Hi Marvin, First of all - many thanks for tracking down the bug that creates the need for this.
On Mon, Apr 17, 2023 at 18:09:15 +0000, Marvin Häuser wrote: > With the current ASM_FUNC() macro, there is no good way to declare an > alignment constraint for a function. As ASM_FUNC() switches sections, > declaring the constraint before the macro invocation applies it to the > current location in the previous section. Declaring the constraint after > the macro invocation lets the function label point to the location prior > to alignment. Depending on toolchain behaviour, this may cause the label > to point to alignment padding preceding the actual function definition. > > To address these issues, introduce the ASM_FUNC_ALIGN() macro, which > declares the alignment constraint right before the function label. > > Signed-off-by: Marvin Häuser <mhaeu...@posteo.de> > Cc: Leif Lindholm <quic_llind...@quicinc.com> > Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org> > Cc: Sami Mujawar <sami.muja...@arm.com> > Cc: Vitaly Cheptsov <vit9...@protonmail.com> > --- > ArmPkg/Include/AsmMacroIoLibV8.h | 22 ++++++++++++++++++---- > 1 file changed, 18 insertions(+), 4 deletions(-) > > diff --git a/ArmPkg/Include/AsmMacroIoLibV8.h > b/ArmPkg/Include/AsmMacroIoLibV8.h > index 135aaeca5d0b..919edc70384d 100644 > --- a/ArmPkg/Include/AsmMacroIoLibV8.h > +++ b/ArmPkg/Include/AsmMacroIoLibV8.h > @@ -34,15 +34,29 @@ > cbnz SAFE_XREG, 1f ;\ > b . ;// We should never get here > > -#define _ASM_FUNC(Name, Section) \ > - .global Name ; \ > - .section #Section, "ax" ; \ > - .type Name, %function ; \ > +#define _ASM_FUNC_HDR(Name, Section) \ > + .global Name ; \ > + .section #Section, "ax" ; \ > + .type Name, %function > + > +#define _ASM_FUNC_FTR(Name) \ > Name: ; \ > AARCH64_BTI(c) > > +#define _ASM_FUNC(Name, Section) \ > + _ASM_FUNC_HDR(Name, Section) ; \ > + _ASM_FUNC_FTR(Name) > + > +#define _ASM_FUNC_ALIGN(Name, Section, Align) \ I like this solution, but I'd like to hear Ard's opinion. I probably want to bikeshed some of the implementation details: Although I generally dislike duplicate definitions, I think I would prefer having _ASM_FUNC and _ASM_FUNC_ALIGN defined self-contained, without _HDR and _FTR. If we do keep the reused primitives, we need better language; the footer of the header is not a footer of the function. / Leif > + _ASM_FUNC_HDR(Name, Section) ; \ > + .balign Align ; \ > + _ASM_FUNC_FTR(Name) > + > #define ASM_FUNC(Name) _ASM_FUNC(ASM_PFX(Name), .text. ## Name) > > +#define ASM_FUNC_ALIGN(Name, Align) \ > + _ASM_FUNC_ALIGN(ASM_PFX(Name), .text. ## Name, Align) > + > #define MOV32(Reg, Val) \ > movz Reg, (Val) >> 16, lsl #16 ; \ > movk Reg, (Val) & 0xffff > -- > 2.40.0 > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#103119): https://edk2.groups.io/g/devel/message/103119 Mute This Topic: https://groups.io/mt/98325898/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/9847357/21656/1706620634/xyzzy [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-