Initial import

1 files changed, 629 insertions, 0 deletions

diff --git a/arch/frv/mm/tlb-miss.S b/arch/frv/mm/tlb-miss.S
new file mode 100644
index 000000000..f3ac019bb
--- /dev/null
+++ b/arch/frv/mm/tlb-miss.S
@@ -0,0 +1,629 @@
+/* tlb-miss.S: TLB miss handlers
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/sys.h>
+#include <linux/linkage.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/spr-regs.h>
+
+	.section	.text..tlbmiss
+	.balign		4
+
+	.globl		__entry_insn_mmu_miss
+__entry_insn_mmu_miss:
+	break
+	nop
+
+	.globl		__entry_insn_mmu_exception
+__entry_insn_mmu_exception:
+	break
+	nop
+
+	.globl		__entry_data_mmu_miss
+__entry_data_mmu_miss:
+	break
+	nop
+
+	.globl		__entry_data_mmu_exception
+__entry_data_mmu_exception:
+	break
+	nop
+
+###############################################################################
+#
+# handle a lookup failure of one sort or another in a kernel TLB handler
+# On entry:
+#   GR29 - faulting address
+#   SCR2 - saved CCR
+#
+###############################################################################
+	.type		__tlb_kernel_fault,@function
+__tlb_kernel_fault:
+	# see if we're supposed to re-enable single-step mode upon return
+	sethi.p		%hi(__break_tlb_miss_return_break),gr30
+	setlo		%lo(__break_tlb_miss_return_break),gr30
+	movsg		pcsr,gr31
+
+	subcc		gr31,gr30,gr0,icc0
+	beq		icc0,#0,__tlb_kernel_fault_sstep
+
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	movgs		gr29,scr2			/* save EAR0 value */
+	sethi.p		%hi(__kernel_current_task),gr29
+	setlo		%lo(__kernel_current_task),gr29
+	ldi.p		@(gr29,#0),gr29			/* restore GR29 */
+
+	bra		__entry_kernel_handle_mmu_fault
+
+	# we've got to re-enable single-stepping
+__tlb_kernel_fault_sstep:
+	sethi.p		%hi(__break_tlb_miss_real_return_info),gr30
+	setlo		%lo(__break_tlb_miss_real_return_info),gr30
+	lddi		@(gr30,0),gr30
+	movgs		gr30,pcsr
+	movgs		gr31,psr
+
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	movgs		gr29,scr2			/* save EAR0 value */
+	sethi.p		%hi(__kernel_current_task),gr29
+	setlo		%lo(__kernel_current_task),gr29
+	ldi.p		@(gr29,#0),gr29			/* restore GR29 */
+	bra		__entry_kernel_handle_mmu_fault_sstep
+
+	.size		__tlb_kernel_fault, .-__tlb_kernel_fault
+
+###############################################################################
+#
+# handle a lookup failure of one sort or another in a user TLB handler
+# On entry:
+#   GR28 - faulting address
+#   SCR2 - saved CCR
+#
+###############################################################################
+	.type		__tlb_user_fault,@function
+__tlb_user_fault:
+	# see if we're supposed to re-enable single-step mode upon return
+	sethi.p		%hi(__break_tlb_miss_return_break),gr30
+	setlo		%lo(__break_tlb_miss_return_break),gr30
+	movsg		pcsr,gr31
+	subcc		gr31,gr30,gr0,icc0
+	beq		icc0,#0,__tlb_user_fault_sstep
+
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	bra		__entry_uspace_handle_mmu_fault
+
+	# we've got to re-enable single-stepping
+__tlb_user_fault_sstep:
+	sethi.p		%hi(__break_tlb_miss_real_return_info),gr30
+	setlo		%lo(__break_tlb_miss_real_return_info),gr30
+	lddi		@(gr30,0),gr30
+	movgs		gr30,pcsr
+	movgs		gr31,psr
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	bra		__entry_uspace_handle_mmu_fault_sstep
+
