On 30/09/2018 00:23, Laszlo Ersek wrote: > The CMPXCHG instruction has the following operands: > - AX (implicit, CompareValue): input and output > - destination operand (*Value): input and output > - source operand (ExchangeValue): input > > The IA32 version of InternalSyncCompareExchange16() correctly marks > CompareValue as input/output, but it marks (*Value) only as input. > > The X64 version of InternalSyncCompareExchange16() attempts to mark both > CompareValue and (*Value) as input/output, but it doesn't use the > appropriate constraints for either operand. > > Fix these issues. Furthermore, prefer the short "+" constraint for I/O > operands over the <output-operand-number> constraint that can be applied > to the input instances of I/O operands. > > Cc: Liming Gao <[email protected]> > Cc: Michael D Kinney <[email protected]> > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1208 > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Laszlo Ersek <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]> > --- > MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c | 9 ++++----- > MdePkg/Library/BaseSynchronizationLib/X64/GccInline.c | 10 ++++------ > 2 files changed, 8 insertions(+), 11 deletions(-) > > diff --git a/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c > b/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c > index 1976720ac636..bd98a5aebfe7 100644 > --- a/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c > +++ b/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c > @@ -115,11 +115,10 @@ InternalSyncCompareExchange16 ( > { > __asm__ __volatile__ ( > "lock \n\t" > - "cmpxchgw %1, %2 \n\t" > - : "=a" (CompareValue) // %0 > - : "q" (ExchangeValue), // %1 > - "m" (*Value), // %2 > - "0" (CompareValue) // %3 > + "cmpxchgw %2, %1 \n\t" > + : "+a" (CompareValue), // %0 > + "+m" (*Value) // %1 > + : "q" (ExchangeValue) // %2 > : "memory", > "cc" > ); > diff --git a/MdePkg/Library/BaseSynchronizationLib/X64/GccInline.c > b/MdePkg/Library/BaseSynchronizationLib/X64/GccInline.c > index 0212798d7a27..4338fb8e65e8 100644 > --- a/MdePkg/Library/BaseSynchronizationLib/X64/GccInline.c > +++ b/MdePkg/Library/BaseSynchronizationLib/X64/GccInline.c > @@ -115,12 +115,10 @@ InternalSyncCompareExchange16 ( > { > __asm__ __volatile__ ( > "lock \n\t" > - "cmpxchgw %3, %1 \n\t" > - : "=a" (CompareValue), // %0 > - "=m" (*Value) // %1 > - : "a" (CompareValue), // %2 > - "r" (ExchangeValue), // %3 > - "m" (*Value) // %4 > + "cmpxchgw %2, %1 \n\t" > + : "+a" (CompareValue), // %0 > + "+m" (*Value) // %1 > + : "r" (ExchangeValue) // %2 > : "memory", > "cc" > ); > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
