Hi Jan,
On Fri, 9 Jun 2023 at 09:40, Jan Kiszka <jan.kiszka@xxxxxxxxxxx> wrote:
>
> On 09.06.23 08:34, Ilias Apalodimas wrote:
> > Hi Jan,
> >
> > [...]
> >
> >>> --- a/drivers/firmware/efi/vars.c
> >>> +++ b/drivers/firmware/efi/vars.c
> >>> @@ -123,7 +123,7 @@ EXPORT_SYMBOL_GPL(efivars_unregister);
> >>>
> >>> bool efivar_supports_writes(void)
> >>> {
> >>> - return __efivars && __efivars->ops->set_variable;
> >>> + return __efivars && __efivars->ops->set_variable != set_variable_int;
> >>> }
> >>> EXPORT_SYMBOL_GPL(efivar_supports_writes);
> >>>
> >>> diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
> >>> index e028fafa04f3..e40b5c4c5106 100644
> >>> --- a/fs/efivarfs/super.c
> >>> +++ b/fs/efivarfs/super.c
> >>> @@ -242,9 +242,6 @@ static int efivarfs_fill_super(struct super_block
> >>> *sb, struct fs_context *fc)
> >>> sb->s_d_op = &efivarfs_d_ops;
> >>> sb->s_time_gran = 1;
> >>>
> >>> - if (!efivar_supports_writes())
> >>> - sb->s_flags |= SB_RDONLY;
> >>> -
> >>> inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
> >>> if (!inode)
> >>> return -ENOMEM;
> >>> diff --git a/include/linux/efi.h b/include/linux/efi.h
> >>> index 58d1c271d3b0..ec0ac6ef50a3 100644
> >>> --- a/include/linux/efi.h
> >>> +++ b/include/linux/efi.h
> >>> @@ -1084,6 +1084,10 @@ int efivars_register(struct efivars *efivars,
> >>> const struct efivar_operations *ops);
> >>> int efivars_unregister(struct efivars *efivars);
> >>>
> >>> +efi_status_t set_variable_int(efi_char16_t *name, efi_guid_t *vendor,
> >>> + u32 attributes, unsigned long data_size,
> >>> + void *data);
> >>> +
> >>> void efivars_generic_ops_register(void);
> >>> void efivars_generic_ops_unregister(void);
> >>>
> >>> Thanks
> >>> /Ilias
> >>
> >> As just written in my other reply: The root cause is the dependency on
> >> tee-supplicant daemon. That needs to be resolved, and then also r/w
> >> mounting will just work.
> >
> > That's partially true. If we solve the dependency your problem will
> > go away only if everything gets compiled as built in. But if you have
> > them as modules there's still a chance you mount the efivarfs before
> > installing all the modules. In that case, you'll end up with the same
> > problem no?
>
> Obviously, this will need proper probing of the TA services in the
> proper order so that the STMM driver is pulled in before efivarfs gets used.
>
> >
> > That's why I think this patch (or a variation of it) is useful. It
> > solves the kernel panic you are seeing if you remount the efivarfs as
> > RW and It unifies the way the kernel responds to userspace no matter
> > what the firmware does with its setvariableRT service.
>
> I'm not against fixes crashes, but the r/w issue is a different thing IMHO.
Fair enough, but if we want to fix the crash only I think there's a
better way to do it.
I'll cook some patches and send them over
Thanks
/Ilias
>
> Jan
>
> --
> Siemens AG, Technology
> Competence Center Embedded Linux
>
