Commit 3e1dedb2 authored May 09, 2023 by Kristina Martsenko Committed by Catalin Marinas Jun 05, 2023

arm64: mops: allow disabling MOPS from the kernel command line



Make it possible to disable the MOPS extension at runtime using the
kernel command line. This can be useful for testing or working around
hardware issues. For example it could be used to test new memory copy
routines that do not use MOPS instructions (e.g. from Arm Optimized
Routines).

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20230509142235.3284028-11-kristina.martsenko@arm.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent b7564127

Documentation/admin-guide/kernel-parameters.txt

+3 −0

Original line number	Diff line number	Diff line
		@@ -429,6 +429,9 @@
		arm64.nosme [ARM64] Unconditionally disable Scalable Matrix
		Extension support

		arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory
		Set instructions support

		ataflop= [HW,M68k]

		atarimouse= [HW,MOUSE] Atari Mouse

arch/arm64/kernel/idreg-override.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -123,6 +123,7 @@ static const struct ftr_set_desc isar2 __initconst = {
		.fields = {
		FIELD("gpa3", ID_AA64ISAR2_EL1_GPA3_SHIFT, NULL),
		FIELD("apa3", ID_AA64ISAR2_EL1_APA3_SHIFT, NULL),
		FIELD("mops", ID_AA64ISAR2_EL1_MOPS_SHIFT, NULL),
		{}
		},
		};
		@@ -174,6 +175,7 @@ static const struct {
		"id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
		"id_aa64isar1.api=0 id_aa64isar1.apa=0 "
		"id_aa64isar2.gpa3=0 id_aa64isar2.apa3=0" },
		{ "arm64.nomops", "id_aa64isar2.mops=0" },
		{ "arm64.nomte", "id_aa64pfr1.mte=0" },
		{ "nokaslr", "kaslr.disabled=1" },
		};