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+/*
+ * arch/ppc/kernel/head_44x.S
+ *
+ * Kernel execution entry point code.
+ *
+ * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org>
+ * Initial PowerPC version.
+ * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu>
+ * Rewritten for PReP
+ * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
+ * Low-level exception handers, MMU support, and rewrite.
+ * Copyright (c) 1997 Dan Malek <dmalek@jlc.net>
+ * PowerPC 8xx modifications.
+ * Copyright (c) 1998-1999 TiVo, Inc.
+ * PowerPC 403GCX modifications.
+ * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
+ * PowerPC 403GCX/405GP modifications.
+ * Copyright 2000 MontaVista Software Inc.
+ * PPC405 modifications
+ * PowerPC 403GCX/405GP modifications.
+ * Author: MontaVista Software, Inc.
+ * frank_rowand@mvista.com or source@mvista.com
+ * debbie_chu@mvista.com
+ * Copyright 2002-2005 MontaVista Software, Inc.
+ * PowerPC 44x support, Matt Porter <mporter@kernel.crashing.org>
+ *
+ * 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/config.h>
+#include <asm/processor.h>
+#include <asm/page.h>
+#include <asm/mmu.h>
+#include <asm/pgtable.h>
+#include <asm/ibm4xx.h>
+#include <asm/ibm44x.h>
+#include <asm/cputable.h>
+#include <asm/thread_info.h>
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include "head_booke.h"
+
+
+/* As with the other PowerPC ports, it is expected that when code
+ * execution begins here, the following registers contain valid, yet
+ * optional, information:
+ *
+ * r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.)
+ * r4 - Starting address of the init RAM disk
+ * r5 - Ending address of the init RAM disk
+ * r6 - Start of kernel command line string (e.g. "mem=128")
+ * r7 - End of kernel command line string
+ *
+ */
+ .text
+_GLOBAL(_stext)
+_GLOBAL(_start)
+ /*
+ * Reserve a word at a fixed location to store the address
+ * of abatron_pteptrs
+ */
+ nop
+/*
+ * Save parameters we are passed
+ */
+ mr r31,r3
+ mr r30,r4
+ mr r29,r5
+ mr r28,r6
+ mr r27,r7
+ li r24,0 /* CPU number */
+
+/*
+ * Set up the initial MMU state
+ *
+ * We are still executing code at the virtual address
+ * mappings set by the firmware for the base of RAM.
+ *
+ * We first invalidate all TLB entries but the one
+ * we are running from. We then load the KERNELBASE
+ * mappings so we can begin to use kernel addresses
+ * natively and so the interrupt vector locations are
+ * permanently pinned (necessary since Book E
+ * implementations always have translation enabled).
+ *
+ * TODO: Use the known TLB entry we are running from to
+ * determine which physical region we are located
+ * in. This can be used to determine where in RAM
+ * (on a shared CPU system) or PCI memory space
+ * (on a DRAMless system) we are located.
+ * For now, we assume a perfect world which means
+ * we are located at the base of DRAM (physical 0).
+ */
+
+/*
+ * Search TLB for entry that we are currently using.
+ * Invalidate all entries but the one we are using.
+ */
+ /* Load our current PID->MMUCR TID and MSR IS->MMUCR STS */
+ mfspr r3,SPRN_PID /* Get PID */
+ mfmsr r4 /* Get MSR */
+ andi. r4,r4,MSR_IS@l /* TS=1? */
+ beq wmmucr /* If not, leave STS=0 */
+ oris r3,r3,PPC44x_MMUCR_STS@h /* Set STS=1 */
+wmmucr: mtspr SPRN_MMUCR,r3 /* Put MMUCR */
+ sync
+
+ bl invstr /* Find our address */
+invstr: mflr r5 /* Make it accessible */
+ tlbsx r23,0,r5 /* Find entry we are in */
+ li r4,0 /* Start at TLB entry 0 */
+ li r3,0 /* Set PAGEID inval value */
+1: cmpw r23,r4 /* Is this our entry? */
+ beq skpinv /* If so, skip the inval */
+ tlbwe r3,r4,PPC44x_TLB_PAGEID /* If not, inval the entry */
+skpinv: addi r4,r4,1 /* Increment */
+ cmpwi r4,64 /* Are we done? */
+ bne 1b /* If not, repeat */
+ isync /* If so, context change */
+
+/*
+ * Configure and load pinned entry into TLB slot 63.
