Commit 1279e8d0 authored Apr 29, 2024 by Andrea della Porta Committed by Will Deacon May 03, 2024

arm64: Add the arm64.no32bit_el0 command line option

Introducing the field 'el0' to the idreg-override for register
ID_AA64PFR0_EL1. This field is also aliased to the new kernel
command line option 'arm64.no32bit_el0' as a more recognizable
and mnemonic name to disable the execution of 32 bit userspace
applications (i.e. avoid Aarch32 execution state in EL0) from
kernel command line.

Link: https://lore.kernel.org/all/20240207105847.7739-1-andrea.porta@suse.com/


Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
Link: https://lore.kernel.org/r/20240429102833.6426-1-andrea.porta@suse.com


Signed-off-by: Will Deacon <will@kernel.org>

parent 080297be

Documentation/admin-guide/kernel-parameters.txt

+3 −0

Original line number	Diff line number	Diff line
		@@ -431,6 +431,9 @@
		arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
		Format: <io>,<irq>,<nodeID>

		arm64.no32bit_el0 [ARM64] Unconditionally disable the execution of
		32 bit applications.

		arm64.nobti [ARM64] Unconditionally disable Branch Target
		Identification support

arch/arm64/kernel/pi/idreg-override.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -108,6 +108,7 @@ static const struct ftr_set_desc pfr0 __prel64_initconst = {
		.override = &id_aa64pfr0_override,
		.fields = {
		FIELD("sve", ID_AA64PFR0_EL1_SVE_SHIFT, pfr0_sve_filter),
		FIELD("el0", ID_AA64PFR0_EL1_EL0_SHIFT, NULL),
		{}
		},
		};
		@@ -223,6 +224,7 @@ static const struct {
		{ "nokaslr", "arm64_sw.nokaslr=1" },
		{ "rodata=off", "arm64_sw.rodataoff=1" },
		{ "arm64.nolva", "id_aa64mmfr2.varange=0" },
		{ "arm64.no32bit_el0", "id_aa64pfr0.el0=1" },
		};

		static int __init parse_hexdigit(const char p, u64 v)