MIPS: Implement Read Inhibit/eXecute Inhibit

The SmartMIPS ASE specifies how Read Inhibit (RI) and eXecute Inhibit
(XI) bits in the page tables work. The upper two bits of EntryLo{0,1}
are RI and XI when the feature is enabled in the PageGrain register.
SmartMIPS only covers 32-bit systems. Cavium Octeon+ extends this to
64-bit systems by continuing to place the RI and XI bits in the top of
EntryLo even when EntryLo is 64-bits wide.

Because we need to carry the RI and XI bits in the PTE, the layout of
the PTE is changed. There is a two instruction overhead in the TLB
refill hot path to get the EntryLo bits into the proper position.
Also the TLB load exception has to probe the TLB to check if RI or XI
caused the exception.

Also of note is that the layout of the PTE bits is done at compile and
runtime rather than statically. In the 32-bit case this allows for
the same number of PFN bits as before the patch as the _PAGE_HUGE is
not supported in 32-bit kernels (we have _PAGE_NO_EXEC and
_PAGE_NO_READ instead of _PAGE_READ and _PAGE_HUGE).

The patch is tested on Cavium Octeon+, but should also work on 32-bit
systems with the Smart-MIPS ASE.

Signed-off-by: David Daney <[e-mail]>
To: [e-mail]
Patchwork: http://patchwork.linux-mips.org/patch/952/
Patchwork: http://patchwork.linux-mips.org/patch/956/
Patchwork: http://patchwork.linux-mips.org/patch/962/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/include/asm/cpu-features.h

···
 #ifndef cpu_has_smartmips
 #define cpu_has_smartmips      (cpu_data[0].ases & MIPS_ASE_SMARTMIPS)
 #endif
+#ifndef kernel_uses_smartmips_rixi
+#define kernel_uses_smartmips_rixi 0
+#endif
 #ifndef cpu_has_vtag_icache
 #define cpu_has_vtag_icache	(cpu_data[0].icache.flags & MIPS_CACHE_VTAG)
 #endif

arch/mips/include/asm/pgtable-32.h

···
 #define pte_pfn(x)		((unsigned long)((x).pte >> (PAGE_SHIFT + 2)))
 #define pfn_pte(pfn, prot)	__pte(((pfn) << (PAGE_SHIFT + 2)) | pgprot_val(prot))
 #else
-#define pte_pfn(x)		((unsigned long)((x).pte >> PAGE_SHIFT))
-#define pfn_pte(pfn, prot)	__pte(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
+#define pte_pfn(x)		((unsigned long)((x).pte >> _PFN_SHIFT))
+#define pfn_pte(pfn, prot)	__pte(((unsigned long long)(pfn) << _PFN_SHIFT) | pgprot_val(prot))
 #endif
 #endif /* defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) */
 

arch/mips/include/asm/pgtable-64.h

···
 #define pte_pfn(x)		((unsigned long)((x).pte >> (PAGE_SHIFT + 2)))
 #define pfn_pte(pfn, prot)	__pte(((pfn) << (PAGE_SHIFT + 2)) | pgprot_val(prot))
 #else
-#define pte_pfn(x)		((unsigned long)((x).pte >> PAGE_SHIFT))
-#define pfn_pte(pfn, prot)	__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
+#define pte_pfn(x)		((unsigned long)((x).pte >> _PFN_SHIFT))
+#define pfn_pte(pfn, prot)	__pte(((pfn) << _PFN_SHIFT) | pgprot_val(prot))
 #endif
 
 #define __pgd_offset(address)	pgd_index(address)

arch/mips/include/asm/pgtable-bits.h

···
 #define _CACHE_SHIFT                3
 #define _CACHE_MASK                 (7<<3)
 
