3 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
4 * Rewritten by Cort Dougan (cort@fsmlabs.com) for PReP
5 * Copyright (C) 1996 Cort Dougan <cort@fsmlabs.com>
6 * Adapted for Power Macintosh by Paul Mackerras.
7 * Low-level exception handlers and MMU support
8 * rewritten by Paul Mackerras.
9 * Copyright (C) 1996 Paul Mackerras.
10 * MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
12 * This file contains the system call entry code, context switch
13 * code, and exception/interrupt return code for PowerPC.
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * as published by the Free Software Foundation; either version
18 * 2 of the License, or (at your option) any later version.
22 #include <linux/errno.h>
23 #include <linux/sys.h>
24 #include <linux/threads.h>
25 #include <asm/processor.h>
28 #include <asm/cputable.h>
29 #include <asm/thread_info.h>
30 #include <asm/ppc_asm.h>
31 #include <asm/asm-offsets.h>
32 #include <asm/unistd.h>
35 #undef SHOW_SYSCALLS_TASK
38 * MSR_KERNEL is > 0x10000 on 4xx/Book-E since it include MSR_CE.
40 #if MSR_KERNEL >= 0x10000
41 #define LOAD_MSR_KERNEL(r, x) lis r,(x)@h; ori r,r,(x)@l
43 #define LOAD_MSR_KERNEL(r, x) li r,(x)
47 #include "head_booke.h"
48 #define TRANSFER_TO_HANDLER_EXC_LEVEL(exc_level) \
49 mtspr exc_level##_SPRG,r8; \
50 BOOKE_LOAD_EXC_LEVEL_STACK(exc_level); \
51 lwz r0,GPR10-INT_FRAME_SIZE(r8); \
53 lwz r0,GPR11-INT_FRAME_SIZE(r8); \
55 mfspr r8,exc_level##_SPRG
57 .globl mcheck_transfer_to_handler
58 mcheck_transfer_to_handler:
59 TRANSFER_TO_HANDLER_EXC_LEVEL(MCHECK)
60 b transfer_to_handler_full
62 .globl debug_transfer_to_handler
63 debug_transfer_to_handler:
64 TRANSFER_TO_HANDLER_EXC_LEVEL(DEBUG)
65 b transfer_to_handler_full
67 .globl crit_transfer_to_handler
68 crit_transfer_to_handler:
69 TRANSFER_TO_HANDLER_EXC_LEVEL(CRIT)
74 .globl crit_transfer_to_handler
75 crit_transfer_to_handler:
84 * This code finishes saving the registers to the exception frame
85 * and jumps to the appropriate handler for the exception, turning
86 * on address translation.
87 * Note that we rely on the caller having set cr0.eq iff the exception
88 * occurred in kernel mode (i.e. MSR:PR = 0).
90 .globl transfer_to_handler_full
91 transfer_to_handler_full:
95 .globl transfer_to_handler
107 tovirt(r2,r2) /* set r2 to current */
108 beq 2f /* if from user, fix up THREAD.regs */
109 addi r11,r1,STACK_FRAME_OVERHEAD
111 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
112 /* Check to see if the dbcr0 register is set up to debug. Use the
113 single-step bit to do this. */
114 lwz r12,THREAD_DBCR0(r12)
115 andis. r12,r12,DBCR0_IC@h
117 /* From user and task is ptraced - load up global dbcr0 */
118 li r12,-1 /* clear all pending debug events */
120 lis r11,global_dbcr0@ha
122 addi r11,r11,global_dbcr0@l
131 2: /* if from kernel, check interrupted DOZE/NAP mode and
132 * check for stack overflow
134 lwz r9,THREAD_INFO-THREAD(r12)
135 cmplw r1,r9 /* if r1 <= current->thread_info */
136 ble- stack_ovf /* then the kernel stack overflowed */
139 tophys(r9,r9) /* check local flags */
140 lwz r12,TI_LOCAL_FLAGS(r9)
142 bt- 31-TLF_NAPPING,4f
143 #endif /* CONFIG_6xx */
144 .globl transfer_to_handler_cont
145 transfer_to_handler_cont:
148 lwz r11,0(r9) /* virtual address of handler */
149 lwz r9,4(r9) /* where to go when done */
154 RFI /* jump to handler, enable MMU */
157 4: rlwinm r12,r12,0,~_TLF_NAPPING
158 stw r12,TI_LOCAL_FLAGS(r9)
159 b power_save_6xx_restore
163 * On kernel stack overflow, load up an initial stack pointer
164 * and call StackOverflow(regs), which should not return.
