MIPS: Add support for XPA.

Add support for extended physical addressing (XPA) so that
32-bit platforms can access equal to or greater than 40 bits
of physical addresses.

NOTE:
      1) XPA and EVA are not the same and cannot be used
         simultaneously.
      2) If you configure your kernel for XPA, the PTEs
         and all address sizes become 64-bit.
      3) Your platform MUST have working HIGHMEM support.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9355/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

11 files changed, 173 insertions, 44 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c7a16904cd03..69a3b0fab926 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -377,6 +377,7 @@ config MIPS_MALTA
         select SYS_HAS_CPU_MIPS32_R1
         select SYS_HAS_CPU_MIPS32_R2
         select SYS_HAS_CPU_MIPS32_R3_5
+        select SYS_HAS_CPU_MIPS32_R5
         select SYS_HAS_CPU_MIPS32_R6
         select SYS_HAS_CPU_MIPS64_R1
         select SYS_HAS_CPU_MIPS64_R2
@@ -386,6 +387,7 @@ config MIPS_MALTA
         select SYS_SUPPORTS_32BIT_KERNEL
         select SYS_SUPPORTS_64BIT_KERNEL
         select SYS_SUPPORTS_BIG_ENDIAN
+        select SYS_SUPPORTS_HIGHMEM
         select SYS_SUPPORTS_LITTLE_ENDIAN
         select SYS_SUPPORTS_MICROMIPS
         select SYS_SUPPORTS_MIPS_CMP
@@ -1596,6 +1598,33 @@ config CPU_MIPS32_3_5_EVA
           One of its primary benefits is an increase in the maximum size
           of lowmem (up to 3GB). If unsure, say 'N' here.
 
+config CPU_MIPS32_R5_FEATURES
+        bool "MIPS32 Release 5 Features"
+        depends on SYS_HAS_CPU_MIPS32_R5
+        depends on CPU_MIPS32_R2
+        help
+          Choose this option to build a kernel for release 2 or later of the
+          MIPS32 architecture including features from release 5 such as
+          support for Extended Physical Addressing (XPA).
+
+config CPU_MIPS32_R5_XPA
+        bool "Extended Physical Addressing (XPA)"
+        depends on CPU_MIPS32_R5_FEATURES
+        depends on !EVA
+        depends on !PAGE_SIZE_4KB
+        depends on SYS_SUPPORTS_HIGHMEM
+        select XPA
+        select HIGHMEM
+        select ARCH_PHYS_ADDR_T_64BIT
+        default n
+        help
+          Choose this option if you want to enable the Extended Physical
+          Addressing (XPA) on your MIPS32 core (such as P5600 series). The
+          benefit is to increase physical addressing equal to or greater
+          than 40 bits. Note that this has the side effect of turning on
+          64-bit addressing which in turn makes the PTEs 64-bit in size.
+          If unsure, say 'N' here.
+
 if CPU_LOONGSON2F
 config CPU_NOP_WORKAROUNDS
         bool
@@ -1699,6 +1728,9 @@ config SYS_HAS_CPU_MIPS32_R2
 config SYS_HAS_CPU_MIPS32_R3_5
         bool
 
+config SYS_HAS_CPU_MIPS32_R5
+        bool
+
 config SYS_HAS_CPU_MIPS32_R6
         bool
 
@@ -1836,6 +1868,9 @@ config CPU_MIPSR6
 config EVA
         bool
 
+config XPA
+        bool
+
 config SYS_SUPPORTS_32BIT_KERNEL
         bool
 config SYS_SUPPORTS_64BIT_KERNEL
diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 0d8208de9a3f..a324751b02ff 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -139,6 +139,9 @@
 # endif
 #endif
 
+#ifndef cpu_has_xpa
+#define cpu_has_xpa             (cpu_data[0].options & MIPS_CPU_XPA)
+#endif
 #ifndef cpu_has_vtag_icache
 #define cpu_has_vtag_icache     (cpu_data[0].icache.flags & MIPS_CACHE_VTAG)
 #endif
diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
index 15687234d70a..e492c740bb94 100644
--- a/arch/mips/include/asm/cpu.h
+++ b/arch/mips/include/asm/cpu.h
@@ -377,6 +377,7 @@ enum cpu_type_enum {
 #define MIPS_CPU_MAAR           0x400000000ull /* MAAR(I) registers are present */
 #define MIPS_CPU_FRE            0x800000000ull /* FRE & UFE bits implemented */
 #define MIPS_CPU_RW_LLB         0x1000000000ull /* LLADDR/LLB writes are allowed */
+#define MIPS_CPU_XPA            0x2000000000ull /* CPU supports Extended Physical Addressing */
 
