Messages in this thread | | | Subject | Re: [kbuild-all] Re: arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to 'msr' is never read [clang-analyzer-deadcode.DeadStores] | From | "Chen, Rong A" <> | Date | Tue, 24 Aug 2021 14:59:24 +0800 |
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On 8/23/2021 10:35 PM, Christophe Leroy wrote: > > > Le 23/08/2021 à 12:59, kernel test robot a écrit : >> tree: >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >> head: e22ce8eb631bdc47a4a4ea7ecf4e4ba499db4f93 >> commit: ef75e73182949a94bde169a774de1b62ae21fbbc powerpc/signal32: >> Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version >> date: 9 months ago >> config: powerpc-randconfig-c003-20210821 (attached as .config) >> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project >> d9c5613e856cf2addfbf892fc4c1ce9ef9feceaa) >> reproduce (this is a W=1 build): >> wget >> https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross >> -O ~/bin/make.cross >> chmod +x ~/bin/make.cross >> # install powerpc cross compiling tool for clang build >> # apt-get install binutils-powerpc-linux-gnu >> # >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ef75e73182949a94bde169a774de1b62ae21fbbc >> >> git remote add linus >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >> git fetch --no-tags linus master >> git checkout ef75e73182949a94bde169a774de1b62ae21fbbc >> # save the attached .config to linux build tree >> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross >> ARCH=powerpc clang-analyzer >> >> If you fix the issue, kindly add following tag as appropriate >> Reported-by: kernel test robot <lkp@intel.com> >> >> >> clang-analyzer warnings: (new ones prefixed by >>) >> ^ >>>> arch/powerpc/kernel/signal_32.c:297:2: warning: Value stored to >>>> 'msr' is never read [clang-analyzer-deadcode.DeadStores] >> msr &= ~MSR_VSX; >> ^ ~~~~~~~~ >> arch/powerpc/kernel/signal_32.c:297:2: note: Value stored to 'msr' >> is never read >> msr &= ~MSR_VSX; >> ^ ~~~~~~~~ > > > This is wrong. > > msr is used at line 326: > > ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy > 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], failed);
Hi Christophe,
The usage is under CONFIG_VSX, the test config (powerpc-randconfig-c003-20210821) didn't enable it which triggered this warning.
Best Regards, Rong Chen
> > > > > >> arch/powerpc/kernel/signal_32.c:765:16: warning: Value stored to >> 'msr' during its initialization is never read >> [clang-analyzer-deadcode.DeadStores] >> unsigned long msr = regs->msr; >> ^~~ ~~~~~~~~~ >> arch/powerpc/kernel/signal_32.c:765:16: note: Value stored to >> 'msr' during its initialization is never read >> unsigned long msr = regs->msr; >> ^~~ ~~~~~~~~~ >> arch/powerpc/kernel/signal_32.c:869:16: warning: Value stored to >> 'msr' during its initialization is never read >> [clang-analyzer-deadcode.DeadStores] >> unsigned long msr = regs->msr; >> ^~~ ~~~~~~~~~ >> arch/powerpc/kernel/signal_32.c:869:16: note: Value stored to >> 'msr' during its initialization is never read >> unsigned long msr = regs->msr; >> ^~~ ~~~~~~~~~ >> >> vim +/msr +297 arch/powerpc/kernel/signal_32.c >> >> 968c4fccd1bb8b arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 262 >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 263 static int save_user_regs_unsafe(struct pt_regs >> *regs, struct mcontext __user *frame, >> 8d33001dd650b8 arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 264 struct mcontext __user *tm_frame, >> int ctx_has_vsx_region) >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 265 { >> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 266 unsigned long msr = regs->msr; >> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 267 >> c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 268 /* save general registers */ >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 269 unsafe_save_general_regs(regs, frame, failed); >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 270 >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 271 #ifdef CONFIG_ALTIVEC >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 272 /* save altivec registers */ >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 273 if (current->thread.used_vr) { >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 274 unsafe_copy_to_user(&frame->mc_vregs, >> ¤t->thread.vr_state, >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 275 ELF_NVRREG * sizeof(vector128), >> failed); >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 276 /* set MSR_VEC in the saved MSR value to >> indicate that >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 277 frame->mc_vregs contains valid data */ >> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 278 msr |= MSR_VEC; >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 279 } >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 280 /* else assert((regs->msr & MSR_VEC) == 0) */ >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 281 >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 282 /* We always copy to/from vrsave, it's 0 if we >> don't have or don't >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 283 * use altivec. Since VSCR only contains 32 bits >> saved in the least >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 284 * significant bits of a vector, we "cheat" and >> stuff VRSAVE in the >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 285 * most significant bits of that same vector. --BenH >> 408a7e08b2112f arch/powerpc/kernel/signal_32.c Paul Mackerras >> 2013-08-05 286 * Note that the current VRSAVE