On Wed, 19 Dec 2018 at 23:50, Ard Biesheuvel <ard.biesheu...@linaro.org> wrote: > > On Tue, 18 Dec 2018 at 00:20, Heinrich Schuchardt <xypron.g...@gmx.de> wrote: > > > > On 12/17/18 11:42 PM, Ard Biesheuvel wrote: > > > On Mon, 17 Dec 2018 at 23:33, Heinrich Schuchardt <xypron.g...@gmx.de> > > > wrote: > > >> > > >> On 12/17/18 7:16 PM, tip-bot for Heinrich Schuchardt wrote: > > >>> Commit-ID: 793423cf07e51e3185b8680167115813589c057d > > >>> Gitweb: > > >>> https://git.kernel.org/tip/793423cf07e51e3185b8680167115813589c057d > > >>> Author: Heinrich Schuchardt <xypron.g...@gmx.de> > > >>> AuthorDate: Mon, 17 Dec 2018 19:02:14 +0100 > > >>> Committer: Ingo Molnar <mi...@kernel.org> > > >>> CommitDate: Mon, 17 Dec 2018 19:12:48 +0100 > > >>> > > >>> efi: Align 'efi_guid_t' to 64 bits > > >>> > > >>> The UEFI Specification Version 2.7 Errata A defines: > > >>> > > >>> "EFI_GUID > > >>> 128-bit buffer containing a unique identifier value. > > >>> Unless otherwise specified, aligned on a 64-bit boundary." > > >>> > > >>> Before this patch efi_guid_t was only 8-bit aligned. > > >>> > > >>> Note that this could potentially trigger alignment faults during > > >>> EFI runtime services calls on 32-bit ARM, given that it does not > > >>> permit load/store double or load/store multiple instructions to > > >>> operate on memory addresses that are not 32-bit aligned. > > >>> > > >>> Signed-off-by: Heinrich Schuchardt <xypron.g...@gmx.de> > > >>> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> > > >>> Cc: <sta...@vger.kernel.org> # v4.9+, or earlier if possible > > >>> Cc: Andy Lutomirski <l...@kernel.org> > > >>> Cc: Borislav Petkov <b...@alien8.de> > > >>> Cc: Dave Hansen <dave.han...@linux.intel.com> > > >>> Cc: H. Peter Anvin <h...@zytor.com> > > >>> Cc: Linus Torvalds <torva...@linux-foundation.org> > > >>> Cc: Peter Zijlstra <pet...@infradead.org> > > >>> Cc: Qian Cai <c...@gmx.us> > > >>> Cc: Rik van Riel <r...@surriel.com> > > >>> Cc: Thomas Gleixner <t...@linutronix.de> > > >>> Cc: linux-...@vger.kernel.org > > >>> Link: > > >>> http://lkml.kernel.org/r/20181217180214.9436-3-ard.biesheu...@linaro.org > > >>> Signed-off-by: Ingo Molnar <mi...@kernel.org> > > >>> --- > > >>> include/linux/efi.h | 2 +- > > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > > >>> > > >>> diff --git a/include/linux/efi.h b/include/linux/efi.h > > >>> index 100ce4a4aff6..e6480c805932 100644 > > >>> --- a/include/linux/efi.h > > >>> +++ b/include/linux/efi.h > > >>> @@ -48,7 +48,7 @@ typedef u16 efi_char16_t; /* UNICODE > > >>> character */ > > >>> typedef u64 efi_physical_addr_t; > > >>> typedef void *efi_handle_t; > > >>> > > >>> -typedef guid_t efi_guid_t; > > >>> + > > >>> > > >>> #define EFI_GUID(a,b,c,d0,d1,d2,d3,d4,d5,d6,d7) \ > > >>> GUID_INIT(a, b, c, d0, d1, d2, d3, d4, d5, d6, d7) > > >>> > > >> > > >> Before rushing this patch in, we should carefully review its side > > >> effects, e.g. on 32bit system this changes the size of > > >> efi_config_table_32_t from 20 to 24, which is part of the interface to > > >> the UEFI firmware. > > >> > > > > > > grmbl. > > > > > > Thanks for spotting that. > > > > > > The UEFI spec defines a GUID struct as { UINT32; UINT16; UINT16; > > > UINT8[8]; } so its natural alignment is 32 bits not 64 bits. The > > > alignment issue on ARM would be solved by using __aligned(4) rather > > > than __aligned(8), while not affecting the size of the config table > > > struct (and potentially others) on 32-bit architectures. > > > > > > Ingo, apologies for the breakage. Do you prefer a replacement patch or > > > a followup patch? > > > > > > > The UEFI spec explicitly requires EFI_GUID to be 64-bit aligned. On the > > other hand neither EDK2 nor GRUB not U-Boot cared about this requirement > > up to now. So the array of efi_config_table_32_t had 20 byte long > > members at least on Linux, EDK2, GRUB, U-Boot, and possibly on other > > UEFI implementations though the UEFI spec does not mention packing here. > > > > As the 4.20 kernel release is imminent, please, keep this patch out > > before causing breakage. > > > > Ingo, > > Let's just drop Heinrich's patch for now, and I will come back to it > for the next release. There is very little EFI on 32-bit ARM in the > field, and this patch in its current form will break IA-32 as well, so > a quick followup fix is probably not the best approach here.
Ingo, Could you please let me know what your plans are with this patch? It has been pulled into -next now. Please either drop it or revert it.
