From: Kees Cook <keescook@chromium.org> To: Peter Zijlstra <peterz@infradead.org> Cc: Kristen Carlson Accardi <kristen@linux.intel.com>, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, arjan@linux.intel.com, rick.p.edgecombe@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: Re: [RFC PATCH 05/11] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Date: Thu, 6 Feb 2020 03:52:54 -0800 [thread overview] Message-ID: <202002060348.7543F4D5@keescook> (raw) In-Reply-To: <20200206103055.GV14879@hirez.programming.kicks-ass.net> On Thu, Feb 06, 2020 at 11:30:55AM +0100, Peter Zijlstra wrote: > On Wed, Feb 05, 2020 at 02:39:44PM -0800, Kristen Carlson Accardi wrote: > > Allow user to select CONFIG_FG_KASLR if dependencies are met. Change > > the make file to build with -ffunction-sections if CONFIG_FG_KASLR > > > > Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com> > > --- > > Makefile | 4 ++++ > > arch/x86/Kconfig | 13 +++++++++++++ > > 2 files changed, 17 insertions(+) > > > > diff --git a/Makefile b/Makefile > > index c50ef91f6136..41438a921666 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -846,6 +846,10 @@ ifdef CONFIG_LIVEPATCH > > KBUILD_CFLAGS += $(call cc-option, -flive-patching=inline-clone) > > endif > > > > +ifdef CONFIG_FG_KASLR > > +KBUILD_CFLAGS += -ffunction-sections > > +endif > [...] > In particular: > > "They prevent optimizations by the compiler and assembler using > relative locations inside a translation unit since the locations are > unknown until link time." I think this mainly a feature of this flag, since it's those relocations that are used to do the post-shuffle fixups. But yes, I would imagine this has some negative impact on code generation. > I suppose in practise this only means tail-calls are affected and will > no longer use JMP.d8. Or are more things affected? It's worth looking at. I'm also curious to see how this will interact with Link Time Optimization. -- Kees Cook
next prev parent reply other threads:[~2020-02-06 11:53 UTC|newest] Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-05 22:39 [RFC PATCH 00/11] Finer grained kernel address space randomization Kristen Carlson Accardi 2020-02-05 22:39 ` [RFC PATCH 01/11] modpost: Support >64K sections Kristen Carlson Accardi 2020-02-06 12:38 ` Kees Cook 2020-02-05 22:39 ` [RFC PATCH 02/11] x86: tools/relocs: Support >64K section headers Kristen Carlson Accardi 2020-02-06 12:39 ` Kees Cook 2020-02-05 22:39 ` [RFC PATCH 03/11] x86/boot: Allow a "silent" kaslr random byte fetch Kristen Carlson Accardi 2020-02-06 1:08 ` Andy Lutomirski 2020-02-06 11:48 ` Kees Cook 2020-02-06 16:58 ` Kristen Carlson Accardi 2020-02-05 22:39 ` [RFC PATCH 04/11] x86/boot/KASLR: Introduce PRNG for faster shuffling Kristen Carlson Accardi 2020-02-06 1:11 ` Andy Lutomirski 2020-02-06 15:10 ` Jason A. Donenfeld 2020-02-07 7:23 ` Jean-Philippe Aumasson 2020-02-07 9:05 ` Kees Cook 2020-02-07 16:52 ` Kristen Carlson Accardi 2020-02-05 22:39 ` [RFC PATCH 05/11] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Kristen Carlson Accardi 2020-02-06 10:30 ` Peter Zijlstra 2020-02-06 11:52 ` Kees Cook [this message] 2020-02-25 17:55 ` Arvind Sankar 2020-02-26 19:13 ` Kristen Carlson Accardi 2020-03-24 21:24 ` Kristen Carlson Accardi 2020-03-25 15:34 ` Kees Cook 2020-02-05 22:39 ` [RFC PATCH 06/11] x86: make sure _etext includes function sections Kristen Carlson Accardi 2020-02-06 12:26 ` Kees Cook 2020-02-06 13:15 ` Jann Horn 2020-02-06 16:27 ` David Laight 2020-02-06 14:39 ` Arvind Sankar 2020-02-06 15:29 ` Arvind Sankar 2020-02-06 16:11 ` Andy Lutomirski 2020-02-06 14:57 ` Arvind Sankar 2020-02-06 15:45 ` Arvind Sankar 2020-02-06 19:41 ` Kristen Carlson Accardi 2020-02-06 20:02 ` Andy Lutomirski 2020-02-07 9:24 ` Peter Zijlstra 2020-02-10 1:43 ` Kees Cook 2020-02-10 10:51 ` Peter Zijlstra 2020-02-10 15:54 ` Arjan van de Ven 2020-02-10 16:36 ` Arvind Sankar 2020-02-21 19:50 ` Josh Poimboeuf 2020-02-21 23:05 ` Arvind Sankar 2020-02-05 22:39 ` [RFC PATCH 07/11] x86/tools: Adding relative relocs for randomized functions Kristen Carlson Accardi 2020-02-06 12:37 ` Kees Cook 2020-02-05 22:39 ` [RFC PATCH 08/11] x86: Add support for finer grained KASLR Kristen Carlson Accardi 2020-02-06 1:17 ` Andy Lutomirski 2020-02-06 11:56 ` Kees Cook 2020-02-06 17:36 ` Kristen Carlson Accardi 2020-02-06 10:38 ` Peter Zijlstra 2020-02-06 12:06 ` Kees Cook 2020-02-06 14:52 ` Peter Zijlstra 2020-02-06 17:25 ` Kristen Carlson Accardi 2020-02-06 17:35 ` Peter Zijlstra 2020-02-06 17:43 ` Kristen Carlson Accardi 2020-02-25 17:49 ` Arvind Sankar 2020-02-26 19:26 ` Kristen Carlson Accardi 2020-02-05 22:39 ` [RFC PATCH 09/11] kallsyms: hide layout and expose seed Kristen Carlson Accardi 2020-02-06 12:32 ` Kees Cook 2020-02-06 17:51 ` Kristen Carlson Accardi 2020-02-06 19:27 ` Jann Horn 2020-03-02 19:01 ` Kristen Carlson Accardi 2020-03-02 19:08 ` Kees Cook 2020-03-02 19:19 ` Kristen Carlson Accardi 2020-02-27 2:42 ` Baoquan He 2020-02-27 16:02 ` Kees Cook 2020-02-28 3:36 ` Baoquan He 2020-02-05 22:39 ` [RFC PATCH 10/11] module: Reorder functions Kristen Carlson Accardi 2020-02-06 12:41 ` Kees Cook 2020-02-11 12:39 ` Jessica Yu 2020-02-05 22:39 ` [RFC PATCH 11/11] x86/boot: Move "boot heap" out of .bss Kristen Carlson Accardi 2020-02-06 0:11 ` Arvind Sankar 2020-02-06 0:33 ` Kristen Carlson Accardi 2020-02-06 11:13 ` Kees Cook 2020-02-06 14:25 ` Arvind Sankar 2020-02-06 21:32 ` Kees Cook
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