Le 07/12/2021 à 07:41, Nathan Chancellor a écrit : > On Tue, Dec 07, 2021 at 05:45:08AM +0000, Christophe Leroy wrote: >> >> >> Le 07/12/2021 à 05:48, Nathan Chancellor a écrit : >>> On Tue, Dec 07, 2021 at 02:37:26PM +1100, Michael Ellerman wrote: >>>> Bill Wendling <mo...@google.com> writes: >>>>> On Tue, Nov 30, 2021 at 10:38 AM Bill Wendling <mo...@google.com> wrote: >>>>>> On Tue, Nov 30, 2021 at 10:17 AM Nathan Chancellor <nat...@kernel.org> >>>>>> wrote: >>>>>>> On Tue, Nov 30, 2021 at 10:25:43PM +1100, Michael Ellerman wrote: >>>>>>>> Christophe Leroy <christophe.le...@csgroup.eu> writes: >>>>>>>>> Le 29/11/2021 à 23:55, kernel test robot a écrit : >>>> ... >>>>>>>>>> All warnings (new ones prefixed by >>): >>>>>>>>>> >>>>>>>>>> In file included from arch/powerpc/kernel/asm-offsets.c:71: >>>>>>>>>> In file included from >>>>>>>>>> arch/powerpc/kernel/../xmon/xmon_bpts.h:7: >>>>>>>>>>>> arch/powerpc/include/asm/inst.h:165:20: warning: variable 'val' is >>>>>>>>>>>> uninitialized when used here [-Wuninitialized] >>>>>>>>>> *inst = ppc_inst(val); >>>>>>>>>> ^~~ >>>>>>>>>> arch/powerpc/include/asm/inst.h:53:22: note: expanded from >>>>>>>>>> macro 'ppc_inst' >>>>>>>>>> #define ppc_inst(x) (x) >>>>>>>>>> ^ >>>>>>>>>> arch/powerpc/include/asm/inst.h:155:18: note: initialize the >>>>>>>>>> variable 'val' to silence this warning >>>>>>>>>> unsigned int val, suffix; >>>>>>>>>> ^ >>>>>>>>>> = 0 >>>>>>>>> >>>>>>>>> I can't understand what's wrong here. >>>> ... >>>>>>>>> >>>>>>>>> I see no possibility, no alternative path where val wouldn't be set. >>>>>>>>> The >>>>>>>>> asm clearly has *addr as an output param so it is always set. >>>>>>>> >>>>>>>> I guess clang can't convince itself of that? >>>> ... >>>>>>> >>>>>>> It certainly looks like there is something wrong with how clang is >>>>>>> tracking the initialization of the variable because it looks to me like >>>>>>> val is only used in the fallthrough path, which happens after it is >>>>>>> initialized via lwz. Perhaps something is wrong with the logic of >>>>>>> https://reviews.llvm.org/D71314? I've added Bill to CC (LLVM issues are >>>>>>> being migrated from Bugzilla to GitHub Issues right now so I cannot file >>>>>>> this upstream at the moment). >>>>>>> >>>>>> If I remove the casts of "val" the warning doesn't appear. I suspect >>>>>> that when I wrote that patch I forgot to remove those when checking. >>>>>> #include "Captain_Picard_facepalm.h" >>>>>> >>>>>> I'll look into it. >>>>>> >>>>> Small retraction. It's the "*(<cast>)&val" that's the issue. (I.e. the >>>>> "*&") >>>> >>>> I guess for now I'll just squash this in as a workaround? >>>> >>>> >>>> diff --git a/arch/powerpc/include/asm/inst.h >>>> b/arch/powerpc/include/asm/inst.h >>>> index 631436f3f5c3..5b591c51fec9 100644 >>>> --- a/arch/powerpc/include/asm/inst.h >>>> +++ b/arch/powerpc/include/asm/inst.h >>>> @@ -157,6 +157,9 @@ static inline int >>>> copy_inst_from_kernel_nofault(ppc_inst_t *inst, u32 *src) >>>> if (unlikely(!is_kernel_addr((unsigned long)src))) >>>> return -ERANGE; >>> >>> Could we add a version check to this and a link to our bug tracker: >>> >>> /* https://github.com/ClangBuiltLinux/linux/issues/1521 */ >>> #if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 140000 >> >> The robot reported the problem on: >> >> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project >> df08b2fe8b35cb63dfb3b49738a3494b9b4e6f8e) >> >> Should it be CONFIG_CLANG_VERSION <= 140000 ? > > The robot tests clang from tip of tree, rebuilding every week or so. The > fix is getting ready to land so it will be released in 14.0.0 final. We > have always written tip of tree version checks with the expectation that > if people are testing tip of tree clang, they are frequently rebuilding. > If that is not true, they need to be using released/stable versions, > otherwise the model is broken. > > If that is too problematic, we could add a version check to Kconfig > (cannot think of a great name for the config off the top of my head) > that checks for this issue and ifdef on that. That might be nice in > case another instance of this crops up in the future. >
It's fine for me. I didn't know robot was using prereleases with the same name as the future release. Christophe
