From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Lendacky Subject: Re: [PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization Date: Thu, 12 Oct 2017 11:28:15 -0500 Message-ID: <18a89941-c80d-7007-574b-584f39f90f49__4279.02130545608$1509080528$gmane$org@amd.com> References: <20171011203027.11248-1-thgarnie@google.com> <22e56a56-978a-738f-52b9-2d0c17839c9e@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Thomas Garnier Cc: Nicolas Pitre , Michal Hocko , linux-doc@vger.kernel.org, Daniel Micay , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Peter Zijlstra , Christopher Li , "=?UTF-8?Q?Jan_H_._Sch=c3=b6nherr?=" , Alexei Starovoitov , virtualization@lists.linux-foundation.org, David Howells , Paul Gortmaker , Waiman Long , Pavel Machek , "H . Peter Anvin" , Kernel Hardening , Christoph Lameter , Thomas Gleixner , the arch/x86 maintainers , Herbert Xu , Daniel Borkmann , Jonathan Corbet Pe List-Id: virtualization@lists.linuxfoundation.org On 10/12/2017 10:34 AM, Thomas Garnier wrote: > On Wed, Oct 11, 2017 at 2:34 PM, Tom Lendacky wrote: >> On 10/11/2017 3:30 PM, Thomas Garnier wrote: >>> Changes: >>> - patch v1: >>> - Simplify ftrace implementation. >>> - Use gcc mstack-protector-guard-reg=%gs with PIE when possible. >>> - rfc v3: >>> - Use --emit-relocs instead of -pie to reduce dynamic relocation space on >>> mapped memory. It also simplifies the relocation process. >>> - Move the start the module section next to the kernel. Remove the need for >>> -mcmodel=large on modules. Extends module space from 1 to 2G maximum. >>> - Support for XEN PVH as 32-bit relocations can be ignored with >>> --emit-relocs. >>> - Support for GOT relocations previously done automatically with -pie. >>> - Remove need for dynamic PLT in modules. >>> - Support dymamic GOT for modules. >>> - rfc v2: >>> - Add support for global stack cookie while compiler default to fs without >>> mcmodel=kernel >>> - Change patch 7 to correctly jump out of the identity mapping on kexec load >>> preserve. >>> >>> These patches make the changes necessary to build the kernel as Position >>> Independent Executable (PIE) on x86_64. A PIE kernel can be relocated below >>> the top 2G of the virtual address space. It allows to optionally extend the >>> KASLR randomization range from 1G to 3G. >> >> Hi Thomas, >> >> I've applied your patches so that I can verify that SME works with PIE. >> Unfortunately, I'm running into build warnings and errors when I enable >> PIE. >> >> With CONFIG_STACK_VALIDATION=y I receive lots of messages like this: >> >> drivers/scsi/libfc/fc_exch.o: warning: objtool: fc_destroy_exch_mgr()+0x0: call without frame pointer save/setup >> >> Disabling CONFIG_STACK_VALIDATION suppresses those. > > I ran into that, I plan to fix it in the next iteration. > >> >> But near the end of the build, I receive errors like this: >> >> arch/x86/kernel/setup.o: In function `dump_kernel_offset': >> .../arch/x86/kernel/setup.c:801:(.text+0x32): relocation truncated to fit: R_X86_64_32S against symbol `_text' defined in .text section in .tmp_vmlinux1 >> . >> . about 10 more of the above type messages >> . >> make: *** [vmlinux] Error 1 >> Error building kernel, exiting >> >> Are there any config options that should or should not be enabled when >> building with PIE enabled? Is there a compiler requirement for PIE (I'm >> using gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.5))? > > I never ran into these ones and I tested compilers older and newer. > What was your exact configuration? I'll send you the config in a separate email. Thanks, Tom > >> >> Thanks, >> Tom >> >>> >>> Thanks a lot to Ard Biesheuvel & Kees Cook on their feedback on compiler >>> changes, PIE support and KASLR in general. Thanks to Roland McGrath on his >>> feedback for using -pie versus --emit-relocs and details on compiler code >>> generation. >>> >>> The patches: >>> - 1-3, 5-1#, 17-18: Change in assembly code to be PIE compliant. >>> - 4: Add a new _ASM_GET_PTR macro to fetch a symbol address generically. >>> - 14: Adapt percpu design to work correctly when PIE is enabled. >>> - 15: Provide an option to default visibility to hidden except for key symbols. >>> It removes errors between compilation units. >>> - 16: Adapt relocation tool to handle PIE binary correctly. >>> - 19: Add support for global cookie. >>> - 20: Support ftrace with PIE (used on Ubuntu config). >>> - 21: Fix incorrect address marker on dump_pagetables. >>> - 22: Add option to move the module section just after the kernel. >>> - 23: Adapt module loading to support PIE with dynamic GOT. >>> - 24: Make the GOT read-only. >>> - 25: Add the CONFIG_X86_PIE option (off by default). >>> - 26: Adapt relocation tool to generate a 64-bit relocation table. >>> - 27: Add the CONFIG_RANDOMIZE_BASE_LARGE option to increase relocation range >>> from 1G to 3G (off by default). >>> >>> Performance/Size impact: >>> >>> Size of vmlinux (Default configuration): >>> File size: >>> - PIE disabled: +0.000031% >>> - PIE enabled: -3.210% (less relocations) >>> .text section: >>> - PIE disabled: +0.000644% >>> - PIE enabled: +0.837% >>> >>> Size of vmlinux (Ubuntu configuration): >>> File size: >>> - PIE disabled: -0.201% >>> - PIE enabled: -0.082% >>> .text section: >>> - PIE disabled: same >>> - PIE enabled: +1.319% >>> >>> Size of vmlinux (Default configuration + ORC): >>> File size: >>> - PIE enabled: -3.167% >>> .text section: >>> - PIE enabled: +0.814% >>> >>> Size of vmlinux (Ubuntu configuration + ORC): >>> File size: >>> - PIE enabled: -3.167% >>> .text section: >>> - PIE enabled: +1.26% >>> >>> The size increase is mainly due to not having access to the 32-bit signed >>> relocation that can be used with mcmodel=kernel. A small part is due to reduced >>> optimization for PIE code. This bug [1] was opened with gcc to provide a better >>> code generation for kernel PIE. >>> >>> Hackbench (50% and 1600% on thread/process for pipe/sockets): >>> - PIE disabled: no significant change (avg +0.1% on latest test). >>> - PIE enabled: between -0.50% to +0.86% in average (default and Ubuntu config). >>> >>> slab_test (average of 10 runs): >>> - PIE disabled: no significant change (-2% on latest run, likely noise). >>> - PIE enabled: between -1% and +0.8% on latest runs. >>> >>> Kernbench (average of 10 Half and Optimal runs): >>> Elapsed Time: >>> - PIE disabled: no significant change (avg -0.239%) >>> - PIE enabled: average +0.07% >>> System Time: >>> - PIE disabled: no significant change (avg -0.277%) >>> - PIE enabled: average +0.7% >>> >>> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82303 >>> >>> diffstat: >>> Documentation/x86/x86_64/mm.txt | 3 >>> arch/x86/Kconfig | 43 ++++++ >>> arch/x86/Makefile | 40 +++++ >>> arch/x86/boot/boot.h | 2 >>> arch/x86/boot/compressed/Makefile | 5 >>> arch/x86/boot/compressed/misc.c | 10 + >>> arch/x86/crypto/aes-x86_64-asm_64.S | 45 ++++-- >>> arch/x86/crypto/aesni-intel_asm.S | 14 +- >>> arch/x86/crypto/aesni-intel_avx-x86_64.S | 6 >>> arch/x86/crypto/camellia-aesni-avx-asm_64.S | 42 +++--- >>> arch/x86/crypto/camellia-aesni-avx2-asm_64.S | 44 +++--- >>> arch/x86/crypto/camellia-x86_64-asm_64.S | 8 - >>> arch/x86/crypto/cast5-avx-x86_64-asm_64.S | 50 ++++--- >>> arch/x86/crypto/cast6-avx-x86_64-asm_64.S | 44 +++--- >>> arch/x86/crypto/des3_ede-asm_64.S | 96 +++++++++----- >>> arch/x86/crypto/ghash-clmulni-intel_asm.S | 4 >>> arch/x86/crypto/glue_helper-asm-avx.S | 4 >>> arch/x86/crypto/glue_helper-asm-avx2.S | 6 >>> arch/x86/entry/entry_32.S | 3 >>> arch/x86/entry/entry_64.S | 29 ++-- >>> arch/x86/include/asm/asm.h | 13 + >>> arch/x86/include/asm/bug.h | 2 >>> arch/x86/include/asm/ftrace.h | 6 >>> arch/x86/include/asm/jump_label.h | 8 - >>> arch/x86/include/asm/kvm_host.h | 6 >>> arch/x86/include/asm/module.h | 11 + >>> arch/x86/include/asm/page_64_types.h | 9 + >>> arch/x86/include/asm/paravirt_types.h | 12 + >>> arch/x86/include/asm/percpu.h | 25 ++- >>> arch/x86/include/asm/pgtable_64_types.h | 6 >>> arch/x86/include/asm/pm-trace.h | 2 >>> arch/x86/include/asm/processor.h | 12 + >>> arch/x86/include/asm/sections.h | 8 + >>> arch/x86/include/asm/setup.h | 2 >>> arch/x86/include/asm/stackprotector.h | 19 ++ >>> arch/x86/kernel/acpi/wakeup_64.S | 31 ++-- >>> arch/x86/kernel/asm-offsets.c | 3 >>> arch/x86/kernel/asm-offsets_32.c | 3 >>> arch/x86/kernel/asm-offsets_64.c | 3 >>> arch/x86/kernel/cpu/common.c | 7 - >>> arch/x86/kernel/cpu/microcode/core.c | 4 >>> arch/x86/kernel/ftrace.c | 42 +++++- >>> arch/x86/kernel/head64.c | 32 +++- >>> arch/x86/kernel/head_32.S | 3 >>> arch/x86/kernel/head_64.S | 41 +++++- >>> arch/x86/kernel/kvm.c | 6 >>> arch/x86/kernel/module.c | 182 ++++++++++++++++++++++++++- >>> arch/x86/kernel/module.lds | 3 >>> arch/x86/kernel/process.c | 5 >>> arch/x86/kernel/relocate_kernel_64.S | 8 - >>> arch/x86/kernel/setup_percpu.c | 2 >>> arch/x86/kernel/vmlinux.lds.S | 13 + >>> arch/x86/kvm/svm.c | 4 >>> arch/x86/lib/cmpxchg16b_emu.S | 8 - >>> arch/x86/mm/dump_pagetables.c | 11 + >>> arch/x86/power/hibernate_asm_64.S | 4 >>> arch/x86/tools/relocs.c | 170 +++++++++++++++++++++++-- >>> arch/x86/tools/relocs.h | 4 >>> arch/x86/tools/relocs_common.c | 15 +- >>> arch/x86/xen/xen-asm.S | 12 - >>> arch/x86/xen/xen-head.S | 9 - >>> arch/x86/xen/xen-pvh.S | 13 + >>> drivers/base/firmware_class.c | 4 >>> include/asm-generic/sections.h | 6 >>> include/asm-generic/vmlinux.lds.h | 12 + >>> include/linux/compiler.h | 8 + >>> init/Kconfig | 9 + >>> kernel/kallsyms.c | 16 +- >>> kernel/trace/trace.h | 4 >>> lib/dynamic_debug.c | 4 >>> 70 files changed, 1032 insertions(+), 308 deletions(-) >>> > > >