Re: [PATCH v6] Avoid crash calling PrintErrMesg from efi_multiboot2

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

On Mon, Feb 17, 2025 at 4:56 PM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 17.02.2025 17:52, Frediano Ziglio wrote:
> > On Mon, Feb 17, 2025 at 4:41 PM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 
> > wrote:
> >>
> >> On 17/02/2025 4:31 pm, Jan Beulich wrote:
> >>> On 17.02.2025 17:26, Frediano Ziglio wrote:
> >>>> --- a/xen/common/efi/efi-common.mk
> >>>> +++ b/xen/common/efi/efi-common.mk
> >>>> @@ -2,6 +2,7 @@ EFIOBJ-y := boot.init.o pe.init.o ebmalloc.o runtime.o
> >>>>  EFIOBJ-$(CONFIG_COMPAT) += compat.o
> >>>>
> >>>>  CFLAGS-y += -fshort-wchar
> >>>> +CFLAGS-y += -fno-jump-tables
> >>>>  CFLAGS-y += -iquote $(srctree)/common/efi
> >>>>  CFLAGS-y += -iquote $(srcdir)
> >>> Do source files other than boot.c really need this? Do any other files 
> >>> outside
> >>> of efi/ maybe also need this (iirc this point was made along with the v5 
> >>> comment
> >>> you got)?
> >>
> >> Every TU reachable from efi_multiboot2() needs this, because all of
> >> those have logic executed at an incorrect virtual address.
> >>
> >> ~Andrew
> >
> > I assume all the files in efi directory will deal with EFI boot so
> > it's good to have the option enabled for the files inside the
> > directory. The only exception seems runtime.c file.
>
> And compat.c, being a wrapper around runtime.c.
>
> > About external dependencies not sure how to detect them (beside
> > looking at all symbols).
>
> Which raises the question whether we don't need to turn on that option
> globally, without (as we have it now) any condition.
>
> Jan

Are you saying enabling that option for all Xen? That potentially
would decrease performances, we have a lot of switches in the code.

Frediano