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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization
On Wed, Oct 11, 2017 at 2:34 PM, Tom Lendacky <thomas.lendacky@xxxxxxx> 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? > > 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(-) >> -- Thomas _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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