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EC software sync uses precomputed hash if available

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This removes the need to load the EC code at all when the precomputed
hash matches.

BUG=chrome-os-partner:17606
BRANCH=spring
TEST=wouldn't that be nice

Change-Id: If4438b9db8b1449b8fd4d90ef3acb3bbec5e09a0
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/42567
This commit is contained in:
Randall Spangler
2013-02-04 15:00:09 -08:00
committed by ChromeBot
parent 9a8e79cc26
commit 5ca4ea087a
4 changed files with 103 additions and 20 deletions
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100
firmware/lib/vboot_api_kernel.c
View File

@@ -555,12 +555,14 @@ VbError_t VbEcSoftwareSync(VbCommonParams *cparams)
(VbSharedDataHeader *)cparams->shared_data_blob;
int in_rw = 0;
int rv;
const uint8_t *ec_hash;
const uint8_t *ec_hash = NULL;
int ec_hash_size;
const uint8_t *expected;
const uint8_t *rw_hash = NULL;
int rw_hash_size;
const uint8_t *expected = NULL;
int expected_size;
uint8_t expected_hash[SHA256_DIGEST_SIZE];
int need_update;
int need_update = 0;
int i;
/* Determine whether the EC is in RO or RW */
@@ -660,29 +662,87 @@ VbError_t VbEcSoftwareSync(VbCommonParams *cparams)
VBDEBUG(("\n"));
/*
* Get expected EC-RW code. Note that we've already checked for
* Get expected EC-RW hash. Note that we've already checked for
* RO_NORMAL, so we know that the BIOS must be RW-A or RW-B, and
* therefore the EC must match.
*/
rv = VbExEcGetExpectedRW(shared->firmware_index ?
rv = VbExEcGetExpectedRWHash(shared->firmware_index ?
VB_SELECT_FIRMWARE_B : VB_SELECT_FIRMWARE_A,
&expected, &expected_size);
if (rv) {
&rw_hash, &rw_hash_size);
if (rv == VBERROR_EC_GET_EXPECTED_HASH_FROM_IMAGE) {
/*
* BIOS has verified EC image but doesn't have a precomputed
* hash for it, so we must compute the hash ourselves.
*/
rw_hash = NULL;
} else if (rv) {
VBDEBUG(("VbEcSoftwareSync() - "
"VbExEcGetExpectedRWHash() returned %d\n", rv));
VbSetRecoveryRequest(VBNV_RECOVERY_EC_EXPECTED_HASH);
return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
} else if (rw_hash_size != SHA256_DIGEST_SIZE) {
VBDEBUG(("VbEcSoftwareSync() - "
"VbExEcGetExpectedRWHash() says size %d, not %d\n",
rw_hash_size, SHA256_DIGEST_SIZE));
VbSetRecoveryRequest(VBNV_RECOVERY_EC_EXPECTED_HASH);
return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
} else {
VBDEBUG(("Expected hash:"));
for (i = 0; i < SHA256_DIGEST_SIZE; i++)
VBDEBUG(("%02x", rw_hash[i]));
VBDEBUG(("\n"));
need_update = SafeMemcmp(ec_hash, rw_hash, SHA256_DIGEST_SIZE);
}
/*
* Get expected EC-RW image if we're sure we need to update (because the
* expected hash didn't match the EC) or we still don't know (because
* there was no expected hash and we need the image to compute one
* ourselves).
*/
if (need_update || !rw_hash) {
/* Get expected EC-RW image */
rv = VbExEcGetExpectedRW(shared->firmware_index ?
VB_SELECT_FIRMWARE_B :
VB_SELECT_FIRMWARE_A,
&expected, &expected_size);
if (rv) {
VBDEBUG(("VbEcSoftwareSync() - "
"VbExEcGetExpectedRW() returned %d\n", rv));
VbSetRecoveryRequest(VBNV_RECOVERY_EC_EXPECTED_IMAGE);
return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
}
VBDEBUG(("VbEcSoftwareSync() - expected len = %d\n",
expected_size));
/* Hash expected image */
internal_SHA256(expected, expected_size, expected_hash);
VBDEBUG(("Computed hash of expected image:"));
for (i = 0; i < SHA256_DIGEST_SIZE; i++)
VBDEBUG(("%02x", expected_hash[i]));
VBDEBUG(("\n"));
}
if (!rw_hash) {
/*
* BIOS didn't have expected EC hash, so check if we need
* update by comparing EC hash to the one we just computed.
*/
need_update = SafeMemcmp(ec_hash, expected_hash,
SHA256_DIGEST_SIZE);
} else if (need_update &&
SafeMemcmp(rw_hash, expected_hash, SHA256_DIGEST_SIZE)) {
/*
* We need to update, but the expected EC image doesn't match
* the expected EC hash we were given.
*/
VBDEBUG(("VbEcSoftwareSync() - "
"VbExEcGetExpectedRW() returned %d\n", rv));
VbSetRecoveryRequest(VBNV_RECOVERY_EC_EXPECTED_IMAGE);
VbSetRecoveryRequest(VBNV_RECOVERY_EC_HASH_MISMATCH);
return VBERROR_EC_REBOOT_TO_RO_REQUIRED;
}
VBDEBUG(("VbEcSoftwareSync() - expected len = %d\n", expected_size));
/* Hash expected code */
internal_SHA256(expected, expected_size, expected_hash);
VBDEBUG(("Expected hash:"));
for (i = 0; i < SHA256_DIGEST_SIZE; i++)
VBDEBUG(("%02x", expected_hash[i]));
VBDEBUG(("\n"));
need_update = SafeMemcmp(ec_hash, expected_hash, SHA256_DIGEST_SIZE);
/*
* TODO: GBB flag to override whether we need update; needed for EC
@@ -692,7 +752,7 @@ VbError_t VbEcSoftwareSync(VbCommonParams *cparams)
if (in_rw) {
if (need_update) {
/*
* EC is running the wrong RW code. Reboot the EC to
* EC is running the wrong RW image. Reboot the EC to
* RO so we can update it on the next boot.
*/
VBDEBUG(("VbEcSoftwareSync() - "
@@ -747,7 +807,7 @@ VbError_t VbEcSoftwareSync(VbCommonParams *cparams)
if (rv != VBERROR_SUCCESS)
return rv;
/* Tell EC to jump to its RW code */
/* Tell EC to jump to its RW image */
VBDEBUG(("VbEcSoftwareSync() jumping to EC-RW\n"));
rv = VbExEcJumpToRW();
if (rv != VBERROR_SUCCESS) {