Laszlo: In edk2, I find the several functions with VA_LIST have no EFIAPI. They may use VA_ARG() or call other functions, but they don't use VA_COPY(). In Base.h, VA_ARG() is defined as __builtin_va_arg(), which is same to native one. VA_COPY() is defined as __builtin_ms_va_copy(). So, I also think this is MS ABI request. That means only if the function implementation uses VA_START(),VA_END() or VA_COPY(), it must be declared with EFIAPI.
MdePkg\Library\BasePrintLib\PrintLibInternal.c BasePrintLibSPrintMarker() ShellPkg\Library\UefiShellLib\UefiShellLib.c InternalShellPrintWorker() Thanks Liming >-----Original Message----- >From: edk2-devel [mailto:[email protected]] On Behalf Of >Laszlo Ersek >Sent: Wednesday, February 22, 2017 3:03 AM >To: Anthony PERARD <[email protected]> >Cc: Ard Biesheuvel <[email protected]>; Justen, Jordan L ><[email protected]>; [email protected]; Gao, Liming ><[email protected]> >Subject: Re: [edk2] [PATCH 0/4] Fix runtime issue in XenBusDxe when >compiled with GCC5 > >On 02/21/17 18:53, Anthony PERARD wrote: >> On Tue, Feb 21, 2017 at 06:07:15PM +0100, Laszlo Ersek wrote: >>> CC Rebecca & Konrad >>> >>> On 02/21/17 17:39, Anthony PERARD wrote: > >[snip] > >>>> So, should I add EFIAPI to XenStoreVSPrint, as it is using VA_COPY? >>>> >>> >>> Hm, please help me jog my memory... >>> >>> If I remember correctly, this is still a GCC bug, one that we suppressed for >gcc-6.2 with your patch as follows: >> >> Yes. >> >>>> commit 432f1d83f77acf92d52ef18d2cee6dbf7c5b9b86 >>>> Author: Anthony PERARD <[email protected]> >>>> Date: Tue Dec 6 12:03:25 2016 +0000 >>>> >>>> OvmfPkg/build.sh: Use GCC49 toolchains with GCC 6.[0-2] >>>> >>>> The goal of the patch is to avoid using -flto with GCC 6.0 to 6.2. >>>> >>>> This is to workaround a GCC bug: >>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70955 >>>> >>>> Contributed-under: TianoCore Contribution Agreement 1.0 >>>> Signed-off-by: Anthony PERARD <[email protected]> >>>> Reviewed-by: Laszlo Ersek <[email protected]> >>>> Regression-tested-by: Laszlo Ersek <[email protected]> >>>> >>>> diff --git a/OvmfPkg/build.sh b/OvmfPkg/build.sh >>>> index 95fe8fb07647..b6e936056ca0 100755 >>>> --- a/OvmfPkg/build.sh >>>> +++ b/OvmfPkg/build.sh >>>> @@ -102,7 +102,7 @@ case `uname` in >>>> 4.8.*) >>>> TARGET_TOOLS=GCC48 >>>> ;; >>>> - 4.9.*) >>>> + 4.9.*|6.[0-2].*) >>>> TARGET_TOOLS=GCC49 >>>> ;; >>>> *) >>> >>> Do I understand correctly that the gcc bug has not been fixed in >>> gcc-6.3, and -- because we don't suppress it for gcc-6.3 as the >>> above expression does not match -- it causes problems again? >> >> The bug describe in the GCC bugzilla is probably fix, but the >> test-case does not make use of __builtin_ms_va_copy. > >:/ > >> >>> You also mention gcc-5.4 as problematic. I think we haven't >>> received such reports about gcc-5 versions up to and including >>> gcc-5.3 (that's why GCC5 is the default selection in >>> "OvmfPkg/build.sh"). Do you mean that the gcc bug has now been >>> "backported" from the gcc-6 series to the gcc-5 series (starting >>> with gcc-5.4)? > >> >> I don't know the state of gcc-5.0 to gcc-5.3, I have never tested -flto >> with gcc-5.x (until now), I would say they are also problematic until >> proven otherwise. > >When we enabled GCC5, it definitely worked for at least one gcc release, >with -flto. (-flto is the default for DEBUG and RELEASE builds with >GCC5; NOOPT disables -Os and -flto.) > >> >>> If that's the case, then I suggest flipping "OvmfPkg/build.sh" from >>> black-listing gcc versions for -flto to white-listing. In other >>> words, assume that -flto is generally broken with GCC, except for a >>> few known versions: 5.0 through 5.3 inclusive. Those versions >>> should trigger the use of the GCC5 toolchain, and everything else >>> (5.4+, 6.*, 4.9.*) should use GCC49. >>> >>> I don't feel comfortable about adding EFIAPI to XenStoreVSPrint >>> just because it takes a VA_LIST parameter -- note: it is *not* a >>> varargs function itself! --; the same issue might hit elsewhere in >>> the edk2 tree at any time, outside of OvmfPkg too. >> >> From the different tests I've done, I feel more like VA_COPY might be >> the issue, but I don't know how __builtin_ms_va_* are supposed to be >> used. > >If I recall correctly, from the upstream GCC bug, the problem is that >__builtin_va_list does not track internally whether it was created in an >msabi or sysvabi function, and therefore the va_* functions cannot be >used transparently on it. Instead, when va_list is accessed, the >accessor builtins seem to apply the currently executing function's >calling convetion to va_list. (Even if the creation context of va_list >was different.) > >> >>> Would the gcc white-listing work for you? >>> >>> Note that the white-listing would practically undo Konrad's commit >>> 2667ad40919a ("OvmfPkg/build.sh: Make GCC5 the default toolchain, >>> catch GCC43 and earlier", 2016-11-23), but given the recent gcc >>> developments (gcc-6.3 has not fixed the gcc bug, and the bug has >>> even surfaced in gcc-5.4), I think it would be justified. >> >> Do be honnest, I don't think the toolchain GCC5 has ever been tested >> with gcc-5.x and the module XenBusDxe. I think most people that want to >> start OVMF under Xen are likely to build it with gcc-4.9 or already had >> gcc-6.x when OVMF switch to the GCC5 toolchain by default. >> > >Okay... I'm equally fine if we just say "given that GCC is broken like >this, we hereby require all functions that take a variable argument >list, *or* a VA_LIST parameter, to be EFIAPI". (The first part of the >requirement already exists.) > >But in this case, the full edk2 codebase has to be grepped for >VA_LIST-taking functions, and all of them must be flipped to EFIAPI, if >they currently aren't EFIAPI. Covering just XenStoreVSPrint() seems >incomplete. (Note: CryptoPkg/Library/OpensslLib is an exception.) > >Also, in this case, your commit 432f1d83f77a should likely be reverted. >(Because we are ultimately giving in to the gcc bug.) > >Thanks >Laszlo >_______________________________________________ >edk2-devel mailing list >[email protected] >https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