 /*
  * CPU ASE encodings
diff --git a/arch/mips/include/asm/pgtable-32.h b/arch/mips/include/asm/pgtable-32.h
index a6be006b6f75..7d56686c0e62 100644
--- a/arch/mips/include/asm/pgtable-32.h
+++ b/arch/mips/include/asm/pgtable-32.h
@@ -105,13 +105,16 @@ static inline void pmd_clear(pmd_t *pmdp)
 
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 #define pte_page(x)             pfn_to_page(pte_pfn(x))
-#define pte_pfn(x)              ((unsigned long)((x).pte_high >> 6))
+#define pte_pfn(x)              (((unsigned long)((x).pte_high >> _PFN_SHIFT)) | (unsigned long)((x).pte_low << _PAGE_PRESENT_SHIFT))
 static inline pte_t
 pfn_pte(unsigned long pfn, pgprot_t prot)
 {
         pte_t pte;
-        pte.pte_high = (pfn << 6) | (pgprot_val(prot) & 0x3f);
-        pte.pte_low = pgprot_val(prot);
+
+        pte.pte_low = (pfn >> _PAGE_PRESENT_SHIFT) |
+                                (pgprot_val(prot) & ~_PFNX_MASK);
+        pte.pte_high = (pfn << _PFN_SHIFT) |
+                                (pgprot_val(prot) & ~_PFN_MASK);
         return pte;
 }
 
@@ -166,9 +169,9 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 
 /* Swap entries must have VALID and GLOBAL bits cleared. */
-#define __swp_type(x)                   (((x).val >> 2) & 0x1f)
-#define __swp_offset(x)                  ((x).val >> 7)
-#define __swp_entry(type,offset)        ((swp_entry_t)  { ((type) << 2) | ((offset) << 7) })
+#define __swp_type(x)                   (((x).val >> 4) & 0x1f)
+#define __swp_offset(x)                  ((x).val >> 9)
+#define __swp_entry(type,offset)        ((swp_entry_t)  { ((type) << 4) | ((offset) << 9) })
 #define __pte_to_swp_entry(pte)         ((swp_entry_t) { (pte).pte_high })
 #define __swp_entry_to_pte(x)           ((pte_t) { 0, (x).val })
 
diff --git a/arch/mips/include/asm/pgtable-bits.h b/arch/mips/include/asm/pgtable-bits.h
index 8e432a8ec4fe..18ae5ddef118 100644
--- a/arch/mips/include/asm/pgtable-bits.h
+++ b/arch/mips/include/asm/pgtable-bits.h
@@ -37,7 +37,11 @@
 /*
  * The following bits are implemented by the TLB hardware
  */
-#define _PAGE_GLOBAL_SHIFT      0
+#define _PAGE_NO_EXEC_SHIFT     0
+#define _PAGE_NO_EXEC           (1 << _PAGE_NO_EXEC_SHIFT)
+#define _PAGE_NO_READ_SHIFT     (_PAGE_NO_EXEC_SHIFT + 1)
+#define _PAGE_NO_READ           (1 << _PAGE_NO_READ_SHIFT)
+#define _PAGE_GLOBAL_SHIFT      (_PAGE_NO_READ_SHIFT + 1)
 #define _PAGE_GLOBAL            (1 << _PAGE_GLOBAL_SHIFT)
 #define _PAGE_VALID_SHIFT       (_PAGE_GLOBAL_SHIFT + 1)
 #define _PAGE_VALID             (1 << _PAGE_VALID_SHIFT)
@@ -49,7 +53,7 @@
 /*
  * The following bits are implemented in software
  */
-#define _PAGE_PRESENT_SHIFT     (_CACHE_SHIFT + 3)
+#define _PAGE_PRESENT_SHIFT     (24)
 #define _PAGE_PRESENT           (1 << _PAGE_PRESENT_SHIFT)
 #define _PAGE_READ_SHIFT        (_PAGE_PRESENT_SHIFT + 1)
 #define _PAGE_READ              (1 << _PAGE_READ_SHIFT)
@@ -62,6 +66,11 @@
 
