Re: [pdx86-platform-drivers-x86:review-hans 40/59] drivers/platform/x86/amd/pmc/mp2_stb.c:94:2: error: call to undeclared function 'writeq'; ISO C99 and later do not support implicit function declarations

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Tue, Apr 16, 2024 at 11:17:15AM -0700, Nathan Chancellor wrote:
> On Tue, Apr 16, 2024 at 09:06:40PM +0300, Andy Shevchenko wrote:
> > On Tue, Apr 16, 2024 at 08:09:16AM -0700, Nathan Chancellor wrote:
> > > On Tue, Apr 16, 2024 at 04:06:23PM +0300, Andy Shevchenko wrote:
> > > > On Tue, Apr 16, 2024 at 10:35:55AM +0800, kernel test robot wrote:
> > > > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git review-hans
> > > > > head:   0aae4c44b032b5ede39405dfc62900adc467f362
> > > > > commit: 2dc77993cb5eb311d6bb5584d30c3d1d42d9fa4a [40/59] platform/x86/amd/pmc: Add AMD MP2 STB functionality
> > > > > config: i386-randconfig-011-20240416 (https://download.01.org/0day-ci/archive/20240416/202404161050.NSNJAxvX-lkp@intel.com/config)
> > > > > compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> > > > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240416/202404161050.NSNJAxvX-lkp@intel.com/reproduce)
> > > > > 
> > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > > > > the same patch/commit), kindly add following tags
> > > > > | Reported-by: kernel test robot <lkp@intel.com>
> > > > > | Closes: https://lore.kernel.org/oe-kbuild-all/202404161050.NSNJAxvX-lkp@intel.com/
> > > > > 
> > > > > All errors (new ones prefixed by >>):
> > > > > 
> > > > > >> drivers/platform/x86/amd/pmc/mp2_stb.c:94:2: error: call to undeclared function 'writeq'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> > > > >       94 |         writeq(mp2->dma_addr, mp2->mmio + AMD_C2P_MSG1);
> > > > >          |         ^
> > > > >    drivers/platform/x86/amd/pmc/mp2_stb.c:267:45: warning: shift count >= width of type [-Wshift-count-overflow]
> > > > >      267 |         rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
> > > > >          |                                                    ^~~~~~~~~~~~~~~~
> > > > >    include/linux/dma-mapping.h:77:54: note: expanded from macro 'DMA_BIT_MASK'
> > > > >       77 | #define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
> > > > >          |                                                      ^ ~~~
> > > > >    1 warning and 1 error generated.
> > > > 
> > > > This is bogus, but can perhaps be 'fixed" with GENMASK((n) - 1, 0).
> > > 
> > > The second warning only appears because of the first error; if the first
> > > error is fixed, I suspect the second one won't appear (although I have
> > > not actually checked it).
> > 
> > Is it confirmed? Because to me it looks not obvious at all ==> complier can be
> > amended as well in warning reporting
> 
> Yes, I see no error or warning with the following diff on top of
> 2dc77993cb5eb311d6bb5584d30c3d1d42d9fa4a. I am not saying that is not an
> issue that should be addressed, I am just explaining why the warning is
> showing up at all.

Yes and this is confusing.

> It happens with -Warray-bounds occasionally as well.

There is a ternary that definitely makes it never happen. How does compiler
miss that?

-- 
With Best Regards,
Andy Shevchenko