diff options
author | Randall Spangler <rspangler@chromium.org> | 2011-03-18 11:24:27 -0700 |
---|---|---|
committer | Randall Spangler <rspangler@chromium.org> | 2011-03-18 11:24:27 -0700 |
commit | 17c712672f2c3a6d928c9bffde5b09c8baa1ba24 (patch) | |
tree | 89978800b045983743fe9f02102b6cfeb0114805 | |
parent | 5ac39bfff0d9e2ad2c3e1fe9b3fd3f314b50a472 (diff) | |
download | vboot-17c712672f2c3a6d928c9bffde5b09c8baa1ba24.tar.gz |
Add VbSharedData debug output to LoadKernel()
Change-Id: Id2837c83877520067e46e2434460349ef001b7b9
R=dlaurie@chromium.org
BUG=chrome-os-partner:2748
TEST=nmake uefi64; boot in normal and recovery modes
Review URL: http://codereview.chromium.org/6688035
-rw-r--r-- | firmware/include/vboot_struct.h | 99 | ||||
-rw-r--r-- | firmware/lib/vboot_kernel.c | 151 |
2 files changed, 220 insertions, 30 deletions
diff --git a/firmware/include/vboot_struct.h b/firmware/include/vboot_struct.h index 7cf88032..f82f7e95 100644 --- a/firmware/include/vboot_struct.h +++ b/firmware/include/vboot_struct.h @@ -131,6 +131,8 @@ typedef struct VbKernelPreambleHeader { #define EXPECTED_VBKERNELPREAMBLEHEADER_SIZE 96 +/* Constants and sub-structures for VbSharedDataHeader */ + /* Magic number for recognizing VbSharedDataHeader ("VbSD") */ #define VB_SHARED_DATA_MAGIC 0x44536256 @@ -141,14 +143,14 @@ typedef struct VbKernelPreambleHeader { /* Flags for VbSharedDataHeader */ /* LoadFirmware() tried firmware B because of VbNvStorage firmware B tries */ #define VBSD_FWB_TRIED 0x00000001 -/* LoadKernel() verified the kernel keyblock using the kernel subkey from +/* LoadKernel() verified the good kernel keyblock using the kernel subkey from * the firmware. If this flag is not present, it just used the hash of the * kernel keyblock. */ #define VBSD_KERNEL_KEY_VERIFIED 0x00000002 /* LoadFirmware() was told the developer switch was on */ #define VBSD_LF_DEV_SWITCH_ON 0x00000004 -/* Result codes for checking firmware A and B */ +/* Result codes for VbSharedDataHeader.check_fw_a_result (and b_result) */ #define VBSD_LF_CHECK_NOT_DONE 0 #define VBSD_LF_CHECK_DEV_MISMATCH 1 #define VBSD_LF_CHECK_REC_MISMATCH 2 @@ -163,6 +165,81 @@ typedef struct VbKernelPreambleHeader { #define VBSD_LF_CHECK_VERIFY_BODY 11 #define VBSD_LF_CHECK_VALID 12 +/* Boot mode for VbSharedDataHeader.lk_boot_mode */ +#define VBSD_LK_BOOT_MODE_RECOVERY 0 +#define VBSD_LK_BOOT_MODE_NORMAL 1 +#define VBSD_LK_BOOT_MODE_DEVELOPER 2 + +/* Flags for VbSharedDataKernelPart.flags */ +#define VBSD_LKP_FLAG_KEY_BLOCK_VALID 0x01 + +/* Result codes for VbSharedDataKernelPart.check_result */ +#define VBSD_LKP_CHECK_NOT_DONE 0 +#define VBSD_LKP_CHECK_TOO_SMALL 1 +#define VBSD_LKP_CHECK_READ_START 2 +#define VBSD_LKP_CHECK_KEY_BLOCK_SIG 3 +#define VBSD_LKP_CHECK_KEY_BLOCK_HASH 4 +#define VBSD_LKP_CHECK_DEV_MISMATCH 5 +#define VBSD_LKP_CHECK_REC_MISMATCH 6 +#define VBSD_LKP_CHECK_KEY_ROLLBACK 7 +#define VBSD_LKP_CHECK_DATA_KEY_PARSE 8 +#define VBSD_LKP_CHECK_VERIFY_PREAMBLE 9 +#define VBSD_LKP_CHECK_KERNEL_ROLLBACK 10 +#define VBSD_LKP_CHECK_PREAMBLE_VALID 11 +#define VBSD_LKP_CHECK_BODY_ADDRESS 12 +#define VBSD_LKP_CHECK_BODY_OFFSET 13 +#define VBSD_LKP_CHECK_BODY_EXCEEDS_MEM 15 +#define VBSD_LKP_CHECK_BODY_EXCEEDS_PART 16 +#define VBSD_LKP_CHECK_READ_DATA 17 +#define