-#else
+#elif defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 
 #define _PAGE_PRESENT               (1<<0)  /* implemented in software */
 #define _PAGE_READ                  (1<<1)  /* implemented in software */
···
 #define _PAGE_ACCESSED              (1<<3)  /* implemented in software */
 #define _PAGE_MODIFIED              (1<<4)  /* implemented in software */
 #define _PAGE_FILE                  (1<<4)  /* set:pagecache unset:swap */
-
-#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 
 #define _PAGE_GLOBAL                (1<<8)
 #define _PAGE_VALID                 (1<<9)
···
 #define _CACHE_UNCACHED             (1<<11)
 #define _CACHE_MASK                 (1<<11)
 
+#else /* 'Normal' r4K case */
+/*
+ * When using the RI/XI bit support, we have 13 bits of flags below
+ * the physical address. The RI/XI bits are placed such that a SRL 5
+ * can strip off the software bits, then a ROTR 2 can move the RI/XI
+ * into bits [63:62]. This also limits physical address to 56 bits,
+ * which is more than we need right now.
+ */
+
+/* implemented in software */
+#define _PAGE_PRESENT_SHIFT	(0)
+#define _PAGE_PRESENT		(1 << _PAGE_PRESENT_SHIFT)
+/* implemented in software, should be unused if kernel_uses_smartmips_rixi. */
+#define _PAGE_READ_SHIFT	(kernel_uses_smartmips_rixi ? _PAGE_PRESENT_SHIFT : _PAGE_PRESENT_SHIFT + 1)
+#define _PAGE_READ ({if (kernel_uses_smartmips_rixi) BUG(); 1 << _PAGE_READ_SHIFT; })
+/* implemented in software */
+#define _PAGE_WRITE_SHIFT	(_PAGE_READ_SHIFT + 1)
+#define _PAGE_WRITE		(1 << _PAGE_WRITE_SHIFT)
+/* implemented in software */
+#define _PAGE_ACCESSED_SHIFT	(_PAGE_WRITE_SHIFT + 1)
+#define _PAGE_ACCESSED		(1 << _PAGE_ACCESSED_SHIFT)
+/* implemented in software */
+#define _PAGE_MODIFIED_SHIFT	(_PAGE_ACCESSED_SHIFT + 1)
+#define _PAGE_MODIFIED		(1 << _PAGE_MODIFIED_SHIFT)
+/* set:pagecache unset:swap */
+#define _PAGE_FILE		(_PAGE_MODIFIED)
+
+#ifdef CONFIG_HUGETLB_PAGE
+/* huge tlb page */
+#define _PAGE_HUGE_SHIFT	(_PAGE_MODIFIED_SHIFT + 1)
+#define _PAGE_HUGE		(1 << _PAGE_HUGE_SHIFT)
 #else
-
-#define _PAGE_R4KBUG                (1<<5)  /* workaround for r4k bug  */
-#define _PAGE_HUGE                  (1<<5)  /* huge tlb page */
-#define _PAGE_GLOBAL                (1<<6)
-#define _PAGE_VALID                 (1<<7)
-#define _PAGE_SILENT_READ           (1<<7)  /* synonym                 */
-#define _PAGE_DIRTY                 (1<<8)  /* The MIPS dirty bit      */
-#define _PAGE_SILENT_WRITE          (1<<8)
-#define _CACHE_SHIFT		    9
-#define _CACHE_MASK                 (7<<9)
-
+#define _PAGE_HUGE_SHIFT	(_PAGE_MODIFIED_SHIFT)
+#define _PAGE_HUGE		({BUG(); 1; })  /* Dummy value */
 #endif
+
+/* Page cannot be executed */
+#define _PAGE_NO_EXEC_SHIFT	(kernel_uses_smartmips_rixi ? _PAGE_HUGE_SHIFT + 1 : _PAGE_HUGE_SHIFT)
+#define _PAGE_NO_EXEC		({if (!kernel_uses_smartmips_rixi) BUG(); 1 << _PAGE_NO_EXEC_SHIFT; })
+
+/* Page cannot be read */
+#define _PAGE_NO_READ_SHIFT	(kernel_uses_smartmips_rixi ? _PAGE_NO_EXEC_SHIFT + 1 : _PAGE_NO_EXEC_SHIFT)
+#define _PAGE_NO_READ		({if (!kernel_uses_smartmips_rixi) BUG(); 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)
+/* synonym                 */
+#define _PAGE_SILENT_READ	(_PAGE_VALID)
+
+/* The MIPS dirty bit      */
+#define _PAGE_DIRTY_SHIFT	(_PAGE_VALID_SHIFT + 1)
+#define _PAGE_DIRTY		(1 << _PAGE_DIRTY_SHIFT)
+#define _PAGE_SILENT_WRITE	(_PAGE_DIRTY)
+
+#define _CACHE_SHIFT		(_PAGE_DIRTY_SHIFT + 1)
+#define _CACHE_MASK		(7 << _CACHE_SHIFT)
+
+#define _PFN_SHIFT		(PAGE_SHIFT - 12 + _CACHE_SHIFT + 3)
+
 #endif /* defined(CONFIG_64BIT_PHYS_ADDR && defined(CONFIG_CPU_MIPS32) */
 
