/* * PowerPC version * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) * Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP * Copyright (C) 1996 Cort Dougan * Low-level exception handlers and MMU support * rewritten by Paul Mackerras. * Copyright (C) 1996 Paul Mackerras. * MPC8xx modifications by Dan Malek * Copyright (C) 1997 Dan Malek (dmalek@jlc.net). * * This file contains low-level support and setup for PowerPC 8xx * embedded processors, including trap and interrupt dispatch. * * 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 #include #include #include #include #include #include #include #include #include /* Macro to make the code more readable. */ #ifdef CONFIG_8xx_CPU6 #define DO_8xx_CPU6(val, reg) \ li reg, val; \ stw reg, 12(r0); \ lwz reg, 12(r0); #else #define DO_8xx_CPU6(val, reg) #endif __HEAD _ENTRY(_stext); _ENTRY(_start); /* MPC8xx * This port was done on an MBX board with an 860. Right now I only * support an ELF compressed (zImage) boot from EPPC-Bug because the * code there loads up some registers before calling us: * r3: ptr to board info data * r4: initrd_start or if no initrd then 0 * r5: initrd_end - unused if r4 is 0 * r6: Start of command line string * r7: End of command line string * * I decided to use conditional compilation instead of checking PVR and * adding more processor specific branches around code I don't need. * Since this is an embedded processor, I also appreciate any memory * savings I can get. * * The MPC8xx does not have any BATs, but it supports large page sizes. * We first initialize the MMU to support 8M byte pages, then load one * entry into each of the instruction and data TLBs to map the first * 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to * the "internal" processor registers before MMU_init is called. * * The TLB code currently contains a major hack. Since I use the condition * code register, I have to save and restore it. I am out of registers, so * I just store it in memory location 0 (the TLB handlers are not reentrant). * To avoid making any decisions, I need to use the "segment" valid bit * in the first level table, but that would require many changes to the * Linux page directory/table functions that I don't want to do right now. * * I used to use SPRG2 for a temporary register in the TLB handler, but it * has since been put to other uses. I now use a hack to save a register * and the CCR at memory location 0.....Someday I'll fix this..... * -- Dan */ .globl __start __start: mr r31,r3 /* save parameters */ mr r30,r4 mr r29,r5 mr r28,r6 mr r27,r7 /* We have to turn on the MMU right away so we get cache modes * set correctly. */ bl initial_mmu /* We now have the lower 8 Meg mapped into TLB entries, and the caches * ready to work. */ turn_on_mmu: mfmsr r0 ori r0,r0,MSR_DR|MSR_IR mtspr SPRN_SRR1,r0 lis r0,start_here@h ori r0,r0,start_here@l mtspr SPRN_SRR0,r0 SYNC rfi /* enables MMU */ /* * Exception entry code. This code runs with address translation * turned off, i.e. using physical addresses. * We assume sprg3 has the physical address of the current * task's thread_struct. */ #define EXCEPTION_PROLOG \ mtspr SPRN_SPRG_SCRATCH0,r10; \ mtspr SPRN_SPRG_SCRATCH1,r11; \ mfcr r10; \ EXCEPTION_PROLOG_1; \ EXCEPTION_PROLOG_2 #define EXCEPTION_PROLOG_1 \ mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \ andi. r11,r11,MSR_PR; \ tophys(r11,r1); /* use tophys(r1) if kernel */ \ beq 1f; \ mfspr r11,SPRN_SPRG_THREAD; \ lwz r11,THREAD_INFO-THREAD(r11); \ addi r11,r11,THREAD_SIZE; \ tophys(r11,r11); \ 1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */ #define EXCEPTION_PROLOG_2 \ CLR_TOP32(r11); \ stw r10,_CCR(r11); /* save registers */ \ stw r12,GPR12(r11); \ stw r9,GPR9(r11); \ mfspr r10,SPRN_SPRG_SCRATCH0; \ stw r10,GPR10(r11); \ mfspr r12,SPRN_SPRG_SCRATCH1; \ stw r12,GPR11(r11); \ mflr r10; \ stw r10,_LINK(r11); \ mfspr r12,SPRN_SRR0; \ mfspr r9,SPRN_SRR1; \ stw r1,GPR1(r11); \ stw r1,0(r11); \ tovirt(r1,r11); /* set new kernel sp */ \ li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \ MTMSRD(r10); /* (except for mach check in rtas) */ \ stw r0,GPR0(r11); \ SAVE_4GPRS(3, r11); \ SAVE_2GPRS(7, r11) /* * Note: code which follows this uses cr0.eq (set if from kernel), * r11, r12 (SRR0), and r9 (SRR1). * * Note2: once we have set r1 we are in a position to take exceptions * again, and we could thus set MSR:RI at that point. */ /* * Exception vectors. */ #define EXCEPTION(n, label, hdlr, xfer) \ . = n; \ label: \ EXCEPTION_PROLOG; \ addi r3,r1,STACK_FRAME_OVERHEAD; \ xfer(n, hdlr) #define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \ li r10,trap; \ stw r10,_TRAP(r11); \ li r10,MSR_KERNEL; \ copyee(r10, r9); \ bl tfer; \ i##n: \ .long hdlr; \ .long ret #define COPY_EE(d, s) rlwimi d,s,0,16,16 #define NOCOPY(d, s) #define EXC_XFER_STD(n, hdlr) \ EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full, \ ret_from_except_full) #define EXC_XFER_LITE(n, hdlr) \ EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \ ret_from_except) #define EXC_XFER_EE(n, hdlr) \ EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \ ret_from_except_full) #define EXC_XFER_EE_LITE(n, hdlr) \ EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \ ret_from_except) /* System reset */ EXCEPTION(0x100, Reset, unknown_exception, EXC_XFER_STD) /* Machine check */ . = 0x200 MachineCheck: EXCEPTION_PROLOG mfspr r4,SPRN_DAR stw r4,_DAR(r11) li r5,0x00f0 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */ mfspr r5,SPRN_DSISR stw r5,_DSISR(r11) addi r3,r1,STACK_FRAME_OVERHEAD EXC_XFER_STD(0x200, machine_check_exception) /* Data access exception. * This is "never generated" by the MPC8xx. We jump to it for other * translation errors. */ . = 0x300 DataAccess: EXCEPTION_PROLOG mfspr r10,SPRN_DSISR stw r10,_DSISR(r11) mr r5,r10 mfspr r4,SPRN_DAR li r10,0x00f0 mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */ EXC_XFER_EE_LITE(0x300, handle_page_fault) /* Instruction access exception. * This is "never generated" by the MPC8xx. We jump to it for other * translation errors. */ . = 0x400 InstructionAccess: EXCEPTION_PROLOG mr r4,r12 mr r5,r9 EXC_XFER_EE_LITE(0x400, handle_page_fault) /* External interrupt */ EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) /* Alignment exception */ . = 0x600 Alignment: EXCEPTION_PROLOG mfspr r4,SPRN_DAR stw r4,_DAR(r11) li r5,0x00f0 mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */ mfspr r5,SPRN_DSISR stw r5,_DSISR(r11) addi r3,r1,STACK_FRAME_OVERHEAD EXC_XFER_EE(0x600, alignment_exception) /* Program check exception */ EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD) /* No FPU on MPC8xx. This exception is not supposed to happen. */ EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD) /* Decrementer */ EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE) EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE) EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE) /* System call */ . = 0xc00 SystemCall: EXCEPTION_PROLOG EXC_XFER_EE_LITE(0xc00, DoSyscall) /* Single