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SubjectRe: [PATCH] x86/entry: add compatibility with IAS
On Tue, Jul 14, 2020 at 11:34 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Tue, Jul 14, 2020 at 12:40 AM Jian Cai <caij2003@gmail.com> wrote:
> >
> > Clang's integrated assembler does not allow symbols with non-absolute
> > values to be reassigned. This patch allows the affected code to be
> > compatible with IAS.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1043
> > Reported-by: Nick Desaulniers <ndesaulniers@google.com>
> > Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
> > Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
> > Suggested-by: Brian Gerst <brgerst@gmail.com>
> > Suggested-by: Arvind Sankar <nivedita@alum.mit.edu>
> > Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
> > Signed-off-by: Jian Cai <caij2003@gmail.com>
>
> Hi Jian,
>
> thanks for the update!
>
> I am glad to see that some Linux/x86 assembler "monsters" jumped on the train.
>
> So, your patch with reviewer's comment got several iterations?
> Not sure if you are aware of the process of submitting patches (see [1])?
>
> It is common to add a ChangeLog below commit-message-body and diffstat
> means add below "--".
> Something like:
> --
> Changes v1 -> v2:
> - I did some cool stuff to improve this
>
> While at it... Please add your version-of-patch to the subject-line:
> You can do this via "git format-patch --signoff --subject-prefix="PATCH v2".
> There might be other cool git tricks I do not know.
>
> Hope I was no "Uberlehrer".
>
> - Sedat -
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst
>
> > ---
> > arch/x86/include/asm/idtentry.h | 14 ++++++--------
> > 1 file changed, 6 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
> > index f3d70830bf2a..5efaaed34eda 100644
> > --- a/arch/x86/include/asm/idtentry.h
> > +++ b/arch/x86/include/asm/idtentry.h
> > @@ -469,16 +469,15 @@ __visible noinstr void func(struct pt_regs *regs, \
> > .align 8
> > SYM_CODE_START(irq_entries_start)
> > vector=FIRST_EXTERNAL_VECTOR
> > - pos = .
> > .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
> > UNWIND_HINT_IRET_REGS
> > +0 :
> > .byte 0x6a, vector
> > jmp asm_common_interrupt
> > nop
> > /* Ensure that the above is 8 bytes max */
> > - . = pos + 8
> > - pos=pos+8
> > - vector=vector+1
> > + . = 0b + 8
> > + vector = vector+1
> > .endr
> > SYM_CODE_END(irq_entries_start)
> >
> > @@ -486,16 +485,15 @@ SYM_CODE_END(irq_entries_start)
> > .align 8
> > SYM_CODE_START(spurious_entries_start)
> > vector=FIRST_SYSTEM_VECTOR
> > - pos = .
> > .rept (NR_VECTORS - FIRST_SYSTEM_VECTOR)
> > UNWIND_HINT_IRET_REGS
> > +0 :
> > .byte 0x6a, vector
> > jmp asm_spurious_interrupt
> > nop
> > /* Ensure that the above is 8 bytes max */
> > - . = pos + 8
> > - pos=pos+8
> > - vector=vector+1
> > + . = 0b + 8
> > + vector = vector+1
> > .endr
> > SYM_CODE_END(spurious_entries_start)
> > #endif
> > --
> > 2.27.0.383.g050319c2ae-goog
> >

Stolen the patch from [1].

Tested-by: Sedat Dilek <sedat.dilek@gmail.com> #
Compile-/Assemble-tested against Linux v5.8-rc5 with LLVM/Clang
v11.0.0-git

- Sedat -

[1] https://lore.kernel.org/patchwork/patch/1272115/

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