+#ifndef _PFN_SHIFT
+#define _PFN_SHIFT                  PAGE_SHIFT
+#endif
+#define _PFN_MASK		(~((1 << (_PFN_SHIFT)) - 1))
+
+#ifndef _PAGE_NO_READ
+#define _PAGE_NO_READ ({BUG(); 0; })
+#define _PAGE_NO_READ_SHIFT ({BUG(); 0; })
+#endif
+#ifndef _PAGE_NO_EXEC
+#define _PAGE_NO_EXEC ({BUG(); 0; })
+#endif
+#ifndef _PAGE_GLOBAL_SHIFT
+#define _PAGE_GLOBAL_SHIFT ilog2(_PAGE_GLOBAL)
+#endif
+
+
+#ifndef __ASSEMBLY__
+/*
+ * pte_to_entrylo converts a page table entry (PTE) into a Mips
+ * entrylo0/1 value.
+ */
+static inline uint64_t pte_to_entrylo(unsigned long pte_val)
+{
+	if (kernel_uses_smartmips_rixi) {
+		int sa;
+#ifdef CONFIG_32BIT
+		sa = 31 - _PAGE_NO_READ_SHIFT;
+#else
+		sa = 63 - _PAGE_NO_READ_SHIFT;
+#endif
+		/*
+		 * C has no way to express that this is a DSRL
+		 * _PAGE_NO_EXEC_SHIFT followed by a ROTR 2.  Luckily
+		 * in the fast path this is done in assembly
+		 */
+		return (pte_val >> _PAGE_GLOBAL_SHIFT) |
+			((pte_val & (_PAGE_NO_EXEC | _PAGE_NO_READ)) << sa);
+	}
+
+	return pte_val >> _PAGE_GLOBAL_SHIFT;
+}
+#endif
 
 /*
  * Cache attributes
···
 
 #endif
 
-#define __READABLE	(_PAGE_READ | _PAGE_SILENT_READ | _PAGE_ACCESSED)
+#define __READABLE	(_PAGE_SILENT_READ | _PAGE_ACCESSED | (kernel_uses_smartmips_rixi ? 0 : _PAGE_READ))
 #define __WRITEABLE	(_PAGE_WRITE | _PAGE_SILENT_WRITE | _PAGE_MODIFIED)
 
-#define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_ACCESSED | _PAGE_MODIFIED | _CACHE_MASK)
+#define _PAGE_CHG_MASK  (_PFN_MASK | _PAGE_ACCESSED | _PAGE_MODIFIED | _CACHE_MASK)
 
 #endif /* _ASM_PGTABLE_BITS_H */

arch/mips/include/asm/pgtable.h

···
 struct vm_area_struct;
 