167 /* sometimes we use a statically-allocated stack, which is OK. */
171 ble 5b /* r1 <= &_end is OK */
173 addi r3,r1,STACK_FRAME_OVERHEAD
174 lis r1,init_thread_union@ha
175 addi r1,r1,init_thread_union@l
176 addi r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
177 lis r9,StackOverflow@ha
178 addi r9,r9,StackOverflow@l
179 LOAD_MSR_KERNEL(r10,MSR_KERNEL)
187 * Handle a system call.
189 .stabs "arch/ppc/kernel/",N_SO,0,0,0f
190 .stabs "entry.S",N_SO,0,0,0f
197 lwz r11,_CCR(r1) /* Clear SO bit in CR */
202 #endif /* SHOW_SYSCALLS */
203 rlwinm r10,r1,0,0,18 /* current_thread_info() */
204 lwz r11,TI_FLAGS(r10)
205 andi. r11,r11,_TIF_SYSCALL_T_OR_A
207 syscall_dotrace_cont:
208 cmplwi 0,r0,NR_syscalls
209 lis r10,sys_call_table@h
210 ori r10,r10,sys_call_table@l
213 lwzx r10,r10,r0 /* Fetch system call handler [ptr] */
215 addi r9,r1,STACK_FRAME_OVERHEAD
217 blrl /* Call handler */
218 .globl ret_from_syscall
221 bl do_show_syscall_exit
224 rlwinm r12,r1,0,0,18 /* current_thread_info() */
225 /* disable interrupts so current_thread_info()->flags can't change */
226 LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
231 andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
232 bne- syscall_exit_work
234 blt+ syscall_exit_cont
235 lwz r11,_CCR(r1) /* Load CR */
237 oris r11,r11,0x1000 /* Set SO bit in CR */
240 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
241 /* If the process has its own DBCR0 value, load it up. The single
242 step bit tells us that dbcr0 should be loaded. */
243 lwz r0,THREAD+THREAD_DBCR0(r2)
244 andis. r10,r0,DBCR0_IC@h
248 lis r4,icache_44x_need_flush@ha
249 lwz r5,icache_44x_need_flush@l(r4)
253 #endif /* CONFIG_44x */
254 stwcx. r0,0,r1 /* to clear the reservation */
271 stw r7,icache_44x_need_flush@l(r4)
273 #endif /* CONFIG_44x */
285 /* Traced system call support */
290 addi r3,r1,STACK_FRAME_OVERHEAD
291 bl do_syscall_trace_enter
292 lwz r0,GPR0(r1) /* Restore original registers */
300 b syscall_dotrace_cont
303 andi. r0,r9,_TIF_RESTOREALL
309 andi. r0,r9,_TIF_NOERROR
311 lwz r11,_CCR(r1) /* Load CR */
313 oris r11,r11,0x1000 /* Set SO bit in CR */
316 1: stw r6,RESULT(r1) /* Save result */
317 stw r3,GPR3(r1) /* Update return value */
318 2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
321 /* Clear per-syscall TIF flags if any are set. */
323 li r11,_TIF_PERSYSCALL_MASK
324 addi r12,r12,TI_FLAGS
327 #ifdef CONFIG_IBM405_ERR77
332 subi r12,r12,TI_FLAGS
334 4: /* Anything which requires enabling interrupts? */
335 andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
338 /* Re-enable interrupts */
343 /* Save NVGPRS if they're not saved already */
351 addi r3,r1,STACK_FRAME_OVERHEAD
352 bl do_syscall_trace_leave
353 b ret_from_except_full
357 #ifdef SHOW_SYSCALLS_TASK
358 lis r11,show_syscalls_task@ha
359 lwz r11,show_syscalls_task@l(r11)
390 do_show_syscall_exit:
391 #ifdef SHOW_SYSCALLS_TASK
392 lis r11,show_syscalls_task@ha
393 lwz r11,show_syscalls_task@l(r11)
399 stw r3,RESULT(r1) /* Save result */
409 7: .string "syscall %d(%x, %x, %x, %x, %x, "
410 77: .string "%x), current=%p\n"
411 79: .string " -> %x\n"
414 #ifdef SHOW_SYSCALLS_TASK
416 .globl show_syscalls_task
421 #endif /* SHOW_SYSCALLS */
424 * The fork/clone functions need to copy the full register set into
425 * the child process. Therefore we need to save all the nonvolatile
426 * registers (r13 - r31) before calling the C code.
