbr_p->tag) { case LB_TAG_TIMESTAMPS: { - struct lb_cbmem_ref *cbmr_p = - (struct lb_cbmem_ref *) lbr_p; - int new_size; - struct timestamp_table *tst_p; - u32 stamp_addr = (u32) - ((uintptr_t)(cbmr_p->cbmem_addr)); - - readmem(buf, stamp_addr, - sizeof(struct timestamp_table)); - tst_p = (struct timestamp_table *) buf; - new_size = sizeof(struct timestamp_table) + - tst_p->num_entries * - sizeof(struct timestamp_entry); - buf = realloc(buf, new_size); - if (!buf) { - fprintf(stderr, - "failed to reallocate %d bytes\n", - new_size); - exit(1); - } - readmem(buf, stamp_addr, new_size); - return buf; + debug("Found timestamp table\n"); + timestamps = *(struct lb_cbmem_ref *) lbr_p; + continue; + } + case LB_TAG_CBMEM_CONSOLE: { + debug("Found cbmem console\n"); + console = *(struct lb_cbmem_ref *) lbr_p; + continue; } case LB_TAG_FORWARD: { /* * This is a forwarding entry - repeat the * search at the new address. */ - struct lb_forward *lbf_p = - (struct lb_forward *) lbr_p; - - free(buf); - return find_tstamps(lbf_p->forward); + struct lb_forward lbf_p = + *(struct lb_forward *) lbr_p; + unmap_memory(); + return parse_cbtable(lbf_p.forward); } default: break; @@ -164,14 +183,16 @@ static const struct timestamp_table *find_tstamps(u64 address)
} } - return 0; + unmap_memory(); + + return found; }
/* * read CPU frequency from a sysfs file, return an frequency in Kilohertz as * an int or exit on any error. */ -static u64 get_cpu_freq_KHz() +static u64 get_cpu_freq_KHz(void) { FILE *cpuf; char freqs[100]; @@ -184,7 +205,8 @@ static u64 get_cpu_freq_KHz()
cpuf = fopen(freq_file, "r"); if (!cpuf) { - fprintf(stderr, "Could not open %s\n", freq_file); + fprintf(stderr, "Could not open %s: %s\n", + freq_file, strerror(errno)); exit(1); }
@@ -228,10 +250,19 @@ static void print_norm(u64 v, int comma) }
/* dump the timestamp table */ -static void dump_timestamps(const struct timestamp_table *tst_p) +static void dump_timestamps(void) { int i; u64 cpu_freq_MHz = get_cpu_freq_KHz() / 1000; + struct timestamp_table *tst_p; + + if (timestamps.tag != LB_TAG_TIMESTAMPS) { + fprintf(stderr, "No timestamps found in coreboot table.\n"); + return; + } + + tst_p = (struct timestamp_table *) + map_memory((unsigned long)timestamps.cbmem_addr);
printf("%d entries total:\n\n", tst_p->num_entries); for (i = 0; i < tst_p->num_entries; i++) { @@ -248,6 +279,8 @@ static void dump_timestamps(const struct timestamp_table *tst_p) } printf("\n"); } + + unmap_memory(); }
void print_version(void) @@ -281,15 +314,21 @@ int main(int argc, char** argv) int j; static const int possible_base_addresses[] = { 0, 0xf0000 };
+ int print_timestamps = 1; + int opt, option_index = 0; static struct option long_options[] = { + {"verbose", 0, 0, 'V'}, {"version", 0, 0, 'v'}, {"help", 0, 0, 'h'}, {0, 0, 0, 0} }; - while ((opt = getopt_long(argc, argv, "vh?", + while ((opt = getopt_long(argc, argv, "Vvh?", long_options, &option_index)) != EOF) { switch (opt) { + case 'V': + verbose = 1; + break; case 'v': print_version(); exit(0); @@ -303,23 +342,22 @@ int main(int argc, char** argv) } }
- fd = fopen("/dev/mem", "r"); - if (!fd) { - printf("failed to gain memory access\n"); + fd = open("/dev/mem", O_RDONLY, 0); + if (fd < 0) { + fprintf(stderr, "Failed to gain memory access: %s\n", + strerror(errno)); return 1; }
+ /* Find and parse coreboot table */ for (j = 0; j < ARRAY_SIZE(possible_base_addresses); j++) { - const struct timestamp_table * tst_p = - find_tstamps(possible_base_addresses[j]); - - if (tst_p) { - dump_timestamps(tst_p); - free((void*)tst_p); + if (parse_cbtable(possible_base_addresses[j])) break; - } }
- fclose(fd); + if (print_timestamps) + dump_timestamps(); + + close(fd); return 0; }