VBSD_LKP_CHECK_VERIFY_DATA 18 +#define VBSD_LKP_CHECK_KERNEL_GOOD 19 + + +/* Information about a single kernel partition check in LoadKernel() */ +typedef struct VbSharedDataKernelPart { + uint64_t sector_start; /* Start sector of partition */ + uint64_t sector_count; /* Sector count of partition */ + uint32_t combined_version; /* Combined key+kernel version */ + uint8_t gpt_index; /* Index of partition in GPT */ + uint8_t check_result; /* Check result; see VBSD_LKP_CHECK_* */ + uint8_t flags; /* Flags (see VBSD_LKP_FLAG_* */ +} VbSharedDataKernelPart; + +/* Number of kernel partitions to track per call. Must be power of 2. */ +#define VBSD_MAX_KERNEL_PARTS 8 + +/* Flags for VbSharedDataKernelCall.flags */ +/* Error initializing TPM in recovery mode */ +#define VBSD_LK_FLAG_REC_TPM_INIT_ERROR 0x00000001 + +/* Result codes for VbSharedDataKernelCall.check_result */ +#define VBSD_LKC_CHECK_NOT_DONE 0 +#define VBSD_LKC_CHECK_DEV_SWITCH_MISMATCH 1 +#define VBSD_LKC_CHECK_GPT_READ_ERROR 2 +#define VBSD_LKC_CHECK_GPT_PARSE_ERROR 3 +#define VBSD_LKC_CHECK_GOOD_PARTITION 4 +#define VBSD_LKC_CHECK_INVALID_PARTITIONS 5 +#define VBSD_LKC_CHECK_NO_PARTITIONS 6 + +/* Information about a single call to LoadKernel() */ +typedef struct VbSharedDataKernelCall { + uint32_t boot_flags; /* Bottom 32 bits of flags passed in + * LoadKernelParams.boot_flags */ + uint32_t flags; /* Debug flags; see VBSD_LK_FLAG_* */ + uint64_t sector_count; /* Number of sectors on drive */ + uint32_t sector_size; /* Sector size in bytes */ + uint8_t check_result; /* Check result; see VBSD_LKC_CHECK_* */ + uint8_t boot_mode; /* Boot mode for LoadKernel(); see + * VBSD_LK_BOOT_MODE_* constants */ + uint8_t test_error_num; /* Test error number, if non-zero */ + uint8_t return_code; /* Return code from LoadKernel() */ + uint8_t kernel_parts_found; /* Number of kernel partitions found */ + VbSharedDataKernelPart parts[VBSD_MAX_KERNEL_PARTS]; /* Data on kernels */ +} VbSharedDataKernelCall; + +/* Number of kernel calls to track. Must be power of 2. */ +#define VBSD_MAX_KERNEL_CALLS 4 + /* Data shared between LoadFirmware(), LoadKernel(), and OS. * * The boot process is: @@ -200,6 +277,11 @@ typedef struct VbSharedDataHeader { uint64_t timer_load_kernel_enter; /* LoadKernel() - enter */ uint64_t timer_load_kernel_exit; /* LoadKernel() - exit */ + /* Information stored in TPM, as retrieved by firmware */ + uint32_t fw_version_tpm; /* Current firmware version in TPM */ + uint32_t kernel_version_tpm; /* Current kernel version in TPM */ + + /* Debugging information from LoadFirmware() */ uint8_t check_fw_a_result; /* Result of checking RW firmware A */ uint8_t check_fw_b_result; /* Result of checking RW firmware B */ uint8_t firmware_index; /* Firmware index returned by @@ -208,8 +290,17 @@ typedef struct VbSharedDataHeader { * LoadFirmware() */ uint32_t fw_version_lowest; /* Firmware lowest version found */ - uint32_t fw_version_tpm; /* Current firmware version in TPM */ - uint32_t kernel_version_tpm; /* Current kernel version in TPM */ + /* Debugging information from LoadKernel() */ + uint32_t lk_call_count; /* Number of times LoadKernel() called */ + VbSharedDataKernelCall lk_calls[VBSD_MAX_KERNEL_CALLS]; /* Info on calls */ + + /* Offset and size of supplemental kernel data. Reserve