+ */
+
+ lis r3,KERNELBASE@h /* Load the kernel virtual address */
+ ori r3,r3,KERNELBASE@l
+
+ /* Kernel is at the base of RAM */
+ li r4, 0 /* Load the kernel physical address */
+
+ /* Load the kernel PID = 0 */
+ li r0,0
+ mtspr SPRN_PID,r0
+ sync
+
+ /* Initialize MMUCR */
+ li r5,0
+ mtspr SPRN_MMUCR,r5
+ sync
+
+ /* pageid fields */
+ clrrwi r3,r3,10 /* Mask off the effective page number */
+ ori r3,r3,PPC44x_TLB_VALID | PPC44x_TLB_256M
+
+ /* xlat fields */
+ clrrwi r4,r4,10 /* Mask off the real page number */
+ /* ERPN is 0 for first 4GB page */
+
+ /* attrib fields */
+ /* Added guarded bit to protect against speculative loads/stores */
+ li r5,0
+ ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)
+
+ li r0,63 /* TLB slot 63 */
+
+ tlbwe r3,r0,PPC44x_TLB_PAGEID /* Load the pageid fields */
+ tlbwe r4,r0,PPC44x_TLB_XLAT /* Load the translation fields */
+ tlbwe r5,r0,PPC44x_TLB_ATTRIB /* Load the attrib/access fields */
+
+ /* Force context change */
+ mfmsr r0
+ mtspr SPRN_SRR1, r0
+ lis r0,3f@h
+ ori r0,r0,3f@l
+ mtspr SPRN_SRR0,r0
+ sync
+ rfi
+
+ /* If necessary, invalidate original entry we used */
+3: cmpwi r23,63
+ beq 4f
+ li r6,0
+ tlbwe r6,r23,PPC44x_TLB_PAGEID
+ isync
+
+4:
+#ifdef CONFIG_SERIAL_TEXT_DEBUG
+ /*
+ * Add temporary UART mapping for early debug.
+ * We can map UART registers wherever we want as long as they don't
+ * interfere with other system mappings (e.g. with pinned entries).
+ * For an example of how we handle this - see ocotea.h. --ebs
+ */
+ /* pageid fields */
+ lis r3,UART0_IO_BASE@h
+ ori r3,r3,PPC44x_TLB_VALID | PPC44x_TLB_4K
+
+ /* xlat fields */
+ lis r4,UART0_PHYS_IO_BASE@h /* RPN depends on SoC */
+#ifndef CONFIG_440EP
+ ori r4,r4,0x0001 /* ERPN is 1 for second 4GB page */
+#endif
+
+ /* attrib fields */
+ li r5,0
+ ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_I | PPC44x_TLB_G)
+
+ li r0,0 /* TLB slot 0 */
+
+ tlbwe r3,r0,PPC44x_TLB_PAGEID /* Load the pageid fields */
+ tlbwe r4,r0,PPC44x_TLB_XLAT /* Load the translation fields */
+ tlbwe r5,r0,PPC44x_TLB_ATTRIB /* Load the attrib/access fields */
+
+ /* Force context change */
+ isync
+#endif /* CONFIG_SERIAL_TEXT_DEBUG */
+
+ /* Establish the interrupt vector offsets */
+ SET_IVOR(0, CriticalInput);
+ SET_IVOR(1, MachineCheck);
+ SET_IVOR(2, DataStorage);
+ SET_IVOR(3, InstructionStorage);
+ SET_IVOR(4, ExternalInput);
+ SET_IVOR(5, Alignment);
+ SET_IVOR(6, Program);
+ SET_IVOR(7, FloatingPointUnavailable);
+ SET_IVOR(8, SystemCall);
+ SET_IVOR(9, AuxillaryProcessorUnavailable);
+ SET_IVOR(10, Decrementer);
+ SET_IVOR(11, FixedIntervalTimer);
+ SET_IVOR(12, WatchdogTimer);
+ SET_IVOR(13, DataTLBError);
+ SET_IVOR(14, InstructionTLBError);
+ SET_IVOR(15, Debug);
+
+ /* Establish the interrupt vector base */
+ lis r4,interrupt_base@h /* IVPR only uses the high 16-bits */
+ mtspr SPRN_IVPR,r4
+
+#ifdef CONFIG_440EP
+ /* Clear DAPUIB flag in CCR0 (enable APU between CPU and FPU) */
+ mfspr r2,SPRN_CCR0
+ lis r3,0xffef
+ ori r3,r3,0xffff
+ and r2,r2,r3
+ mtspr SPRN_CCR0,r2
+ isync
+#endif
+
+ /*
+ * This is where the main kernel code starts.
