linux-kernel - [PATCH v2 09/16] powerpc/kuap: Prepare for supporting KUAP on BOOK3E/64

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Message-Id: <4b67460f6820694ab54ca29028a6972e1d113bb7.1633707305.git.christophe.leroy@csgroup.eu>
Date:   Fri,  8 Oct 2021 17:40:37 +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 v2 09/16] 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 <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/book3s/64/kup.h | 9 +++++++++
 arch/powerpc/include/asm/interrupt.h     | 2 ++
 arch/powerpc/include/asm/kup.h           | 2 --
 arch/powerpc/kernel/process.c            | 6 +++---
 4 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index 503828709d55..69fcf63eec94 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -298,6 +298,15 @@ static inline unsigned long __kuap_get_and_assert_locked(void)
 	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.
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index ae719e200c80..cd78dbca49e5 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -154,12 +154,14 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
 	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.
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index 2e0c2df21b3b..0cafcf8319cd 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -94,7 +94,6 @@ static __always_inline void kuap_assert_locked(void)
 		__kuap_get_and_assert_locked();
 }
 
-#ifdef CONFIG_PPC32
 static __always_inline void kuap_lock(void)
 {
 	if (kuap_is_disabled())
@@ -110,7 +109,6 @@ static __always_inline void kuap_save_and_lock(struct pt_regs *regs)
 
 	__kuap_save_and_lock(regs);
 }
-#endif
 
 static __always_inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long amr)
 {
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 50436b52c213..2c637740c0c2 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1281,9 +1281,9 @@ struct task_struct *__switch_to(struct task_struct *prev,
 
 	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);
 
 	/*
-- 
2.31.1