+	.size		__tlb_user_fault, .-__tlb_user_fault
+
+###############################################################################
+#
+# Kernel instruction TLB miss handler
+# On entry:
+#   GR1   - kernel stack pointer
+#   GR28  - saved exception frame pointer
+#   GR29  - faulting address
+#   GR31  - EAR0 ^ SCR0
+#   SCR0  - base of virtual range covered by cached PGE from last ITLB miss (or 0xffffffff)
+#   DAMR3 - mapped page directory
+#   DAMR4 - mapped page table as matched by SCR0
+#
+###############################################################################
+	.globl		__entry_kernel_insn_tlb_miss
+	.type		__entry_kernel_insn_tlb_miss,@function
+__entry_kernel_insn_tlb_miss:
+#if 0
+	sethi.p		%hi(0xe1200004),gr30
+	setlo		%lo(0xe1200004),gr30
+	st		gr0,@(gr30,gr0)
+	sethi.p		%hi(0xffc00100),gr30
+	setlo		%lo(0xffc00100),gr30
+	sth		gr30,@(gr30,gr0)
+	membar
+#endif
+
+	movsg		ccr,gr30			/* save CCR */
+	movgs		gr30,scr2
+
+	# see if the cached page table mapping is appropriate
+	srlicc.p	gr31,#26,gr0,icc0
+	setlos		0x3ffc,gr30
+	srli.p		gr29,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bne		icc0,#0,__itlb_k_PTD_miss
+
+__itlb_k_PTD_mapped:
+	# access the PTD with EAR0[25:14]
+	# - DAMLR4 points to the virtual address of the appropriate page table
+	# - the PTD holds 4096 PTEs
+	# - the PTD must be accessed uncached
+	# - the PTE must be marked accessed if it was valid
+	#
+	and		gr31,gr30,gr31
+	movsg		damlr4,gr30
+	add		gr30,gr31,gr31
+	ldi		@(gr31,#0),gr30			/* fetch the PTE */
+	andicc		gr30,#_PAGE_PRESENT,gr0,icc0
+	ori.p		gr30,#_PAGE_ACCESSED,gr30
+	beq		icc0,#0,__tlb_kernel_fault	/* jump if PTE invalid */
+	sti.p		gr30,@(gr31,#0)			/* update the PTE */
+	andi		gr30,#~_PAGE_ACCESSED,gr30
+
+	# we're using IAMR1 as an extra TLB entry
+	# - punt the entry here (if valid) to the real TLB and then replace with the new PTE
+	# - need to check DAMR1 lest we cause an multiple-DAT-hit exception
+	# - IAMPR1 has no WP bit, and we mustn't lose WP information
+	movsg		iampr1,gr31
+	andicc		gr31,#xAMPRx_V,gr0,icc0
+	setlos.p	0xfffff000,gr31
+	beq		icc0,#0,__itlb_k_nopunt		/* punt not required */
+
+	movsg		iamlr1,gr31
+	movgs		gr31,tplr			/* set TPLR.CXN */
+	tlbpr		gr31,gr0,#4,#0			/* delete matches from TLB, IAMR1, DAMR1 */
+
+	movsg		dampr1,gr31
+	ori		gr31,#xAMPRx_V,gr31		/* entry was invalidated by tlbpr #4 */
+	movgs		gr31,tppr
+	movsg		iamlr1,gr31			/* set TPLR.CXN */
+	movgs		gr31,tplr
+	tlbpr		gr31,gr0,#2,#0			/* save to the TLB */
+	movsg		tpxr,gr31			/* check the TLB write error flag */
+	andicc.p	gr31,#TPXR_E,gr0,icc0
+	setlos		#0xfffff000,gr31
+	bne		icc0,#0,__tlb_kernel_fault
+
+__itlb_k_nopunt:
+
+	# assemble the new TLB entry
+	and		gr29,gr31,gr29
+	movsg		cxnr,gr31
+	or		gr29,gr31,gr29
+	movgs		gr29,iamlr1			/* xAMLR = address | context number */
+	movgs		gr30,iampr1
+	movgs		gr29,damlr1
+	movgs		gr30,dampr1
+
+	# return, restoring registers
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	sethi.p		%hi(__kernel_current_task),gr29
+	setlo		%lo(__kernel_current_task),gr29
+	ldi		@(gr29,#0),gr29
+	rett		#0
+	beq		icc0,#3,0			/* prevent icache prefetch */
+
+	# the PTE we want wasn't in the PTD we have mapped, so we need to go looking for a more
+	# appropriate page table and map that instead
