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List:       kernel-hardening
Subject:    Re: [PATCH 11/22] pci: lto: fix PREL32 relocations
From:       Sami Tolvanen <samitolvanen () google ! com>
Date:       2020-06-24 23:21:37
Message-ID: 20200624232137.GA243469 () google ! com
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On Wed, Jun 24, 2020 at 04:03:48PM -0700, Nick Desaulniers wrote:
> On Wed, Jun 24, 2020 at 3:50 PM kernel test robot <lkp@intel.com> wrote:
> > 
> > Hi Sami,
> > 
> > Thank you for the patch! Perhaps something to improve:
> > 
> > [auto build test WARNING on 26e122e97a3d0390ebec389347f64f3730fdf48f]
> > 
> > url:    https://github.com/0day-ci/linux/commits/Sami-Tolvanen/add-support-for-Clang-LTO/20200625-043816
> >                 
> > base:    26e122e97a3d0390ebec389347f64f3730fdf48f
> > config: i386-alldefconfig (attached as .config)
> > compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
> > reproduce (this is a W=1 build):
> > # save the attached .config to linux build tree
> > make W=1 ARCH=i386
> 
> Note: W=1 ^
> 
> > 
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@intel.com>
> > 
> > All warnings (new ones prefixed by >>):
> > 
> > In file included from arch/x86/kernel/pci-dma.c:9:
> > > > include/linux/compiler-gcc.h:72:45: warning: no previous prototype for \
> > > > '__UNIQUE_ID_via_no_dac190' [-Wmissing-prototypes]
> > 72 | #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), \
> > __COUNTER__) |                                             ^~~~~~~~~~~~
> > include/linux/pci.h:1914:7: note: in definition of macro \
> > '___DECLARE_PCI_FIXUP_SECTION' 1914 |  void stub(struct pci_dev *dev) { \
> > hook(dev); }   \ |       ^~~~
> 
> Should `stub` be qualified as `static inline`? https://godbolt.org/z/cPBXxW
> Or should stub be declared in this header, but implemented in a .c
> file?  (I'm guessing the former, since the `hook` callback comes from
> the macro).

Does static inline guarantee that the compiler won't rename the symbol?
The purpose of this change is to have a stable symbol name, which we can
safely use in inline assembly.

Sami


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