 #define PAGE_NONE	__pgprot(_PAGE_PRESENT | _CACHE_CACHABLE_NONCOHERENT)
-#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_WRITE | (kernel_uses_smartmips_rixi ? 0 : _PAGE_READ) | \
 				 _page_cachable_default)
-#define PAGE_COPY	__pgprot(_PAGE_PRESENT | _PAGE_READ | \
-				 _page_cachable_default)
-#define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_READ | \
+#define PAGE_COPY	__pgprot(_PAGE_PRESENT | (kernel_uses_smartmips_rixi ? 0 : _PAGE_READ) | \
+				 (kernel_uses_smartmips_rixi ?  _PAGE_NO_EXEC : 0) | _page_cachable_default)
+#define PAGE_READONLY	__pgprot(_PAGE_PRESENT | (kernel_uses_smartmips_rixi ? 0 : _PAGE_READ) | \
 				 _page_cachable_default)
 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
 				 _PAGE_GLOBAL | _page_cachable_default)
-#define PAGE_USERIO	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+#define PAGE_USERIO	__pgprot(_PAGE_PRESENT | (kernel_uses_smartmips_rixi ? 0 : _PAGE_READ) | _PAGE_WRITE | \
 				 _page_cachable_default)
 #define PAGE_KERNEL_UNCACHED __pgprot(_PAGE_PRESENT | __READABLE | \
 			__WRITEABLE | _PAGE_GLOBAL | _CACHE_UNCACHED)
 
 /*
- * MIPS can't do page protection for execute, and considers that the same like
- * read. Also, write permissions imply read permissions. This is the closest
- * we can get by reasonable means..
+ * If _PAGE_NO_EXEC is not defined, we can't do page protection for
+ * execute, and consider it to be the same as read. Also, write
+ * permissions imply read permissions. This is the closest we can get
+ * by reasonable means..
  */
 
 /*
···
 static inline pte_t pte_mkyoung(pte_t pte)
 {
 	pte_val(pte) |= _PAGE_ACCESSED;
-	if (pte_val(pte) & _PAGE_READ)
-		pte_val(pte) |= _PAGE_SILENT_READ;
+	if (kernel_uses_smartmips_rixi) {
+		if (!(pte_val(pte) & _PAGE_NO_READ))
+			pte_val(pte) |= _PAGE_SILENT_READ;
+	} else {
+		if (pte_val(pte) & _PAGE_READ)
+			pte_val(pte) |= _PAGE_SILENT_READ;
+	}
 	return pte;
 }
 

arch/mips/mm/cache.c

···
 
 static inline void setup_protection_map(void)
 {
-	protection_map[0] = PAGE_NONE;
-	protection_map[1] = PAGE_READONLY;
-	protection_map[2] = PAGE_COPY;
-	protection_map[3] = PAGE_COPY;
-	protection_map[4] = PAGE_READONLY;
-	protection_map[5] = PAGE_READONLY;
-	protection_map[6] = PAGE_COPY;
-	protection_map[7] = PAGE_COPY;
-	protection_map[8] = PAGE_NONE;
-	protection_map[9] = PAGE_READONLY;
-	protection_map[10] = PAGE_SHARED;
-	protection_map[11] = PAGE_SHARED;
-	protection_map[12] = PAGE_READONLY;
-	protection_map[13] = PAGE_READONLY;
-	protection_map[14] = PAGE_SHARED;
-	protection_map[15] = PAGE_SHARED;
+	if (kernel_uses_smartmips_rixi) {
+		protection_map[0]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
+		protection_map[1]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
+		protection_map[2]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
+		protection_map[3]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
+		protection_map[4]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_READ);
+		protection_map[5]  = __pgprot(_page_cachable_default | _PAGE_PRESENT);
+		protection_map[6]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_READ);
+		protection_map[7]  = __pgprot(_page_cachable_default | _PAGE_PRESENT);
+
+		protection_map[8]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
+		protection_map[9]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
+		protection_map[10] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | _PAGE_NO_READ);
+		protection_map[11] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE);
+		protection_map[12] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_READ);
+		protection_map[13] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
+		protection_map[14] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE  | _PAGE_NO_READ);
+		protection_map[15] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE);
+
+	} else {
+		protection_map[0] = PAGE_NONE;
+		protection_map[1] = PAGE_READONLY;
+		protection_map[2] = PAGE_COPY;
+		protection_map[3] = PAGE_COPY;
+		protection_map[4] = PAGE_READONLY;
+		protection_map[5] = PAGE_READONLY;
+		protection_map[6] = PAGE_COPY;
+		protection_map[7] = PAGE_COPY;
+		protection_map[8] = PAGE_NONE;
+		protection_map[9] = PAGE_READONLY;
+		protection_map[10] = PAGE_SHARED;
+		protection_map[11] = PAGE_SHARED;
+		protection_map[12] = PAGE_READONLY;
+		protection_map[13] = PAGE_READONLY;
+		protection_map[14] = PAGE_SHARED;
+		protection_map[15] = PAGE_SHARED;
+	}
 }
 
