Commit 57efac2f authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Catalin Marinas

arm64: enable CONFIG_DEBUG_RODATA by default

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 2f39b5f9 ("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performance concerns related to enabling CONFIG_DEBUG_RODATA are no longer
valid.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: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent dbd4d7ca
...@@ -50,11 +50,11 @@ config DEBUG_SET_MODULE_RONX ...@@ -50,11 +50,11 @@ config DEBUG_SET_MODULE_RONX
config DEBUG_RODATA config DEBUG_RODATA
bool "Make kernel text and rodata read-only" bool "Make kernel text and rodata read-only"
default y
help help
If this is set, kernel text and rodata will be made read-only. This 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 is to help catch accidental or malicious attempts to change the
kernel's executable code. Additionally splits rodata from kernel kernel's executable code.
text so it can be made explicitly non-executable.
If in doubt, say Y If in doubt, say Y
......
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