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Peter Anvin" , Peter Zijlstra , Uros Bizjak , Brian Gerst Subject: [PATCH v2 00/11] x86-64: Stack protector and percpu improvements Date: Thu, 26 Oct 2023 12:00:49 -0400 Message-ID: <20231026160100.195099-1-brgerst@gmail.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, x86-64 uses an unusual percpu layout, where the percpu section is linked at absolute address 0. The reason behind this is that older GCC versions placed the stack protector (if enabled) at a fixed offset from the GS segment base. Since the GS segement is also used for percpu variables, this forced the current layout. GCC since version 8.1 supports a configurable location for the stack protector value, which allows removal of the restriction on how the percpu section is linked. This allows the percpu section to be linked normally, like most other architectures. In turn, this allows removal of code that was needed to support the zero-based percpu section. v2: - Include PVH boot in GSBASE changes. - Split out removal of 64-bit test script to give full context on why it's not needed anymore. - Formatting and comment cleanups. Brian Gerst (11): x86/stackprotector/32: Remove stack protector test script x86/stackprotector/64: Remove stack protector test script x86/boot: Disable stack protector for early boot code x86/pvh: Use fixed_percpu_data for early boot GSBASE x86/stackprotector/64: Convert stack protector to normal percpu variable x86/percpu/64: Remove fixed_percpu_data x86/percpu/64: Use relative percpu offsets x86/boot/64: Remove inverse relocations x86/percpu/64: Remove INIT_PER_CPU macros percpu: Remove PER_CPU_FIRST_SECTION kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU arch/x86/Kconfig | 7 +- arch/x86/Makefile | 19 +-- arch/x86/boot/compressed/misc.c | 14 +-- arch/x86/entry/entry_64.S | 2 +- arch/x86/include/asm/percpu.h | 22 ---- arch/x86/include/asm/processor.h | 28 +---- arch/x86/include/asm/stackprotector.h | 37 ++---- arch/x86/kernel/Makefile | 2 + arch/x86/kernel/asm-offsets_64.c | 6 - arch/x86/kernel/cpu/common.c | 8 +- arch/x86/kernel/head_64.S | 10 +- arch/x86/kernel/irq_64.c | 1 - arch/x86/kernel/setup_percpu.c | 12 +- arch/x86/kernel/vmlinux.lds.S | 35 ------ arch/x86/platform/pvh/head.S | 4 +- arch/x86/tools/relocs.c | 136 +--------------------- arch/x86/xen/xen-head.S | 6 +- include/asm-generic/vmlinux.lds.h | 1 - include/linux/percpu-defs.h | 12 -- init/Kconfig | 11 +- kernel/kallsyms.c | 12 +- scripts/gcc-x86_32-has-stack-protector.sh | 8 -- scripts/gcc-x86_64-has-stack-protector.sh | 4 - scripts/kallsyms.c | 80 +++---------- scripts/link-vmlinux.sh | 4 - 25 files changed, 61 insertions(+), 420 deletions(-) delete mode 100755 scripts/gcc-x86_32-has-stack-protector.sh delete mode 100755 scripts/gcc-x86_64-has-stack-protector.sh -- 2.41.0