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Message-ID: <CABCJKudRywi7FgNOb8V7vmS39k59fbO1D3dwfmMZmBpApRX5eQ@mail.gmail.com> Date: Fri, 2 Sep 2022 08:39:29 -0700 From: Sami Tolvanen <samitolvanen@...gle.com> To: Peter Zijlstra <peterz@...radead.org> Cc: Nathan Chancellor <nathan@...nel.org>, LKML <linux-kernel@...r.kernel.org>, Kees Cook <keescook@...omium.org>, Josh Poimboeuf <jpoimboe@...hat.com>, X86 ML <x86@...nel.org>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, Nick Desaulniers <ndesaulniers@...gle.com>, Joao Moreira <joao@...rdrivepizza.com>, Sedat Dilek <sedat.dilek@...il.com>, Steven Rostedt <rostedt@...dmis.org>, linux-hardening@...r.kernel.org, linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, llvm@...ts.linux.dev Subject: Re: [PATCH v4 00/21] KCFI support On Fri, Sep 2, 2022 at 12:51 AM Peter Zijlstra <peterz@...radead.org> wrote: > > On Thu, Sep 01, 2022 at 05:33:29PM -0700, Sami Tolvanen wrote: > > > > I do see a few new objtool warnings as well: > > > > > > vmlinux.o: warning: objtool: apply_relocate_add+0x34: relocation to !ENDBR: memcpy+0x0 > > > vmlinux.o: warning: objtool: ___ksymtab+__memcpy+0x0: data relocation to !ENDBR: memcpy+0x0 > > > vmlinux.o: warning: objtool: ___ksymtab+memcpy+0x0: data relocation to !ENDBR: memcpy+0x0 > > > > That's interesting. I can only reproduce this warning with > > allmodconfig+LTO, even though the relocation exists in all builds (the > > code makes an indirect call to memcpy) and memcpy (aliased to > > __memcpy) doesn't start with endbr. I'll have to take a closer look at > > why this warning only appears with LTO. > > From just looking at the patches I'd say patch #19 breaks it. IIRC you > forgot to make the SYM_TYPED_FUNC things emit ENDBR. > > Look at how x86/asm/linkage.h is overriding SYM_FUNC_START*(). Yes, that's the reason, I'll fix this next week. I was mostly wondering why I'm not getting this warning with my other test configs, but it looks like IBT isn't enabled by default. Sami
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