step - not used on 601 */ EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD) EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE) EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE) /* On the MPC8xx, this is a software emulation interrupt. It occurs * for all unimplemented and illegal instructions. */ EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD) . = 0x1100 /* * For the MPC8xx, this is a software tablewalk to load the instruction * TLB. It is modelled after the example in the Motorola manual. The task * switch loads the M_TWB register with the pointer to the first level table. * If we discover there is no second level table (value is zero) or if there * is an invalid pte, we load that into the TLB, which causes another fault * into the TLB Error interrupt where we can handle such problems. * We have to use the MD_xxx registers for the tablewalk because the * equivalent MI_xxx registers only perform the attribute functions. */ InstructionTLBMiss: #ifdef CONFIG_8xx_CPU6 stw r3, 8(r0) #endif DO_8xx_CPU6(0x3f80, r3) mtspr SPRN_M_TW, r10 /* Save a couple of working registers */ mfcr r10 stw r10, 0(r0) stw r11, 4(r0) mfspr r10, SPRN_SRR0 /* Get effective address of fault */ #ifdef CONFIG_8xx_CPU15 addi r11, r10, 0x1000 tlbie r11 addi r11, r10, -0x1000 tlbie r11 #endif DO_8xx_CPU6(0x3780, r3) mtspr SPRN_MD_EPN, r10 /* Have to use MD_EPN for walk, MI_EPN can't */ mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ /* If we are faulting a kernel address, we have to use the * kernel page tables. */ andi. r11, r10, 0x0800 /* Address >= 0x80000000 */ beq 3f lis r11, swapper_pg_dir@h ori r11, r11, swapper_pg_dir@l rlwimi r10, r11, 0, 2, 19 3: lwz r11, 0(r10) /* Get the level 1 entry */ rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */ beq 2f /* If zero, don't try to find a pte */ /* We have a pte table, so load the MI_TWC with the attributes * for this "segment." */ ori r11,r11,1 /* Set valid bit */ DO_8xx_CPU6(0x2b80, r3) mtspr SPRN_MI_TWC, r11 /* Set segment attributes */ DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ lwz r10, 0(r11) /* Get the pte */ andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT bne- cr0, 2f /* Clear PP lsb, 0x400 */ rlwinm r10, r10, 0, 22, 20 /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ li r11, 0x00f0 rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ DO_8xx_CPU6(0x2d80, r3) mtspr SPRN_MI_RPN, r10 /* Update TLB entry */ mfspr r10, SPRN_M_TW /* Restore registers */ lwz r11, 0(r0) mtcr r11 lwz r11, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif rfi 2: mfspr r11, SPRN_SRR1 /* clear all error bits as TLB Miss * sets a few unconditionally */ rlwinm r11, r11, 0, 0xffff mtspr SPRN_SRR1, r11 mfspr r10, SPRN_M_TW /* Restore registers */ lwz r11, 0(r0) mtcr r11 lwz r11, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif b InstructionAccess . = 0x1200 DataStoreTLBMiss: #ifdef CONFIG_8xx_CPU6 stw r3, 8(r0) #endif DO_8xx_CPU6(0x3f80, r3) mtspr SPRN_M_TW, r10 /* Save a couple of working registers */ mfcr r10 stw r10, 0(r0) stw r11, 4(r0) mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ /* If we are faulting a kernel address, we have to use the * kernel page tables. */ andi. r11, r10, 0x0800 beq 3f lis r11, swapper_pg_dir@h ori r11, r11, swapper_pg_dir@l rlwimi r10, r11, 0, 2, 19 3: lwz r11, 0(r10) /* Get the level 1 entry */ rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */ beq 2f /* If zero, don't try to find a pte */ /* We have a pte table, so