 #define _PFN_SHIFT              (PAGE_SHIFT - 12 + _CACHE_SHIFT + 3)
 
+/*
+ * Bits for extended EntryLo0/EntryLo1 registers
+ */
+#define _PFNX_MASK              0xffffff
+
 #elif defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 
 /*
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index e1fec0237ce2..bffd46ca3694 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -133,7 +133,7 @@ extern void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 
-#define pte_none(pte)           (!(((pte).pte_low | (pte).pte_high) & ~_PAGE_GLOBAL))
+#define pte_none(pte)           (!(((pte).pte_high) & ~_PAGE_GLOBAL))
 #define pte_present(pte)        ((pte).pte_low & _PAGE_PRESENT)
 
 static inline void set_pte(pte_t *ptep, pte_t pte)
@@ -142,16 +142,14 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
         smp_wmb();
         ptep->pte_low = pte.pte_low;
 
-        if (pte.pte_low & _PAGE_GLOBAL) {
+        if (pte.pte_high & _PAGE_GLOBAL) {
                 pte_t *buddy = ptep_buddy(ptep);
                 /*
                  * Make sure the buddy is global too (if it's !none,
                  * it better already be global)
                  */
-                if (pte_none(*buddy)) {
-                        buddy->pte_low  |= _PAGE_GLOBAL;
+                if (pte_none(*buddy))
                         buddy->pte_high |= _PAGE_GLOBAL;
-                }
         }
 }
 
@@ -161,8 +159,8 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *pt
 
         htw_stop();
         /* Preserve global status for the pair */
-        if (ptep_buddy(ptep)->pte_low & _PAGE_GLOBAL)
-                null.pte_low = null.pte_high = _PAGE_GLOBAL;
+        if (ptep_buddy(ptep)->pte_high & _PAGE_GLOBAL)
+                null.pte_high = _PAGE_GLOBAL;
 
         set_pte_at(mm, addr, ptep, null);
         htw_start();
@@ -242,21 +240,21 @@ static inline int pte_young(pte_t pte)	{ return pte.pte_low & _PAGE_ACCESSED; }
 
 static inline pte_t pte_wrprotect(pte_t pte)
 {
-        pte.pte_low  &= ~(_PAGE_WRITE | _PAGE_SILENT_WRITE);
+        pte.pte_low  &= ~_PAGE_WRITE;
         pte.pte_high &= ~_PAGE_SILENT_WRITE;
         return pte;
 }
 
 static inline pte_t pte_mkclean(pte_t pte)
 {
-        pte.pte_low  &= ~(_PAGE_MODIFIED | _PAGE_SILENT_WRITE);
+        pte.pte_low  &= ~_PAGE_MODIFIED;
         pte.pte_high &= ~_PAGE_SILENT_WRITE;
         return pte;
 }
 
 static inline pte_t pte_mkold(pte_t pte)
 {
-        pte.pte_low  &= ~(_PAGE_ACCESSED | _PAGE_SILENT_READ);
+        pte.pte_low  &= ~_PAGE_ACCESSED;
         pte.pte_high &= ~_PAGE_SILENT_READ;
         return pte;
 }
@@ -264,30 +262,24 @@ static inline pte_t pte_mkold(pte_t pte)
 static inline pte_t pte_mkwrite(pte_t pte)
 {
         pte.pte_low |= _PAGE_WRITE;
-        if (pte.pte_low & _PAGE_MODIFIED) {
-                pte.pte_low  |= _PAGE_SILENT_WRITE;
+        if (pte.pte_low & _PAGE_MODIFIED)
                 pte.pte_high |= _PAGE_SILENT_WRITE;
-        }
         return pte;
 }
 