space for these + * fields now, so that future LoadKernel() versions can store information + * there without needing to shift down whatever data the original + * LoadFirmware() might have put immediately following its + * VbSharedDataHeader. */ + uint64_t kernel_supplemental_offset; + uint64_t kernel_supplemental_size; /* After read-only firmware which uses version 1 is released, any additional * fields must be added below, and the struct version must be increased. diff --git a/firmware/lib/vboot_kernel.c b/firmware/lib/vboot_kernel.c index 204874f6..302a7f66 100644 --- a/firmware/lib/vboot_kernel.c +++ b/firmware/lib/vboot_kernel.c @@ -21,9 +21,9 @@ #define LOWEST_TPM_VERSION 0xffffffff typedef enum BootMode { - kBootNormal, /* Normal firmware */ - kBootDev, /* Dev firmware AND dev switch is on */ - kBootRecovery /* Recovery firmware, regardless of dev switch position */ + kBootRecovery = 0, /* Recovery firmware, regardless of dev switch position */ + kBootNormal = 1, /* Normal firmware */ + kBootDev = 2 /* Dev firmware AND dev switch is on */ } BootMode; @@ -121,6 +121,7 @@ __pragma(warning(disable: 4127)) int LoadKernel(LoadKernelParams* params) { VbSharedDataHeader* shared = (VbSharedDataHeader*)params->shared_data_blob; + VbSharedDataKernelCall* shcall = NULL; VbNvContext* vnc = params->nv_context; GoogleBinaryBlockHeader* gbb = (GoogleBinaryBlockHeader*)params->gbb_data; VbPublicKey* kernel_subkey; @@ -161,11 +162,51 @@ int LoadKernel(LoadKernelParams* params) { params->bootloader_address = 0; params->bootloader_size = 0; + /* Calculate switch positions and boot mode */ + rec_switch = (BOOT_FLAG_RECOVERY & params->boot_flags ? 1 : 0); + dev_switch = (BOOT_FLAG_DEVELOPER & params->boot_flags ? 1 : 0); + if (rec_switch) + boot_mode = kBootRecovery; + else if (BOOT_FLAG_DEV_FIRMWARE & params->boot_flags) + boot_mode = kBootDev; + else { + /* Normal firmware */ + boot_mode = kBootNormal; + dev_switch = 0; /* Always do a fully verified boot */ + } + + if (kBootRecovery == boot_mode) { + /* Initialize the shared data structure, since LoadFirmware() didn't do it + * for us. */ + if (0 != VbSharedDataInit(shared, params->shared_data_size)) { + /* Error initializing the shared data, but we can keep going. We just + * can't use the shared data. */ + VBDEBUG(("Shared data init error\n")); + params->shared_data_size = 0; + shared = NULL; + } + } + + if (shared) { + /* Set up tracking for this call. This wraps around if called many times, + * so we need to initialize the call entry each time. */ + shcall = shared->lk_calls + (shared->lk_call_count + & (VBSD_MAX_KERNEL_CALLS - 1)); + Memset(shcall, 0, sizeof(VbSharedDataKernelCall)); + shcall->boot_flags = (uint32_t)params->boot_flags; + shcall->boot_mode = boot_mode; + shcall->sector_size = (uint32_t)params->bytes_per_lba; + shcall->sector_count = params->ending_lba + 1; + shared->lk_call_count++; + } + /* Handle test errors */ VbNvGet(vnc, VBNV_TEST_ERROR_FUNC, &test_err); if (VBNV_TEST_ERROR_LOAD_KERNEL == test_err) { /* Get error code */ VbNvGet(vnc, VBNV_TEST_ERROR_NUM, &test_err); + if (shcall) + shcall->test_error_num = (uint8_t)test_err; /* Clear test params so we don't repeat the error */ VbNvSet(vnc, VBNV_TEST_ERROR_FUNC, 0); VbNvSet(vnc, VBNV_TEST_ERROR_NUM, 0); @@ -192,43 +233,25 @@ int LoadKernel(LoadKernelParams* params) { goto LoadKernelExit; } - rec_switch = (BOOT_FLAG_RECOVERY & params->boot_flags ? 