value is in the >> SPR at this point. >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 287 */ >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 288 unsafe_put_user(current->thread.vrsave, (u32 >> __user *)&frame->mc_vregs[32], >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 289 failed); >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 290 #endif /* CONFIG_ALTIVEC */ >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 291 unsafe_copy_fpr_to_user(&frame->mc_fregs, >> current, failed); >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 292 >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 293 /* >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 294 * Clear the MSR VSX bit to indicate there is no >> valid state attached >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 295 * to this context, except in the specific case >> below where we set it. >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 296 */ >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 @297 msr &= ~MSR_VSX; >> 6a274c08f2f4df arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-07-02 298 #ifdef CONFIG_VSX >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 299 /* >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 300 * Copy VSR 0-31 upper half from thread_struct to >> local >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 301 * buffer, then write that to userspace. Also >> set MSR_VSX in >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 302 * the saved MSR value to indicate that >> frame->mc_vregs >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 303 * contains valid data >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 304 */ >> 16c29d180becc5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-10-23 305 if (current->thread.used_vsr && >> ctx_has_vsx_region) { >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 306 unsafe_copy_vsx_to_user(&frame->mc_vsregs, >> current, failed); >> ce48b2100785e5 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 307 msr |= MSR_VSX; >> ec67ad82814bee arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-11-25 308 } >> c6e6771b87d4e3 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 309 #endif /* CONFIG_VSX */ >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 310 #ifdef CONFIG_SPE >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 311 /* save spe registers */ >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 312 if (current->thread.used_spe) { >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 313 unsafe_copy_to_user(&frame->mc_vregs, >> current->thread.evr, >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 314 ELF_NEVRREG * sizeof(u32), failed); >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 315 /* set MSR_SPE in the saved MSR value to >> indicate that >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 316 frame->mc_vregs contains valid data */ >> 9e7511861c4f8d arch/powerpc/kernel/signal_32.c Michael Neuling >> 2008-06-25 317 msr |= MSR_SPE; >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 318 } >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 319 /* else assert((regs->msr & MSR_SPE) == 0) */ >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 320 >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 321 /* We always copy to/from spefscr */ >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 322 unsafe_put_user(current->thread.spefscr, >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 323 (u32 __user *)&frame->mc_vregs + >> ELF_NEVRREG, failed); >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 324 #endif /* CONFIG_SPE */ >> 81e7009ea46c95 arch/powerpc/kernel/signal_32.c Stephen Rothwell >> 2005-10-18 325 >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 326 unsafe_put_user(msr, &frame->mc_gregs[PT_MSR], >> failed); >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 327 >> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-06-09 328 /* We need to write 0 the MSR top 32 bits in the >> tm frame so that we >> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-06-09 329 * can check it on the restore to see if TM is >> active >> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-06-09 330 */ >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 331 if (tm_frame) >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 332 unsafe_put_user(0, >> &tm_frame->mc_gregs[PT_MSR], failed); >> 1d25f11fdbcc53 arch/powerpc/kernel/signal_32.c Michael Neuling >> 2013-06-09 333 >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 334 return 0; >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 335 >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 336 failed: >> ef75e73182949a arch/powerpc/kernel/signal_32.c Christophe Leroy >> 2020-08-18 337 return 1; >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 338 } >> ^1da177e4c3f41 arch/ppc64/kernel/signal32.c Linus Torvalds >> 2005-04-16 339 >> >> :::::: The code at line 297 was first introduced by commit >> :::::: ec67ad82814bee92251fd963bf01c7a173856555 powerpc/signals: >> Improved mark VSX not saved with small contexts fix >> >> :::::: TO: Michael Neuling <mikey@neuling.org> >> :::::: CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> >> >> --- >> 0-DAY CI Kernel Test Service, Intel Corporation >> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org >> > _______________________________________________ > kbuild-all mailing list -- kbuild-all@lists.01.org > To unsubscribe send an email to kbuild-all-leave@lists.01.org
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