+	#   - access the PGD with EAR0[31:26]
+	#   - DAMLR3 points to the virtual address of the page directory
+	#   - the PGD holds 64 PGEs and each PGE/PME points to a set of page tables
+__itlb_k_PTD_miss:
+	srli		gr29,#26,gr31			/* calculate PGE offset */
+	slli		gr31,#8,gr31			/* and clear bottom bits */
+
+	movsg		damlr3,gr30
+	ld		@(gr31,gr30),gr30		/* access the PGE */
+
+	andicc.p	gr30,#_PAGE_PRESENT,gr0,icc0
+	andicc		gr30,#xAMPRx_SS,gr0,icc1
+
+	# map this PTD instead and record coverage address
+	ori.p		gr30,#xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V,gr30
+	beq		icc0,#0,__tlb_kernel_fault	/* jump if PGE not present */
+	slli.p		gr31,#18,gr31
+	bne		icc1,#0,__itlb_k_bigpage
+	movgs		gr30,dampr4
+	movgs		gr31,scr0
+
+	# we can now resume normal service
+	setlos		0x3ffc,gr30
+	srli.p		gr29,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bra		__itlb_k_PTD_mapped
+
+__itlb_k_bigpage:
+	break
+	nop
+
+	.size		__entry_kernel_insn_tlb_miss, .-__entry_kernel_insn_tlb_miss
+
+###############################################################################
+#
+# Kernel data TLB miss handler
+# On entry:
+#   GR1   - kernel stack pointer
+#   GR28  - saved exception frame pointer
+#   GR29  - faulting address
+#   GR31  - EAR0 ^ SCR1
+#   SCR1  - base of virtual range covered by cached PGE from last DTLB miss (or 0xffffffff)
+#   DAMR3 - mapped page directory
+#   DAMR5 - mapped page table as matched by SCR1
+#
+###############################################################################
+	.globl		__entry_kernel_data_tlb_miss
+	.type		__entry_kernel_data_tlb_miss,@function
+__entry_kernel_data_tlb_miss:
+#if 0
+	sethi.p		%hi(0xe1200004),gr30
+	setlo		%lo(0xe1200004),gr30
+	st		gr0,@(gr30,gr0)
+	sethi.p		%hi(0xffc00100),gr30
+	setlo		%lo(0xffc00100),gr30
+	sth		gr30,@(gr30,gr0)
+	membar
+#endif
+
+	movsg		ccr,gr30			/* save CCR */
+	movgs		gr30,scr2
+
+	# see if the cached page table mapping is appropriate
+	srlicc.p	gr31,#26,gr0,icc0
+	setlos		0x3ffc,gr30
+	srli.p		gr29,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bne		icc0,#0,__dtlb_k_PTD_miss
+
+__dtlb_k_PTD_mapped:
+	# access the PTD with EAR0[25:14]
+	# - DAMLR5 points to the virtual address of the appropriate page table
+	# - the PTD holds 4096 PTEs
+	# - the PTD must be accessed uncached
+	# - the PTE must be marked accessed if it was valid
+	#
+	and		gr31,gr30,gr31
+	movsg		damlr5,gr30
+	add		gr30,gr31,gr31
+	ldi		@(gr31,#0),gr30			/* fetch the PTE */
+	andicc		gr30,#_PAGE_PRESENT,gr0,icc0
+	ori.p		gr30,#_PAGE_ACCESSED,gr30
+	beq		icc0,#0,__tlb_kernel_fault	/* jump if PTE invalid */
+	sti.p		gr30,@(gr31,#0)			/* update the PTE */
+	andi		gr30,#~_PAGE_ACCESSED,gr30
+
+	# we're using DAMR1 as an extra TLB entry
+	# - punt the entry here (if valid) to the real TLB and then replace with the new PTE
+	# - need to check IAMR1 lest we cause an multiple-DAT-hit exception
+	movsg		dampr1,gr31
+	andicc		gr31,#xAMPRx_V,gr0,icc0
+	setlos.p	0xfffff000,gr31
+	beq		icc0,#0,__dtlb_k_nopunt		/* punt not required */
+
+	movsg		damlr1,gr31
+	movgs		gr31,tplr			/* set TPLR.CXN */
+	tlbpr		gr31,gr0,#4,#0			/* delete matches from TLB, IAMR1, DAMR1 */
+
+	movsg		dampr1,gr31
+	ori		gr31,#xAMPRx_V,gr31		/* entry was invalidated by tlbpr #4 */
