Messages in this thread | | | From | Sami Tolvanen <> | Date | Fri, 2 Sep 2022 08:39:29 -0700 | Subject | Re: [PATCH v4 00/21] KCFI support |
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On Fri, Sep 2, 2022 at 12:51 AM Peter Zijlstra <peterz@infradead.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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