From: Sami Tolvanen <samitolvanen@google.com> To: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com>, Jann Horn <jannh@google.com>, "the arch/x86 maintainers" <x86@kernel.org>, Masahiro Yamada <masahiroy@kernel.org>, Steven Rostedt <rostedt@goodmis.org>, Will Deacon <will@kernel.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Paul E. McKenney" <paulmck@kernel.org>, Kees Cook <keescook@chromium.org>, Nick Desaulniers <ndesaulniers@google.com>, clang-built-linux <clang-built-linux@googlegroups.com>, Kernel Hardening <kernel-hardening@lists.openwall.com>, linux-arch <linux-arch@vger.kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, linux-kbuild <linux-kbuild@vger.kernel.org>, kernel list <linux-kernel@vger.kernel.org>, linux-pci@vger.kernel.org Subject: Re: [PATCH v6 22/25] x86/asm: annotate indirect jumps Date: Wed, 21 Oct 2020 17:22:59 -0700 [thread overview] Message-ID: <CABCJKufL6=FiaeD8T0P+mK4JeR9J80hhjvJ6Z9S-m9UnCESxVA@mail.gmail.com> (raw) In-Reply-To: <20201021085606.GZ2628@hirez.programming.kicks-ass.net> On Wed, Oct 21, 2020 at 1:56 AM Peter Zijlstra <peterz@infradead.org> wrote: > > On Tue, Oct 20, 2020 at 12:24:37PM -0700, Sami Tolvanen wrote: > > > > Building allyesconfig with this series and LTO enabled, I still see > > > > the following objtool warnings for vmlinux.o, grouped by source file: > > > > > > > > arch/x86/entry/entry_64.S: > > > > __switch_to_asm()+0x0: undefined stack state > > > > .entry.text+0xffd: sibling call from callable instruction with > > > > modified stack frame > > > > .entry.text+0x48: stack state mismatch: cfa1=7-8 cfa2=-1+0 > > > > > > Not sure what this one's about, there's no OBJECT_FILES_NON_STANDARD? > > > > Correct, because with LTO, we won't have an ELF binary to process > > until we compile everything into vmlinux.o, and at that point we can > > no longer skip individual object files. > > I think what Josh was trying to say is; this file is subject to objtool > on a normal build and does not generate warnings. So why would it > generate warnings when subject to objtool as result of a vmlinux run > (due to LTO or otherwise). > > In fact, when I build a x86_64-defconfig and then run: > > $ objtool check -barf defconfig-build/vmlinux.o Note that I'm passing also --vmlinux and --duplicate to objtool when processing vmlinux.o, and this series has a patch to split noinstr validation from --vmlinux, so that's skipped. > I do not see these in particular, although I do see a lot of: > > "sibling call from callable instruction with modified stack frame" > "falls through to next function" > > that did not show up in the individual objtool runs during the build. I'm able to reproduce these warnings with gcc 9.3 + allyesconfig, with KASAN and GCOV_KERNEL disabled, as they are not enabled in LTO builds either. This is without the LTO series applied, so we also have the retpoline warnings: $ ./tools/objtool/objtool check -arfld vmlinux.o 2>&1 | grep -vE '(sibling|instr)' vmlinux.o: warning: objtool: wakeup_long64()+0x61: indirect jump found in RETPOLINE build vmlinux.o: warning: objtool: .text+0x826308a: indirect jump found in RETPOLINE build vmlinux.o: warning: objtool: .text+0x82630c5: indirect jump found in RETPOLINE build vmlinux.o: warning: objtool: .head.text+0x748: indirect jump found in RETPOLINE build vmlinux.o: warning: objtool: set_bringup_idt_handler.constprop.0()+0x0: undefined stack state vmlinux.o: warning: objtool: .entry.text+0x1634: redundant CLD vmlinux.o: warning: objtool: camellia_cbc_dec_32way()+0xb3: stack state mismatch: cfa1=7+520 cfa2=7+8 vmlinux.o: warning: objtool: camellia_ctr_32way()+0x1a: stack state mismatch: cfa1=7+520 cfa2=7+8 vmlinux.o: warning: objtool: aesni_gcm_init_avx_gen2()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_enc_update_avx_gen2()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_dec_update_avx_gen2()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_finalize_avx_gen2()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_init_avx_gen4()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_enc_update_avx_gen4()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_dec_update_avx_gen4()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: aesni_gcm_finalize_avx_gen4()+0x12: unsupported stack pointer realignment vmlinux.o: warning: objtool: sha1_transform_avx2()+0xc: unsupported stack pointer realignment vmlinux.o: warning: objtool: sha1_ni_transform()+0x7: unsupported stack pointer realignment vmlinux.o: warning: objtool: sha256_transform_rorx()+0x13: unsupported stack pointer realignment vmlinux.o: warning: objtool: sha512_transform_ssse3()+0x14: unsupported stack pointer realignment vmlinux.o: warning: objtool: sha512_transform_avx()+0x14: unsupported stack pointer realignment vmlinux.o: warning: objtool: sha512_transform_rorx()+0x7: unsupported stack pointer realignment vmlinux.o: warning: objtool: __x86_retpoline_rdi()+0x10: return with modified stack frame vmlinux.o: warning: objtool: __x86_retpoline_rdi()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8 vmlinux.o: warning: objtool: __x86_retpoline_rdi()+0x0: stack state mismatch: cfa1=7+32 cfa2=-1+0 vmlinux.o: warning: objtool: reset_early_page_tables()+0x0: stack state mismatch: cfa1=7+8 cfa2=-1+0 vmlinux.o: warning: objtool: .entry.text+0x48: stack state mismatch: cfa1=7-8 cfa2=-1+0 vmlinux.o: warning: objtool: .entry.text+0x15fd: stack state mismatch: cfa1=7-8 cfa2=-1+0 vmlinux.o: warning: objtool: .entry.text+0x168c: stack state mismatch: cfa1=7-8 cfa2=-1+0 There are a couple of differences, like the first "undefined stack state" warning pointing to set_bringup_idt_handler.constprop.0() instead of __switch_to_asm(). I tried running this with --backtrace, but objtool segfaults at the first .entry.text warning: $ ./tools/objtool/objtool check -barfld vmlinux.o ... vmlinux.o: warning: objtool: set_bringup_idt_handler.constprop.0()+0x0: undefined stack state vmlinux.o: warning: objtool: xen_hypercall_set_trap_table()+0x0: <=== (sym) ... vmlinux.o: warning: objtool: .entry.text+0xffd: sibling call from callable instruction with modified stack frame vmlinux.o: warning: objtool: .entry.text+0xfcb: (branch) Segmentation fault Going back to the allyesconfig+LTO vmlinux.o, the "undefined stack state" warning looks quite similar: $ ./tools/objtool/objtool check -barlfd vmlinux.o vmlinux.o: warning: objtool: __switch_to_asm()+0x0: undefined stack state vmlinux.o: warning: objtool: xen_hypercall_set_trap_table()+0x0: <=== (sym) vmlinux.o: warning: objtool: .entry.text+0xffd: sibling call from callable instruction with modified stack frame vmlinux.o: warning: objtool: .entry.text+0xfcb: (branch) Segmentation fault Sami