load fetch the pte from the table. */ ori r11, r11, 1 /* Set valid bit in physical L2 page */ DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ mfspr r10, SPRN_MD_TWC /* ....and get the pte address */ lwz r10, 0(r10) /* Get the pte */ /* Insert the Guarded flag into the TWC from the Linux PTE. * It is bit 27 of both the Linux PTE and the TWC (at least * I got that right :-). It will be better when we can put * this into the Linux pgd/pmd and load it in the operation * above. */ rlwimi r11, r10, 0, 27, 27 DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 /* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set. * We also need to know if the insn is a load/store, so: * Clear _PAGE_PRESENT and load that which will * trap into DTLB Error with store bit set accordinly. */ /* PRESENT=0x1, ACCESSED=0x20 * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5)); * r10 = (r10 & ~PRESENT) | r11; */ rlwinm r11, r10, 32-5, 31, 31 and r11, r11, r10 rlwimi r10, r11, 0, 31, 31 /* Honour kernel RO, User NA */ andi. r11, r10, _PAGE_USER | _PAGE_RW bne- cr0, 5f ori r10,r10, 0x200 /* Extended encoding, bit 22 */ 5: xori r10, r10, _PAGE_RW /* invert RW bit */ /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ 2: li r11, 0x00f0 mtspr SPRN_DAR,r11 /* Tag DAR */ rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ DO_8xx_CPU6(0x3d80, r3) mtspr SPRN_MD_RPN, r10 /* Update TLB entry */ mfspr r10, SPRN_M_TW /* Restore registers */ lwz r11, 0(r0) mtcr r11 lwz r11, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif rfi /* This is an instruction TLB error on the MPC8xx. This could be due * to many reasons, such as executing guarded memory or illegal instruction * addresses. There is nothing to do but handle a big time error fault. */ . = 0x1300 InstructionTLBError: b InstructionAccess /* This is the data TLB error on the MPC8xx. This could be due to * many reasons, including a dirty update to a pte. We can catch that * one here, but anything else is an error. First, we track down the * Linux pte. If it is valid, write access is allowed, but the * page dirty bit is not set, we will set it and reload the TLB. For * any other case, we bail out to a higher level function that can * handle it. */ . = 0x1400 DataTLBError: #ifdef CONFIG_8xx_CPU6 stw r3, 8(r0) #endif DO_8xx_CPU6(0x3f80, r3) mtspr SPRN_M_TW, r10 /* Save a couple of working registers */ mfcr r10 stw r10, 0(r0) stw r11, 4(r0) mfspr r10, SPRN_DAR cmpwi cr0, r10, 0x00f0 beq- FixupDAR /* must be a buggy dcbX, icbi insn. */ DARFixed:/* Return from dcbx instruction bug workaround, r10 holds value of DAR */ mfspr r11, SPRN_DSISR /* As the DAR fixup may clear store we may have all 3 states zero. * Make sure only 0x0200(store) falls down into DIRTY handling */ andis. r11, r11, 0x4a00 /* !translation, protection or store */ srwi r11, r11, 16 cmpwi cr0, r11, 0x0200 /* just store ? */ bne 2f /* Only Change bit left now, do it here as it is faster * than trapping to the C fault handler. */ /* The EA of a data TLB miss is automatically stored in the MD_EPN * register. The EA of a data TLB error is automatically stored in * the DAR, but not the MD_EPN register. We must copy the 20 most * significant bits of the EA from the DAR to MD_EPN before we * start walking the page tables. We also need to copy the CASID * value from the M_CASID register. * Addendum: The EA of a data TLB error is _supposed_ to be stored * in DAR, but it seems that this doesn't happen in some cases, such * as when the error is due to