Nathan Chancellor <nat...@kernel.org> writes: > 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
Yep, thanks I'll use that. cheers
