linux-kernel - [PATCH v3 05/22] powerpc/32s: Remove capability to disable KUEP at boottime

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Message-Id: <96f583f82423a29a4205c60b9721079111b35567.1634627931.git.christophe.leroy@csgroup.eu>
Date:   Tue, 19 Oct 2021 09:29:16 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 05/22] powerpc/32s: Remove capability to disable KUEP at boottime

Disabling KUEP at boottime makes things unnecessarily complex.

Still allow disabling KUEP at build time, but when it's built-in
it is always there.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/book3s/32/kup.h |  3 +--
 arch/powerpc/mm/book3s32/kuep.c          | 10 ++--------
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 9f38040f0641..fb6c39225dd1 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -12,7 +12,6 @@
 #include <linux/jump_label.h>
 
 extern struct static_key_false disable_kuap_key;
-extern struct static_key_false disable_kuep_key;
 
 static __always_inline bool kuap_is_disabled(void)
 {
@@ -21,7 +20,7 @@ static __always_inline bool kuap_is_disabled(void)
 
 static __always_inline bool kuep_is_disabled(void)
 {
-	return !IS_ENABLED(CONFIG_PPC_KUEP) || static_branch_unlikely(&disable_kuep_key);
+	return !IS_ENABLED(CONFIG_PPC_KUEP);
 }
 
 static inline void kuep_lock(void)
diff --git a/arch/powerpc/mm/book3s32/kuep.c b/arch/powerpc/mm/book3s32/kuep.c
index c20733d6e02c..8474edce3df9 100644
--- a/arch/powerpc/mm/book3s32/kuep.c
+++ b/arch/powerpc/mm/book3s32/kuep.c
@@ -3,18 +3,12 @@
 #include <asm/kup.h>
 #include <asm/smp.h>
 
-struct static_key_false disable_kuep_key;
-
 void setup_kuep(bool disabled)
 {
-	if (!disabled)
-		kuep_lock();
+	kuep_lock();
 
 	if (smp_processor_id() != boot_cpuid)
 		return;
 
-	if (disabled)
-		static_branch_enable(&disable_kuep_key);
-	else
-		pr_info("Activating Kernel Userspace Execution Prevention\n");
+	pr_info("Activating Kernel Userspace Execution Prevention\n");
 }
-- 
2.31.1