From: Sami Tolvanen <samitolvanen@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Nathan Chancellor <nathan@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>, X86 ML <x86@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Joao Moreira <joao@overdrivepizza.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-hardening@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
llvm@lists.linux.dev
Subject: Re: [PATCH v4 00/21] KCFI support
Date: Fri, 2 Sep 2022 08:39:29 -0700 [thread overview]
Message-ID: <CABCJKudRywi7FgNOb8V7vmS39k59fbO1D3dwfmMZmBpApRX5eQ@mail.gmail.com> (raw)
In-Reply-To: <YxG2DUEBnIpAMKF2@hirez.programming.kicks-ass.net>
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
WARNING: multiple messages have this Message-ID (diff)
From: Sami Tolvanen <samitolvanen@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Nathan Chancellor <nathan@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>, X86 ML <x86@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Joao Moreira <joao@overdrivepizza.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-hardening@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
llvm@lists.linux.dev
Subject: Re: [PATCH v4 00/21] KCFI support
Date: Fri, 2 Sep 2022 08:39:29 -0700 [thread overview]
Message-ID: <CABCJKudRywi7FgNOb8V7vmS39k59fbO1D3dwfmMZmBpApRX5eQ@mail.gmail.com> (raw)
In-Reply-To: <YxG2DUEBnIpAMKF2@hirez.programming.kicks-ass.net>
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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next prev parent reply other threads:[~2022-09-02 15:40 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 23:31 [PATCH v4 00/21] KCFI support Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 01/21] treewide: Filter out CC_FLAGS_CFI Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 02/21] scripts/kallsyms: Ignore __kcfi_typeid_ Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 03/21] cfi: Remove CONFIG_CFI_CLANG_SHADOW Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 04/21] cfi: Drop __CFI_ADDRESSABLE Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 05/21] cfi: Switch to -fsanitize=kcfi Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 06/21] cfi: Add type helper macros Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 07/21] lkdtm: Emit an indirect call for CFI tests Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 08/21] psci: Fix the function type for psci_initcall_t Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-31 18:22 ` Kees Cook
2022-08-31 18:22 ` Kees Cook
2022-08-30 23:31 ` [PATCH v4 09/21] arm64: Add types to indirect called assembly functions Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 10/21] arm64: Add CFI error handling Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 11/21] arm64: Drop unneeded __nocfi attributes Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 12/21] init: Drop __nocfi from __init Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 13/21] treewide: Drop function_nocfi Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 14/21] treewide: Drop WARN_ON_FUNCTION_MISMATCH Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 15/21] treewide: Drop __cficanonical Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 16/21] objtool: Disable CFI warnings Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-31 18:23 ` Kees Cook
2022-08-31 18:23 ` Kees Cook
2022-08-30 23:31 ` [PATCH v4 17/21] kallsyms: Drop CONFIG_CFI_CLANG workarounds Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-31 18:23 ` Kees Cook
2022-08-31 18:23 ` Kees Cook
2022-08-30 23:31 ` [PATCH v4 18/21] x86/tools/relocs: Ignore __kcfi_typeid_ relocations Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 19/21] x86: Add types to indirectly called assembly functions Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 20/21] x86/purgatory: Disable CFI Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-30 23:31 ` [PATCH v4 21/21] x86: Add support for CONFIG_CFI_CLANG Sami Tolvanen
2022-08-30 23:31 ` Sami Tolvanen
2022-08-31 18:28 ` Kees Cook
2022-08-31 18:28 ` Kees Cook
2022-08-31 22:04 ` [PATCH v4 00/21] KCFI support Kees Cook
2022-08-31 22:04 ` Kees Cook
2022-09-01 21:19 ` Nathan Chancellor
2022-09-01 21:19 ` Nathan Chancellor
2022-09-02 0:33 ` Sami Tolvanen
2022-09-02 0:33 ` Sami Tolvanen
2022-09-02 7:51 ` Peter Zijlstra
2022-09-02 7:51 ` Peter Zijlstra
2022-09-02 15:39 ` Sami Tolvanen [this message]
2022-09-02 15:39 ` Sami Tolvanen
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