a dcbi instruction to a page with a * TLB that doesn't have the changed bit set. In such cases, there * does not appear to be any way to recover the EA of the error * since it is neither in DAR nor MD_EPN. As a workaround, the * _PAGE_HWWRITE bit is set for all kernel data pages when the PTEs * are initialized in mapin_ram(). This will avoid the problem, * assuming we only use the dcbi instruction on kernel addresses. */ /* DAR is in r10 already */ rlwinm r11, r10, 0, 0, 19 ori r11, r11, MD_EVALID mfspr r10, SPRN_M_CASID rlwimi r11, r10, 0, 28, 31 DO_8xx_CPU6(0x3780, r3) mtspr SPRN_MD_EPN, r11 mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ /* If we are faulting a kernel address, we have to use the * kernel page tables. */ andi. r11, r10, 0x0800 beq 3f lis r11, swapper_pg_dir@h ori r11, r11, swapper_pg_dir@l rlwimi r10, r11, 0, 2, 19 3: lwz r11, 0(r10) /* Get the level 1 entry */ rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */ beq 2f /* If zero, bail */ /* We have a pte table, so fetch the pte from the table. */ ori r11, r11, 1 /* Set valid bit in physical L2 page */ DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ mfspr r10, SPRN_MD_TWC /* ....and get the pte address */ lwz r10, 0(r10) /* Get the pte */ /* Insert the Guarded flag into the TWC from the Linux PTE. * It is bit 27 of both the Linux PTE and the TWC */ rlwimi r11, r10, 0, 27, 27 DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 mfspr r11, SPRN_MD_TWC /* get the pte address again */ ori r10, r10, _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_HWWRITE stw r10, 0(r11) /* and update pte in table */ xori r10, r10, _PAGE_RW /* RW bit is inverted */ /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ li r11, 0x00f0 mtspr SPRN_DAR,r11 /* Tag DAR */ rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ DO_8xx_CPU6(0x3d80, r3) mtspr SPRN_MD_RPN, r10 /* Update TLB entry */ mfspr r10, SPRN_M_TW /* Restore registers */ lwz r11, 0(r0) mtcr r11 lwz r11, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif rfi 2: mfspr r10, SPRN_M_TW /* Restore registers */ lwz r11, 0(r0) mtcr r11 lwz r11, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif b DataAccess EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_EE) /* On the MPC8xx, these next four traps are used for development * support of breakpoints and such. Someday I will get around to * using them. */ EXCEPTION(0x1c00, Trap_1c, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE) EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE) . = 0x2000 /* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions * by decoding the registers used by the dcbx instruction and adding them. * DAR is set to the calculated address and r10 also holds the EA on exit. */ /* define if you don't want to use self modifying code */ #define NO_SELF_MODIFYING_CODE FixupDAR:/* Entry point for dcbx workaround. */ /* fetch instruction from memory. */ mfspr r10, SPRN_SRR0 DO_8xx_CPU6(0x3780, r3) mtspr SPRN_MD_EPN, r10 mfspr r11, SPRN_M_TWB /* Get level 1 table entry address */ cmplwi cr0, r11, 0x0800 blt- 3f /* Branch if user space */ lis r11, (swapper_pg_dir-PAGE_OFFSET)@h ori r11, r11, (swapper_pg_dir-PAGE_OFFSET)@l rlwimi r11, r10, 32-20, 0xffc /* r11 = r11&~0xffc|(r10>>20)&0xffc */ 3: lwz r11, 0(r11) /* Get the level 1 entry */ DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 /* Load pte table base address */ mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ lwz r11, 0(r11) /* Get the pte */ /* concat physical