 void __cpuinit cpu_cache_init(void)

arch/mips/mm/fault.c

···
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 	} else {
-		if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
-			goto bad_area;
+		if (kernel_uses_smartmips_rixi) {
+			if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
+#if 0
+				pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
+					  raw_smp_processor_id(),
+					  current->comm, current->pid,
+					  field, address, write,
+					  field, regs->cp0_epc);
+#endif
+				goto bad_area;
+			}
+			if (!(vma->vm_flags & VM_READ)) {
+#if 0
+				pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
+					  raw_smp_processor_id(),
+					  current->comm, current->pid,
+					  field, address, write,
+					  field, regs->cp0_epc);
+#endif
+				goto bad_area;
+			}
+		} else {
+			if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
+				goto bad_area;
+		}
 	}
 
 	/*

arch/mips/mm/init.c

···
 #if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
 	entrylo = pte.pte_high;
 #else
-	entrylo = pte_val(pte) >> 6;
+	entrylo = pte_to_entrylo(pte_val(pte));
 #endif
 
 	ENTER_CRITICAL(flags);

arch/mips/mm/tlb-r4k.c

···
 		unsigned long lo;
 		write_c0_pagemask(PM_HUGE_MASK);
 		ptep = (pte_t *)pmdp;
-		lo = pte_val(*ptep) >> 6;
+		lo = pte_to_entrylo(pte_val(*ptep));
 		write_c0_entrylo0(lo);
 		write_c0_entrylo1(lo + (HPAGE_SIZE >> 7));
 
···
 		ptep++;
 		write_c0_entrylo1(ptep->pte_high);
 #else
-		write_c0_entrylo0(pte_val(*ptep++) >> 6);
-		write_c0_entrylo1(pte_val(*ptep) >> 6);
+		write_c0_entrylo0(pte_to_entrylo(pte_val(*ptep++)));
+		write_c0_entrylo1(pte_to_entrylo(pte_val(*ptep)));
 #endif
 		mtc0_tlbw_hazard();
 		if (idx < 0)
···
 	    current_cpu_type() == CPU_R12000 ||
 	    current_cpu_type() == CPU_R14000)
 		write_c0_framemask(0);
+
+	if (kernel_uses_smartmips_rixi) {
+		/*
+		 * Enable the no read, no exec bits, and enable large virtual
+		 * address.
+		 */
+		u32 pg = PG_RIE | PG_XIE;
+#ifdef CONFIG_64BIT
+		pg |= PG_ELPA;
+#endif
+		write_c0_pagegrain(pg);
+	}
+
 	temp_tlb_entry = current_cpu_data.tlbsize - 1;
 
