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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2016-03-03 15:10:59 +0100
committerAlex Shi <alex.shi@linaro.org>2017-03-23 16:33:20 +0800
commita34cb2390f7f28f4a44568cccbc2c65a9bdff721 (patch)
tree697a2847b3af6e6bbd416f7130b5690d8d50ddca
parent957413466cde02bee0b6540889376d35d6b0b41e (diff)
downloadlinux-linaro-stable-v4.4/topic/ro-vdso.tar.gz
arm64: enable CONFIG_DEBUG_RODATA by defaultv4.4/topic/ro-vdso
In spite of its name, CONFIG_DEBUG_RODATA is an important hardening feature for production kernels, and distros all enable it by default in their kernel configs. However, since enabling it used to result in more granular, and thus less efficient kernel mappings, it is not enabled by default for performance reasons. However, since commit 2f39b5f91eb4 ("arm64: mm: Mark .rodata as RO"), the various kernel segments (.text, .rodata, .init and .data) are already mapped individually, and the only effect of setting CONFIG_DEBUG_RODATA is that the existing .text and .rodata mappings are updated late in the boot sequence to have their read-only attributes set, which means that any performance concerns related to enabling CONFIG_DEBUG_RODATA are no longer valid. So from now on, make CONFIG_DEBUG_RODATA default to 'y' Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> (cherry picked from commit 57efac2f7108e3255d0dfe512290c9896f4ed55f) Signed-off-by: Alex Shi <alex.shi@linaro.org>
-rw-r--r--arch/arm64/Kconfig.debug6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index 04fb73b..8b0cd45 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -64,13 +64,13 @@ config DEBUG_SET_MODULE_RONX
config DEBUG_RODATA
bool "Make kernel text and rodata read-only"
+ default y
help
If this is set, kernel text and rodata will be made read-only. This
is to help catch accidental or malicious attempts to change the
- kernel's executable code. Additionally splits rodata from kernel
- text so it can be made explicitly non-executable.
+ kernel's executable code.
- If in doubt, say Y
+ If in doubt, say Y
config DEBUG_ALIGN_RODATA
depends on DEBUG_RODATA && ARM64_4K_PAGES