+	movgs		gr31,tppr
+	movsg		damlr1,gr31			/* set TPLR.CXN */
+	movgs		gr31,tplr
+	tlbpr		gr31,gr0,#2,#0			/* save to the TLB */
+	movsg		tpxr,gr31			/* check the TLB write error flag */
+	andicc.p	gr31,#TPXR_E,gr0,icc0
+	setlos		#0xfffff000,gr31
+	bne		icc0,#0,__tlb_kernel_fault
+
+__dtlb_k_nopunt:
+
+	# assemble the new TLB entry
+	and		gr29,gr31,gr29
+	movsg		cxnr,gr31
+	or		gr29,gr31,gr29
+	movgs		gr29,iamlr1			/* xAMLR = address | context number */
+	movgs		gr30,iampr1
+	movgs		gr29,damlr1
+	movgs		gr30,dampr1
+
+	# return, restoring registers
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	sethi.p		%hi(__kernel_current_task),gr29
+	setlo		%lo(__kernel_current_task),gr29
+	ldi		@(gr29,#0),gr29
+	rett		#0
+	beq		icc0,#3,0			/* prevent icache prefetch */
+
+	# the PTE we want wasn't in the PTD we have mapped, so we need to go looking for a more
+	# appropriate page table and map that instead
+	#   - access the PGD with EAR0[31:26]
+	#   - DAMLR3 points to the virtual address of the page directory
+	#   - the PGD holds 64 PGEs and each PGE/PME points to a set of page tables
+__dtlb_k_PTD_miss:
+	srli		gr29,#26,gr31			/* calculate PGE offset */
+	slli		gr31,#8,gr31			/* and clear bottom bits */
+
+	movsg		damlr3,gr30
+	ld		@(gr31,gr30),gr30		/* access the PGE */
+
+	andicc.p	gr30,#_PAGE_PRESENT,gr0,icc0
+	andicc		gr30,#xAMPRx_SS,gr0,icc1
+
+	# map this PTD instead and record coverage address
+	ori.p		gr30,#xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V,gr30
+	beq		icc0,#0,__tlb_kernel_fault	/* jump if PGE not present */
+	slli.p		gr31,#18,gr31
+	bne		icc1,#0,__dtlb_k_bigpage
+	movgs		gr30,dampr5
+	movgs		gr31,scr1
+
+	# we can now resume normal service
+	setlos		0x3ffc,gr30
+	srli.p		gr29,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bra		__dtlb_k_PTD_mapped
+
+__dtlb_k_bigpage:
+	break
+	nop
+
+	.size		__entry_kernel_data_tlb_miss, .-__entry_kernel_data_tlb_miss
+
+###############################################################################
+#
+# Userspace instruction TLB miss handler (with PGE prediction)
+# On entry:
+#   GR28  - faulting address
+#   GR31  - EAR0 ^ SCR0
+#   SCR0  - base of virtual range covered by cached PGE from last ITLB miss (or 0xffffffff)
+#   DAMR3 - mapped page directory
+#   DAMR4 - mapped page table as matched by SCR0
+#
+###############################################################################
+	.globl		__entry_user_insn_tlb_miss
+	.type		__entry_user_insn_tlb_miss,@function
+__entry_user_insn_tlb_miss:
+#if 0
+	sethi.p		%hi(0xe1200004),gr30
+	setlo		%lo(0xe1200004),gr30
+	st		gr0,@(gr30,gr0)
+	sethi.p		%hi(0xffc00100),gr30
+	setlo		%lo(0xffc00100),gr30
+	sth		gr30,@(gr30,gr0)
+	membar
+#endif
+
+	movsg		ccr,gr30			/* save CCR */
+	movgs		gr30,scr2
+
+	# see if the cached page table mapping is appropriate
+	srlicc.p	gr31,#26,gr0,icc0
+	setlos		0x3ffc,gr30
+	srli.p		gr28,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bne		icc0,#0,__itlb_u_PTD_miss
+
+__itlb_u_PTD_mapped:
+	# access the PTD with EAR0[25:14]
+	# - DAMLR4 points to the virtual address of the appropriate page table
+	# - the PTD holds 4096 PTEs
+	# - the PTD must be accessed uncached
+	# - the PTE must be marked accessed if it was valid
+	#
+	and		gr31,gr30,gr31
+	movsg		damlr4,gr30