         /* From this point on the ARC firmware is dead.  */

arch/mips/mm/tlbex.c

···
 	label_vmalloc_done,
 	label_tlbw_hazard,
 	label_split,
+	label_tlbl_goaround1,
+	label_tlbl_goaround2,
 	label_nopage_tlbl,
 	label_nopage_tlbs,
 	label_nopage_tlbm,
···
 UASM_L_LA(_vmalloc_done)
 UASM_L_LA(_tlbw_hazard)
 UASM_L_LA(_split)
+UASM_L_LA(_tlbl_goaround1)
+UASM_L_LA(_tlbl_goaround2)
 UASM_L_LA(_nopage_tlbl)
 UASM_L_LA(_nopage_tlbs)
 UASM_L_LA(_nopage_tlbm)
···
 	}
 }
 
+static __cpuinit __maybe_unused void build_convert_pte_to_entrylo(u32 **p,
+								  unsigned int reg)
+{
+	if (kernel_uses_smartmips_rixi) {
+		UASM_i_SRL(p, reg, reg, ilog2(_PAGE_NO_EXEC));
+		UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
+	} else {
+#ifdef CONFIG_64BIT_PHYS_ADDR
+		uasm_i_dsrl(p, reg, reg, ilog2(_PAGE_GLOBAL));
+#else
+		UASM_i_SRL(p, reg, reg, ilog2(_PAGE_GLOBAL));
+#endif
+	}
+}
+
 #ifdef CONFIG_HUGETLB_PAGE
+
+static __cpuinit void build_restore_pagemask(u32 **p,
+					     struct uasm_reloc **r,
+					     unsigned int tmp,
+					     enum label_id lid)
+{
+	/* Reset default page size */
+	if (PM_DEFAULT_MASK >> 16) {
+		uasm_i_lui(p, tmp, PM_DEFAULT_MASK >> 16);
+		uasm_i_ori(p, tmp, tmp, PM_DEFAULT_MASK & 0xffff);
+		uasm_il_b(p, r, lid);
+		uasm_i_mtc0(p, tmp, C0_PAGEMASK);
+	} else if (PM_DEFAULT_MASK) {
+		uasm_i_ori(p, tmp, 0, PM_DEFAULT_MASK);
+		uasm_il_b(p, r, lid);
+		uasm_i_mtc0(p, tmp, C0_PAGEMASK);
+	} else {
+		uasm_il_b(p, r, lid);
+		uasm_i_mtc0(p, 0, C0_PAGEMASK);
+	}
+}
+
 static __cpuinit void build_huge_tlb_write_entry(u32 **p,
 						 struct uasm_label **l,
 						 struct uasm_reloc **r,
···
 
 	build_tlb_write_entry(p, l, r, wmode);
 
-	/* Reset default page size */
-	if (PM_DEFAULT_MASK >> 16) {
-		uasm_i_lui(p, tmp, PM_DEFAULT_MASK >> 16);
-		uasm_i_ori(p, tmp, tmp, PM_DEFAULT_MASK & 0xffff);
-		uasm_il_b(p, r, label_leave);
-		uasm_i_mtc0(p, tmp, C0_PAGEMASK);
-	} else if (PM_DEFAULT_MASK) {
-		uasm_i_ori(p, tmp, 0, PM_DEFAULT_MASK);
-		uasm_il_b(p, r, label_leave);
-		uasm_i_mtc0(p, tmp, C0_PAGEMASK);
-	} else {
-		uasm_il_b(p, r, label_leave);
-		uasm_i_mtc0(p, 0, C0_PAGEMASK);
-	}
+	build_restore_pagemask(p, r, tmp, label_leave);
 }
 
 /*
···
 	if (!small_sequence)
 		uasm_i_lui(p, tmp, HPAGE_SIZE >> (7 + 16));
 
