/* * arch/ppc/kernel/entry.S * * $Id: entry.S,v 1.4 1999/09/14 05:18:14 dmalek Exp $ * * 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 * Adapted for Power Macintosh by Paul Mackerras. * Low-level exception handlers and MMU support * rewritten by Paul Mackerras. * Copyright (C) 1996 Paul Mackerras. * MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net). * * This file contains the system call entry code, context switch * code, and exception/interrupt return code for PowerPC. * * 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 "ppc_asm.h" #include #include #include #include #include #include #define SHOW_SYSCALLS #define SHOW_SYSCALLS_TASK #ifdef SHOW_SYSCALLS_TASK .data show_syscalls_task: .long -1 #endif /* * Handle a system call. */ .text _GLOBAL(DoSyscall) stw r0,THREAD+LAST_SYSCALL(r2) lwz r11,_CCR(r1) /* Clear SO bit in CR */ lis r10,0x1000 andc r11,r11,r10 stw r11,_CCR(r1) #ifdef SHOW_SYSCALLS #ifdef SHOW_SYSCALLS_TASK lis r31,show_syscalls_task@ha lwz r31,show_syscalls_task@l(r31) cmp 0,r2,r31 bne 1f #endif lis r3,7f@ha addi r3,r3,7f@l lwz r4,GPR0(r1) lwz r5,GPR3(r1) lwz r6,GPR4(r1) lwz r7,GPR5(r1) lwz r8,GPR6(r1) lwz r9,GPR7(r1) bl printk lis r3,77f@ha addi r3,r3,77f@l lwz r4,GPR8(r1) lwz r5,GPR9(r1) mr r6,r2 bl printk lwz r0,GPR0(r1) lwz r3,GPR3(r1) lwz r4,GPR4(r1) lwz r5,GPR5(r1) lwz r6,GPR6(r1) lwz r7,GPR7(r1) lwz r8,GPR8(r1) 1: #endif /* SHOW_SYSCALLS */ cmpi 0,r0,0x7777 /* Special case for 'sys_sigreturn' */ beq- 10f lwz r10,TASK_FLAGS(r2) andi. r10,r10,PF_TRACESYS bne- 50f cmpli 0,r0,NR_syscalls bge- 66f lis r10,sys_call_table@h ori r10,r10,sys_call_table@l slwi r0,r0,2 lwzx r10,r10,r0 /* Fetch system call handler [ptr] */ cmpi 0,r10,0 beq- 66f mtlr r10 addi r9,r1,STACK_FRAME_OVERHEAD blrl /* Call handler */ .globl ret_from_syscall_1 ret_from_syscall_1: 20: stw r3,RESULT(r1) /* Save result */ #ifdef SHOW_SYSCALLS #ifdef SHOW_SYSCALLS_TASK cmp 0,r2,r31 bne 91f #endif mr r4,r3 lis r3,79f@ha addi r3,r3,79f@l bl printk lwz r3,RESULT(r1) 91: #endif li r10,-_LAST_ERRNO cmpl 0,r3,r10 blt 30f neg r3,r3 cmpi 0,r3,ERESTARTNOHAND bne 22f li r3,EINTR 22: lwz r10,_CCR(r1) /* Set SO bit in CR */ oris r10,r10,0x1000 stw r10,_CCR(r1) 30: stw r3,GPR3(r1) /* Update return value */ b ret_from_except 66: li r3,ENOSYS b 22b /* sys_sigreturn */ 10: addi r3,r1,STACK_FRAME_OVERHEAD bl sys_sigreturn cmpi 0,r3,0 /* Check for restarted system call */ bge ret_from_except b 20b /* Traced system call support */ 50: bl syscall_trace lwz r0,GPR0(r1) /* Restore original registers */ lwz r3,GPR3(r1) lwz r4,GPR4(r1) lwz r5,GPR5(r1) lwz r6,GPR6(r1) lwz r7,GPR7(r1) lwz r8,GPR8(r1) lwz r9,GPR9(r1) cmpli 0,r0,NR_syscalls bge- 66f lis r10,sys_call_table@h ori r10,r10,sys_call_table@l slwi r0,r0,2 lwzx r10,r10,r0 /* Fetch system call handler [ptr] */ cmpi 0,r10,0 beq- 66f mtlr r10 addi r9,r1,STACK_FRAME_OVERHEAD blrl /* Call handler */ .globl ret_from_syscall_2 ret_from_syscall_2: stw r3,RESULT(r1) /* Save result */ stw r3,GPR0(r1) /* temporary gross hack to make strace work */ li r10,-_LAST_ERRNO cmpl 0,r3,r10 blt 60f neg r3,r3 cmpi 0,r3,ERESTARTNOHAND bne 52f li r3,EINTR 52: lwz r10,_CCR(r1) /* Set SO bit in CR */ oris r10,r10,0x1000 stw r10,_CCR(r1) 60: stw r3,GPR3(r1) /* Update return value */ bl syscall_trace b ret_from_except 66: li r3,ENOSYS b 52b #ifdef SHOW_SYSCALLS 7: .string "syscall %d(%x, %x, %x, %x, %x, " 77: .string "%x, %x), current=%p\n" 79: .string " -> %x\n" .align 2 #endif /* * This routine switches between two different tasks. The process * state of one is saved on its kernel stack. Then the state * of the other is restored from its kernel stack. The memory * management hardware is updated to the second process's state. * Finally, we can return to the second process, via ret_from_except. * On entry, r3 points to the THREAD for the current task, r4 * points to the THREAD for the new task. * * Note: there are two ways to get to the "going out" portion * of this code; either by coming in via the entry (_switch) * or via "fork" which must set up an environment equivalent * to the "_switch" path. If you change this (or in particular, the * SAVE_REGS macro), you'll have to change the fork code also. * * The code which creates the new task context is in 'copy_thread' * in arch/ppc/kernel/process.c */ _GLOBAL(_switch) stwu r1,-INT_FRAME_SIZE(r1) stw r0,GPR0(r1) lwz r0,0(r1) stw r0,GPR1(r1) /* r3-r13 are caller saved -- Cort */ SAVE_GPR(2, r1) SAVE_8GPRS(14, r1) SAVE_10GPRS(22, r1) mflr r20 /* Return to switch caller */ mfmsr r22 li r0,MSR_FP /* Disable floating-point */ andc r22,r22,r0 stw r20,_NIP(r1) stw r22,_MSR(r1) stw r20,_LINK(r1) mfcr r20 mfctr r22 mfspr r23,XER stw r20,_CCR(r1) stw r22,_CTR(r1) stw r23,_XER(r1) li r0,0x0ff0 stw r0,TRAP(r1) stw r1,KSP(r3) /* Set old stack pointer */ sync tophys(r0,r4) mtspr SPRG3,r0 /* Update current THREAD phys addr */ #ifdef CONFIG_8xx /* XXX it would be nice to find a SPRGx for this on 6xx,7xx too */ lwz r9,PGDIR(r4) /* cache the page table root */ tophys(r9,r9) /* convert to phys addr */ mtspr M_TWB,r9 /* Update MMU base address */ #endif /* CONFIG_8xx */ lwz r1,KSP(r4) /* Load new stack pointer */ /* save the old current 'last' for return value */ mr r3,r2 addi r2,r4,-THREAD /* Update current */ lwz r9,_MSR(r1) /* Returning to user mode? */ andi. r9,r9,MSR_PR beq+ 10f /* if not, don't adjust kernel stack */ 8: addi r4,r1,INT_FRAME_SIZE /* size of frame */ stw r4,THREAD+KSP(r2) /* save kernel stack pointer */ tophys(r9,r1) mtspr SPRG2,r9 /* phys exception stack pointer */ 10: lwz r2,_CTR(r1) lwz r0,_LINK(r1) mtctr r2 mtlr r0 lwz r2,_XER(r1) lwz r0,_CCR(r1) mtspr XER,r2 mtcrf 0xFF,r0 /* r3-r13 are destroyed -- Cort */ REST_GPR(14, r1) REST_8GPRS(15, r1) REST_8GPRS(23, r1) REST_GPR(31, r1) lwz r2,_NIP(r1) /* Restore environment */ lwz r0,_MSR(r1) mtspr SRR0,r2 mtspr SRR1,r0 lwz r0,GPR0(r1) lwz r2,GPR2(r1) lwz r1,GPR1(r1) SYNC rfi /* * ret_from_int(): * * Return from an interrupt (external interrupt and * decrementer). This checks the first argument so * we know if rtl_intercept wants us to check for * a bottom half, signals and so on (normal return) or * we're returning from a real-time interrupt or have * interrupts soft disabled so we cannot enter Linux. * -- Cort */ .globl ret_from_int