+	add		gr30,gr31,gr31
+	ldi		@(gr31,#0),gr30			/* fetch the PTE */
+	andicc		gr30,#_PAGE_PRESENT,gr0,icc0
+	ori.p		gr30,#_PAGE_ACCESSED,gr30
+	beq		icc0,#0,__tlb_user_fault	/* jump if PTE invalid */
+	sti.p		gr30,@(gr31,#0)			/* update the PTE */
+	andi		gr30,#~_PAGE_ACCESSED,gr30
+
+	# we're using IAMR1/DAMR1 as an extra TLB entry
+	# - punt the entry here (if valid) to the real TLB and then replace with the new PTE
+	movsg		dampr1,gr31
+	andicc		gr31,#xAMPRx_V,gr0,icc0
+	setlos.p	0xfffff000,gr31
+	beq		icc0,#0,__itlb_u_nopunt		/* punt not required */
+
+	movsg		dampr1,gr31
+	movgs		gr31,tppr
+	movsg		damlr1,gr31			/* set TPLR.CXN */
+	movgs		gr31,tplr
+	tlbpr		gr31,gr0,#2,#0			/* save to the TLB */
+	movsg		tpxr,gr31			/* check the TLB write error flag */
+	andicc.p	gr31,#TPXR_E,gr0,icc0
+	setlos		#0xfffff000,gr31
+	bne		icc0,#0,__tlb_user_fault
+
+__itlb_u_nopunt:
+
+	# assemble the new TLB entry
+	and		gr28,gr31,gr28
+	movsg		cxnr,gr31
+	or		gr28,gr31,gr28
+	movgs		gr28,iamlr1			/* xAMLR = address | context number */
+	movgs		gr30,iampr1
+	movgs		gr28,damlr1
+	movgs		gr30,dampr1
+
+	# return, restoring registers
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	rett		#0
+	beq		icc0,#3,0			/* prevent icache prefetch */
+
+	# the PTE we want wasn't in the PTD we have mapped, so we need to go looking for a more
+	# appropriate page table and map that instead
+	#   - access the PGD with EAR0[31:26]
+	#   - DAMLR3 points to the virtual address of the page directory
+	#   - the PGD holds 64 PGEs and each PGE/PME points to a set of page tables
+__itlb_u_PTD_miss:
+	srli		gr28,#26,gr31			/* calculate PGE offset */
+	slli		gr31,#8,gr31			/* and clear bottom bits */
+
+	movsg		damlr3,gr30
+	ld		@(gr31,gr30),gr30		/* access the PGE */
+
+	andicc.p	gr30,#_PAGE_PRESENT,gr0,icc0
+	andicc		gr30,#xAMPRx_SS,gr0,icc1
+
+	# map this PTD instead and record coverage address
+	ori.p		gr30,#xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V,gr30
+	beq		icc0,#0,__tlb_user_fault	/* jump if PGE not present */
+	slli.p		gr31,#18,gr31
+	bne		icc1,#0,__itlb_u_bigpage
+	movgs		gr30,dampr4
+	movgs		gr31,scr0
+
+	# we can now resume normal service
+	setlos		0x3ffc,gr30
+	srli.p		gr28,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bra		__itlb_u_PTD_mapped
+
+__itlb_u_bigpage:
+	break
+	nop
+
+	.size		__entry_user_insn_tlb_miss, .-__entry_user_insn_tlb_miss
+
+###############################################################################
+#
+# Userspace data TLB miss handler
+# On entry:
+#   GR28  - faulting address
+#   GR31  - EAR0 ^ SCR1
+#   SCR1  - base of virtual range covered by cached PGE from last DTLB miss (or 0xffffffff)
+#   DAMR3 - mapped page directory
+#   DAMR5 - mapped page table as matched by SCR1
+#
+###############################################################################
+	.globl		__entry_user_data_tlb_miss
+	.type		__entry_user_data_tlb_miss,@function
+__entry_user_data_tlb_miss:
+#if 0
+	sethi.p		%hi(0xe1200004),gr30
+	setlo		%lo(0xe1200004),gr30
+	st		gr0,@(gr30,gr0)
+	sethi.p		%hi(0xffc00100),gr30
+	setlo		%lo(0xffc00100),gr30
+	sth		gr30,@(gr30,gr0)
+	membar
+#endif
+
+	movsg		ccr,gr30			/* save CCR */
+	movgs		gr30,scr2
+
+	# see if the cached page table mapping is appropriate
+	srlicc.p	gr31,#26,gr0,icc0
