[PATCH 1/1] arm64/cpufeature: Add option to disable mte support

[Marc Zyngier]

On Wed, 28 Jul 2021 10:42:58 +0100,
<yee.lee at mediatek.com> wrote:
> 
> From: Yee Lee <yee.lee at mediatek.com>
> 
> Add a static key to exapnd the logic of system_supports_mte().
> This function controls mte enablement in both EL1 and EL0.
> 
> The static key, "arm64_mte_support" is default true and can
> be disabled via the early_param.
> 
> Signed-off-by: Yee Lee <yee.lee at mediatek.com>
> ---
>  arch/arm64/include/asm/cpufeature.h |  4 +++-
>  arch/arm64/kernel/cpufeature.c      | 13 +++++++++++++
>  arch/arm64/kernel/image-vars.h      |  3 +++
>  3 files changed, 19 insertions(+), 1 deletion(-)

This seems terribly complicated. How about this instead ("arm64.nomte"
on the command line)?

Thanks,

	M.

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 53a381a7f65d..eaf17beb2420 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -54,6 +54,7 @@ static const struct ftr_set_desc pfr1 __initconst = {
 	.override	= &id_aa64pfr1_override,
 	.fields		= {
 	        { "bt", ID_AA64PFR1_BT_SHIFT },
+	        { "mte", ID_AA64PFR1_MTE_SHIFT },
 		{}
 	},
 };
@@ -100,6 +101,7 @@ static const struct {
 	{ "arm64.nopauth",
 	  "id_aa64isar1.gpi=0 id_aa64isar1.gpa=0 "
 	  "id_aa64isar1.api=0 id_aa64isar1.apa=0"	   },
+	{ "arm64.nomte",		"id_aa64pfr1.mte=0" },
 	{ "nokaslr",			"kaslr.disabled=1" },
 };
 

-- 
Without deviation from the norm, progress is not possible.