+ */
+
+ /* ptr to current */
+ lis r2,init_task@h
+ ori r2,r2,init_task@l
+
+ /* ptr to current thread */
+ addi r4,r2,THREAD /* init task's THREAD */
+ mtspr SPRN_SPRG3,r4
+
+ /* stack */
+ lis r1,init_thread_union@h
+ ori r1,r1,init_thread_union@l
+ li r0,0
+ stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+
+ bl early_init
+
+/*
+ * Decide what sort of machine this is and initialize the MMU.
+ */
+ mr r3,r31
+ mr r4,r30
+ mr r5,r29
+ mr r6,r28
+ mr r7,r27
+ bl machine_init
+ bl MMU_init
+
+ /* Setup PTE pointers for the Abatron bdiGDB */
+ lis r6, swapper_pg_dir@h
+ ori r6, r6, swapper_pg_dir@l
+ lis r5, abatron_pteptrs@h
+ ori r5, r5, abatron_pteptrs@l
+ lis r4, KERNELBASE@h
+ ori r4, r4, KERNELBASE@l
+ stw r5, 0(r4) /* Save abatron_pteptrs at a fixed location */
+ stw r6, 0(r5)
+
+ /* Let's move on */
+ lis r4,start_kernel@h
+ ori r4,r4,start_kernel@l
+ lis r3,MSR_KERNEL@h
+ ori r3,r3,MSR_KERNEL@l
+ mtspr SPRN_SRR0,r4
+ mtspr SPRN_SRR1,r3
+ rfi /* change context and jump to start_kernel */
+
+/*
+ * Interrupt vector entry code
+ *
+ * The Book E MMUs are always on so we don't need to handle
+ * interrupts in real mode as with previous PPC processors. In
+ * this case we handle interrupts in the kernel virtual address
+ * space.
+ *
+ * Interrupt vectors are dynamically placed relative to the
+ * interrupt prefix as determined by the address of interrupt_base.
+ * The interrupt vectors offsets are programmed using the labels
+ * for each interrupt vector entry.
+ *
+ * Interrupt vectors must be aligned on a 16 byte boundary.
+ * We align on a 32 byte cache line boundary for good measure.
+ */
+
+interrupt_base:
+ /* Critical Input Interrupt */
+ CRITICAL_EXCEPTION(0x0100, CriticalInput, UnknownException)
+
+ /* Machine Check Interrupt */
+#ifdef CONFIG_440A
+ MCHECK_EXCEPTION(0x0200, MachineCheck, MachineCheckException)
+#else
+ CRITICAL_EXCEPTION(0x0200, MachineCheck, MachineCheckException)
+#endif
+
+ /* Data Storage Interrupt */
+ START_EXCEPTION(DataStorage)
+ mtspr SPRN_SPRG0, r10 /* Save some working registers */
+ mtspr SPRN_SPRG1, r11
+ mtspr SPRN_SPRG4W, r12
+ mtspr SPRN_SPRG5W, r13
+ mfcr r11
+ mtspr SPRN_SPRG7W, r11
+
+ /*
+ * Check if it was a store fault, if not then bail
+ * because a user tried to access a kernel or
+ * read-protected page. Otherwise, get the
+ * offending address and handle it.
+ */
+ mfspr r10, SPRN_ESR
+ andis. r10, r10, ESR_ST@h
+ beq 2f
+
+ mfspr r10, SPRN_DEAR /* Get faulting address */
+
+ /* If we are faulting a kernel address, we have to use the
+ * kernel page tables.