next prev parent reply other threads:[~2020-10-22 0:23 UTC|newest] Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-13 0:31 [PATCH v6 00/25] Add support for Clang LTO Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 01/25] kbuild: preprocess module linker script Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 02/25] objtool: Add a pass for generating __mcount_loc Sami Tolvanen 2020-10-14 16:50 ` Ingo Molnar 2020-10-14 18:21 ` Peter Zijlstra 2020-10-15 20:10 ` Josh Poimboeuf 2020-10-13 0:31 ` [PATCH v6 03/25] objtool: Don't autodetect vmlinux.o Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 04/25] tracing: move function tracer options to Kconfig Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 05/25] tracing: add support for objtool mcount Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 06/25] x86, build: use " Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 07/25] treewide: remove DISABLE_LTO Sami Tolvanen 2020-10-14 22:43 ` Kees Cook 2020-10-17 1:46 ` Masahiro Yamada 2020-10-13 0:31 ` [PATCH v6 08/25] kbuild: add support for Clang LTO Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 09/25] kbuild: lto: fix module versioning Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 10/25] objtool: Split noinstr validation from --vmlinux Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 11/25] kbuild: lto: postpone objtool Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 12/25] kbuild: lto: limit inlining Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 13/25] kbuild: lto: merge module sections Sami Tolvanen 2020-10-14 22:49 ` Kees Cook 2020-10-20 16:42 ` Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 14/25] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen 2020-10-14 22:50 ` Kees Cook 2020-12-03 17:59 ` Masahiro Yamada 2020-12-03 18:47 ` Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 15/25] init: lto: ensure initcall ordering Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 16/25] init: lto: fix PREL32 relocations Sami Tolvanen 2020-10-14 22:53 ` Kees Cook 2020-10-15 0:12 ` Jann Horn 2020-10-13 0:31 ` [PATCH v6 17/25] PCI: Fix PREL32 relocations for LTO Sami Tolvanen 2020-10-14 22:58 ` Kees Cook 2020-10-13 0:31 ` [PATCH v6 18/25] modpost: lto: strip .lto from module names Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 19/25] scripts/mod: disable LTO for empty.c Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 20/25] efi/libstub: disable LTO Sami Tolvanen 2020-10-13 0:31 ` [PATCH v6 21/25] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen 2020-10-13 0:32 ` [PATCH v6 22/25] x86/asm: annotate indirect jumps Sami Tolvanen 2020-10-14 22:46 ` Kees Cook 2020-10-14 23:23 ` Jann Horn 2020-10-15 10:22 ` Peter Zijlstra 2020-10-15 20:39 ` Josh Poimboeuf 2020-10-20 16:45 ` Sami Tolvanen 2020-10-20 18:52 ` Josh Poimboeuf 2020-10-20 19:24 ` Sami Tolvanen 2020-10-21 8:56 ` Peter Zijlstra 2020-10-21 9:08 ` Peter Zijlstra 2020-10-21 9:32 ` Peter Zijlstra 2020-10-21 21:27 ` Josh Poimboeuf 2020-10-22 7:25 ` Peter Zijlstra 2020-10-23 17:48 ` Sami Tolvanen 2020-10-23 18:04 ` Nick Desaulniers 2020-10-21 15:01 ` Sami Tolvanen 2020-10-22 0:22 ` Sami Tolvanen [this message] 2020-10-23 17:36 ` Sami Tolvanen 2020-11-09 23:11 ` Sami Tolvanen 2020-11-10 2:29 ` Josh Poimboeuf 2020-11-10 3:18 ` Nick Desaulniers 2020-11-10 4:48 ` Sami Tolvanen 2020-11-10 16:11 ` Josh Poimboeuf 2020-11-10 17:46 ` Josh Poimboeuf 2020-11-10 18:59 ` Sami Tolvanen 2020-11-13 19:54 ` Josh Poimboeuf 2020-11-13 20:24 ` Sami Tolvanen 2020-11-13 20:52 ` Josh Poimboeuf 2020-11-13 22:34 ` Josh Poimboeuf 2020-11-13 22:54 ` Sami Tolvanen 2020-11-13 22:56 ` Josh Poimboeuf 2020-11-13 23:31 ` Sami Tolvanen 2020-11-14 0:49 ` Josh Poimboeuf 2020-10-21 9:51 ` Peter Zijlstra 2020-10-21 18:30 ` Josh Poimboeuf 2020-10-13 0:32 ` [PATCH v6 23/25] x86, vdso: disable LTO only for vDSO Sami Tolvanen 2020-10-13 0:32 ` [PATCH v6 24/25] x86, cpu: disable LTO for cpu.c Sami Tolvanen 2020-10-13 0:32 ` [PATCH v6 25/25] x86, build: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
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