/********************************************************************************/ /* */ /* Used by the simulator to mimic a hardware clock */ /* Written by Ken Goldman */ /* IBM Thomas J. Watson Research Center */ /* $Id: Clock.c 1529 2019-11-21 23:29:01Z kgoldman $ */ /* */ /* Licenses and Notices */ /* */ /* 1. 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Description */ /* This file contains the routines that are used by the simulator to mimic a hardware clock on a TPM. In this implementation, all the time values are measured in millisecond. However, the precision of the clock functions may be implementation dependent. */ /* C.3.2. Includes and Data Definitions */ #include #include "Platform.h" #include "TpmFail_fp.h" /* C.3.3. Simulator Functions */ /* C.3.3.1. Introduction */ /* This set of functions is intended to be called by the simulator environment in order to simulate hardware events. */ /* C.3.3.2. _plat__TimerReset() */ /* This function sets current system clock time as t0 for counting TPM time. This function is called at a power on event to reset the clock. When the clock is reset, the indication that the clock was stopped is also set. */ LIB_EXPORT void _plat__TimerReset( void ) { s_lastSystemTime = 0; s_tpmTime = 0; s_adjustRate = CLOCK_NOMINAL; s_timerReset = TRUE; s_timerStopped = TRUE; return; } /* C.3.3.3. _plat__TimerRestart() */ /* This function should be called in order to simulate the restart of the timer should it be stopped while power is still applied. */ LIB_EXPORT void _plat__TimerRestart( void ) { s_timerStopped = TRUE; return; } /* C.3.4. Functions Used by TPM */ /* C.3.4.1. Introduction */ /* These functions are called by the TPM code. They should be replaced by appropriated hardware functions. */ clock_t debugTime; /* C.3.4.2. _plat__Time() */ /* This is another, probably futile, attempt to define a portable function that will return a 64-bit clock value that has mSec resolution. */ LIB_EXPORT uint64_t _plat__RealTime( void ) { clock64_t time; //#ifdef _MSC_VER kgold #ifdef TPM_WINDOWS #include struct _timeb sysTime; // _ftime(&sysTime); /* kgold, mingw doesn't have _ftime_s */ time = (clock64_t)(sysTime.time) * 1000 + sysTime.millitm; // set the time back by one hour if daylight savings if(sysTime.dstflag) time -= 1000 * 60 * 60; // mSec/sec * sec/min * min/hour = ms/hour #else // hopefully, this will work with most UNIX systems struct timespec systime; // clock_gettime(CLOCK_MONOTONIC, &systime); time = (clock64_t)systime.tv_sec * 1000 + (systime.tv_nsec / 1000000); #endif return time; } /* C.3.4.3. _plat__TimerRead() */ /* This function provides access to the tick timer of the platform. The TPM code uses this value to drive the TPM Clock. */ /* The tick timer is supposed to run when power is applied to the device. This timer should not be reset by time events including _TPM_Init(). It should only be reset when TPM power is re-applied. */ /* If the TPM is run in a protected environment, that environment may provide the tick time to the TPM as long as the time provided by the environment is not allowed to go backwards. If the time provided by the system can go backwards during a power discontinuity, then the _plat__Signal_PowerOn() should call _plat__TimerReset(). */ LIB_EXPORT uint64_t _plat__TimerRead( void ) { #ifdef HARDWARE_CLOCK #error "need a defintion for reading the hardware clock" return HARDWARE_CLOCK #else clock64_t timeDiff; clock64_t adjustedTimeDiff; clock64_t timeNow; clock64_t readjustedTimeDiff; // This produces a timeNow that is basically locked to the system clock. timeNow = _plat__RealTime(); // if this hasn't been initialized, initialize it if(s_lastSystemTime == 0) { s_lastSystemTime = timeNow; debugTime = clock(); s_lastReportedTime = 0; s_realTimePrevious = 0; } // The system time can bounce around and that's OK as long as we don't allow // time to go backwards. When the time does appear to go