 static inline pte_t pte_mkdirty(pte_t pte)
 {
         pte.pte_low |= _PAGE_MODIFIED;
-        if (pte.pte_low & _PAGE_WRITE) {
-                pte.pte_low  |= _PAGE_SILENT_WRITE;
+        if (pte.pte_low & _PAGE_WRITE)
                 pte.pte_high |= _PAGE_SILENT_WRITE;
-        }
         return pte;
 }
 
 static inline pte_t pte_mkyoung(pte_t pte)
 {
         pte.pte_low |= _PAGE_ACCESSED;
-        if (pte.pte_low & _PAGE_READ) {
-                pte.pte_low  |= _PAGE_SILENT_READ;
+        if (pte.pte_low & _PAGE_READ)
                 pte.pte_high |= _PAGE_SILENT_READ;
-        }
         return pte;
 }
 #else
@@ -391,10 +383,10 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
-        pte.pte_low  &= _PAGE_CHG_MASK;
+        pte.pte_low  &= (_PAGE_MODIFIED | _PAGE_ACCESSED | _PFNX_MASK);
         pte.pte_high &= (_PFN_MASK | _CACHE_MASK);
-        pte.pte_low  |= pgprot_val(newprot);
-        pte.pte_high |= pgprot_val(newprot) & ~(_PFN_MASK | _CACHE_MASK);
+        pte.pte_low  |= pgprot_val(newprot) & ~_PFNX_MASK;
+        pte.pte_high |= pgprot_val(newprot) & ~_PFN_MASK;
         return pte;
 }
 #else
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 48dfb9de853d..ac96817d1f99 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -516,6 +516,10 @@ static inline unsigned int decode_config5(struct cpuinfo_mips *c)
                 c->options |= MIPS_CPU_MAAR;
         if (config5 & MIPS_CONF5_LLB)
                 c->options |= MIPS_CPU_RW_LLB;
+#ifdef CONFIG_XPA
+        if (config5 & MIPS_CONF5_MVH)
+                c->options |= MIPS_CPU_XPA;
+#endif
 
         return config5 & MIPS_CONF_M;
 }
diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c
index 130af7d26a9c..298b2b773d12 100644
--- a/arch/mips/kernel/proc.c
+++ b/arch/mips/kernel/proc.c
@@ -120,6 +120,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
         if (cpu_has_msa)        seq_printf(m, "%s", " msa");
         if (cpu_has_eva)        seq_printf(m, "%s", " eva");
         if (cpu_has_htw)        seq_printf(m, "%s", " htw");
+        if (cpu_has_xpa)        seq_printf(m, "%s", " xpa");
         seq_printf(m, "\n");
 
         if (cpu_has_mmips) {
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 448cde372af0..faa5c9822ecc 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -96,7 +96,7 @@ static void *__kmap_pgprot(struct page *page, unsigned long addr, pgprot_t prot)
         vaddr = __fix_to_virt(FIX_CMAP_END - idx);
         pte = mk_pte(page, prot);
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
-        entrylo = pte.pte_high;
+        entrylo = pte_to_entrylo(pte.pte_high);
 #else
         entrylo = pte_to_entrylo(pte_val(pte));
 #endif
@@ -106,6 +106,11 @@ static void *__kmap_pgprot(struct page *page, unsigned long addr, pgprot_t prot)
         write_c0_entryhi(vaddr & (PAGE_MASK << 1));
         write_c0_entrylo0(entrylo);
         write_c0_entrylo1(entrylo);
+#ifdef CONFIG_XPA
+        entrylo = (pte.pte_low & _PFNX_MASK);
+        writex_c0_entrylo0(entrylo);
+        writex_c0_entrylo1(entrylo);
+#endif
         tlbidx = read_c0_wired();
         write_c0_wired(tlbidx + 1);
         write_c0_index(tlbidx);
diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c
index b2afa49beab0..c2500f4cb1d1 100644
--- a/arch/mips/mm/tlb-r4k.c
+++ b/arch/mips/mm/tlb-r4k.c
@@ -333,9 +333,17 @@ void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
                 ptep = pte_offset_map(pmdp, address);
 
