Patch "powerpc/32s: Remove capability to disable KUEP at boottime" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    powerpc/32s: Remove capability to disable KUEP at boottime

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-32s-remove-capability-to-disable-kuep-at-boo.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 10ea835ab61d34200c05e870d69b6b6fcaf26993
Author: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Date:   Tue Oct 19 09:29:16 2021 +0200

    powerpc/32s: Remove capability to disable KUEP at boottime
    
    [ Upstream commit df415cd758261bceff27f34a145dd8328bbfb018 ]
    
    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@xxxxxxxxxx>
    Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/96f583f82423a29a4205c60b9721079111b35567.1634627931.git.christophe.leroy@xxxxxxxxxx
    Stable-dep-of: f0eee815babe ("powerpc/47x: Fix 47x syscall return crash")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 9f38040f0641d..fb6c39225dd19 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 c20733d6e02cb..8474edce3df9a 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");
 }