432 rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
433 stw r0,TRAP(r1) /* register set saved */
440 rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
441 stw r0,TRAP(r1) /* register set saved */
448 rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
449 stw r0,TRAP(r1) /* register set saved */
452 .globl ppc_swapcontext
456 rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
457 stw r0,TRAP(r1) /* register set saved */
461 * Top-level page fault handling.
462 * This is in assembler because if do_page_fault tells us that
463 * it is a bad kernel page fault, we want to save the non-volatile
464 * registers before calling bad_page_fault.
466 .globl handle_page_fault
469 addi r3,r1,STACK_FRAME_OVERHEAD
478 addi r3,r1,STACK_FRAME_OVERHEAD
481 b ret_from_except_full
484 * This routine switches between two different tasks. The process
485 * state of one is saved on its kernel stack. Then the state
486 * of the other is restored from its kernel stack. The memory
487 * management hardware is updated to the second process's state.
488 * Finally, we can return to the second process.
489 * On entry, r3 points to the THREAD for the current task, r4
490 * points to the THREAD for the new task.
492 * This routine is always called with interrupts disabled.
494 * Note: there are two ways to get to the "going out" portion
495 * of this code; either by coming in via the entry (_switch)
496 * or via "fork" which must set up an environment equivalent
497 * to the "_switch" path. If you change this , you'll have to
498 * change the fork code also.
500 * The code which creates the new task context is in 'copy_thread'
501 * in arch/ppc/kernel/process.c
504 stwu r1,-INT_FRAME_SIZE(r1)
506 stw r0,INT_FRAME_SIZE+4(r1)
507 /* r3-r12 are caller saved -- Cort */
509 stw r0,_NIP(r1) /* Return to switch caller */
511 li r0,MSR_FP /* Disable floating-point */
512 #ifdef CONFIG_ALTIVEC
514 oris r0,r0,MSR_VEC@h /* Disable altivec */
515 mfspr r12,SPRN_VRSAVE /* save vrsave register value */
516 stw r12,THREAD+THREAD_VRSAVE(r2)
517 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
518 #endif /* CONFIG_ALTIVEC */
520 oris r0,r0,MSR_SPE@h /* Disable SPE */
521 mfspr r12,SPRN_SPEFSCR /* save spefscr register value */
522 stw r12,THREAD+THREAD_SPEFSCR(r2)
523 #endif /* CONFIG_SPE */
524 and. r0,r0,r11 /* FP or altivec or SPE enabled? */
532 stw r1,KSP(r3) /* Set old stack pointer */
535 /* We need a sync somewhere here to make sure that if the
536 * previous task gets rescheduled on another CPU, it sees all
537 * stores it has performed on this one.