1 : 0); - dev_switch = (BOOT_FLAG_DEVELOPER & params->boot_flags ? 1 : 0); - - if (rec_switch) - boot_mode = kBootRecovery; - else if (BOOT_FLAG_DEV_FIRMWARE & params->boot_flags) { - if (!dev_switch) { + if (kBootDev == boot_mode && !dev_switch) { /* Dev firmware should be signed such that it never boots with the dev * switch is off; so something is terribly wrong. */ VBDEBUG(("LoadKernel() called with dev firmware but dev switch off\n")); + if (shcall) + shcall->check_result = VBSD_LKC_CHECK_DEV_SWITCH_MISMATCH; recovery = VBNV_RECOVERY_RW_DEV_MISMATCH; goto LoadKernelExit; } - boot_mode = kBootDev; - } else { - /* Normal firmware */ - boot_mode = kBootNormal; - dev_switch = 0; /* Always do a fully verified boot */ - } if (kBootRecovery == boot_mode) { - /* Initialize the shared data structure, since LoadFirmware() didn't do it - * for us. */ - if (0 != VbSharedDataInit(shared, params->shared_data_size)) { - /* Error initializing the shared data, but we can keep going. We just - * can't use the shared data. */ - VBDEBUG(("Shared data init error\n")); - params->shared_data_size = 0; - shared = NULL; - } - /* Use the recovery key to verify the kernel */ kernel_subkey = (VbPublicKey*)((uint8_t*)gbb + gbb->recovery_key_offset); /* Let the TPM know if we're in recovery mode */ if (0 != RollbackKernelRecovery(dev_switch)) { VBDEBUG(("Error setting up TPM for recovery kernel\n")); + if (shcall) + shcall->flags |= VBSD_LK_FLAG_REC_TPM_INIT_ERROR; /* Ignore return code, since we need to boot recovery mode to * fix the TPM. */ } @@ -263,12 +286,16 @@ int LoadKernel(LoadKernelParams* params) { gpt.drive_sectors = params->ending_lba + 1; if (0 != AllocAndReadGptData(&gpt)) { VBDEBUG(("Unable to read GPT data\n")); + if (shcall) + shcall->check_result = VBSD_LKC_CHECK_GPT_READ_ERROR; break; } /* Initialize GPT library */ if (GPT_SUCCESS != GptInit(&gpt)) { VBDEBUG(("Error parsing GPT\n")); + if (shcall) + shcall->check_result = VBSD_LKC_CHECK_GPT_PARSE_ERROR; break; } @@ -279,6 +306,7 @@ int LoadKernel(LoadKernelParams* params) { /* Loop over candidate kernel partitions */ while (GPT_SUCCESS == GptNextKernelEntry(&gpt, &part_start, &part_size)) { + VbSharedDataKernelPart* shpart = NULL; VbKeyBlockHeader* key_block; VbKernelPreambleHeader* preamble; RSAPublicKey* data_key = NULL; @@ -292,17 +320,35 @@ int LoadKernel(LoadKernelParams* params) { VBDEBUG(("Found kernel entry at %" PRIu64 " size %" PRIu64 "\n", part_start, part_size)); + if (shcall) { + /* Set up tracking for this partition. This wraps around if called + * many times, so initialize the partition entry each time. */ + shpart = shcall->parts + (shcall->kernel_parts_found + & (VBSD_MAX_KERNEL_PARTS - 1)); + Memset(shpart, 0, sizeof(VbSharedDataKernelPart)); + shpart->sector_start = part_start; + shpart->sector_count = part_size; + /* TODO: GPT partitions start at 1, but cgptlib starts them at 0. + * Adjust here, until cgptlib is fixed. */ + shpart->gpt_index = (uint8_t)(gpt.current_kernel + 1); + shcall->kernel_parts_found++; + } + /* Found at least one kernel partition. */ found_partitions++; /* Read the first part of the kernel partition. */ if (part_size < kbuf_sectors) { VBDEBUG(("Partition too small to hold kernel.