On Tue, 26 Feb 2019 at 00:52, Pete Batard <p...@akeo.ie> wrote:
>
> LibGetTime():
> - Two variables were used for the epoch, where only one should have been.
> - Also harmonize variable name to match the one used in LibSetTime.
> LiBSetTime():
> - Address possible underflows if time is set to start of epoch.
> - Ensure that time being read does actually match time that was manually
> set (plus the time elapsed since), by subtracting number of seconds
> since reset.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Pete Batard <p...@akeo.ie>
Thanks Pete
Reviewed-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
Pushed as 9ab4ec518882..1342d7679e10
> ---
> EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c | 34
> ++++++++++++++------
> 1 file changed, 25 insertions(+), 9 deletions(-)
>
> diff --git
> a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> index 4c354730d02b..5559106b696f 100644
> --- a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> +++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
> @@ -54,13 +54,12 @@ LibGetTime (
> )
> {
> EFI_STATUS Status;
> - UINT32 EpochSeconds;
> INT16 TimeZone;
> UINT8 Daylight;
> UINT64 Freq;
> UINT64 Counter;
> UINT64 Remainder;
> - UINTN ElapsedSeconds;
> + UINTN EpochSeconds;
> UINTN Size;
>
> if (Time == NULL) {
> @@ -75,13 +74,13 @@ LibGetTime (
>
> // Get the epoch time from non-volatile storage
> Size = sizeof (UINTN);
> - ElapsedSeconds = 0;
> + EpochSeconds = 0;
> Status = EfiGetVariable (
> (CHAR16 *)mEpochVariableName,
> &gEfiCallerIdGuid,
> NULL,
> &Size,
> - (VOID *)&ElapsedSeconds
> + (VOID *)&EpochSeconds
> );
> // Fall back to compilation-time epoch if not set
> if (EFI_ERROR (Status)) {
> @@ -93,7 +92,7 @@ LibGetTime (
> // If you are attempting to use this library on such an environment,
> please
> // contact the edk2 mailing list, so we can try to add support for it.
> //
> - ElapsedSeconds = BUILD_EPOCH;
> + EpochSeconds = BUILD_EPOCH;
> DEBUG ((
> DEBUG_INFO,
> "LibGetTime: %s non volatile variable was not found - Using
> compilation time epoch.\n",
> @@ -101,7 +100,7 @@ LibGetTime (
> ));
> }
> Counter = GetPerformanceCounter ();
> - ElapsedSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
> + EpochSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
>
> // Get the current time zone information from non-volatile storage
> Size = sizeof (TimeZone);
> @@ -204,7 +203,7 @@ LibGetTime (
> }
> }
>
> - EpochToEfiTime (ElapsedSeconds, Time);
> + EpochToEfiTime (EpochSeconds, Time);
>
> // Because we use the performance counter, we can fill the Nanosecond
> attribute
> // provided that the remainder doesn't overflow 64-bit during
> multiplication.
> @@ -240,6 +239,9 @@ LibSetTime (
> )
> {
> EFI_STATUS Status;
> + UINT64 Freq;
> + UINT64 Counter;
> + UINT64 Remainder;
> UINTN EpochSeconds;
>
> if (!IsTimeValid (Time)) {
> @@ -249,16 +251,30 @@ LibSetTime (
> EpochSeconds = EfiTimeToEpoch (Time);
>
> // Adjust for the correct time zone, i.e. convert to UTC time zone
> - if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
> + if ((Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)
> + && (EpochSeconds > Time->TimeZone * SEC_PER_MIN)) {
> EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
> }
>
> // Adjust for the correct period
> - if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> + if (((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT)
> + && (EpochSeconds > SEC_PER_HOUR)) {
> // Convert to un-adjusted time, i.e. fall back one hour
> EpochSeconds -= SEC_PER_HOUR;
> }
>
> + // Use the performance counter to substract the number of seconds
> + // since platform reset. Without this, setting time from the shell
> + // and immediately reading it back would result in a forward time
> + // offset, of the duration during which the platform has been up.
> + Freq = GetPerformanceCounterProperties (NULL, NULL);
> + if (Freq != 0) {
> + Counter = GetPerformanceCounter ();
> + if (EpochSeconds > DivU64x64Remainder (Counter, Freq, &Remainder)) {
> + EpochSeconds -= DivU64x64Remainder (Counter, Freq, &Remainder);
> + }
> + }
> +
> // Save the current time zone information into non-volatile storage
> Status = EfiSetVariable (
> (CHAR16 *)mTimeZoneVariableName,
> --
> 2.17.0.windows.1
>
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