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. Changes in V2: - fixed the order of appearance of arm64.no32bit_el0 entry in kernel-parameters.txt documentation. Link: https://lore.kernel.org/r/ZVTleETzfFUchs77@apocalypse Signed-off-by: Andrea della Porta <andrea.porta@xxxxxxxx> --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ arch/arm64/kernel/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 65731b060e3f..fa7cdf2f4f3a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -415,6 +415,9 @@ 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 diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c index e30fd9e32ef3..642cda19e42d 100644 --- a/arch/arm64/kernel/idreg-override.c +++ b/arch/arm64/kernel/idreg-override.c @@ -86,6 +86,7 @@ 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), {} }, }; @@ -197,6 +198,7 @@ static const struct { { "arm64.nomops", "id_aa64isar2.mops=0" }, { "arm64.nomte", "id_aa64pfr1.mte=0" }, { "nokaslr", "arm64_sw.nokaslr=1" }, + { "arm64.no32bit_el0", "id_aa64pfr0.el0=1" }, }; static int __init parse_hexdigit(const char *p, u64 *v) -- 2.41.0
