On Tue, Sep 15, 2020 at 10:02 AM Josh Poimboeuf <jpoim...@redhat.com> wrote: > > On Tue, Sep 15, 2020 at 06:05:54PM +0200, Borislav Petkov wrote: > > On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote: > > > On Tue, Sep 15, 2020 at 03:55:19PM +0200, Borislav Petkov wrote: > > > > On Tue, Sep 15, 2020 at 09:42:56PM +0800, kernel test robot wrote: > > > > > tree/branch: > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git > > > > > x86/seves > > > > > branch HEAD: e6eb15c9ba3165698488ae5c34920eea20eaa38e KVM: nSVM: > > > > > Avoid freeing uninitialized pointers in svm_set_nested_state() > > > > > > > > > > Warning in current branch: > > > > > > > > > > arch/x86/kernel/sev-es.o: warning: objtool: > > > > > ist_exc_vmm_communication()+0x12: unreachable instruction > > > > > > > > > > Warning ids grouped by kconfigs: > > > > > > > > > > clang_recent_errors > > > > > `-- x86_64-randconfig-r001-20200913 > > > > > `-- > > > > > arch-x86-kernel-sev-es.o:warning:objtool:ist_exc_vmm_communication():unreachable-instruction > > > > Ok, I can't trigger this with gcc-9, gcc-10 and clang-10. > > > > .config below says clang-12 so it could be some experimental > > bug^Wfeature :) > > > > peterz says this has been fixed by: > > > > 318af7b80b6a ("Revert "kbuild: use -flive-patching when CONFIG_LIVEPATCH is > > enabled"") > > > > but that was reportedly for gcc. > > > > Lemme Cc the people of interest and leave the rest in here for > > reference. Note that CONFIG_LIVEPATCH is enabled in that .config. > > If somebody can share the .o file, I can take a look.
Taking a look at the latest report of unreachable instruction from objtool from 0day bot: https://groups.google.com/g/clang-built-linux/c/IbF96FeMT8g $ cd /tmp $ git clone --depth=1 https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git --branch x86/seves $ cd tip $ gunzip <attached config.gz> $ cp config .config $ make LLVM=1 -j71 2> log.txt $ grep warning: log.txt | cut -d ' ' -f 2- | sort | uniq -c 3737 warning: objtool: asan.module_ctor()+0xc: call without frame pointer save/setup 3737 warning: objtool: asan.module_dtor()+0xc: call without frame pointer save/setup 1 warning: objtool: early_alloc()+0x6b: unreachable instruction 1 warning: objtool: ist_exc_vmm_communication()+0x12: unreachable instruction 1 warning: objtool: kmem_cache_create_usercopy()+0x286: unreachable instruction 1 warning: objtool: oops_end()+0xc1: unreachable instruction 1 warning: objtool: __register_nosave_region()+0x87: unreachable instruction $ ag ist_exc_vmm_communication arch/x86/kernel/sev-es.c 1351: ist_exc_vmm_communication(regs, error_code); $ gzip -9 arch/x86/kernel/sev-es.o <attached> If I remove CONFIG_KASAN=y, I actually get way more unreachable instruction failures! Let me play with tools/testing/ktest/config-bisect.pl and see if I can narrow down the set of configs from the randconfig. Also, it's possible that there's more than one bug here. -- Thanks, ~Nick Desaulniers
config.gz
Description: application/gzip
sev-es.o.gz
Description: application/gzip