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
+#ifdef CONFIG_XPA
+                write_c0_entrylo0(pte_to_entrylo(ptep->pte_high));
+                writex_c0_entrylo0(ptep->pte_low & _PFNX_MASK);
+                ptep++;
+                write_c0_entrylo1(pte_to_entrylo(ptep->pte_high));
+                writex_c0_entrylo1(ptep->pte_low & _PFNX_MASK);
+#else
                 write_c0_entrylo0(ptep->pte_high);
                 ptep++;
                 write_c0_entrylo1(ptep->pte_high);
+#endif
 #else
                 write_c0_entrylo0(pte_to_entrylo(pte_val(*ptep++)));
                 write_c0_entrylo1(pte_to_entrylo(pte_val(*ptep)));
@@ -355,6 +363,9 @@ void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
 void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
                      unsigned long entryhi, unsigned long pagemask)
 {
+#ifdef CONFIG_XPA
+        panic("Broken for XPA kernels");
+#else
         unsigned long flags;
         unsigned long wired;
         unsigned long old_pagemask;
@@ -383,6 +394,7 @@ void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
         write_c0_pagemask(old_pagemask);
         local_flush_tlb_all();
         local_irq_restore(flags);
+#endif
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 20d985901e44..7709920e0cef 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -35,6 +35,17 @@
 #include <asm/uasm.h>
 #include <asm/setup.h>
 
+static int __cpuinitdata mips_xpa_disabled;
+
+static int __init xpa_disable(char *s)
+{
+        mips_xpa_disabled = 1;
+
+        return 1;
+}
+
+__setup("noxpa", xpa_disable);
+
 /*
  * TLB load/store/modify handlers.
  *
@@ -1027,12 +1038,27 @@ static void build_update_entries(u32 **p, unsigned int tmp, unsigned int ptep)
         } else {
                 int pte_off_even = sizeof(pte_t) / 2;
                 int pte_off_odd = pte_off_even + sizeof(pte_t);
+#ifdef CONFIG_XPA
+                const int scratch = 1; /* Our extra working register */
 
-                /* The pte entries are pre-shifted */
-                uasm_i_lw(p, tmp, pte_off_even, ptep); /* get even pte */
-                UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
-                uasm_i_lw(p, ptep, pte_off_odd, ptep); /* get odd pte */
-                UASM_i_MTC0(p, ptep, C0_ENTRYLO1); /* load it */
+                uasm_i_addu(p, scratch, 0, ptep);
+#endif
+                uasm_i_lw(p, tmp, pte_off_even, ptep); /* even pte */
+                uasm_i_lw(p, ptep, pte_off_odd, ptep); /* odd pte */
+                UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL));
+                UASM_i_ROTR(p, ptep, ptep, ilog2(_PAGE_GLOBAL));
+                UASM_i_MTC0(p, tmp, C0_ENTRYLO0);
+                UASM_i_MTC0(p, ptep, C0_ENTRYLO1);
+#ifdef CONFIG_XPA
+                uasm_i_lw(p, tmp, 0, scratch);
+                uasm_i_lw(p, ptep, sizeof(pte_t), scratch);
+                uasm_i_lui(p, scratch, 0xff);
+                uasm_i_ori(p, scratch, scratch, 0xffff);
+                uasm_i_and(p, tmp, scratch, tmp);
+                uasm_i_and(p, ptep, scratch, ptep);
+                uasm_i_mthc0(p, tmp, C0_ENTRYLO0);
+                uasm_i_mthc0(p, ptep, C0_ENTRYLO1);
+#endif
         }
 #else
         UASM_i_LW(p, tmp, 0, ptep); /* get even pte */
@@ -1533,8 +1559,14 @@ iPTE_SW(u32 **p, struct uasm_reloc **r, unsigned int pte, unsigned int ptr,
 {
 #ifdef CONFIG_PHYS_ADDR_T_64BIT
         unsigned int hwmode = mode & (_PAGE_VALID | _PAGE_DIRTY);
-#endif
 