-	UASM_i_SRL(p, pte, pte, 6); /* convert to entrylo */
+	build_convert_pte_to_entrylo(p, pte);
 	UASM_i_MTC0(p, pte, C0_ENTRYLO0); /* load it */
 	/* convert to entrylo1 */
 	if (small_sequence)
···
 	if (cpu_has_64bits) {
 		uasm_i_ld(p, tmp, 0, ptep); /* get even pte */
 		uasm_i_ld(p, ptep, sizeof(pte_t), ptep); /* get odd pte */
-		uasm_i_dsrl(p, tmp, tmp, 6); /* convert to entrylo0 */
-		UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
-		uasm_i_dsrl(p, ptep, ptep, 6); /* convert to entrylo1 */
+		if (kernel_uses_smartmips_rixi) {
+			UASM_i_SRL(p, tmp, tmp, ilog2(_PAGE_NO_EXEC));
+			UASM_i_SRL(p, ptep, ptep, ilog2(_PAGE_NO_EXEC));
+			UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
+			UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
+			UASM_i_ROTR(p, ptep, ptep, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
+		} else {
+			uasm_i_dsrl(p, tmp, tmp, ilog2(_PAGE_GLOBAL)); /* convert to entrylo0 */
+			UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
+			uasm_i_dsrl(p, ptep, ptep, ilog2(_PAGE_GLOBAL)); /* convert to entrylo1 */
+		}
 		UASM_i_MTC0(p, ptep, C0_ENTRYLO1); /* load it */
 	} else {
 		int pte_off_even = sizeof(pte_t) / 2;
···
 	UASM_i_LW(p, ptep, sizeof(pte_t), ptep); /* get odd pte */
 	if (r45k_bvahwbug())
 		build_tlb_probe_entry(p);
-	UASM_i_SRL(p, tmp, tmp, 6); /* convert to entrylo0 */
-	if (r4k_250MHZhwbug())
-		UASM_i_MTC0(p, 0, C0_ENTRYLO0);
-	UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
-	UASM_i_SRL(p, ptep, ptep, 6); /* convert to entrylo1 */
-	if (r45k_bvahwbug())
-		uasm_i_mfc0(p, tmp, C0_INDEX);
+	if (kernel_uses_smartmips_rixi) {
+		UASM_i_SRL(p, tmp, tmp, ilog2(_PAGE_NO_EXEC));
+		UASM_i_SRL(p, ptep, ptep, ilog2(_PAGE_NO_EXEC));
+		UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
+		if (r4k_250MHZhwbug())
+			UASM_i_MTC0(p, 0, C0_ENTRYLO0);
+		UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
+		UASM_i_ROTR(p, ptep, ptep, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
+	} else {
+		UASM_i_SRL(p, tmp, tmp, ilog2(_PAGE_GLOBAL)); /* convert to entrylo0 */
+		if (r4k_250MHZhwbug())
+			UASM_i_MTC0(p, 0, C0_ENTRYLO0);
+		UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
+		UASM_i_SRL(p, ptep, ptep, ilog2(_PAGE_GLOBAL)); /* convert to entrylo1 */
+		if (r45k_bvahwbug())
+			uasm_i_mfc0(p, tmp, C0_INDEX);
+	}
 	if (r4k_250MHZhwbug())
 		UASM_i_MTC0(p, 0, C0_ENTRYLO1);
 	UASM_i_MTC0(p, ptep, C0_ENTRYLO1); /* load it */
···
 build_pte_present(u32 **p, struct uasm_reloc **r,
 		  unsigned int pte, unsigned int ptr, enum label_id lid)
 {
-	uasm_i_andi(p, pte, pte, _PAGE_PRESENT | _PAGE_READ);
-	uasm_i_xori(p, pte, pte, _PAGE_PRESENT | _PAGE_READ);
-	uasm_il_bnez(p, r, pte, lid);
+	if (kernel_uses_smartmips_rixi) {
+		uasm_i_andi(p, pte, pte, _PAGE_PRESENT);
+		uasm_il_beqz(p, r, pte, lid);
+	} else {
+		uasm_i_andi(p, pte, pte, _PAGE_PRESENT | _PAGE_READ);
+		uasm_i_xori(p, pte, pte, _PAGE_PRESENT | _PAGE_READ);
+		uasm_il_bnez(p, r, pte, lid);
+	}
 	iPTE_LW(p, pte, ptr);
 }
 