page address(r11) and page offset(r10) */ rlwimi r11, r10, 0, 20, 31 lwz r11,0(r11) /* Check if it really is a dcbx instruction. */ /* dcbt and dcbtst does not generate DTLB Misses/Errors, * no need to include them here */ srwi r10, r11, 26 /* check if major OP code is 31 */ cmpwi cr0, r10, 31 bne- 141f rlwinm r10, r11, 0, 21, 30 cmpwi cr0, r10, 2028 /* Is dcbz? */ beq+ 142f cmpwi cr0, r10, 940 /* Is dcbi? */ beq+ 142f cmpwi cr0, r10, 108 /* Is dcbst? */ beq+ 144f /* Fix up store bit! */ cmpwi cr0, r10, 172 /* Is dcbf? */ beq+ 142f cmpwi cr0, r10, 1964 /* Is icbi? */ beq+ 142f 141: mfspr r10, SPRN_DAR /* r10 must hold DAR at exit */ b DARFixed /* Nope, go back to normal TLB processing */ 144: mfspr r10, SPRN_DSISR rlwinm r10, r10,0,7,5 /* Clear store bit for buggy dcbst insn */ mtspr SPRN_DSISR, r10 142: /* continue, it was a dcbx, dcbi instruction. */ #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) /* restore r3 from memory */ #endif #ifndef NO_SELF_MODIFYING_CODE andis. r10,r11,0x1f /* test if reg RA is r0 */ li r10,modified_instr@l dcbtst r0,r10 /* touch for store */ rlwinm r11,r11,0,0,20 /* Zero lower 10 bits */ oris r11,r11,640 /* Transform instr. to a "add r10,RA,RB" */ ori r11,r11,532 stw r11,0(r10) /* store add/and instruction */ dcbf 0,r10 /* flush new instr. to memory. */ icbi 0,r10 /* invalidate instr. cache line */ lwz r11, 4(r0) /* restore r11 from memory */ mfspr r10, SPRN_M_TW /* restore r10 from M_TW */ isync /* Wait until new instr is loaded from memory */ modified_instr: .space 4 /* this is where the add instr. is stored */ bne+ 143f subf r10,r0,r10 /* r10=r10-r0, only if reg RA is r0 */ 143: mtdar r10 /* store faulting EA in DAR */ b DARFixed /* Go back to normal TLB handling */ #else mfctr r10 mtdar r10 /* save ctr reg in DAR */ rlwinm r10, r11, 24, 24, 28 /* offset into jump table for reg RB */ addi r10, r10, 150f@l /* add start of table */ mtctr r10 /* load ctr with jump address */ xor r10, r10, r10 /* sum starts at zero */ bctr /* jump into table */ 150: add r10, r10, r0 ;b 151f add r10, r10, r1 ;b 151f add r10, r10, r2 ;b 151f add r10, r10, r3 ;b 151f add r10, r10, r4 ;b 151f add r10, r10, r5 ;b 151f add r10, r10, r6 ;b 151f add r10, r10, r7 ;b 151f add r10, r10, r8 ;b 151f add r10, r10, r9 ;b 151f mtctr r11 ;b 154f /* r10 needs special handling */ mtctr r11 ;b 153f /* r11 needs special handling */ add r10, r10, r12 ;b 151f add r10, r10, r13 ;b 151f add r10, r10, r14 ;b 151f add r10, r10, r15 ;b 151f add r10, r10, r16 ;b 151f add r10, r10, r17 ;b 151f add r10, r10, r18 ;b 151f add r10, r10, r19 ;b 151f add r10, r10, r20 ;b 151f add r10, r10, r21 ;b 151f add r10, r10, r22 ;b 151f add r10, r10, r23 ;b 151f add r10, r10, r24 ;b 151f add r10, r10, r25 ;b 151f add r10, r10, r26 ;b 151f add r10, r10, r27 ;b 151f add r10, r10, r28 ;b 151f add r10, r10, r29 ;b 151f add r10, r10, r30 ;b 151f add r10, r10, r31 151: rlwinm. r11,r11,19,24,28 /* offset into jump table for reg RA */ beq 152f /* if reg RA is zero, don't add it */ addi r11, r11, 150b@l /* add start of table */ mtctr r11 /* load ctr with jump address */ rlwinm r11,r11,0,16,10 /* make sure we don't execute this more than once */ bctr /* jump into table */ 152: mfdar r11 mtctr r11 /* restore ctr reg from DAR */ mtdar r10 /* save fault EA to DAR */ b DARFixed /* Go back to normal TLB handling */ /* special handling for r10,r11 since these are modified already */ 153: lwz r11, 4(r0) /* load r11 from memory */ b 155f 154: mfspr r11, SPRN_M_TW /* load r10 from M_TW */ 155: add r10, r10, r11 /* add it */ mfctr r11 /* restore r11 */ b 151b #endif .globl giveup_fpu giveup_fpu: blr /* * This is where the main kernel code starts. */ start_here: /* ptr to current */ lis r2,init_task@h ori r2,r2,init_task@l /* ptr to phys current thread */ tophys(r4,r2) addi r4,r4,THREAD /* init task's THREAD */ mtspr SPRN_SPRG_THREAD,r4 li r3,0 /* XXX What is that for ? SPRG2 appears otherwise unused on 8xx */ mtspr SPRN_SPRG2,r3 /* 0 => r1 has kernel sp */ /* stack */ lis r1,init_thread_union@ha addi r1,r1,init_thread_union@l li r0,0 stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1) bl early_init /* We have to do this with MMU on */ /* * 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 /* * Go back to running unmapped so we can load up new values * and change to using our exception vectors. * On the 8xx, all we have to do is invalidate the TLB to clear * the old 8M byte TLB mappings and load the page table base register. */ /* The right way to do this would be to track it down through * init's THREAD like the context switch code does, but this is * easier......until someone changes init's static structures. */ lis r6, swapper_pg_dir@h ori r6, r6, swapper_pg_dir@l tophys(r6,r6) #ifdef CONFIG_8xx_CPU6 lis r4, cpu6_errata_word@h ori r4, r4, cpu6_errata_word@l li r3, 0x3980 stw r3, 12(r4) lwz r3, 12(r4) #endif mtspr SPRN_M_TWB, r6 lis r4,2f@h ori r4,r4,2f@l tophys(r4,r4) li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR) mtspr SPRN_SRR0,r4 mtspr SPRN_SRR1,r3 rfi /* Load up the kernel context */ 2: SYNC /* Force all PTE updates to finish */ tlbia /* Clear all TLB entries */ sync /* wait for tlbia/tlbie to finish */ TLBSYNC /* ... on all CPUs */ /* set up the PTE pointers for the Abatron bdiGDB. */ tovirt(r6,r6) lis r5, abatron_pteptrs@h ori r5, r5, abatron_pteptrs@l stw r5, 0xf0(r0) /* Must match your Abatron config file */ tophys(r5,r5) stw r6, 0(r5) /* Now turn on the MMU for real! */ li r4,MSR_KERNEL lis r3,start_kernel@h ori r3,r3,start_kernel@l mtspr SPRN_SRR0,r3 mtspr SPRN_SRR1,r4 rfi /* enable MMU and jump to start_kernel */ /* Set up the initial MMU state so we can do the first level of * kernel initialization. This maps the first 8 MBytes of memory 1:1 * virtual to physical. Also, set the cache mode since that is defined * by TLB entries and perform any additional mapping (like of the IMMR). * If configured to pin some TLBs, we pin the first 8 Mbytes of kernel, * 24 Mbytes of data, and the 8M IMMR space. Anything not covered by * these mappings is mapped by page tables. */ initial_mmu: tlbia /* Invalidate all TLB entries */ #ifdef CONFIG_PIN_TLB lis r8, MI_RSV4I@h ori r8, r8, 0x1c00 #else li r8, 0 #endif mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */ #ifdef CONFIG_PIN_TLB lis r10, (MD_RSV4I | MD_RESETVAL)@h ori r10, r10, 0x1c00 mr r8, r10 #else lis r10, MD_RESETVAL@h #endif #ifndef CONFIG_8xx_COPYBACK oris r10, r10, MD_WTDEF@h #endif mtspr SPRN_MD_CTR, r10 /* Set data TLB control */ /* Now map the lower 8 Meg into the TLBs. For this quick hack, * we can load the instruction and data TLB registers with the * same values. */ lis r8, KERNELBASE@h /* Create vaddr for TLB */ ori r8, r8, MI_EVALID /* Mark it valid */ mtspr SPRN_MI_EPN, r8 mtspr SPRN_MD_EPN, r8 li r8, MI_PS8MEG /* Set 8M byte page */ ori r8, r8, MI_SVALID /* Make it valid */ mtspr SPRN_MI_TWC, r8 mtspr SPRN_MD_TWC, r8 li r8, MI_BOOTINIT /* Create RPN for address 0 */ mtspr SPRN_MI_RPN, r8 /* Store TLB entry */ mtspr SPRN_MD_RPN, r8 