On Fri, 11 Aug 2017, Ard Biesheuvel wrote:
> On 11 August 2017 at 20:58, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:
> > On Fri, 11 Aug 2017, Ard Biesheuvel wrote:
> >
> >> On 11 August 2017 at 16:13, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> >> > * Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> [170805 13:54]:
> >> >> Replace the open coded PC relative offset calculations with a pair
> >> >> of adr_l invocations.
> >> >>
> >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> >> >> ---
> >> >> arch/arm/kernel/head.S | 12 ++----------
> >> >> 1 file changed, 2 insertions(+), 10 deletions(-)
> >> >>
> >> >> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> >> >> index 6e9df3663a57..aed341e0f530 100644
> >> >> --- a/arch/arm/kernel/head.S
> >> >> +++ b/arch/arm/kernel/head.S
> >> >> @@ -523,19 +523,11 @@ ARM_BE8(rev r0, r0) @ byteswap if big endian
> >> >> retne lr
> >> >>
> >> >> __fixup_smp_on_up:
> >> >> - adr r0, 1f
> >> >> - ldmia r0, {r3 - r5}
> >> >> - sub r3, r0, r3
> >> >> - add r4, r4, r3
> >> >> - add r5, r5, r3
> >> >> + adr_l r4, __smpalt_begin
> >> >> + adr_l r5, __smpalt_end
> >> >> b __do_fixup_smp_on_up
> >> >> ENDPROC(__fixup_smp)
> >> >>
> >> >> - .align
> >> >> -1: .word .
> >> >> - .word __smpalt_begin
> >> >> - .word __smpalt_end
> >> >> -
> >> >> .pushsection .data
> >> >> .globl smp_on_up
> >> >> smp_on_up:
> >> >
> >> > Ard, it's this one that cause boot to fail on omap3.
> >> > The rest of your set works for me with just this one
> >> > left out.
> >> >
> >>
> >> I'm completely puzzled.
> >
> > Found it.
> >
> > You replaced:
> >
> > - adr r0, 1f
> > - ldmia r0, {r3 - r5}
> > - sub r3, r0, r3
> > - add r4, r4, r3
> > - add r5, r5, r3
> > + adr_l r4, __smpalt_begin
> > + adr_l r5, __smpalt_end
> > b __do_fixup_smp_on_up
> >
> > Notice that r3 is now uninitialized.
> >
> > Now have a look at the code for __do_fixup_smp_on_up.
> >
>
> I still don't see it :-)
>
> __do_fixup_smp_on_up() mentions r3 in the comment block, but it does
> not actually refer to it in the code, does it?
__do_fixup_smp_on_up:
cmp r4, r5
reths lr
ldmia r4!, {r0, r6}
ARM( str r6, [r0, r3] ) <<============
THUMB( add r0, r0, r3 ) <<============
[...]
Nicolas
