On Wed, Feb 10, 2021 at 09:39:20PM +0100, Pierre Labastie wrote: > On Wed, 2021-02-10 at 16:32 +0000, Ken Moffat wrote: > > On Wed, Feb 10, 2021 at 10:44:31AM +0100, Pierre Labastie wrote: > > > On Tue, 2021-02-09 at 17:14 -0500, Jean-Marc Pigeon wrote:
> > > > > > Since you two are the only ones (among the persons on this list, up > > > to > > > now) who see this, I guess it has something to do with either: > > > - an option in the config, that you use and the others don't > > > - some CFLAGS settings, but I doubt it, because the kernel build > > > system > > > resets them > > > > > > > > > > > > > > > > > > > Feb 8 20:45:13 leshp klogd: [62379.838193] objtool[10870]: > > > > > > segfault at 70 ip 000000000040c13e sp 00007ffd0f655670 error > > > > > > 4 in > > > > > > objtool[402000+11000] > > > > > > followed by a dump of the code bytes. > > > > > > objtool is a kernel thing. According to > > > tools/objtool/Documentation/stack-validation.txt, > > > " > > > The kernel CONFIG_STACK_VALIDATION option enables a host tool named > > > objtool which runs at compile time. It has a "check" subcommand > > > which > > > analyzes every .o file and ensures the validity of its stack > > > metadata. > > > It enforces a set of rules on asm code and C inline assembly code > > > so > > > that stack traces can be reliable. > > > " > > > > > > Note that I do have that option set to y, but maybe other options > > > in > > > the "Compile-time checks and compiler options" may differ... > > > > > > rebuilding with "make V=1", I see that objtool is run after each > > > compilation. It might be interesting to compare the options that > > > are > > > passed to objtool in my case and in yours. Mine has: > > > ./tools/objtool/objtool check --retpoline --uaccess \ > > > arch/x86/kernel/apic/apic.o > > > > > > (same options for any object file, but I show the one that might be > > > faulty in your case). > > > > > > Maybe "gdb objtool" would allow to learn more (but may need to > > > recompile objtool with debug enabled, I'm not sure how to do that) > > > > > > Pierre > > > > > > > Hi all, > > > > I've gone back to my skylake and attempted a fresh build of 5.10.14. > > I used KBUILD_VERBOSE=1, for objtool I have: > > > > ./tools/objtool/objtool orc generate --no-fp --retpoline --uaccess \ > > arch/x86/kernel/apic/apic.o > > > > Note that the segfault seems to be happening *before* what you quote > > above (in generate, check presumably comes after that). > > > > The full command leading up to the error (not reformatted, > > everything between gcc and apic.c is one line): > > > > make -f ./scripts/Makefile.build obj=arch/x86/kernel/apic \ > > \ > > need-builtin=1 \ > > need-modorder=1 > > gcc -Wp,-MMD,arch/x86/kernel/apic/.apic.o.d -nostdinc -isystem > > /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include -I./arch/x86/include > > -I./arch/x86/include/generated -I./include > > -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi > > -I./include/uapi -I./include/generated/uapi -include > > ./include/linux/kconfig.h -include ./include/linux/compiler_types.h > > -D__KERNEL__ -fmacro-prefix-map=./= -Wall -Wundef > > -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing > > -fno-common -fshort-wchar -fno-PIE > > -Werror=implicit-function-declaration -Werror=implicit-int > > -Werror=return-type -Wno-format-security -std=gnu89 -mno-sse > > -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -falign-jumps=1 > > -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 > > -mpreferred-stack-boundary=3 -mskip-rax-setup -march=core2 > > -mno-red-zone -mcmodel=kernel -DCONFIG_X86_X32_ABI -Wno-sign-compare > > -fno-asynchronous-unwind-tables -mindirect-branch=thunk-extern > > -mindirect-branch-register -fno-jump-tables > > -fno-delete-null-pointer-checks -Wno-frame-address > > -Wno-format-truncation -Wno-format-overflow > > -Wno-address-of-packed-member -O2 -fno-allow-store-data-races > > -Wframe-larger-than=2048 -fstack-protector-strong > > -Wno-unused-but-set-variable -Wimplicit-fallthrough > > -Wno-unused-const-variable -pg -mrecord-mcount -mfentry > > -DCC_USING_FENTRY -Wdeclaration-after-statement -Wvla > > -Wno-pointer-sign -Wno-stringop-truncation -Wno-zero-length-bounds > > -Wno-array-bounds -Wno-stringop-overflow -Wno-restrict > > -Wno-maybe-uninitialized -fno-strict-overflow -fno-stack-check > > -fconserve-stack -Werror=date-time > > -Werror=incompatible-pointer-types -Werror=designated-init > > -fcf-protection=none -Wno-packed-not-aligned > > -fplugin=./scripts/gcc-plugins/latent_entropy_plugin.so > > -fplugin=./scripts/gcc-plugins/structleak_plugin.so > > -fplugin=./scripts/gcc-plugins/randomize_layout_plugin.so > > -DLATENT_ENTROPY_PLUGIN -fplugin-arg-structleak_plugin-byref-all > > -DSTRUCTLEAK_PLUGIN -DRANDSTRUCT_PLUGIN > > -fplugin-arg-randomize_layout_plugin-performance-mode > > -DKBUILD_MODFILE='"arch/x86/kernel/apic/apic"' > > -DKBUILD_BASENAME='"apic"' -DKBUILD_MODNAME='"apic"' -c -o > > arch/x86/kernel/apic/apic.o arch/x86/kernel/apic/apic.c > > ./tools/objtool/objtool orc generate --no-fp --retpoline > > --uaccess arch/x86/kernel/apic/apic.o > > make[3]: *** [scripts/Makefile.build:279: > > arch/x86/kernel/apic/apic.o] Segmentation fault > > make[3]: *** Deleting file 'arch/x86/kernel/apic/apic.o' > > make[2]: *** [scripts/Makefile.build:496: arch/x86/kernel/apic] > > Error 2 > > make[1]: *** [scripts/Makefile.build:496: arch/x86/kernel] Error 2 > > make: *** [Makefile:1805: arch/x86] Error 2 > > > > I'm attaching my gzipped config. > > > > The segfault is actually in objtool - > > > > Feb 10 16:10:09 leshp klogd: [ 176.318096] objtool[11443]: segfault > > at 70 ip 000000000040c07e sp 00007ffc68d330c0 error 4 in > > objtool[402000+11000] > > Feb 10 16:10:09 leshp klogd: [ 176.318106] Code: 89 68 10 49 89 6d > > 50 49 39 dc 74 b9 48 8b 43 48 8b 4b 50 48 83 c2 18 48 89 42 e8 48 63 > > 43 54 48 89 42 f8 48 8b 43 40 48 8b 1b <8b> 40 70 48 c1 e0 20 48 01 > > c8 48 89 42 f0 49 39 dc 75 cf 45 31 c0 > > Feb 10 16:12:54 leshp klogd: [ 340.875536] objtool[21151]: segfault > > at 70 ip 000000000040c07e sp 00007ffe2c1a00a0 error 4 in > > objtool[402000+11000] > > Feb 10 16:12:54 leshp klogd: [ 340.875545] Code: 89 68 10 49 89 6d > > 50 49 39 dc 74 b9 48 8b 43 48 8b 4b 50 48 83 c2 18 48 89 42 e8 48 63 > > 43 54 48 89 42 f8 48 8b 43 40 48 8b 1b <8b> 40 70 48 c1 e0 20 48 01 > > c8 48 89 42 f0 49 39 dc 75 cf 45 31 c0 > > > > Unfortunately, at this point I'm out of my depth and I don't have > > gdb installed yet. > > At least, I can see why there is a difference with me: The objtool > command is different: mine is: > objtool check --retpoline --uaccess <.o file> > yours is: > objtool orc generate --no-fp --retpoline --uaccess <.o file> > > Looks like I need to change the Frame pointer unwinder to the ORC > unwinder to have the same config as you. > The benefits of the ORC unwinder are mentioned at https://www.kernel.org/doc/html/latest/x86/orc-unwinder.html It has been around for quite some time, but I probably picked it up when it first appeared (test an -rc kernel, pick up new options which might be useful). I guess that old configs from before its introduction still default to the old unwinder. > No segfault with the orc unwinder, but now the objtool command is the > same as you. > > Not sure what to do now. Will have a look at your files. > > Pierre > Thanks. ĸen -- Any attempt to brew coffee with a teapot should result in the error code "418 I'm a teapot". The resulting entity body MAY be short and stout. -- rfc 2324 (1st April 1998) -- http://lists.linuxfromscratch.org/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page Do not top post on this list. A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? http://en.wikipedia.org/wiki/Posting_style
