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Commit 40982fd6 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
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arm64: always enable DEBUG_RODATA and remove the Kconfig option 



Follow the example set by x86 in commit 9ccaf77c ("x86/mm:
Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option"), and
make these protections a fundamental security feature rather than an
opt-in. This also results in a minor code simplification.

For those rare cases when users wish to disable this protection (e.g.
for debugging), this can be done by passing 'rodata=off' on the command
line.

As DEBUG_RODATA_ALIGN is only intended to address a performance/memory
tradeoff, and does not affect correctness, this is left user-selectable.
DEBUG_MODULE_RONX is also left user-selectable until the core code
provides a boot-time option to disable the protection for debugging
use-cases.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarLaura Abbott <labbott@redhat.com>
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent e7cd1903

arch/arm64/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -122,6 +122,9 @@ config ARCH_PHYS_ADDR_T_64BIT 
config MMU

	def_bool y



config DEBUG_RODATA

	def_bool y



config ARM64_PAGE_SHIFT

	int

	default 16 if ARM64_64K_PAGES

arch/arm64/Kconfig.debug

+0 −10
Original line number Diff line number Diff line
@@ -49,16 +49,6 @@ config DEBUG_SET_MODULE_RONX 


	  If in doubt, say Y.



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.



	  If in doubt, say Y.



config DEBUG_ALIGN_RODATA

	depends on DEBUG_RODATA

	bool "Align linker sections up to SECTION_SIZE"

arch/arm64/kernel/insn.c

+1 −1
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ static void __kprobes *patch_map(void *addr, int fixmap) 


	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))

		page = vmalloc_to_page(addr);

	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))

	else if (!module)

		page = pfn_to_page(PHYS_PFN(__pa(addr)));

	else

		return addr;