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_TOO_SMALL; goto bad_kernel; } if (0 != BootDeviceReadLBA(part_start, kbuf_sectors, kbuf)) { VBDEBUG(("Unable to read start of partition.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_READ_START; goto bad_kernel; } @@ -310,6 +356,9 @@ int LoadKernel(LoadKernelParams* params) { key_block = (VbKeyBlockHeader*)kbuf; if (0 != KeyBlockVerify(key_block, KBUF_SIZE, kernel_subkey, 0)) { VBDEBUG(("Verifying key block signature failed.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_KEY_BLOCK_SIG; + key_block_valid = 0; /* If we're not in developer mode, this kernel is bad. */ @@ -320,6 +369,8 @@ int LoadKernel(LoadKernelParams* params) { * block is valid. */ if (0 != KeyBlockVerify(key_block, KBUF_SIZE, kernel_subkey, 1)) { VBDEBUG(("Verifying key block hash failed.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_KEY_BLOCK_HASH; goto bad_kernel; } } @@ -329,12 +380,16 @@ int LoadKernel(LoadKernelParams* params) { (dev_switch ? KEY_BLOCK_FLAG_DEVELOPER_1 : KEY_BLOCK_FLAG_DEVELOPER_0))) { VBDEBUG(("Key block developer flag mismatch.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_DEV_MISMATCH; key_block_valid = 0; } if (!(key_block->key_block_flags & (rec_switch ? KEY_BLOCK_FLAG_RECOVERY_1 : KEY_BLOCK_FLAG_RECOVERY_0))) { VBDEBUG(("Key block recovery flag mismatch.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_REC_MISMATCH; key_block_valid = 0; } @@ -343,6 +398,8 @@ int LoadKernel(LoadKernelParams* params) { if (kBootRecovery != boot_mode) { if (key_version < (tpm_version >> 16)) { VBDEBUG(("Key version too old.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_KEY_ROLLBACK; key_block_valid = 0; } } @@ -357,6 +414,8 @@ int LoadKernel(LoadKernelParams* params) { data_key = PublicKeyToRSA(&key_block->data_key); if (!data_key) { VBDEBUG(("Data key bad.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_DATA_KEY_PARSE; goto bad_kernel; } @@ -366,6 +425,8 @@ int LoadKernel(LoadKernelParams* params) { KBUF_SIZE - key_block->key_block_size, data_key))) { VBDEBUG(("Preamble verification failed.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_VERIFY_PREAMBLE; goto bad_kernel; } @@ -373,9 +434,13 @@ int LoadKernel(LoadKernelParams* params) { * rollback of the kernel version. */ combined_version = ((key_version << 16) | (preamble->kernel_version & 0xFFFF)); + if (shpart) + shpart->combined_version = (uint32_t)combined_version; if (key_block_valid && kBootRecovery != boot_mode) { if (combined_version < tpm_version) { VBDEBUG(("Kernel version too low.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_KERNEL_ROLLBACK; /* If we're not in developer mode, kernel version must be valid. */ if (kBootDev != boot_mode) goto bad_kernel; @@ -383,6 +448,8 @@ int LoadKernel(LoadKernelParams* params) { } VBDEBUG(("Kernel preamble is good.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_PREAMBLE_VALID; /* Check for lowest version from a valid header. */ if (key_block_valid && lowest_version > combined_version) @@ -402,6 +469,8 @@ int LoadKernel(LoadKernelParams* params) { if ((preamble->body_load_address != (size_t)params->kernel_buffer) && !