Thanks - I agree, the fallthrough was totally non-obvious and inconsistent with other cases. The whole '1f' syntax is pretty odd as well - I had to dig deep to find out what the locally defined numbered forward-only labels were.
Reviewed-by: Eugene Cohen <[email protected]> > -----Original Message----- > From: Ard Biesheuvel [mailto:[email protected]] > Sent: Thursday, March 17, 2016 7:20 AM > To: [email protected]; [email protected]; Cohen, Eugene > <[email protected]> > Cc: Ard Biesheuvel <[email protected]> > Subject: [PATCH 1/7] ArmPkg/AsmMacroIoLibV8: remove undocumented > assumption from ELx macros > > The macros EL1_OR_EL2() and EL1_OR_EL2_OR_EL3() allow conditional > execution of assembly sequences based on the current exception level, by > jumping to caller supplied labels 1f, 2f or 3f. However, the jump to 1f is > actually a fallthrough, which means the EL1 code needs to follow right after > the macro invocation, and the 1f label is ignored. > > So let's fix this by making all jumps explicit. > > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Ard Biesheuvel <[email protected]> > --- > ArmPkg/Include/AsmMacroIoLibV8.h | 15 +++++++-------- > 1 file changed, 7 insertions(+), 8 deletions(-) > > diff --git a/ArmPkg/Include/AsmMacroIoLibV8.h > b/ArmPkg/Include/AsmMacroIoLibV8.h > index a9f8491bc922..efc47d3bbbc7 100644 > --- a/ArmPkg/Include/AsmMacroIoLibV8.h > +++ b/ArmPkg/Include/AsmMacroIoLibV8.h > @@ -25,9 +25,9 @@ > mrs SAFE_XREG, CurrentEL ;\ > cmp SAFE_XREG, #0x8 ;\ > b.eq 2f ;\ > - cmp SAFE_XREG, #0x4 ;\ > - b.ne . ;// We should never get here > -// EL1 code starts here > + tbnz SAFE_XREG, #2, 1f ;\ > + b . ;// We should never get here > + > > // CurrentEL : 0xC = EL3; 8 = EL2; 4 = EL1 // This only selects between EL1 > and > EL2 and EL3, else we die. > @@ -36,11 +36,10 @@ > mrs SAFE_XREG, CurrentEL ;\ > cmp SAFE_XREG, #0xC ;\ > b.eq 3f ;\ > - cmp SAFE_XREG, #0x8 ;\ > - b.eq 2f ;\ > - cmp SAFE_XREG, #0x4 ;\ > - b.ne . ;// We should never get here > -// EL1 code starts here > + tbnz SAFE_XREG, #3, 2f ;\ > + tbnz SAFE_XREG, #2, 1f ;\ > + b . ;// We should never get here > + > #if defined(__clang__) > > // load x0 with _Data > -- > 2.5.0 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
