On 14 August 2017 at 17:19, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> * Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> [170811 12:37]:
>> 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. The change is so simple that it is difficult
>> to reduce it in parts, but if you still have the time to spare, mind
>> trying the diff below?
>>
>>
>> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
>> index 6e9df3663a57..c0361e608210 100644
>> --- a/arch/arm/kernel/head.S
>> +++ b/arch/arm/kernel/head.S
>> @@ -524,17 +524,15 @@ ARM_BE8(rev r0, r0) @
>> byteswap if big endian
>>
>> __fixup_smp_on_up:
>> adr r0, 1f
>> - ldmia r0, {r3 - r5}
>> - sub r3, r0, r3
>> - add r4, r4, r3
>> - add r5, r5, r3
>> + ldmia r0, {r4 - r5}
>> + add r4, r4, r0
>> + add r5, r5, r0
>> b __do_fixup_smp_on_up
>> ENDPROC(__fixup_smp)
>>
>> .align
>> -1: .word .
>> - .word __smpalt_begin
>> - .word __smpalt_end
>> +1: .word __smpalt_begin - 1b
>> + .word __smpalt_end - 1b
>>
>> .pushsection .data
>> .globl smp_on_up
>>
>> The main point of these changes is to eliminate absolute references,
>> not to use the new macros, so if this does work, I will go with this
>> instead.
>
> For reference, I manually did this changes as it did not apply
> after reverting your earlier version of this patch. No luck with
> this change, so I'll test again when you you have updated patches
> available.
>
Thanks Tony,
But Nico already found the issue: I was looking at the code with
another patch on top, which removed the reference to r3 in the
followup code.
In the KASLR series I just posted, I reordered that patch with this
one, so everything should be good.
