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 V3: - idreg-override.c has been moved to arch/arm64/kernel/pi/ directory, so this patch revision adjust for that change. Link: https://lore.kernel.org/all/20240207105847.7739-1-andrea.porta@xxxxxxxx/ Signed-off-by: Andrea della Porta <andrea.porta@xxxxxxxx> --- 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 bb884c14b2f6..3e70963599df 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: <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/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) -- 2.35.3
