Messages in this thread | | | From | Alexander Lobakin <> | Subject | Re: [: [norov:fns 9/23] include/asm-generic/percpu.h:21:44: warning: array subscript 4 is above array bounds of 'long unsigned int[4]'] | Date | Mon, 4 Jul 2022 14:38:18 +0200 |
| |
From: Yury Norov <yury.norov@gmail.com> Date: Fri, 1 Jul 2022 19:33:24 -0700
> Hi Alexander,
Hi!
> > I'm working on top of your recent cons bitmap series, and again > received a bug report from LKP regarding one of you patches. Can > you please look at this report? > > I tried reproduce it myself, but the build is failed for me: > arch/arc/kernel/entry.S: Assembler messages: > arch/arc/kernel/entry.S:280: Error: operand out of range (260 is not between -256 and 255) > make[2]: *** [scripts/Makefile.build:322: arch/arc/kernel/entry-compact.o] Error 1 > make[2]: *** Waiting for unfinished jobs.... > > If you think it's mis-attributed, we should let LKP people know that > something is wrong on their side. > > Thanks, > Yury > > ----- Forwarded message from kernel test robot <lkp@intel.com> ----- > > Date: Sat, 2 Jul 2022 08:42:59 +0800 > From: kernel test robot <lkp@intel.com> > To: Yury Norov <yury.norov@gmail.com> > Cc: kbuild-all@lists.01.org > Subject: [norov:fns 9/23] include/asm-generic/percpu.h:21:44: warning: array subscript 4 is above array bounds of > 'long unsigned int[4]' > > tree: https://github.com/norov/linux fns > head: 1df9509fd92a58cb37e9a419235823bbb13367de > commit: 3e7e5baaaba78075a7f3a57432609e363bf2a486 [9/23] bitmap: don't assume compiler evaluates small mem*() builtins calls > config: arc-randconfig-r035-20220629 (https://download.01.org/0day-ci/archive/20220702/202207020812.oTFxIVue-lkp@intel.com/config) > compiler: arc-elf-gcc (GCC) 11.3.0 > 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 > # https://github.com/norov/linux/commit/3e7e5baaaba78075a7f3a57432609e363bf2a486 > git remote add norov https://github.com/norov/linux > git fetch --no-tags norov fns > git checkout 3e7e5baaaba78075a7f3a57432609e363bf2a486 > # save the config file > mkdir build_dir && cp config build_dir/.config > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash kernel/ > > If you fix the issue, kindly add following tag where applicable > Reported-by: kernel test robot <lkp@intel.com> > > All warnings (new ones prefixed by >>): > > In file included from include/linux/compiler_types.h:93, > from <command-line>: > kernel/sched/topology.c: In function 'build_sched_domains': > >> include/asm-generic/percpu.h:21:44: warning: array subscript 4 is above array bounds of 'long unsigned int[4]' [-Warray-bounds] > 21 | #define per_cpu_offset(x) (__per_cpu_offset[x]) > include/linux/compiler-gcc.h:35:33: note: in definition of macro 'RELOC_HIDE' > 35 | (typeof(ptr)) (__ptr + (off)); \ > | ^~~ > include/linux/percpu-defs.h:236:9: note: in expansion of macro 'SHIFT_PERCPU_PTR' > 236 | SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); \ > | ^~~~~~~~~~~~~~~~ > include/linux/percpu-defs.h:236:33: note: in expansion of macro 'per_cpu_offset' > 236 | SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); \ > | ^~~~~~~~~~~~~~ > kernel/sched/topology.c:969:20: note: in expansion of macro 'per_cpu_ptr' > 969 | sg->sgc = *per_cpu_ptr(sdd->sgc, cpu); > | ^~~~~~~~~~~ > In file included from ./arch/arc/include/generated/asm/percpu.h:1, > from include/linux/irqflags.h:17, > from include/linux/rcupdate.h:26, > from include/linux/rculist.h:11, > from include/linux/sched/signal.h:5, > from include/linux/sched/cputime.h:5, > from kernel/sched/build_utility.c:13: > include/asm-generic/percpu.h:19:22: note: while referencing '__per_cpu_offset' > 19 | extern unsigned long __per_cpu_offset[NR_CPUS]; > | ^~~~~~~~~~~~~~~~
Ah, I've seen that one and tried to reproduce it hardly, but didn't manage to do that. Then I took a look at the code mentioned here, but again couldn't find any code pieces which would go past the array (with CPU ID higher than 3 on a 4-CPU kernel). I've heard that `-Warray-bounds` is still somewhat noisy and produces a fair amount of false-positives, so that it's been even disabled for 5.19-rc1 after being enabled during the merge window.
I'm super fine with letting lkp guys know that it's an unrelated stuff, whom should I write to? BTW, I didn't receive any reports from the linux-next bots and haven't found a single over the LKML, so looks like it should be okay in general :)
> > > vim +21 include/asm-generic/percpu.h > > ^1da177e4c3f415 Linus Torvalds 2005-04-16 20 > a875a69f8b00a38 Ingo Molnar 2006-07-03 @21 #define per_cpu_offset(x) (__per_cpu_offset[x]) > acdac87202a4081 travis@sgi.com 2008-01-30 22 #endif > acdac87202a4081 travis@sgi.com 2008-01-30 23 > > :::::: The code at line 21 was first introduced by commit > :::::: a875a69f8b00a38b4f40d9632a4fc71a159f0e0d [PATCH] lockdep: add per_cpu_offset() > > :::::: TO: Ingo Molnar <mingo@elte.hu> > :::::: CC: Linus Torvalds <torvalds@g5.osdl.org> > > -- > 0-DAY CI Kernel Test Service > https://01.org/lkp > > ----- End forwarded message -----
Thanks, Olek
| |