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linux/arch/ppc/kernel/entry.S
Paul Mackerras 1bd79336a4 powerpc: Fix various syscall/signal/swapcontext bugs 
A careful reading of the recent changes to the system call entry/exit
paths revealed several problems, plus some things that could be
simplified and improved:

* 32-bit wasn't testing the _TIF_NOERROR bit in the syscall fast exit
  path, so it was only doing anything with it once it saw some other
  bit being set.  In other words, the noerror behaviour would apply to
  the next system call where we had to reschedule or deliver a signal,
  which is not necessarily the current system call.

* 32-bit wasn't doing the call to ptrace_notify in the syscall exit
  path when the _TIF_SINGLESTEP bit was set.

* _TIF_RESTOREALL was in both _TIF_USER_WORK_MASK and
  _TIF_PERSYSCALL_MASK, which is odd since _TIF_RESTOREALL is only set
  by system calls.  I took it out of _TIF_USER_WORK_MASK.

* On 64-bit, _TIF_RESTOREALL wasn't causing the non-volatile registers
  to be restored (unless perhaps a signal was delivered or the syscall
  was traced or single-stepped).  Thus the non-volatile registers
  weren't restored on exit from a signal handler.  We probably got
  away with it mostly because signal handlers written in C wouldn't
  alter the non-volatile registers.

* On 32-bit I simplified the code and made it more like 64-bit by
  making the syscall exit path jump to ret_from_except to handle
  preemption and signal delivery.

* 32-bit was calling do_signal unnecessarily when _TIF_RESTOREALL was
  set - but I think because of that 32-bit was actually restoring the
  non-volatile registers on exit from a signal handler.

* I changed the order of enabling interrupts and saving the
  non-volatile registers before calling do_syscall_trace_leave; now we
  enable interrupts first.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-03-08 13:24:22 +11:00

