On 12/12/17 02:32, Gao, Liming wrote: > Laszlo: > Have you any comments for this patch? Seemly, you discussed this topic in > bugzillar.
Thanks for the ping, I'll comment under the thread starter message. Thanks! Laszlo >> -----Original Message----- >> From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of >> Zenith432 >> Sent: Monday, December 11, 2017 10:58 PM >> To: Gao, Liming <liming....@intel.com>; edk2-devel@lists.01.org >> Cc: Kinney, Michael D <michael.d.kin...@intel.com> >> Subject: Re: [edk2] [PATCH] MdePkg: correct and clarify documentation of >> VA_LIST in Base.h >> >> Yes, that's right, in mixed ABI on GCC 7.2 (which is what GCC5 toolchain in >> tools_def.sample creates...), VA_COPY when >> used inside native (non-EFIAPI) function causes incorrect code generation >> that leads to crash (it mistreats the >> __builtin_ms_va_list as a __builtin_sysv_va_list). >> >> The same source code works in current versions of LLVM and Apple clang - so >> it's a compiler-specific bug. >> >> The text I wrote >> >> +// -- VA_END, VA_ARG, VA_COPY, va_end, va_arg, and va_copy may be used >> >> +// in functions of either calling conventions. >> >> is the hypothetical desired condition, but it depends on compilers >> generating proper code in mixed ABI. It obviously >> does not hold for current GCC. >> >> However, the part of the documentation to add EFIAPI to ExampleVarArg should >> definitely be fixed. Using >> __builtin_ms_va_list (=VA_LIST) in a sysv_abi (native) function probably >> yields a compile-time diagnostic, and if not - >> generates code that crashes for sure. >> >> On 11/12/2017 04:35 PM, Gao, Liming wrote: >>> Hi, >>> I see you and Laszlo are still in discussion on GCC behavior. Because >>> there is one bug in GCC compiler, the following functions in >> edk2 must be EFIAPI. Right? >>> >>> - functions that have a variable argument list and call VA_START / VA_END >>> - functions that call VA_COPY >>> >>> Thanks >>> Liming >>>> -----Original Message----- >>>> From: Zenith432 [mailto:zenith...@users.sourceforge.net] >>>> Sent: Sunday, December 10, 2017 11:43 PM >>>> To: Gao, Liming <liming....@intel.com>; edk2-devel@lists.01.org >>>> Cc: Kinney, Michael D <michael.d.kin...@intel.com> >>>> Subject: Re: [PATCH] MdePkg: correct and clarify documentation of VA_LIST >>>> in Base.h >>>> >>>> On 10/12/2017 03:53 PM, Gao, Liming wrote: >>>>> Could you add bug 457 link in the commit message? >>>> --- >>>> Subject: [PATCH] MdePkg: correct and clarify documentation of VA_LIST in >>>> Base.h >>>> >>>> This is to resolve bug 457. >>>> https://bugzilla.tianocore.org/show_bug.cgi?id=457 >>>> >>>> Contributed-under: TianoCore Contribution Agreement 1.1 >>>> Signed-off-by: Zenith432 <zenith432 at users.sourceforge.net> >>>> --- >>>> MdePkg/Include/Base.h | 24 ++++++++++++++++++++---- >>>> 1 file changed, 20 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h >>>> index 02140a5a..19f36872 100644 >>>> --- a/MdePkg/Include/Base.h >>>> +++ b/MdePkg/Include/Base.h >>>> @@ -560,13 +560,14 @@ struct _LIST_ENTRY { >>>> // VA_LIST - typedef for argument list. >>>> // VA_START (VA_LIST Marker, argument before the ...) - Init Marker >>>> for use. >>>> // VA_END (VA_LIST Marker) - Clear Marker >>>> -// VA_ARG (VA_LIST Marker, var arg size) - Use Marker to get an argument >>>> from >>>> -// the ... list. You must know the size and pass it in this macro. >>>> +// VA_ARG (VA_LIST Marker, var arg type) - Use Marker to get an argument >>>> from >>>> +// the ... list. You must know the type and pass it in this macro. >>>> // VA_COPY (VA_LIST Dest, VA_LIST Start) - Initialize Dest as a copy >>>> of Start. >>>> // >>>> -// example: >>>> +// Example: >>>> // >>>> // UINTN >>>> +// EFIAPI >>>> // ExampleVarArg ( >>>> // IN UINTN NumberOfArgs, >>>> // ... >>>> @@ -582,7 +583,7 @@ struct _LIST_ENTRY { >>>> // VA_START (Marker, NumberOfArgs); >>>> // for (Index = 0, Result = 0; Index < NumberOfArgs; Index++) { >>>> // // >>>> -// // The ... list is a series of UINTN values, so average them up. >>>> +// // The ... list is a series of UINTN values, so sum them up. >>>> // // >>>> // Result += VA_ARG (Marker, UINTN); >>>> // } >>>> @@ -591,6 +592,21 @@ struct _LIST_ENTRY { >>>> // return Result >>>> // } >>>> // >>>> +// Notes: >>>> +// >>>> +// This set of macros is intended to support variadic functions that >>>> +// use the EFIAPI calling convention. Variadic functions that use a >>>> +// native calling convention should use stdarg.h. >>>> +// In particular: >>>> +// -- VA_START may only be used in a variadic EFIAPI function. >>>> +// -- va_start may only be used in a variadic native function. >>>> +// -- VA_START, VA_END, VA_ARG and VA_COPY may only be used on a VA_LIST. >>>> +// -- va_start, va_end, va_arg and va_copy may only be used on a va_list. >>>> +// -- Both VA_LIST or va_list may be passed as arguments to functions >>>> +// of either EFIAPI or native calling conventions. >>>> +// -- VA_END, VA_ARG, VA_COPY, va_end, va_arg, and va_copy may be used >>>> +// in functions of either calling conventions. >>>> +// >>>> >>>> /** >>>> Return the size of argument that has been aligned to sizeof (UINTN). >>>> -- >>>> 2.14.3 >>> >> >> _______________________________________________ >> edk2-devel mailing list >> edk2-devel@lists.01.org >> https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