+	setlos		0x3ffc,gr30
+	srli.p		gr28,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bne		icc0,#0,__dtlb_u_PTD_miss
+
+__dtlb_u_PTD_mapped:
+	# access the PTD with EAR0[25:14]
+	# - DAMLR5 points to the virtual address of the appropriate page table
+	# - the PTD holds 4096 PTEs
+	# - the PTD must be accessed uncached
+	# - the PTE must be marked accessed if it was valid
+	#
+	and		gr31,gr30,gr31
+	movsg		damlr5,gr30
+
+__dtlb_u_using_iPTD:
+	add		gr30,gr31,gr31
+	ldi		@(gr31,#0),gr30			/* fetch the PTE */
+	andicc		gr30,#_PAGE_PRESENT,gr0,icc0
+	ori.p		gr30,#_PAGE_ACCESSED,gr30
+	beq		icc0,#0,__tlb_user_fault	/* jump if PTE invalid */
+	sti.p		gr30,@(gr31,#0)			/* update the PTE */
+	andi		gr30,#~_PAGE_ACCESSED,gr30
+
+	# we're using DAMR1 as an extra TLB entry
+	# - punt the entry here (if valid) to the real TLB and then replace with the new PTE
+	movsg		dampr1,gr31
+	andicc		gr31,#xAMPRx_V,gr0,icc0
+	setlos.p	0xfffff000,gr31
+	beq		icc0,#0,__dtlb_u_nopunt		/* punt not required */
+
+	movsg		dampr1,gr31
+	movgs		gr31,tppr
+	movsg		damlr1,gr31			/* set TPLR.CXN */
+	movgs		gr31,tplr
+	tlbpr		gr31,gr0,#2,#0			/* save to the TLB */
+	movsg		tpxr,gr31			/* check the TLB write error flag */
+	andicc.p	gr31,#TPXR_E,gr0,icc0
+	setlos		#0xfffff000,gr31
+	bne		icc0,#0,__tlb_user_fault
+
+__dtlb_u_nopunt:
+
+	# assemble the new TLB entry
+	and		gr28,gr31,gr28
+	movsg		cxnr,gr31
+	or		gr28,gr31,gr28
+	movgs		gr28,iamlr1			/* xAMLR = address | context number */
+	movgs		gr30,iampr1
+	movgs		gr28,damlr1
+	movgs		gr30,dampr1
+
+	# return, restoring registers
+	movsg		scr2,gr30
+	movgs		gr30,ccr
+	rett		#0
+	beq		icc0,#3,0			/* prevent icache prefetch */
+
+	# the PTE we want wasn't in the PTD we have mapped, so we need to go looking for a more
+	# appropriate page table and map that instead
+	#   - first of all, check the insn PGE cache - we may well get a hit there
+	#   - access the PGD with EAR0[31:26]
+	#   - DAMLR3 points to the virtual address of the page directory
+	#   - the PGD holds 64 PGEs and each PGE/PME points to a set of page tables
+__dtlb_u_PTD_miss:
+	movsg		scr0,gr31			/* consult the insn-PGE-cache key */
+	xor		gr28,gr31,gr31
+	srlicc		gr31,#26,gr0,icc0
+	srli		gr28,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bne		icc0,#0,__dtlb_u_iPGE_miss
+
+	# what we're looking for is covered by the insn-PGE-cache
+	setlos		0x3ffc,gr30
+	and		gr31,gr30,gr31
+	movsg		damlr4,gr30
+	bra		__dtlb_u_using_iPTD
+
+__dtlb_u_iPGE_miss:
+	srli		gr28,#26,gr31			/* calculate PGE offset */
+	slli		gr31,#8,gr31			/* and clear bottom bits */
+
+	movsg		damlr3,gr30
+	ld		@(gr31,gr30),gr30		/* access the PGE */
+
+	andicc.p	gr30,#_PAGE_PRESENT,gr0,icc0
+	andicc		gr30,#xAMPRx_SS,gr0,icc1
+
+	# map this PTD instead and record coverage address
+	ori.p		gr30,#xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V,gr30
+	beq		icc0,#0,__tlb_user_fault	/* jump if PGE not present */
+	slli.p		gr31,#18,gr31
+	bne		icc1,#0,__dtlb_u_bigpage
+	movgs		gr30,dampr5
+	movgs		gr31,scr1
+
+	# we can now resume normal service
+	setlos		0x3ffc,gr30
+	srli.p		gr28,#12,gr31			/* use EAR0[25:14] as PTE index */
+	bra		__dtlb_u_PTD_mapped
+
+__dtlb_u_bigpage:
+	break
+	nop
+
+	.size		__entry_user_data_tlb_miss, .-__entry_user_data_tlb_miss