+ */
+ lis r11, TASK_SIZE@h
+ cmplw r10, r11
+ blt+ 3f
+ lis r11, swapper_pg_dir@h
+ ori r11, r11, swapper_pg_dir@l
+
+ mfspr r12,SPRN_MMUCR
+ rlwinm r12,r12,0,0,23 /* Clear TID */
+
+ b 4f
+
+ /* Get the PGD for the current thread */
+3:
+ mfspr r11,SPRN_SPRG3
+ lwz r11,PGDIR(r11)
+
+ /* Load PID into MMUCR TID */
+ mfspr r12,SPRN_MMUCR /* Get MMUCR */
+ mfspr r13,SPRN_PID /* Get PID */
+ rlwimi r12,r13,0,24,31 /* Set TID */
+
+4:
+ mtspr SPRN_MMUCR,r12
+
+ rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
+ lwzx r11, r12, r11 /* Get pgd/pmd entry */
+ rlwinm. r12, r11, 0, 0, 20 /* Extract pt base address */
+ beq 2f /* Bail if no table */
+
+ rlwimi r12, r10, 23, 20, 28 /* Compute pte address */
+ lwz r11, 4(r12) /* Get pte entry */
+
+ andi. r13, r11, _PAGE_RW /* Is it writeable? */
+ beq 2f /* Bail if not */
+
+ /* Update 'changed'.
+ */
+ ori r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
+ stw r11, 4(r12) /* Update Linux page table */
+
+ li r13, PPC44x_TLB_SR@l /* Set SR */
+ rlwimi r13, r11, 29, 29, 29 /* SX = _PAGE_HWEXEC */
+ rlwimi r13, r11, 0, 30, 30 /* SW = _PAGE_RW */
+ rlwimi r13, r11, 29, 28, 28 /* UR = _PAGE_USER */
+ rlwimi r12, r11, 31, 26, 26 /* (_PAGE_USER>>1)->r12 */
+ rlwimi r12, r11, 29, 30, 30 /* (_PAGE_USER>>3)->r12 */
+ and r12, r12, r11 /* HWEXEC/RW & USER */
+ rlwimi r13, r12, 0, 26, 26 /* UX = HWEXEC & USER */
+ rlwimi r13, r12, 3, 27, 27 /* UW = RW & USER */
+
+ rlwimi r11,r13,0,26,31 /* Insert static perms */
+
+ rlwinm r11,r11,0,20,15 /* Clear U0-U3 */
+
+ /* find the TLB index that caused the fault. It has to be here. */
+ tlbsx r10, 0, r10
+
+ tlbwe r11, r10, PPC44x_TLB_ATTRIB /* Write ATTRIB */
+
+ /* Done...restore registers and get out of here.
+ */
+ mfspr r11, SPRN_SPRG7R
+ mtcr r11
+ mfspr r13, SPRN_SPRG5R
+ mfspr r12, SPRN_SPRG4R
+
+ mfspr r11, SPRN_SPRG1
+ mfspr r10, SPRN_SPRG0
+ rfi /* Force context change */
+
+2:
+ /*
+ * The bailout. Restore registers to pre-exception conditions
+ * and call the heavyweights to help us out.
