[RFC PATCH v1 40/41] powerpc/8xx: Create C version of kuap save/restore/check helpers

[Christophe Leroy]

In preparation of porting PPC32 to C syscall entry/exit,
create C version of kuap_save_and_lock() and kuap_user_restore() and
kuap_kernel_restore() and kuap_check() and kuap_get_and_check() on 8xx.

Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
---
 arch/powerpc/include/asm/nohash/32/kup-8xx.h | 33 ++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
index 17a4a616436f..6f191fe08a2e 100644
--- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
@@ -34,6 +34,39 @@
 
 #include <asm/reg.h>
 
+static inline void kuap_save_and_lock(struct pt_regs *regs)
+{
+	regs->kuap = mfspr(SPRN_MD_AP);
+	mtspr(SPRN_MD_AP, MD_APG_KUAP);
+}
+
+static inline void kuap_user_restore(struct pt_regs *regs)
+{
+}
+
+static inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
+{
+	mtspr(SPRN_MD_AP, regs->kuap);
+}
+
+static inline void kuap_check(void)
+{
+	if (!IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
+		return;
+
+	WARN_ON_ONCE(mfspr(SPRN_MD_AP) >> 16 != MD_APG_KUAP >> 16);
+}
+
+static inline unsigned long kuap_get_and_check(void)
+{
+	unsigned long kuap = mfspr(SPRN_MD_AP);
+
+	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
+		WARN_ON_ONCE(kuap >> 16 != MD_APG_KUAP >> 16);
+
+	return kuap;
+}
+
 static inline void allow_user_access(void __user *to, const void __user *from,
 				     unsigned long size, unsigned long dir)
 {
-- 
2.25.0