Date: Wed, 21 Oct 2020 08:01:38 -0700 From: Sami Tolvanen <samitolvanen@...gle.com> To: Peter Zijlstra <peterz@...radead.org> Cc: Josh Poimboeuf <jpoimboe@...hat.com>, Jann Horn <jannh@...gle.com>, "the arch/x86 maintainers" <x86@...nel.org>, Masahiro Yamada <masahiroy@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, Will Deacon <will@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Paul E. McKenney" <paulmck@...nel.org>, Kees Cook <keescook@...omium.org>, Nick Desaulniers <ndesaulniers@...gle.com>, clang-built-linux <clang-built-linux@...glegroups.com>, Kernel Hardening <kernel-hardening@...ts.openwall.com>, linux-arch <linux-arch@...r.kernel.org>, Linux ARM <linux-arm-kernel@...ts.infradead.org>, linux-kbuild <linux-kbuild@...r.kernel.org>, kernel list <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org Subject: Re: [PATCH v6 22/25] x86/asm: annotate indirect jumps On Wed, Oct 21, 2020 at 1:56 AM Peter Zijlstra <peterz@...radead.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). Ah, right. It also doesn't generate warnings when I build defconfig with LTO, so clearly something confuses objtool here. Sami
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