(params->boot_flags & BOOT_FLAG_SKIP_ADDR_CHECK)) { VBDEBUG(("Wrong body load address.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_BODY_ADDRESS; goto bad_kernel; } @@ -409,6 +478,8 @@ int LoadKernel(LoadKernelParams* params) { body_offset = key_block->key_block_size + preamble->preamble_size; if (0 != body_offset % blba) { VBDEBUG(("Kernel body not at multiple of sector size.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_BODY_OFFSET; goto bad_kernel; } body_offset_sectors = body_offset / blba; @@ -417,12 +488,16 @@ int LoadKernel(LoadKernelParams* params) { body_sectors = (preamble->body_signature.data_size + blba - 1) / blba; if (body_sectors * blba > params->kernel_buffer_size) { VBDEBUG(("Kernel body doesn't fit in memory.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_BODY_EXCEEDS_MEM; goto bad_kernel; } /* Verify kernel body fits in the partition */ if (body_offset_sectors + body_sectors > part_size) { VBDEBUG(("Kernel body doesn't fit in partition.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_BODY_EXCEEDS_PART; goto bad_kernel; } @@ -433,6 +508,8 @@ int LoadKernel(LoadKernelParams* params) { params->kernel_buffer)) { VBDEBUG(("Unable to read kernel data.\n")); VBPERFEND("VB_RKD"); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_READ_DATA; goto bad_kernel; } VBPERFEND("VB_RKD"); @@ -442,6 +519,8 @@ int LoadKernel(LoadKernelParams* params) { params->kernel_buffer_size, &preamble->body_signature, data_key)) { VBDEBUG(("Kernel data verification failed.\n")); + if (shpart) + shpart->check_result = VBSD_LKP_CHECK_VERIFY_DATA; goto bad_kernel; } @@ -452,6 +531,12 @@ int LoadKernel(LoadKernelParams* params) { /* If we're still here, the kernel is valid. */ /* Save the first good partition we find; that's the one we'll boot */ VBDEBUG(("Partition is good.\n")); + if (shpart) { + shpart->check_result = VBSD_LKP_CHECK_KERNEL_GOOD; + if (key_block_valid) + shpart->flags |= VBSD_LKP_FLAG_KEY_BLOCK_VALID; + } + good_partition_key_block_valid = key_block_valid; /* TODO: GPT partitions start at 1, but cgptlib starts them at 0. * Adjust here, until cgptlib is fixed. */ @@ -508,6 +593,8 @@ int LoadKernel(LoadKernelParams* params) { /* Handle finding a good partition */ if (good_partition >= 0) { VBDEBUG(("Good_partition >= 0\n")); + if (shcall) + shcall->check_result = VBSD_LKC_CHECK_GOOD_PARTITION; /* See if we need to update the TPM */ if (kBootRecovery != boot_mode && good_partition_key_block_valid) { @@ -551,6 +638,11 @@ int LoadKernel(LoadKernelParams* params) { /* Success! */ retval = LOAD_KERNEL_SUCCESS; } else { + if (shcall) + shcall->check_result = (found_partitions > 0 + ? VBSD_LKC_CHECK_INVALID_PARTITIONS + : VBSD_LKC_CHECK_NO_PARTITIONS); + /* TODO: differentiate between finding an invalid kernel * (found_partitions>0) and not finding one at all. Right now we * treat them the same, and return LOAD_KERNEL_INVALID for both. */ @@ -568,6 +660,13 @@ LoadKernelExit: VbNvTeardown(vnc); if (shared) { + if (shcall) + shcall->return_code = (uint8_t)retval; + + /* Save whether the good partition's key block was fully verified */ + if (good_partition_key_block_valid) + shared->flags |= VBSD_KERNEL_KEY_VERIFIED; + /* Save timer values */ shared->timer_load_kernel_enter = timer_enter; shared->timer_load_kernel_exit = VbGetTimer(); |