···
 	build_pte_present(&p, &r, K0, K1, label_nopage_tlbl);
 	if (m4kc_tlbp_war())
 		build_tlb_probe_entry(&p);
+
+	if (kernel_uses_smartmips_rixi) {
+		/*
+		 * If the page is not _PAGE_VALID, RI or XI could not
+		 * have triggered it.  Skip the expensive test..
+		 */
+		uasm_i_andi(&p, K0, K0, _PAGE_VALID);
+		uasm_il_beqz(&p, &r, K0, label_tlbl_goaround1);
+		uasm_i_nop(&p);
+
+		uasm_i_tlbr(&p);
+		/* Examine  entrylo 0 or 1 based on ptr. */
+		uasm_i_andi(&p, K0, K1, sizeof(pte_t));
+		uasm_i_beqz(&p, K0, 8);
+
+		UASM_i_MFC0(&p, K0, C0_ENTRYLO0); /* load it in the delay slot*/
+		UASM_i_MFC0(&p, K0, C0_ENTRYLO1); /* load it if ptr is odd */
+		/*
+		 * If the entryLo (now in K0) is valid (bit 1), RI or
+		 * XI must have triggered it.
+		 */
+		uasm_i_andi(&p, K0, K0, 2);
+		uasm_il_bnez(&p, &r, K0, label_nopage_tlbl);
+
+		uasm_l_tlbl_goaround1(&l, p);
+		/* Reload the PTE value */
+		iPTE_LW(&p, K0, K1);
+	}
 	build_make_valid(&p, &r, K0, K1);
 	build_r4000_tlbchange_handler_tail(&p, &l, &r, K0, K1);
 
···
 	iPTE_LW(&p, K0, K1);
 	build_pte_present(&p, &r, K0, K1, label_nopage_tlbl);
 	build_tlb_probe_entry(&p);
+
+	if (kernel_uses_smartmips_rixi) {
+		/*
+		 * If the page is not _PAGE_VALID, RI or XI could not
+		 * have triggered it.  Skip the expensive test..
+		 */
+		uasm_i_andi(&p, K0, K0, _PAGE_VALID);
+		uasm_il_beqz(&p, &r, K0, label_tlbl_goaround2);
+		uasm_i_nop(&p);
+
+		uasm_i_tlbr(&p);
+		/* Examine  entrylo 0 or 1 based on ptr. */
+		uasm_i_andi(&p, K0, K1, sizeof(pte_t));
+		uasm_i_beqz(&p, K0, 8);
+
+		UASM_i_MFC0(&p, K0, C0_ENTRYLO0); /* load it in the delay slot*/
+		UASM_i_MFC0(&p, K0, C0_ENTRYLO1); /* load it if ptr is odd */
+		/*
+		 * If the entryLo (now in K0) is valid (bit 1), RI or
+		 * XI must have triggered it.
+		 */
+		uasm_i_andi(&p, K0, K0, 2);
+		uasm_il_beqz(&p, &r, K0, label_tlbl_goaround2);
+		/* Reload the PTE value */
+		iPTE_LW(&p, K0, K1);
+
+		/*
+		 * We clobbered C0_PAGEMASK, restore it.  On the other branch
+		 * it is restored in build_huge_tlb_write_entry.
+		 */
+		build_restore_pagemask(&p, &r, K0, label_nopage_tlbl);
+
+		uasm_l_tlbl_goaround2(&l, p);
+	}
 	uasm_i_ori(&p, K0, K0, (_PAGE_ACCESSED | _PAGE_VALID));
 	build_huge_handler_tail(&p, &r, &l, K0, K1);
 #endif