[PATCH] mips/mm: Add page soft dirty tracking

[Guoyun Sun]

User space checkpoint and restart tool (CRIU) needs the page's change
to be soft tracked. This allows to do a pre checkpoint and then dump
only touched pages.

Signed-off-by: Guoyun Sun <sunguoyun@xxxxxxxxxxx>
---
 arch/mips/Kconfig                    |  1 +
 arch/mips/include/asm/pgtable-bits.h |  8 ++++--
 arch/mips/include/asm/pgtable.h      | 48 ++++++++++++++++++++++++++++++++++--
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 690718b..642fb47 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -491,6 +491,7 @@ config MACH_LOONGSON64
 	select COMMON_CLK
 	select USE_OF
 	select BUILTIN_DTB
+	select HAVE_ARCH_SOFT_DIRTY
 	help
 	  This enables the support of Loongson-2/3 family of machines.
 
diff --git a/arch/mips/include/asm/pgtable-bits.h b/arch/mips/include/asm/pgtable-bits.h
index 4da79b8..d43fb6f 100644
--- a/arch/mips/include/asm/pgtable-bits.h
+++ b/arch/mips/include/asm/pgtable-bits.h
@@ -55,6 +55,7 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+	_PAGE_SOFT_DIRTY_SHIFT,
 };
 
 /*
@@ -84,6 +85,7 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+	_PAGE_SOFT_DIRTY_SHIFT,
 };
 
 #elif defined(CONFIG_CPU_R3K_TLB)
@@ -99,6 +101,7 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
+	_PAGE_SOFT_DIRTY_SHIFT,
 
 	/* Used by TLB hardware (placed in EntryLo) */
 	_PAGE_GLOBAL_SHIFT = 8,
@@ -125,7 +128,7 @@ enum pgtable_bits {
 #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
 	_PAGE_SPECIAL_SHIFT,
 #endif
-
+	_PAGE_SOFT_DIRTY_SHIFT,
 	/* Used by TLB hardware (placed in EntryLo*) */
 #if defined(CONFIG_CPU_HAS_RIXI)
 	_PAGE_NO_EXEC_SHIFT,
@@ -152,6 +155,7 @@ enum pgtable_bits {
 #else
 # define _PAGE_SPECIAL		0
 #endif
+#define _PAGE_SOFT_DIRTY	(1 << _PAGE_SOFT_DIRTY_SHIFT)
 
 /* Used by TLB hardware (placed in EntryLo*) */
 #if defined(CONFIG_XPA)
@@ -269,6 +273,6 @@ static inline uint64_t pte_to_entrylo(unsigned long pte_val)
 #define __WRITEABLE	(_PAGE_SILENT_WRITE | _PAGE_WRITE | _PAGE_MODIFIED)
 
 #define _PAGE_CHG_MASK	(_PAGE_ACCESSED | _PAGE_MODIFIED |	\
-			 _PFN_MASK | _CACHE_MASK)
+			 _PAGE_SOFT_DIRTY | _PFN_MASK | _CACHE_MASK)
 
 #endif /* _ASM_PGTABLE_BITS_H */
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index f1801e7..64b07ff 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -400,7 +400,7 @@ static inline pte_t pte_mkwrite(pte_t pte)
 
 static inline pte_t pte_mkdirty(pte_t pte)
 {
-	pte_val(pte) |= _PAGE_MODIFIED;
+	pte_val(pte) |= _PAGE_MODIFIED | _PAGE_SOFT_DIRTY;
 	if (pte_val(pte) & _PAGE_WRITE)
 		pte_val(pte) |= _PAGE_SILENT_WRITE;
 	return pte;
@@ -423,6 +423,30 @@ static inline pte_t pte_mkhuge(pte_t pte)
 	return pte;
 }
 #endif /* CONFIG_MIPS_HUGE_TLB_SUPPORT */
+
+#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
+static inline bool pte_soft_dirty(pte_t pte)
+{
+	return pte_val(pte) & _PAGE_SOFT_DIRTY;
+}
+#define pte_swp_soft_dirty pte_soft_dirty
+
+static inline pte_t pte_mksoft_dirty(pte_t pte)
+{
+	pte_val(pte) |= _PAGE_SOFT_DIRTY;
+	return pte;
+}
+#define pte_swp_mksoft_dirty pte_mksoft_dirty
+
+static inline pte_t pte_clear_soft_dirty(pte_t pte)
+{
+	pte_val(pte) &= ~(_PAGE_SOFT_DIRTY);
+	return pte;
+}
+#define pte_swp_clear_soft_dirty pte_clear_soft_dirty
+
+#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
+
 #endif
 
 /*
@@ -579,7 +603,7 @@ static inline pmd_t pmd_mkclean(pmd_t pmd)
 
 static inline pmd_t pmd_mkdirty(pmd_t pmd)
 {
-	pmd_val(pmd) |= _PAGE_MODIFIED;
+	pmd_val(pmd) |= _PAGE_MODIFIED | _PAGE_SOFT_DIRTY;
 	if (pmd_val(pmd) & _PAGE_WRITE)
 		pmd_val(pmd) |= _PAGE_SILENT_WRITE;
 
@@ -608,6 +632,26 @@ static inline pmd_t pmd_mkyoung(pmd_t pmd)
 	return pmd;
 }
 
+#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
+static inline int pmd_soft_dirty(pmd_t pmd)
+{
+	return !!(pmd_val(pmd) & _PAGE_SOFT_DIRTY);
+}
+
+static inline pmd_t pmd_mksoft_dirty(pmd_t pmd)
+{
+	pmd_val(pmd) |= _PAGE_SOFT_DIRTY;
+	return pmd;
+}
+
+static inline pmd_t pmd_clear_soft_dirty(pmd_t pmd)
+{
+	pmd_val(pmd) &= ~(_PAGE_SOFT_DIRTY);
+	return pmd;
+}
+
+#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
+
 /* Extern to avoid header file madness */
 extern pmd_t mk_pmd(struct page *page, pgprot_t prot);
 
-- 
2.1.0