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

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

On Thu, Feb 20, 2025 at 7:32 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 19.02.2025 17:34, Frediano Ziglio wrote:
> > 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.
> >>>
> >>> 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.
> >
> > I would avoid adding a potential option that could affect performances
> > so badly at the moment.
> > These changes are pretty contained.
> > I would merge this patch and check any external dependencies as a follow up.
>
> Well. It's a judgement call to the maintainers. If I were them, I'd demand
> that Andrew's remark be addressed, one way or another.
>
> Jan

I think I did, but only Andres can confirm it.

Frediano