[U-Boot] [PATCH 2/5] ARM: arm926ejs: fix lowlevel_init call

[Måns Rullgård]

Chris Packham <judge.packham at gmail.com> writes:

> Hi Mans, Stefano,
>
> On Fri, Apr 27, 2018 at 9:00 PM Stefano Babic <sbabic at denx.de> wrote:
>
>> On 21/04/2018 17:11, Mans Rullgard wrote:
>> > The code attempts to preserve the value of LR by storing it in R12/IP
>> > across the lowevel_init() call.  However, this register is not saved
>> > by the callee.  Use a register that guaranteed to be preserved instead.
>> >
>> > Signed-off-by: Mans Rullgard <mans at mansr.com>
>> > ---
>> >  arch/arm/cpu/arm926ejs/start.S | 4 ++--
>> >  1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/arch/arm/cpu/arm926ejs/start.S
> b/arch/arm/cpu/arm926ejs/start.S
>> > index 959d1ed86d8a..a6f0bdb70345 100644
>> > --- a/arch/arm/cpu/arm926ejs/start.S
>> > +++ b/arch/arm/cpu/arm926ejs/start.S
>> > @@ -105,9 +105,9 @@ flush_dcache:
>> >       /*
>> >        * Go setup Memory and board specific bits prior to relocation.
>> >        */
>> > -     mov     ip, lr          /* perserve link reg across call */
>> > +     mov     r4, lr          /* perserve link reg across call */
>> >       bl      lowlevel_init   /* go setup pll,mux,memory */
>> > -     mov     lr, ip          /* restore link */
>> > +     mov     lr, r4          /* restore link */
>> >  #endif
>> >       mov     pc, lr          /* back to my caller */
>> >  #endif /* CONFIG_SKIP_LOWLEVEL_INIT */
>> >
>
>> Applied to u-boot-imx, thanks !
>
> I think this might be causing me a problem on a Marvell Kirkwood board I'm
> working on getting into upstream. It may also be problematic for orion5x
> boards. Both of these use r4 in lowlevel_init.

I've just sent an untested patch for orion5x.

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Måns Rullgård