lis r8, MI_Kp@h /* Set the protection mode */ mtspr SPRN_MI_AP, r8 mtspr SPRN_MD_AP, r8 /* Map another 8 MByte at the IMMR to get the processor * internal registers (among other things). */ #ifdef CONFIG_PIN_TLB addi r10, r10, 0x0100 mtspr SPRN_MD_CTR, r10 #endif mfspr r9, 638 /* Get current IMMR */ andis. r9, r9, 0xff80 /* Get 8Mbyte boundary */ mr r8, r9 /* Create vaddr for TLB */ ori r8, r8, MD_EVALID /* Mark it valid */ mtspr SPRN_MD_EPN, r8 li r8, MD_PS8MEG /* Set 8M byte page */ ori r8, r8, MD_SVALID /* Make it valid */ mtspr SPRN_MD_TWC, r8 mr r8, r9 /* Create paddr for TLB */ ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */ mtspr SPRN_MD_RPN, r8 #ifdef CONFIG_PIN_TLB /* Map two more 8M kernel data pages. */ addi r10, r10, 0x0100 mtspr SPRN_MD_CTR, r10 lis r8, KERNELBASE@h /* Create vaddr for TLB */ addis r8, r8, 0x0080 /* Add 8M */ ori r8, r8, MI_EVALID /* Mark it valid */ mtspr SPRN_MD_EPN, r8 li r9, MI_PS8MEG /* Set 8M byte page */ ori r9, r9, MI_SVALID /* Make it valid */ mtspr SPRN_MD_TWC, r9 li r11, MI_BOOTINIT /* Create RPN for address 0 */ addis r11, r11, 0x0080 /* Add 8M */ mtspr SPRN_MD_RPN, r11 addis r8, r8, 0x0080 /* Add 8M */ mtspr SPRN_MD_EPN, r8 mtspr SPRN_MD_TWC, r9 addis r11, r11, 0x0080 /* Add 8M */ mtspr SPRN_MD_RPN, r11 #endif /* Since the cache is enabled according to the information we * just loaded into the TLB, invalidate and enable the caches here. * We should probably check/set other modes....later. */ lis r8, IDC_INVALL@h mtspr SPRN_IC_CST, r8 mtspr SPRN_DC_CST, r8 lis r8, IDC_ENABLE@h mtspr SPRN_IC_CST, r8 #ifdef CONFIG_8xx_COPYBACK mtspr SPRN_DC_CST, r8 #else /* For a debug option, I left this here to easily enable * the write through cache mode */ lis r8, DC_SFWT@h mtspr SPRN_DC_CST, r8 lis r8, IDC_ENABLE@h mtspr SPRN_DC_CST, r8 #endif blr /* * Set up to use a given MMU context. * r3 is context number, r4 is PGD pointer. * * We place the physical address of the new task page directory loaded * into the MMU base register, and set the ASID compare register with * the new "context." */ _GLOBAL(set_context) #ifdef CONFIG_BDI_SWITCH /* Context switch the PTE pointer for the Abatron BDI2000. * The PGDIR is passed as second argument. */ lis r5, KERNELBASE@h lwz r5, 0xf0(r5) stw r4, 0x4(r5) #endif #ifdef CONFIG_8xx_CPU6 lis r6, cpu6_errata_word@h ori r6, r6, cpu6_errata_word@l tophys (r4, r4) li r7, 0x3980 stw r7, 12(r6) lwz r7, 12(r6) mtspr SPRN_M_TWB, r4 /* Update MMU base address */ li r7, 0x3380 stw r7, 12(r6) lwz r7, 12(r6) mtspr SPRN_M_CASID, r3 /* Update context */ #else mtspr SPRN_M_CASID,r3 /* Update context */ tophys (r4, r4) mtspr SPRN_M_TWB, r4 /* and pgd */ #endif SYNC blr #ifdef CONFIG_8xx_CPU6 /* It's here because it is unique to the 8xx. * It is important we get called with interrupts disabled. I used to * do that, but it appears that all code that calls this already had * interrupt disabled. */ .globl set_dec_cpu6 set_dec_cpu6: lis r7, cpu6_errata_word@h ori r7, r7, cpu6_errata_word@l li r4, 0x2c00 stw r4, 8(r7) lwz r4, 8(r7) mtspr 22, r3 /* Update Decrementer */ SYNC blr #endif /* * 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 .globl sdata sdata: .globl empty_zero_page empty_zero_page: .space 4096 .globl swapper_pg_dir swapper_pg_dir: .space 4096 /* Room for two PTE table poiners, usually the kernel and current user * pointer to their respective root page table (pgdir). */ abatron_pteptrs: .space 8 #ifdef CONFIG_8xx_CPU6 .globl cpu6_errata_word cpu6_errata_word: .space 16 #endif