540 #endif /* CONFIG_SMP */
544 mtspr SPRN_SPRG3,r0 /* Update current THREAD phys addr */
545 lwz r1,KSP(r4) /* Load new stack pointer */
547 /* save the old current 'last' for return value */
549 addi r2,r4,-THREAD /* Update current */
551 #ifdef CONFIG_ALTIVEC
553 lwz r0,THREAD+THREAD_VRSAVE(r2)
554 mtspr SPRN_VRSAVE,r0 /* if G4, restore VRSAVE reg */
555 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
556 #endif /* CONFIG_ALTIVEC */
558 lwz r0,THREAD+THREAD_SPEFSCR(r2)
559 mtspr SPRN_SPEFSCR,r0 /* restore SPEFSCR reg */
560 #endif /* CONFIG_SPE */
564 /* r3-r12 are destroyed -- Cort */
567 lwz r4,_NIP(r1) /* Return to _switch caller in new task */
569 addi r1,r1,INT_FRAME_SIZE
572 .globl fast_exception_return
573 fast_exception_return:
574 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
575 andi. r10,r9,MSR_RI /* check for recoverable interrupt */
576 beq 1f /* if not, we've got problems */
579 2: REST_4GPRS(3, r11)
594 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
595 /* check if the exception happened in a restartable section */
596 1: lis r3,exc_exit_restart_end@ha
597 addi r3,r3,exc_exit_restart_end@l
600 lis r4,exc_exit_restart@ha
601 addi r4,r4,exc_exit_restart@l
604 lis r3,fee_restarts@ha
606 lwz r5,fee_restarts@l(r3)
608 stw r5,fee_restarts@l(r3)
609 mr r12,r4 /* restart at exc_exit_restart */
618 /* aargh, a nonrecoverable interrupt, panic */
619 /* aargh, we don't know which trap this is */
620 /* but the 601 doesn't implement the RI bit, so assume it's OK */
624 END_FTR_SECTION_IFSET(CPU_FTR_601)
627 addi r3,r1,STACK_FRAME_OVERHEAD
629 ori r10,r10,MSR_KERNEL@l
630 bl transfer_to_handler_full
631 .long nonrecoverable_exception
632 .long ret_from_except
635 .globl ret_from_except_full
636 ret_from_except_full:
640 .globl ret_from_except
642 /* Hard-disable interrupts so that current_thread_info()->flags
643 * can't change between when we test it and when we return
644 * from the interrupt. */
645 LOAD_MSR_KERNEL(r10,MSR_KERNEL)
646 SYNC /* Some chip revs have problems here... */
647 MTMSRD(r10) /* disable interrupts */
649 lwz r3,_MSR(r1) /* Returning to user mode? */
653 user_exc_return: /* r10 contains MSR_KERNEL here */
654 /* Check current_thread_info()->flags */
657 andi. r0,r9,(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK|_TIF_NEED_RESCHED)
661 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
662 /* Check whether this process has its own DBCR0 value. The single
663 step bit tells us that dbcr0 should be loaded. */
664 lwz r0,THREAD+THREAD_DBCR0(r2)
665 andis. r10,r0,DBCR0_IC@h
669 #ifdef CONFIG_PREEMPT
672 /* N.B. the only way to get here is from the beq following ret_from_except. */
674 /* check current_thread_info->preempt_count */
676 lwz r0,TI_PREEMPT(r9)
677 cmpwi 0,r0,0 /* if non-zero, just restore regs and return */
680 andi. r0,r0,_TIF_NEED_RESCHED
682 andi. r0,r3,MSR_EE /* interrupts off? */
683 beq restore /* don't schedule if so */
684 1: bl preempt_schedule_irq
687 andi. r0,r3,_TIF_NEED_RESCHED
691 #endif /* CONFIG_PREEMPT */
693 /* interrupts are hard-disabled at this point */
696 lis r4,icache_44x_need_flush@ha
697 lwz r5,icache_44x_need_flush@l(r4)
702 stw r6,icache_44x_need_flush@l(r4)
704 #endif /* CONFIG_44x */
716 stwcx. r0,0,r1 /* to clear the reservation */
718 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
720 andi. r10,r9,MSR_RI /* check if this exception occurred */
721 beql nonrecoverable /* at a bad place (MSR:RI = 0) */
729 * Once we put values in SRR0 and SRR1, we are in a state
730 * where exceptions are not recoverable, since taking an
731 * exception will trash SRR0 and SRR1. Therefore we clear the
732 * MSR:RI bit to indicate this. If we do take an exception,
733 * we can't return to the point of the exception but we
734 * can restart the exception exit path at the label
735 * exc_exit_restart below. -- paulus
737 LOAD_MSR_KERNEL(r10,MSR_KERNEL & ~MSR_RI)
739 MTMSRD(r10) /* clear the RI bit */
740 .globl exc_exit_restart
749 .globl exc_exit_restart_end
750 exc_exit_restart_end:
754 #else /* !(CONFIG_4xx || CONFIG_BOOKE) */
756 * This is a bit different on 4xx/Book-E because it doesn't have
757 * the RI bit in the MSR.
758 * The TLB miss handler checks if we have interrupted
759 * the exception exit path and restarts it if so
760 * (well maybe one day it will... :).