+ */
+ mfspr r11, SPRN_SPRG7R
+ mtcr r11
+ mfspr r13, SPRN_SPRG5R
+ mfspr r12, SPRN_SPRG4R
+
+ mfspr r11, SPRN_SPRG1
+ mfspr r10, SPRN_SPRG0
+ b data_access
+
+ /* Instruction Storage Interrupt */
+ INSTRUCTION_STORAGE_EXCEPTION
+
+ /* External Input Interrupt */
+ EXCEPTION(0x0500, ExternalInput, do_IRQ, EXC_XFER_LITE)
+
+ /* Alignment Interrupt */
+ ALIGNMENT_EXCEPTION
+
+ /* Program Interrupt */
+ PROGRAM_EXCEPTION
+
+ /* Floating Point Unavailable Interrupt */
+#ifdef CONFIG_PPC_FPU
+ FP_UNAVAILABLE_EXCEPTION
+#else
+ EXCEPTION(0x2010, FloatingPointUnavailable, UnknownException, EXC_XFER_EE)
+#endif
+
+ /* System Call Interrupt */
+ START_EXCEPTION(SystemCall)
+ NORMAL_EXCEPTION_PROLOG
+ EXC_XFER_EE_LITE(0x0c00, DoSyscall)
+
+ /* Auxillary Processor Unavailable Interrupt */
+ EXCEPTION(0x2020, AuxillaryProcessorUnavailable, UnknownException, EXC_XFER_EE)
+
+ /* Decrementer Interrupt */
+ DECREMENTER_EXCEPTION
+
+ /* Fixed Internal Timer Interrupt */
+ /* TODO: Add FIT support */
+ EXCEPTION(0x1010, FixedIntervalTimer, UnknownException, EXC_XFER_EE)
+
+ /* Watchdog Timer Interrupt */
+ /* TODO: Add watchdog support */
+#ifdef CONFIG_BOOKE_WDT
+ CRITICAL_EXCEPTION(0x1020, WatchdogTimer, WatchdogException)
+#else
+ CRITICAL_EXCEPTION(0x1020, WatchdogTimer, UnknownException)
+#endif
+
+ /* Data TLB Error Interrupt */
+ START_EXCEPTION(DataTLBError)
+ mtspr SPRN_SPRG0, r10 /* Save some working registers */
+ mtspr SPRN_SPRG1, r11
+ mtspr SPRN_SPRG4W, r12
+ mtspr SPRN_SPRG5W, r13
+ mfcr r11
+ mtspr SPRN_SPRG7W, r11
+ mfspr r10, SPRN_DEAR /* Get faulting address */
+
+ /* If we are faulting a kernel address, we have to use the
+ * kernel page tables.
+ */
+ lis r11, TASK_SIZE@h
+ cmplw r10, r11
+ blt+ 3f
+ lis r11, swapper_pg_dir@h
+ ori r11, r11, swapper_pg_dir@l
+
+ mfspr r12,SPRN_MMUCR
+ rlwinm r12,r12,0,0,23 /* Clear TID */
+
+ b 4f
+
+ /* Get the PGD for the current thread */
+3:
+ mfspr r11,SPRN_SPRG3
+ lwz r11,PGDIR(r11)
+
+ /* Load PID into MMUCR TID */
+ mfspr r12,SPRN_MMUCR
+ mfspr r13,SPRN_PID /* Get PID */
+ rlwimi r12,r13,0,24,31 /* Set TID */
+
+4:
+ mtspr SPRN_MMUCR,r12
+
+ rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
+ lwzx r11, r12, r11 /* Get pgd/pmd entry */
+ rlwinm. r12, r11, 0, 0, 20 /* Extract pt base address */
+ beq 2f /* Bail if no table */
+
+ rlwimi r12, r10, 23, 20, 28 /* Compute pte address */
+ lwz r11, 4(r12) /* Get pte entry */
+ andi. r13, r11, _PAGE_PRESENT /* Is the page present? */
+ beq 2f /* Bail if not present */
+
+ ori r11, r11, _PAGE_ACCESSED
+ stw r11, 4(r12)
+
+ /* Jump to common tlb load */
+ b finish_tlb_load
+
+2:
+ /* The bailout. Restore registers to pre-exception conditions
+ * and call the heavyweights to help us out.
+ */
+ mfspr r11, SPRN_SPRG7R
+ mtcr r11
+ mfspr r13, SPRN_SPRG5R
+ mfspr r12, SPRN_SPRG4R
+ mfspr r11, SPRN_SPRG1
+ mfspr r10, SPRN_SPRG0
+ b data_access
+
+ /* Instruction TLB Error Interrupt */
+ /*
+ * Nearly the same as above, except we get our
+ * information from different registers and bailout
+ * to a different point.
+ */
+ START_EXCEPTION(InstructionTLBError)
+ mtspr SPRN_SPRG0, r10 /* Save some working registers */
+ mtspr SPRN_SPRG1, r11
+ mtspr SPRN_SPRG4W, r12
+ mtspr SPRN_SPRG5W, r13
+ mfcr r11
+ mtspr SPRN_SPRG7W, r11
+ mfspr r10, SPRN_SRR0 /* Get faulting address */
+
+ /* If we are faulting a kernel address, we have to use the
+ * kernel page tables.
