Thanks Laszlo for the detailed description. I will communicate will ECC owner to see whether ECC tool can be enhanced for these issues firstly. Thank you all.
Regards, Dandan -----Original Message----- From: Laszlo Ersek [mailto:ler...@redhat.com] Sent: Friday, April 13, 2018 1:51 AM To: Kinney, Michael D <michael.d.kin...@intel.com>; Bi, Dandan <dandan...@intel.com>; edk2-devel@lists.01.org Cc: Dong, Eric <eric.d...@intel.com> Subject: Re: [edk2] [patch] UefiCpuPkg/PiSmmCpuDxeSmm: Add "extern" keyword for "gPatchxxx" On 04/12/18 18:47, Kinney, Michael D wrote: > Laszlo, > > I think I would rather see the ECC tool fixed. I didn't dare suggest that, but I agree it's a superior solution. When I tried ECC last time, I was surprised how powerful it was, so if it recognized even this case, that would certainly fit its quality :) Thanks! Laszlo > > Mike > >> -----Original Message----- >> From: edk2-devel [mailto:edk2-devel- >> boun...@lists.01.org] On Behalf Of Laszlo Ersek >> Sent: Thursday, April 12, 2018 2:34 AM >> To: Bi, Dandan <dandan...@intel.com>; edk2- de...@lists.01.org >> Cc: Dong, Eric <eric.d...@intel.com> >> Subject: Re: [edk2] [patch] UefiCpuPkg/PiSmmCpuDxeSmm: >> Add "extern" keyword for "gPatchxxx" >> >> Hello Dandan, >> >> On 04/12/18 10:50, Dandan Bi wrote: >>> Background description: >>> In SmmProfileInternal.h, ECC check tool report an >> issue at line 103. >>> Detailed ECC Error info:Variable definition appears >> in header file. >>> Include files should contain only public or only >> private data and >>> cannot contain code or define data variables >>> >>> ECC report similar issues in PiSmmCpuDxeSmm.h. >>> >>> Then we review all the new introduced "gPatchxxx", >> since they have >>> been defined in the nasm file, we can add "extern" >> keyword for them >>> in the C source or header files. >>> >>> Cc: Eric Dong <eric.d...@intel.com> >>> Cc: Laszlo Ersek <ler...@redhat.com> >>> Contributed-under: TianoCore Contribution Agreement >> 1.1 >>> Signed-off-by: Dandan Bi <dandan...@intel.com> >>> --- >>> UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 8 >> ++++---- >>> UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfileInternal.h | 2 >> +- >>> UefiCpuPkg/PiSmmCpuDxeSmm/SmramSaveState.c | 6 >> +++--- >>> UefiCpuPkg/PiSmmCpuDxeSmm/X64/Semaphore.c | 4 >> ++-- >>> 4 files changed, 10 insertions(+), 10 deletions(-) >> >> This is a bug (a false positive) in the ECC tool. The following >> declaration: >> >>> X86_ASSEMBLY_PATCH_LABEL gPatchSmmCr0; >> >> does not declare an *object* (a variable). Instead, it declares a >> *function* (and not a pointer to a function!), because (from >> "MdePkg/Include/Library/BaseLib.h"): >> >>> /// >>> /// Type definition for representing labels in NASM >> source code that allow for >>> /// the patching of immediate operands of IA32 and >> X64 instructions. >>> /// >>> /// While the type is technically defined as a >> function type (note: not a >>> /// pointer-to-function type), such labels in NASM >> source code never stand for >>> /// actual functions, and identifiers declared with >> this function type should >>> /// never be called. This is also why the EFIAPI >> calling convention specifier >>> /// is missing from the typedef, and why the typedef >> does not follow the usual >>> /// edk2 coding style for function (or pointer-to- >> function) typedefs. The VOID >>> /// return type and the VOID argument list are merely >> artifacts. >>> /// >>> typedef VOID (X86_ASSEMBLY_PATCH_LABEL) (VOID); >> >> That is, when you see >> >>> X86_ASSEMBLY_PATCH_LABEL gPatchSmmCr0; >> >> That is identical to the following function >> declaration: >> >>> VOID gPatchSmmCr0 (VOID); >> >> Now, the ISO C99 standard says: >> >>> 6.2.2 Linkages of identifiers >>> >>> [...] >>> >>> 5 If the declaration of an identifier for a >> function has no >>> storage-class specifier, its linkage is >> determined exactly as if >>> it were declared with the storage-class specifier >> /extern/. [...] >> >> Thus, the report from ECC is a false positive. >> >> I don't mind the patch (the changes don't make any difference at the >> C-language level, see the spec above); however, the commit message >> should be 100% clear that the patch works around a limitation with >> the ECC tool. >> >> Can you please submit v2 with an updated commit message? >> >> Thanks! >> Laszlo >> _______________________________________________ >> 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