ret_from_int: cmpi 0,r3,0 beq 10f /* we're allowed to do signal/bh checks */ b ret_from_syscall #ifdef __SMP__ .globl ret_from_smpfork ret_from_smpfork: bl schedule_tail #endif .globl ret_from_syscall ret_from_syscall: .globl ret_from_except ret_from_except: 0: mfmsr r30 /* Disable interrupts */ rlwinm r30,r30,0,17,15 /* clear MSR_EE */ SYNC /* Some chip revs need this... */ mtmsr r30 SYNC lwz r5,_MSR(r1) andi. r5,r5,MSR_EE beq 2f 3: lis r4,ppc_n_lost_interrupts@ha lwz r4,ppc_n_lost_interrupts@l(r4) cmpi 0,r4,0 beq+ 1f addi r3,r1,STACK_FRAME_OVERHEAD bl do_IRQ .globl lost_irq_ret lost_irq_ret: b 3b 1: lis r4,bh_mask@ha lwz r4,bh_mask@l(r4) lis r5,bh_active@ha lwz r5,bh_active@l(r5) and. r4,r4,r5 beq+ 2f bl do_bottom_half .globl do_bottom_half_ret do_bottom_half_ret: 2: SYNC mtmsr r30 /* disable interrupts again */ SYNC lwz r3,_MSR(r1) /* Returning to user mode? */ andi. r3,r3,MSR_PR beq+ 10f /* if so, check need_resched and signals */ lwz r3,NEED_RESCHED(r2) cmpi 0,r3,0 /* check need_resched flag */ beq+ 7f bl schedule b 0b 7: lwz r5,SIGPENDING(r2) /* Check for pending unblocked signals */ cmpwi 0,r5,0 beq+ 8f li r3,0 addi r4,r1,STACK_FRAME_OVERHEAD bl do_signal .globl do_signal_ret do_signal_ret: b 0b 8: addi r4,r1,INT_FRAME_SIZE /* size of frame */ stw r4,THREAD+KSP(r2) /* save kernel stack pointer */ tophys(r3,r1) mtspr SPRG2,r3 /* phys exception stack pointer */ 10: lwz r2,_CTR(r1) lwz r0,_LINK(r1) mtctr r2 mtlr r0 lwz r2,_XER(r1) lwz r0,_CCR(r1) mtspr XER,r2 mtcrf 0xFF,r0 REST_10GPRS(3, r1) REST_10GPRS(13, r1) REST_8GPRS(23, r1) REST_GPR(31, r1) lwz r2,_NIP(r1) /* Restore environment */ lwz r0,_MSR(r1) mtspr SRR0,r2 mtspr SRR1,r0 lwz r0,GPR0(r1) lwz r2,GPR2(r1) lwz r1,GPR1(r1) SYNC rfi /* * Fake an interrupt from kernel mode. * This is used when enable_irq loses an interrupt. * We only fill in the stack frame minimally. */ _GLOBAL(fake_interrupt) mflr r0 stw r0,4(r1) stwu r1,-INT_FRAME_SIZE(r1) stw r0,_NIP(r1) stw r0,_LINK(r1) mfmsr r3 stw r3,_MSR(r1) li r0,0x0fac stw r0,TRAP(r1) addi r3,r1,STACK_FRAME_OVERHEAD li r4,1 bl do_IRQ addi r1,r1,INT_FRAME_SIZE lwz r0,4(r1) mtlr r0 blr #ifndef CONFIG_8xx /* * PROM code for specific machines follows. Put it * here so it's easy to add arch-specific sections later. * -- Cort */ /* * On CHRP, the Run-Time Abstraction Services (RTAS) have to be * called with the MMU off. */ .globl enter_rtas enter_rtas: mflr r0 stw r0,20(r1) lis r4,rtas_data@ha lwz r4,rtas_data@l(r4) addis r4,r4,-KERNELBASE@h lis r6,1f@ha /* physical return address for rtas */ addi r6,r6,1f@l addis r6,r6,-KERNELBASE@h subi r7,r1,INT_FRAME_SIZE addis r7,r7,-KERNELBASE@h lis r8,rtas_entry@ha lwz r8,rtas_entry@l(r8) addis r5,r8,-KERNELBASE@h mfmsr r9 stw r9,8(r1) ori r0,r0,MSR_EE|MSR_SE|MSR_BE andc r0,r9,r0 andi. r9,r9,MSR_ME|MSR_RI sync /* disable interrupts so SRR0/1 */ mtmsr r0 /* don't get trashed */ mtlr r6 mtspr SPRG2,r7 mtspr SRR0,r8 mtspr SRR1,r9 rfi 1: addis r9,r1,-KERNELBASE@h lwz r8,20(r9) /* get return address */ lwz r9,8(r9) /* original msr value */ li r0,0 mtspr SPRG2,r0 mtspr SRR0,r8 mtspr SRR1,r9 rfi /* return to caller */ #endif /* CONFIG_8xx */