+ */
+ lis r11, TASK_SIZE@h
+ cmplw r10, r11
+ blt+ 3f
+ lis r11, swapper_pg_dir@h
+ ori r11, r11, swapper_pg_dir@l
+
+ mfspr r12,SPRN_MMUCR
+ rlwinm r12,r12,0,0,23 /* Clear TID */
+
+ b 4f
+
+ /* Get the PGD for the current thread */
+3:
+ mfspr r11,SPRN_SPRG3
+ lwz r11,PGDIR(r11)
+
+ /* Load PID into MMUCR TID */
+ mfspr r12,SPRN_MMUCR
+ mfspr r13,SPRN_PID /* Get PID */
+ rlwimi r12,r13,0,24,31 /* Set TID */
+
+4:
+ mtspr SPRN_MMUCR,r12
+
+ rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
+ lwzx r11, r12, r11 /* Get pgd/pmd entry */
+ rlwinm. r12, r11, 0, 0, 20 /* Extract pt base address */
+ beq 2f /* Bail if no table */
+
+ rlwimi r12, r10, 23, 20, 28 /* Compute pte address */
+ lwz r11, 4(r12) /* Get pte entry */
+ andi. r13, r11, _PAGE_PRESENT /* Is the page present? */
+ beq 2f /* Bail if not present */
+
+ ori r11, r11, _PAGE_ACCESSED
+ stw r11, 4(r12)
+
+ /* Jump to common TLB load point */
+ b finish_tlb_load
+
+2:
+ /* The bailout. Restore registers to pre-exception conditions
+ * and call the heavyweights to help us out.
+ */
+ mfspr r11, SPRN_SPRG7R
+ mtcr r11
+ mfspr r13, SPRN_SPRG5R
+ mfspr r12, SPRN_SPRG4R
+ mfspr r11, SPRN_SPRG1
+ mfspr r10, SPRN_SPRG0
+ b InstructionStorage
+
+ /* Debug Interrupt */
+ DEBUG_EXCEPTION
+
+/*
+ * Local functions
+ */
+ /*
+ * Data TLB exceptions will bail out to this point
+ * if they can't resolve the lightweight TLB fault.
+ */
+data_access:
+ NORMAL_EXCEPTION_PROLOG
+ mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */
+ stw r5,_ESR(r11)
+ mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */
+ EXC_XFER_EE_LITE(0x0300, handle_page_fault)
+
+/*
+
+ * Both the instruction and data TLB miss get to this
+ * point to load the TLB.
+ * r10 - EA of fault
+ * r11 - available to use
+ * r12 - Pointer to the 64-bit PTE
+ * r13 - available to use
+ * MMUCR - loaded with proper value when we get here
+ * Upon exit, we reload everything and RFI.
+ */
+finish_tlb_load:
+ /*
+ * We set execute, because we don't have the granularity to
+ * properly set this at the page level (Linux problem).
+ * If shared is set, we cause a zero PID->TID load.
+ * Many of these bits are software only. Bits we don't set
+ * here we (properly should) assume have the appropriate value.
+ */
+
+ /* Load the next available TLB index */
+ lis r13, tlb_44x_index@ha
+ lwz r13, tlb_44x_index@l(r13)
+ /* Load the TLB high watermark */
+ lis r11, tlb_44x_hwater@ha
+ lwz r11, tlb_44x_hwater@l(r11)
+
+ /* Increment, rollover, and store TLB index */
+ addi r13, r13, 1
+ cmpw 0, r13, r11 /* reserve entries */
+ ble 7f
+ li r13, 0
+7:
+ /* Store the next available TLB index */
+ lis r11, tlb_44x_index@ha
+ stw r13, tlb_44x_index@l(r11)
+
+ lwz r11, 0(r12) /* Get MS word of PTE */
+ lwz r12, 4(r12) /* Get LS word of PTE */
+ rlwimi r11, r12, 0, 0 , 19 /* Insert RPN */
+ tlbwe r11, r13, PPC44x_TLB_XLAT /* Write XLAT */
+
+ /*
+ * Create PAGEID. This is the faulting address,
+ * page size, and valid flag.
