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SubjectRe: [patch V6 19/37] x86/irq: Convey vector as argument and not in ptregs
On Fri, May 22, 2020 at 02:48:53PM -0400, Boris Ostrovsky wrote:
> > Yes. They just make objtool very unhappy:
> >
> > arch/x86/entry/entry_64.o: warning: objtool: .entry.text+0xfd0: special:
> > can't find orig instruction
> >
> > Peter suggested to use:
> >
> > .pos = .
> > .byte..
> > jmp
> > .nops (pos + 8) - .
>
>
> Unfortunately this (.nops directive) only works for newer assemblers
> (2.31, per
> https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob_plain;f=gas/NEWS;h=9a3f352108e439754688e19e63a6235b38801182;hb=5eb617a71463fa6810cd14f57adfe7a1efc93a96)
>
>
> I have 2.27 and things don't go well.

A single nop should be fine, since gas will complain if it tries to move
the IP backwards. (Also I'd vote for normal indentation instead of the
"assembler magic at 4 spaces" thing.)

.align 8
SYM_CODE_START(irq_entries_start)
vector = FIRST_EXTERNAL_VECTOR
.rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
pos = .
UNWIND_HINT_IRET_REGS
.byte 0x6a, vector
jmp asm_common_interrupt
nop
. = pos + 8
vector = vector + 1
.endr
SYM_CODE_END(irq_entries_start)

--
Josh

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