767 .globl exc_exit_restart
776 .globl exc_exit_restart_end
777 exc_exit_restart_end:
780 b . /* prevent prefetch past rfi */
783 * Returning from a critical interrupt in user mode doesn't need
784 * to be any different from a normal exception. For a critical
785 * interrupt in the kernel, we just return (without checking for
786 * preemption) since the interrupt may have happened at some crucial
787 * place (e.g. inside the TLB miss handler), and because we will be
788 * running with r1 pointing into critical_stack, not the current
789 * process's kernel stack (and therefore current_thread_info() will
790 * give the wrong answer).
791 * We have to restore various SPRs that may have been in use at the
792 * time of the critical interrupt.
796 #define PPC_40x_TURN_OFF_MSR_DR \
797 /* avoid any possible TLB misses here by turning off MSR.DR, we \
798 * assume the instructions here are mapped by a pinned TLB entry */ \
804 #define PPC_40x_TURN_OFF_MSR_DR
807 #define RET_FROM_EXC_LEVEL(exc_lvl_srr0, exc_lvl_srr1, exc_lvl_rfi) \
810 andi. r3,r3,MSR_PR; \
811 LOAD_MSR_KERNEL(r10,MSR_KERNEL); \
812 bne user_exc_return; \
819 mtspr SPRN_XER,r10; \
821 PPC405_ERR77(0,r1); \
822 stwcx. r0,0,r1; /* to clear the reservation */ \
827 PPC_40x_TURN_OFF_MSR_DR; \
830 mtspr SPRN_DEAR,r9; \
831 mtspr SPRN_ESR,r10; \
834 mtspr exc_lvl_srr0,r11; \
835 mtspr exc_lvl_srr1,r12; \
843 b .; /* prevent prefetch past exc_lvl_rfi */
845 .globl ret_from_crit_exc
847 RET_FROM_EXC_LEVEL(SPRN_CSRR0, SPRN_CSRR1, RFCI)
850 .globl ret_from_debug_exc
852 RET_FROM_EXC_LEVEL(SPRN_DSRR0, SPRN_DSRR1, RFDI)
854 .globl ret_from_mcheck_exc
856 RET_FROM_EXC_LEVEL(SPRN_MCSRR0, SPRN_MCSRR1, RFMCI)
857 #endif /* CONFIG_BOOKE */
860 * Load the DBCR0 value for a task that is being ptraced,
861 * having first saved away the global DBCR0. Note that r0
862 * has the dbcr0 value to set upon entry to this.
865 mfmsr r10 /* first disable debug exceptions */
866 rlwinm r10,r10,0,~MSR_DE
870 lis r11,global_dbcr0@ha
871 addi r11,r11,global_dbcr0@l
878 mtspr SPRN_DBSR,r11 /* clear all pending debug events */
886 #endif /* !(CONFIG_4xx || CONFIG_BOOKE) */
888 do_work: /* r10 contains MSR_KERNEL here */
889 andi. r0,r9,_TIF_NEED_RESCHED
892 do_resched: /* r10 contains MSR_KERNEL here */
895 MTMSRD(r10) /* hard-enable interrupts */
898 LOAD_MSR_KERNEL(r10,MSR_KERNEL)
900 MTMSRD(r10) /* disable interrupts */
903 andi. r0,r9,_TIF_NEED_RESCHED
905 andi. r0,r9,_TIF_SIGPENDING
907 do_user_signal: /* r10 contains MSR_KERNEL here */
910 MTMSRD(r10) /* hard-enable interrupts */
911 /* save r13-r31 in the exception frame, if not already done */
919 addi r4,r1,STACK_FRAME_OVERHEAD
925 * We come here when we are at the end of handling an exception
926 * that occurred at a place where taking an exception will lose
927 * state information, such as the contents of SRR0 and SRR1.
930 lis r10,exc_exit_restart_end@ha
931 addi r10,r10,exc_exit_restart_end@l
934 lis r11,exc_exit_restart@ha
935 addi r11,r11,exc_exit_restart@l
938 lis r10,ee_restarts@ha
939 lwz r12,ee_restarts@l(r10)
941 stw r12,ee_restarts@l(r10)
942 mr r12,r11 /* restart at exc_exit_restart */
944 3: /* OK, we can't recover, kill this process */
945 /* but the 601 doesn't implement the RI bit, so assume it's OK */
948 END_FTR_SECTION_IFSET(CPU_FTR_601)
955 4: addi r3,r1,STACK_FRAME_OVERHEAD
956 bl nonrecoverable_exception
957 /* shouldn't return */