linux-kernel - [PATCH 2/5] powerpc/32s: Refactor update of user segment registers

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Message-Id: <47bd1f30d659bf0e00bbe81c8dde03ef22423198.1620808468.git.christophe.leroy@csgroup.eu>
Date:   Wed, 12 May 2021 08:35:03 +0000 (UTC)
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:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 2/5] powerpc/32s: Refactor update of user segment registers

KUEP implements the update of user segment registers.

Move it into mmu-hash.h in order to use it from other places.

And inline kuep_lock() and kuep_unlock() and remove kuep.c
inlining kuep_lock() is important for system_call_exception(),
otherwise system_call_exception() has to save into stack the
system call parameters that are used just after, and doing
that takes more instructions than kuep_lock() itself.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/book3s/32/mmu-hash.h | 27 +++++++++++++
 arch/powerpc/include/asm/kup.h                | 11 ++++-
 arch/powerpc/mm/book3s32/Makefile             |  1 -
 arch/powerpc/mm/book3s32/kuep.c               | 40 -------------------
 4 files changed, 36 insertions(+), 43 deletions(-)
 delete mode 100644 arch/powerpc/mm/book3s32/kuep.c

diff --git a/arch/powerpc/include/asm/book3s/32/mmu-hash.h b/arch/powerpc/include/asm/book3s/32/mmu-hash.h
index b85f8e114a9c..cc0284bbac86 100644
--- a/arch/powerpc/include/asm/book3s/32/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/32/mmu-hash.h
@@ -102,6 +102,33 @@ extern s32 patch__hash_page_B, patch__hash_page_C;
 extern s32 patch__flush_hash_A0, patch__flush_hash_A1, patch__flush_hash_A2;
 extern s32 patch__flush_hash_B;
 
+#include <asm/reg.h>
+#include <asm/task_size_32.h>
+
+#define UPDATE_TWO_USER_SEGMENTS(n) do {		\
+	if (TASK_SIZE > ((n) << 28))			\
+		mtsr(val1, (n) << 28);			\
+	if (TASK_SIZE > (((n) + 1) << 28))		\
+		mtsr(val2, ((n) + 1) << 28);		\
+	val1 = (val1 + 0x222) & 0xf0ffffff;		\
+	val2 = (val2 + 0x222) & 0xf0ffffff;		\
+} while (0)
+
+static __always_inline void update_user_segments(u32 val)
+{
+	int val1 = val;
+	int val2 = (val + 0x111) & 0xf0ffffff;
+
+	UPDATE_TWO_USER_SEGMENTS(0);
+	UPDATE_TWO_USER_SEGMENTS(2);
+	UPDATE_TWO_USER_SEGMENTS(4);
+	UPDATE_TWO_USER_SEGMENTS(6);
+	UPDATE_TWO_USER_SEGMENTS(8);
+	UPDATE_TWO_USER_SEGMENTS(10);
+	UPDATE_TWO_USER_SEGMENTS(12);
+	UPDATE_TWO_USER_SEGMENTS(14);
+}
+
 #endif /* !__ASSEMBLY__ */
 
 /* We happily ignore the smaller BATs on 601, we don't actually use
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
index a35ded8bedcd..ea83970734cf 100644
--- a/arch/powerpc/include/asm/kup.h
+++ b/arch/powerpc/include/asm/kup.h
@@ -47,8 +47,15 @@ static inline void setup_kuep(bool disabled) { }
 #endif /* CONFIG_PPC_KUEP */
 
 #if defined(CONFIG_PPC_KUEP) && defined(CONFIG_PPC_BOOK3S_32)
-void kuep_lock(void);
-void kuep_unlock(void);
+static inline void kuep_lock(void)
+{
+	update_user_segments(mfsr(0) | SR_NX);
+}
+
+static inline void kuep_unlock(void)
+{
+	update_user_segments(mfsr(0) & ~SR_NX);
+}
 #else
 static inline void kuep_lock(void) { }
 static inline void kuep_unlock(void) { }
diff --git a/arch/powerpc/mm/book3s32/Makefile b/arch/powerpc/mm/book3s32/Makefile
index 7f0c8a78ba0c..446d9de88ce4 100644
--- a/arch/powerpc/mm/book3s32/Makefile
+++ b/arch/powerpc/mm/book3s32/Makefile
@@ -9,4 +9,3 @@ endif
 obj-y += mmu.o mmu_context.o
 obj-$(CONFIG_PPC_BOOK3S_603) += nohash_low.o
 obj-$(CONFIG_PPC_BOOK3S_604) += hash_low.o tlb.o
-obj-$(CONFIG_PPC_KUEP) += kuep.o
diff --git a/arch/powerpc/mm/book3s32/kuep.c b/arch/powerpc/mm/book3s32/kuep.c
deleted file mode 100644
index 8ed1b8634839..000000000000
--- a/arch/powerpc/mm/book3s32/kuep.c
+++ /dev/null
@@ -1,40 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#include <asm/kup.h>
-#include <asm/reg.h>
-#include <asm/task_size_32.h>
-#include <asm/mmu.h>
-
-#define KUEP_UPDATE_TWO_USER_SEGMENTS(n) do {		\
-	if (TASK_SIZE > ((n) << 28))			\
-		mtsr(val1, (n) << 28);			\
-	if (TASK_SIZE > (((n) + 1) << 28))		\
-		mtsr(val2, ((n) + 1) << 28);		\
-	val1 = (val1 + 0x222) & 0xf0ffffff;		\
-	val2 = (val2 + 0x222) & 0xf0ffffff;		\
-} while (0)
-
-static __always_inline void kuep_update(u32 val)
-{
-	int val1 = val;
-	int val2 = (val + 0x111) & 0xf0ffffff;
-
-	KUEP_UPDATE_TWO_USER_SEGMENTS(0);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(2);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(4);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(6);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(8);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(10);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(12);
-	KUEP_UPDATE_TWO_USER_SEGMENTS(14);
-}
-
-void kuep_lock(void)
-{
-	kuep_update(mfsr(0) | SR_NX);
-}
-
-void kuep_unlock(void)
-{
-	kuep_update(mfsr(0) & ~SR_NX);
-}
-- 
2.25.0