diff options
| -rw-r--r-- | util/nvmutil/nvmutil.c | 55 |
1 files changed, 39 insertions, 16 deletions
diff --git a/util/nvmutil/nvmutil.c b/util/nvmutil/nvmutil.c index cdfcbc32..b77b28ad 100644 --- a/util/nvmutil/nvmutil.c +++ b/util/nvmutil/nvmutil.c @@ -21,6 +21,11 @@ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ +/* + * This file is part of the Libreboot project. Documentation available here: + * https://libreboot.org/docs/install/nvmutil.html + */ + #include <stdint.h> #include <string.h> #include <stdlib.h> @@ -78,33 +83,33 @@ main(int argc, char *argv[]) const char *strMac = NULL, *strRMac = "??:??:??:??:??:??"; #ifdef HAVE_PLEDGE - if (pledge("stdio wpath", NULL) == -1) - err(errno, "pledge"); + if (pledge("stdio wpath", NULL) == -1) /* only used on openbsd */ + err(errno, "pledge"); /* https://man.openbsd.org/pledge.2 */ #endif buf = (uint8_t *) &buf16; gbe[1] = (gbe[0] = (size_t) buf) + SIZE_4KB; test = 1; - big_endian = ((uint8_t *) &test)[0] ^ 1; + big_endian = ((uint8_t *) &test)[0] ^ 1; /* check host endianness */ if (argc == 3) { if (strcmp(COMMAND, "dump") == 0) { #ifdef HAVE_PLEDGE if (pledge("stdio rpath", NULL) == -1) - err(errno, "pledge"); + err(errno, "pledge"); /* not very puffy */ #endif flags = O_RDONLY; cmd = &cmd_dump; } else if (strcmp(COMMAND, "setmac") == 0) - strMac = (char *) strRMac; + strMac = (char *) strRMac; /* random mac address */ else if (strcmp(COMMAND, "swap") == 0) cmd = &cmd_swap; } else if (argc == 4) { if (strcmp(COMMAND, "setmac") == 0) - strMac = MAC_ADDRESS; + strMac = MAC_ADDRESS; /* user-supplied mac address */ else if ((!((part = PARTNUM[0] - '0') == 0 || part == 1)) - || PARTNUM[1]) + || PARTNUM[1]) /* only allow '1' or '0' */ errno = EINVAL; else if (strcmp(COMMAND, "setchecksum") == 0) cmd = &cmd_setchecksum; @@ -129,6 +134,7 @@ main(int argc, char *argv[]) readGbeFile(&fd, FILENAME, flags, nr); + /* perform operation specified by the user */ if (strMac != NULL) cmd_setmac(strMac); else if (cmd != NULL) @@ -145,6 +151,7 @@ nvmutil_exit: return errno; } +/* load the gbe file into memory */ void readGbeFile(int *fd, const char *path, int flags, size_t nr) { @@ -174,6 +181,7 @@ readGbeFile(int *fd, const char *path, int flags, size_t nr) } } +/* set mac address on valid nvm parts, per user input */ void cmd_setmac(const char *strMac) { @@ -193,12 +201,13 @@ cmd_setmac(const char *strMac) if (!validChecksum(partnum)) continue; for (int w = 0; w < 3; w++) - setWord(w, partnum, mac[w]); + setWord(w, partnum, mac[w]); /* do not use memcpy! */ part = partnum; cmd_setchecksum(); } } +/* read mac address from user input */ int parseMacAddress(const char *strMac, uint16_t *mac) { @@ -239,11 +248,12 @@ hextonum(char ch) else if ((ch >= 'a') && (ch <= 'f')) return ch - 'a' + 10; else if (ch == '?') - return rhex(); + return rhex(); /* random number */ else return 16; } +/* generate a random number from 0 to 15, the unix way */ uint8_t rhex(void) { @@ -261,6 +271,7 @@ rhex(void) return rval; } +/* show mac address and hexdump of each nvm part */ void cmd_dump(void) { @@ -276,6 +287,7 @@ cmd_dump(void) errno = 0; } +/* show formatted mac address contained within the nvm part */ void showmac(int partnum) { @@ -290,6 +302,7 @@ showmac(int partnum) } } +/* output a hexdump of both nvm parts, bytes reversed to big-endian order */ void hexdump(int partnum) { @@ -304,6 +317,7 @@ hexdump(int partnum) } } +/* set a valid checksum on a given part */ void cmd_setchecksum(void) { @@ -313,6 +327,7 @@ cmd_setchecksum(void) setWord(0x3F, part, 0xBABA - val16); } +/* set invalid checksum, intentionally */ void cmd_brick(void) { @@ -320,26 +335,28 @@ cmd_brick(void) setWord(0x3F, part, (word(0x3F, part)) ^ 0xFF); } +/* swap the words of each part with each other */ void cmd_swap(void) { if (validChecksum(1) || validChecksum(0)) { - gbe[0] ^= gbe[1]; + gbe[0] ^= gbe[1]; /* speed hack: xorswap pointers, not words */ gbe[1] ^= gbe[0]; gbe[0] ^= gbe[1]; - gbeFileModified = 1; + gbeFileModified = 1; /* not using setWord, so must set these */ nvmPartModified[0] = 1; nvmPartModified[1] = 1; errno = 0; } } +/* overwrite one part with the other */ void cmd_copy(void) { if (validChecksum(part)) { - gbe[part ^ 1] = gbe[part]; - gbeFileModified = 1; + gbe[part ^ 1] = gbe[part]; /* pointer-based speed hack */ + gbeFileModified = 1; /* not using setWord, so must set these */ nvmPartModified[part ^ 1] = 1; } } @@ -358,12 +375,14 @@ validChecksum(int partnum) return 0; } +/* fetch a word from gbe buffer */ uint16_t word(int pos16, int partnum) { return buf16[pos16 + (partnum << 11)]; } +/* write a word to gbe buffer, and record that a write has occured */ void setWord(int pos16, int partnum, uint16_t val16) { @@ -375,6 +394,7 @@ setWord(int pos16, int partnum, uint16_t val16) nvmPartModified[partnum] = 1; } +/* big-endian host compatibility: called post-read and again pre-write */ void byteswap(int n, int partnum) { @@ -382,24 +402,27 @@ byteswap(int n, int partnum) uint8_t *nbuf = (uint8_t *) gbe[partnum]; for (int w = 0; w < wcount; w++) { b1 = b2 = w << 1; + + /* xor-based swap method */ nbuf[b1] ^= nbuf[++b2]; nbuf[b2] ^= nbuf[b1]; nbuf[b1] ^= nbuf[b2]; } } +/* called after all operations are done, if gbe was modified */ void writeGbeFile(int *fd, const char *filename) { int p, nw; errno = 0; if ((gbe[0] != gbe[1]) && (gbe[0] < gbe[1])) - nw = 128; /* copy/swap command, so only write the nvm part */ + nw = 128; /* write only the nvm part */ else - nw = SIZE_4KB; + nw = SIZE_4KB; /* copy/swap, so only write everything */ for (p = 0; p < 2; p++) { - if (gbe[0] > gbe[1]) + if (gbe[0] > gbe[1]) /* write sequentially on-disk */ p ^= 1; if (!nvmPartModified[p]) goto next_part; |