backwards, set // lastSystemTime to be the new value and then update the reported time. if(timeNow < s_lastReportedTime) s_lastSystemTime = timeNow; s_lastReportedTime = s_lastReportedTime + timeNow - s_lastSystemTime; s_lastSystemTime = timeNow; timeNow = s_lastReportedTime; // The code above produces a timeNow that is similar to the value returned // by Clock(). The difference is that timeNow does not max out, and it is // at a ms. rate rather than at a CLOCKS_PER_SEC rate. The code below // uses that value and does the rate adjustment on the time value. // If there is no difference in time, then skip all the computations if(s_realTimePrevious >= timeNow) return s_tpmTime; // Compute the amount of time since the last update of the system clock timeDiff = timeNow - s_realTimePrevious; // Do the time rate adjustment and conversion from CLOCKS_PER_SEC to mSec adjustedTimeDiff = (timeDiff * CLOCK_NOMINAL) / ((uint64_t)s_adjustRate); // update the TPM time with the adjusted timeDiff s_tpmTime += (clock64_t)adjustedTimeDiff; // Might have some rounding error that would loose CLOCKS. See what is not // being used. As mentioned above, this could result in putting back more than // is taken out. Here, we are trying to recreate timeDiff. readjustedTimeDiff = (adjustedTimeDiff * (uint64_t)s_adjustRate ) / CLOCK_NOMINAL; // adjusted is now converted back to being the amount we should advance the // previous sampled time. It should always be less than or equal to timeDiff. // That is, we could not have use more time than we started with. s_realTimePrevious = s_realTimePrevious + readjustedTimeDiff; #ifdef DEBUGGING_TIME // Put this in so that TPM time will pass much faster than real time when // doing debug. // A value of 1000 for DEBUG_TIME_MULTIPLER will make each ms into a second // A good value might be 100 return (s_tpmTime * DEBUG_TIME_MULTIPLIER); #endif return s_tpmTime; #endif } /* C.3.4.3. _plat__TimerWasReset() */ /* This function is used to interrogate the flag indicating if the tick timer has been reset. */ /* If the resetFlag parameter is SET, then the flag will be CLEAR before the function returns. */ LIB_EXPORT int _plat__TimerWasReset( void ) { int retVal = s_timerReset; s_timerReset = FALSE; return retVal; } /* C.3.4.4. _plat__TimerWasStopped() */ /* This function is used to interrogate the flag indicating if the tick timer has been stopped. If so, this is typically a reason to roll the nonce. */ /* This function will CLEAR the s_timerStopped flag before returning. This provides functionality that is similar to status register that is cleared when read. This is the model used here because it is the one that has the most impact on the TPM code as the flag can only be accessed by one entity in the TPM. Any other implementation of the hardware can be made to look like a read-once register. */ LIB_EXPORT int _plat__TimerWasStopped( void ) { BOOL retVal = s_timerStopped; s_timerStopped = FALSE; return retVal; } /* C.3.4.5. _plat__ClockAdjustRate() */ /* Adjust the clock rate */ LIB_EXPORT void _plat__ClockAdjustRate( int adjust // IN: the adjust number. It could be positive // or negative ) { // We expect the caller should only use a fixed set of constant values to // adjust the rate switch(adjust) { case CLOCK_ADJUST_COARSE: s_adjustRate += CLOCK_ADJUST_COARSE; break; case -CLOCK_ADJUST_COARSE: s_adjustRate -= CLOCK_ADJUST_COARSE; break; case CLOCK_ADJUST_MEDIUM: s_adjustRate += CLOCK_ADJUST_MEDIUM; break; case -CLOCK_ADJUST_MEDIUM: s_adjustRate -= CLOCK_ADJUST_MEDIUM; break; case CLOCK_ADJUST_FINE: s_adjustRate += CLOCK_ADJUST_FINE; break; case -CLOCK_ADJUST_FINE: s_adjustRate -= CLOCK_ADJUST_FINE; break; default: // ignore any other values; break; } if(s_adjustRate > (CLOCK_NOMINAL + CLOCK_ADJUST_LIMIT)) s_adjustRate = CLOCK_NOMINAL + CLOCK_ADJUST_LIMIT; if(s_adjustRate < (CLOCK_NOMINAL - CLOCK_ADJUST_LIMIT)) s_adjustRate = CLOCK_NOMINAL - CLOCK_ADJUST_LIMIT; return; }