Re: [PATCH v2 2/6] xen/riscv: introduce reset_stack() function

[Oleksii <oleksii.kurochko@xxxxxxxxx>]

On Fri, 2023-07-07 at 11:33 +0200, Jan Beulich wrote:
> On 07.07.2023 11:08, Oleksii wrote:
> > On Thu, 2023-07-06 at 13:17 +0200, Jan Beulich wrote:
> > > On 19.06.2023 15:34, Oleksii Kurochko wrote:
> > > > --- a/xen/arch/riscv/riscv64/head.S
> > > > +++ b/xen/arch/riscv/riscv64/head.S
> > > > @@ -27,8 +27,16 @@ ENTRY(start)
> > > >          add     t3, t3, __SIZEOF_POINTER__
> > > >          bltu    t3, t4, .L_clear_bss
> > > >  
> > > > +        jal     reset_stack
> > > > +
> > > > +        tail    start_xen
> > > > +
> > > > +        .section .text, "ax", %progbits
> > > > +
> > > > +ENTRY(reset_stack)
> > > >          la      sp, cpu0_boot_stack
> > > >          li      t0, STACK_SIZE
> > > >          add     sp, sp, t0
> > > >  
> > > > -        tail    start_xen
> > > > +        ret
> > > > +
> > > 
> > > Looking at patch 4 you will want to add a comment here to
> > > emphasize
> > > that a0 and a1 have to remain unclobbered.
> > Thanks for a note. I'll add it in the new patch version
> 
> Having seen how things end up by the end of the series, there's an
> alternative: You could save a0 and a1 ahead of the 1st call to
> reset_stack, rather than immediately afterwards.
It makes sense. So lets stick to saving of a0 and a1 before 1st call of
reset_stack().

~ Oleksii