+ */
+ li r11, PPC44x_TLB_VALID | PPC44x_TLB_4K
+ rlwimi r10, r11, 0, 20, 31 /* Insert valid and page size */
+ tlbwe r10, r13, PPC44x_TLB_PAGEID /* Write PAGEID */
+
+ li r10, PPC44x_TLB_SR@l /* Set SR */
+ rlwimi r10, r12, 0, 30, 30 /* Set SW = _PAGE_RW */
+ rlwimi r10, r12, 29, 29, 29 /* SX = _PAGE_HWEXEC */
+ rlwimi r10, r12, 29, 28, 28 /* UR = _PAGE_USER */
+ rlwimi r11, r12, 31, 26, 26 /* (_PAGE_USER>>1)->r12 */
+ and r11, r12, r11 /* HWEXEC & USER */
+ rlwimi r10, r11, 0, 26, 26 /* UX = HWEXEC & USER */
+
+ rlwimi r12, r10, 0, 26, 31 /* Insert static perms */
+ rlwinm r12, r12, 0, 20, 15 /* Clear U0-U3 */
+ tlbwe r12, r13, PPC44x_TLB_ATTRIB /* Write ATTRIB */
+
+ /* Done...restore registers and get out of here.
+ */
+ mfspr r11, SPRN_SPRG7R
+ mtcr r11
+ mfspr r13, SPRN_SPRG5R
+ mfspr r12, SPRN_SPRG4R
+ mfspr r11, SPRN_SPRG1
+ mfspr r10, SPRN_SPRG0
+ rfi /* Force context change */
+
+/*
+ * Global functions
+ */
+
+/*
+ * extern void giveup_altivec(struct task_struct *prev)
+ *
+ * The 44x core does not have an AltiVec unit.
+ */
+_GLOBAL(giveup_altivec)
+ blr
+
+/*
+ * extern void giveup_fpu(struct task_struct *prev)
+ *
+ * The 44x core does not have an FPU.
+ */
+#ifndef CONFIG_PPC_FPU
+_GLOBAL(giveup_fpu)
+ blr
+#endif
+
+/*
+ * extern void abort(void)
+ *
+ * At present, this routine just applies a system reset.
+ */
+_GLOBAL(abort)
+ mfspr r13,SPRN_DBCR0
+ oris r13,r13,DBCR0_RST_SYSTEM@h
+ mtspr SPRN_DBCR0,r13
+
+_GLOBAL(set_context)
+
+#ifdef CONFIG_BDI_SWITCH
+ /* Context switch the PTE pointer for the Abatron BDI2000.
+ * The PGDIR is the second parameter.
+ */
+ lis r5, abatron_pteptrs@h
+ ori r5, r5, abatron_pteptrs@l
+ stw r4, 0x4(r5)
+#endif
+ mtspr SPRN_PID,r3
+ isync /* Force context change */
+ blr
+
+/*
+ * We put a few things here that have to be page-aligned. This stuff
+ * goes at the beginning of the data segment, which is page-aligned.
+ */
+ .data
+_GLOBAL(sdata)
+_GLOBAL(empty_zero_page)
+ .space 4096
+
+/*
+ * To support >32-bit physical addresses, we use an 8KB pgdir.
+ */
+_GLOBAL(swapper_pg_dir)
+ .space 8192
+
+/* Reserved 4k for the critical exception stack & 4k for the machine
+ * check stack per CPU for kernel mode exceptions */
+ .section .bss
+ .align 12
+exception_stack_bottom:
+ .space BOOKE_EXCEPTION_STACK_SIZE
+_GLOBAL(exception_stack_top)
+
+/*
+ * This space gets a copy of optional info passed to us by the bootstrap
+ * which is used to pass parameters into the kernel like root=/dev/sda1, etc.
+ */
+_GLOBAL(cmd_line)
+ .space 512
+
+/*
+ * Room for two PTE pointers, usually the kernel and current user pointers
+ * to their respective root page table.
+ */
+abatron_pteptrs:
+ .space 8
+
+
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.