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Message-ID: <20240207105847.7739-1-andrea.porta@suse.com>
Date: Wed, 7 Feb 2024 11:58:47 +0100
From: Andrea della Porta <andrea.porta@...e.com>
To: Jonathan Corbet <corbet@....net>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: Andrea della Porta <andrea.porta@...e.com>
Subject: [PATCH v2] 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.
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@...e.com>
---
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
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