From 1279e8d0dcead53cf1f51e926a1cf6d2a79332d6 Mon Sep 17 00:00:00 2001 From: Andrea della Porta Date: Mon, 29 Apr 2024 12:28:33 +0200 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/20240429102833.6426-1-andrea.porta@suse.com Signed-off-by: Will Deacon --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ arch/arm64/kernel/pi/idreg-override.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 623fce7d5fcd..afd6fcc1e8b9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -431,6 +431,9 @@ arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards Format: ,, + arm64.no32bit_el0 [ARM64] Unconditionally disable the execution of + 32 bit applications. + arm64.nobti [ARM64] Unconditionally disable Branch Target Identification support diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/idreg-override.c index aad399796e81..48c1aa456af9 100644 --- a/arch/arm64/kernel/pi/idreg-override.c +++ b/arch/arm64/kernel/pi/idreg-override.c @@ -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)