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From:   Jiaxun Yang <jiaxun.yang@flygoat.com>
To:     akpm@linux-foundation.org
Cc:     sunguoyun@loongson.cn, Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Paul Burton <paulburton@kernel.org>,
        =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= <f4bug@amsat.org>,
        Daniel Silsby <dansilsby@gmail.com>,
        Dmitry Korotin <dkorotin@wavecomp.com>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] mips/mm: Guard SOFT_DIRTY bit with config option
Date:   Mon, 27 Apr 2020 01:40:55 +0800
Message-Id: <20200426174058.1181837-1-jiaxun.yang@flygoat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

After guarding SOFT_DIRTY with config option, it won't occupy
precious page table bit on systems that didn't enable SOFT_DIRTY.

It can prevent page btis overflow on MIPS32R2 systems with RIXI
enabled.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reported-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
---
 arch/mips/include/asm/pgtable-bits.h | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/pgtable-bits.h b/arch/mips/include/asm/pgtable-bits.h
index d43fb6f8af14..e26dc41a8a68 100644
--- a/arch/mips/include/asm/pgtable-bits.h
+++ b/arch/mips/include/asm/pgtable-bits.h
@@ -55,7 +55,9 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+#if defined(CONFIG_HAVE_ARCH_SOFT_DIRTY)
 	_PAGE_SOFT_DIRTY_SHIFT,
+#endif
 };
 
 /*
@@ -85,7 +87,9 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+#if defined(CONFIG_HAVE_ARCH_SOFT_DIRTY)
 	_PAGE_SOFT_DIRTY_SHIFT,
+#endif
 };
 
 #elif defined(CONFIG_CPU_R3K_TLB)
@@ -101,7 +105,9 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+#if defined(CONFIG_HAVE_ARCH_SOFT_DIRTY)
 	_PAGE_SOFT_DIRTY_SHIFT,
+#endif
 
 	/* Used by TLB hardware (placed in EntryLo) */
 	_PAGE_GLOBAL_SHIFT = 8,
@@ -128,7 +134,9 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+#if defined(CONFIG_HAVE_ARCH_SOFT_DIRTY)
 	_PAGE_SOFT_DIRTY_SHIFT,
+#endif
 	/* Used by TLB hardware (placed in EntryLo*) */
 #if defined(CONFIG_CPU_HAS_RIXI)
 	_PAGE_NO_EXEC_SHIFT,
@@ -155,7 +163,11 @@ enum pgtable_bits {
 #else
 # define _PAGE_SPECIAL		0
 #endif
-#define _PAGE_SOFT_DIRTY	(1 << _PAGE_SOFT_DIRTY_SHIFT)
+#if defined(CONFIG_HAVE_ARCH_SOFT_DIRTY)
+# define _PAGE_SOFT_DIRTY	(1 << _PAGE_SOFT_DIRTY_SHIFT)
+#else
+# define _PAGE_SOFT_DIRTY	0
+#endif
 
 /* Used by TLB hardware (placed in EntryLo*) */
 #if defined(CONFIG_XPA)
-- 
2.26.0.rc2