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From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [RFC PATCH v2 02/13] powerpc/32s: Create C version of kuap_restore()
 and kuap_check()
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, npiggin@gmail.com,
        msuchanek@suse.de
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Date:   Sun,  5 Apr 2020 17:44:37 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In preparation of porting PPC32 to C syscall entry/exit,
create C version of kuap_restore() and kuap_check() on book3s/32.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/book3s/32/kup.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 3c0ba22dc360..c85bc5b56366 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -102,6 +102,27 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end)
 	isync();	/* Context sync required after mtsrin() */
 }
 
+static inline void kuap_restore(struct pt_regs *regs)
+{
+	u32 kuap = current->thread.kuap;
+	u32 addr = kuap & 0xf0000000;
+	u32 end = kuap << 28;
+
+	if (unlikely(!kuap))
+		return;
+
+	current->thread.kuap = 0;
+	kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end);	/* Clear Ks */
+}
+
+static inline void kuap_check(void)
+{
+	if (!IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
+		return;
+
+	WARN_ON_ONCE(current->thread.kuap != 0);
+}
+
 static __always_inline void allow_user_access(void __user *to, const void __user *from,
 					      u32 size, unsigned long dir)
 {
-- 
2.25.0