+        if (!cpu_has_64bits) {
+                const int scratch = 1; /* Our extra working register */
+
+                uasm_i_lui(p, scratch, (mode >> 16));
+                uasm_i_or(p, pte, pte, scratch);
+        } else
+#endif
         uasm_i_ori(p, pte, pte, mode);
 #ifdef CONFIG_SMP
 # ifdef CONFIG_PHYS_ADDR_T_64BIT
@@ -1598,15 +1630,17 @@ build_pte_present(u32 **p, struct uasm_reloc **r,
                         uasm_il_bbit0(p, r, pte, ilog2(_PAGE_PRESENT), lid);
                         uasm_i_nop(p);
                 } else {
-                        uasm_i_andi(p, t, pte, _PAGE_PRESENT);
+                        uasm_i_srl(p, t, pte, _PAGE_PRESENT_SHIFT);
+                        uasm_i_andi(p, t, t, 1);
                         uasm_il_beqz(p, r, t, lid);
                         if (pte == t)
                                 /* You lose the SMP race :-(*/
                                 iPTE_LW(p, pte, ptr);
                 }
         } else {
-                uasm_i_andi(p, t, pte, _PAGE_PRESENT | _PAGE_READ);
-                uasm_i_xori(p, t, t, _PAGE_PRESENT | _PAGE_READ);
+                uasm_i_srl(p, t, pte, _PAGE_PRESENT_SHIFT);
+                uasm_i_andi(p, t, t, 3);
+                uasm_i_xori(p, t, t, 3);
                 uasm_il_bnez(p, r, t, lid);
                 if (pte == t)
                         /* You lose the SMP race :-(*/
@@ -1635,8 +1669,9 @@ build_pte_writable(u32 **p, struct uasm_reloc **r,
 {
         int t = scratch >= 0 ? scratch : pte;
 
-        uasm_i_andi(p, t, pte, _PAGE_PRESENT | _PAGE_WRITE);
-        uasm_i_xori(p, t, t, _PAGE_PRESENT | _PAGE_WRITE);
+        uasm_i_srl(p, t, pte, _PAGE_PRESENT_SHIFT);
+        uasm_i_andi(p, t, t, 5);
+        uasm_i_xori(p, t, t, 5);
         uasm_il_bnez(p, r, t, lid);
         if (pte == t)
                 /* You lose the SMP race :-(*/
@@ -1672,7 +1707,8 @@ build_pte_modifiable(u32 **p, struct uasm_reloc **r,
                 uasm_i_nop(p);
         } else {
                 int t = scratch >= 0 ? scratch : pte;
-                uasm_i_andi(p, t, pte, _PAGE_WRITE);
+                uasm_i_srl(p, t, pte, _PAGE_WRITE_SHIFT);
+                uasm_i_andi(p, t, t, 1);
                 uasm_il_beqz(p, r, t, lid);
                 if (pte == t)
                         /* You lose the SMP race :-(*/
@@ -2285,6 +2321,11 @@ static void config_htw_params(void)
 
         pwsize = ilog2(PTRS_PER_PGD) << MIPS_PWSIZE_GDW_SHIFT;
         pwsize |= ilog2(PTRS_PER_PTE) << MIPS_PWSIZE_PTW_SHIFT;
+
+        /* If XPA has been enabled, PTEs are 64-bit in size. */
+        if (read_c0_pagegrain() & PG_ELPA)
+                pwsize |= 1;
+
         write_c0_pwsize(pwsize);
 
         /* Make sure everything is set before we enable the HTW */
@@ -2298,6 +2339,28 @@ static void config_htw_params(void)
         print_htw_config();
 }
 
+static void config_xpa_params(void)
+{
+#ifdef CONFIG_XPA
+        unsigned int pagegrain;
+
+        if (mips_xpa_disabled) {
+                pr_info("Extended Physical Addressing (XPA) disabled\n");
+                return;
+        }
+
+        pagegrain = read_c0_pagegrain();
+        write_c0_pagegrain(pagegrain | PG_ELPA);
+        back_to_back_c0_hazard();
+        pagegrain = read_c0_pagegrain();
+
+        if (pagegrain & PG_ELPA)
+                pr_info("Extended Physical Addressing (XPA) enabled\n");
+        else
+                panic("Extended Physical Addressing (XPA) disabled");
+#endif
+}
+
 void build_tlb_refill_handler(void)
 {
         /*
@@ -2362,8 +2425,9 @@ void build_tlb_refill_handler(void)
                 }
                 if (cpu_has_local_ebase)
                         build_r4000_tlb_refill_handler();
+                if (cpu_has_xpa)
+                        config_xpa_params();
                 if (cpu_has_htw)
                         config_htw_params();
-
         }
 }