powerpc/kuap: Prepare for supporting KUAP on BOOK3E/64

Also call kuap_lock() and kuap_save_and_lock() from
interrupt functions with CONFIG_PPC64.

For book3s/64 we keep them empty as it is done in assembly.

Also do the locked assert when switching task unless it is
book3s/64.

Signed-off-by: Christophe Leroy <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/1cbf94e2[e-mail]

arch/powerpc/include/asm/book3s/64/kup.h

···
 	return amr;
 }
 
+/* Do nothing, book3s/64 does that in ASM */
+static inline void __kuap_lock(void)
+{
+}
+
+static inline void __kuap_save_and_lock(struct pt_regs *regs)
+{
+}
+
 /*
  * We support individually allowing read or write, but we don't support nesting
  * because that would require an expensive read/modify write of the AMR.

arch/powerpc/include/asm/interrupt.h

···
 	local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
 
 	if (user_mode(regs)) {
+		kuap_lock();
 		CT_WARN_ON(ct_state() != CONTEXT_USER);
 		user_exit_irqoff();
 
 		account_cpu_user_entry();
 		account_stolen_time();
 	} else {
+		kuap_save_and_lock(regs);
 		/*
 		 * CT_WARN_ON comes here via program_check_exception,
 		 * so avoid recursion.

arch/powerpc/include/asm/kup.h

···
 		__kuap_get_and_assert_locked();
 }
 
-#ifdef CONFIG_PPC32
 static __always_inline void kuap_lock(void)
 {
 	if (kuap_is_disabled())
···
 
 	__kuap_save_and_lock(regs);
 }
-#endif
 
 static __always_inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)
 {

arch/powerpc/kernel/process.c

···
 
 	set_return_regs_changed(); /* _switch changes stack (and regs) */
 
-#ifdef CONFIG_PPC32
-	kuap_assert_locked();
-#endif
+	if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64))
+		kuap_assert_locked();
+
 	last = _switch(old_thread, new_thread);
 
 	/*