Re: [RFC PATCH 2/2] x86/kexec: Add data section to relocate_kernel

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Nov 12, 2024 at 08:44:33AM +0000, David Woodhouse wrote:
> On Fri, 2024-11-08 at 12:26 +0100, H. Peter Anvin wrote:
> > 
> > > --- a/arch/x86/kernel/vmlinux.lds.S
> > > +++ b/arch/x86/kernel/vmlinux.lds.S
> > > @@ -100,7 +100,7 @@ const_pcpu_hot = pcpu_hot;
> > >         . = ALIGN(PAGE_SIZE);                                   \
> > >         __relocate_kernel_start = .;                            \
> > >         *(.text.relocate_kernel);                               \
> > > -       *(.rodata.relocate_kernel);                             \
> > > +       *(.data.relocate_kernel);                               \

Why are we having data in the middle of the text section?

> > >         __relocate_kernel_end = .;
> > > #else
> > > #define KEXEC_RELOCATE_KERNEL_TEXT
> > 
> > Looks good at first glance. I'm currently traveling so I haven't
> > fully reviewed it though.
> 
> Turns out it doesn't help much. It's neater, obviously, but objtool
> still wants to disassemble the .data.relocate_kernel section after it
> gets included in the overall kernel text section.

Objtool only decodes stuff that has SHF_EXECINSTR set. Why would your
data sections have that on?