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/*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
* Rewritten by Cort Dougan (cort@fsmlabs.com) for PReP
* Copyright (C) 1996 Cort Dougan <cort@fsmlabs.com>
* 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 <linux/config.h>
#include <linux/errno.h>
#include <linux/sys.h>
#include <linux/threads.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#undef SHOW_SYSCALLS
#undef SHOW_SYSCALLS_TASK
/*
* MSR_KERNEL is > 0x10000 on 4xx/Book-E since it include MSR_CE.
*/
#if MSR_KERNEL >= 0x10000
#define LOAD_MSR_KERNEL(r, x) lis r,(x)@h; ori r,r,(x)@l
#else
#define LOAD_MSR_KERNEL(r, x) li r,(x)
#endif
#ifdef CONFIG_BOOKE
#include "head_booke.h"
#define TRANSFER_TO_HANDLER_EXC_LEVEL(exc_level) \
mtspr exc_level##_SPRG,r8; \
BOOKE_LOAD_EXC_LEVEL_STACK(exc_level); \
lwz r0,GPR10-INT_FRAME_SIZE(r8); \
stw r0,GPR10(r11); \
lwz r0,GPR11-INT_FRAME_SIZE(r8); \
stw r0,GPR11(r11); \
mfspr r8,exc_level##_SPRG
.globl mcheck_transfer_to_handler
mcheck_transfer_to_handler:
TRANSFER_TO_HANDLER_EXC_LEVEL(MCHECK)
b transfer_to_handler_full
.globl debug_transfer_to_handler
debug_transfer_to_handler:
TRANSFER_TO_HANDLER_EXC_LEVEL(DEBUG)
b transfer_to_handler_full
.globl crit_transfer_to_handler
crit_transfer_to_handler:
TRANSFER_TO_HANDLER_EXC_LEVEL(CRIT)
/* fall through */
#endif
#ifdef CONFIG_40x
.globl crit_transfer_to_handler
crit_transfer_to_handler:
lwz r0,crit_r10@l(0)
stw r0,GPR10(r11)
lwz r0,crit_r11@l(0)
stw r0,GPR11(r11)
/* fall through */
#endif
/*
* This code finishes saving the registers to the exception frame
* and jumps to the appropriate handler for the exception, turning
* on address translation.
* Note that we rely on the caller having set cr0.eq iff the exception
* occurred in kernel mode (i.e. MSR:PR = 0).
*/
.globl transfer_to_handler_full
transfer_to_handler_full:
SAVE_NVGPRS(r11)
/* fall through */
.globl transfer_to_handler
transfer_to_handler:
stw r2,GPR2(r11)
stw r12,_NIP(r11)
stw r9,_MSR(r11)
andi. r2,r9,MSR_PR
mfctr r12
mfspr r2,SPRN_XER
stw r12,_CTR(r11)
stw r2,_XER(r11)
mfspr r12,SPRN_SPRG3
addi r2,r12,-THREAD
tovirt(r2,r2) /* set r2 to current */
beq 2f /* if from user, fix up THREAD.regs */
addi r11,r1,STACK_FRAME_OVERHEAD
stw r11,PT_REGS(r12)
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
/* Check to see if the dbcr0 register is set up to debug. Use the
single-step bit to do this. */
lwz r12,THREAD_DBCR0(r12)
andis. r12,r12,DBCR0_IC@h
beq+ 3f
/* From user and task is ptraced - load up global dbcr0 */
li r12,-1 /* clear all pending debug events */
mtspr SPRN_DBSR,r12
lis r11,global_dbcr0@ha
tophys(r11,r11)
addi r11,r11,global_dbcr0@l
lwz r12,0(r11)
mtspr SPRN_DBCR0,r12
lwz r12,4(r11)
addi r12,r12,-1
stw r12,4(r11)
#endif
b 3f
2: /* if from kernel, check interrupted DOZE/NAP mode and
* check for stack overflow
*/
#ifdef CONFIG_6xx
mfspr r11,SPRN_HID0
mtcr r11
BEGIN_FTR_SECTION
bt- 8,power_save_6xx_restore /* Check DOZE */
END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
BEGIN_FTR_SECTION
bt- 9,power_save_6xx_restore /* Check NAP */
END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
#endif /* CONFIG_6xx */
.globl transfer_to_handler_cont
transfer_to_handler_cont:
lwz r11,THREAD_INFO-THREAD(r12)
cmplw r1,r11 /* if r1 <= current->thread_info */
ble- stack_ovf /* then the kernel stack overflowed */
3:
mflr r9
lwz r11,0(r9) /* virtual address of handler */
lwz r9,4(r9) /* where to go when done */
FIX_SRR1(r10,r12)
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r10
mtlr r9
SYNC
RFI /* jump to handler, enable MMU */
/*
* On kernel stack overflow, load up an initial stack pointer
* and call StackOverflow(regs), which should not return.
*/
stack_ovf:
/* sometimes we use a statically-allocated stack, which is OK. */
lis r11,_end@h
ori r11,r11,_end@l
cmplw r1,r11
ble 3b /* r1 <= &_end is OK */
SAVE_NVGPRS(r11)
addi r3,r1,STACK_FRAME_OVERHEAD
lis r1,init_thread_union@ha
addi r1,r1,init_thread_union@l
addi r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
lis r9,StackOverflow@ha
addi r9,r9,StackOverflow@l
LOAD_MSR_KERNEL(r10,MSR_KERNEL)
FIX_SRR1(r10,r12)
mtspr SPRN_SRR0,r9
mtspr SPRN_SRR1,r10
SYNC
RFI
/*
* Handle a system call.
*/
.stabs "arch/ppc/kernel/",N_SO,0,0,0f
.stabs "entry.S",N_SO,0,0,0f
0:
_GLOBAL(DoSyscall)
stw r0,THREAD+LAST_SYSCALL(r2)
stw r3,ORIG_GPR3(r1)
li r12,0
stw r12,RESULT(r1)
lwz r11,_CCR(r1) /* Clear SO bit in CR */
rlwinm r11,r11,0,4,2
stw r11,_CCR(r1)
#ifdef SHOW_SYSCALLS
bl do_show_syscall
#endif /* SHOW_SYSCALLS */
rlwinm r10,r1,0,0,18 /* current_thread_info() */
lwz r11,TI_FLAGS(r10)
andi. r11,r11,_TIF_SYSCALL_T_OR_A
bne- syscall_dotrace
syscall_dotrace_cont:
cmplwi 0,r0,NR_syscalls
lis r10,sys_call_table@h
ori r10,r10,sys_call_table@l
slwi r0,r0,2
bge- 66f
lwzx r10,r10,r0 /* Fetch system call handler [ptr] */
mtlr r10
addi r9,r1,STACK_FRAME_OVERHEAD
PPC440EP_ERR42
blrl /* Call handler */
.globl ret_from_syscall
ret_from_syscall:
#ifdef SHOW_SYSCALLS
bl do_show_syscall_exit
#endif
mr r6,r3
rlwinm r12,r1,0,0,18 /* current_thread_info() */
/* disable interrupts so current_thread_info()->flags can't change */
LOAD_MSR_KERNEL(r10,MSR_KERNEL) /* doesn't include MSR_EE */
SYNC
MTMSRD(r10)
lwz r9,TI_FLAGS(r12)
li r8,-_LAST_ERRNO
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
bne- syscall_exit_work
cmplw 0,r3,r8
blt+ syscall_exit_cont
lwz r11,_CCR(r1) /* Load CR */
neg r3,r3
oris r11,r11,0x1000 /* Set SO bit in CR */
stw r11,_CCR(r1)
syscall_exit_cont:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
/* If the process has its own DBCR0 value, load it up. The single
step bit tells us that dbcr0 should be loaded. */
lwz r0,THREAD+THREAD_DBCR0(r2)
andis. r10,r0,DBCR0_IC@h
bnel- load_dbcr0
#endif
stwcx. r0,0,r1 /* to clear the reservation */
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
mtlr r4
mtcr r5
lwz r7,_NIP(r1)
lwz r8,_MSR(r1)
FIX_SRR1(r8, r0)
lwz r2,GPR2(r1)
lwz r1,GPR1(r1)
mtspr SPRN_SRR0,r7
mtspr SPRN_SRR1,r8
SYNC
RFI
66: li r3,-ENOSYS
b ret_from_syscall
.globl ret_from_fork
ret_from_fork:
REST_NVGPRS(r1)
bl schedule_tail
li r3,0
b ret_from_syscall
/* Traced system call support */
syscall_dotrace:
SAVE_NVGPRS(r1)
li r0,0xc00
stw r0,TRAP(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_enter
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)
REST_NVGPRS(r1)
b syscall_dotrace_cont
syscall_exit_work:
andi. r0,r9,_TIF_RESTOREALL
beq+ 0f
REST_NVGPRS(r1)
b 2f
0: cmplw 0,r3,r8
blt+ 1f
andi. r0,r9,_TIF_NOERROR
bne- 1f
lwz r11,_CCR(r1) /* Load CR */
neg r3,r3
oris r11,r11,0x1000 /* Set SO bit in CR */
stw r11,_CCR(r1)
1: stw r6,RESULT(r1) /* Save result */
stw r3,GPR3(r1) /* Update return value */
2: andi. r0,r9,(_TIF_PERSYSCALL_MASK)
beq 4f
/* Clear per-syscall TIF flags if any are set. */
li r11,_TIF_PERSYSCALL_MASK
addi r12,r12,TI_FLAGS
3: lwarx r8,0,r12
andc r8,r8,r11
#ifdef CONFIG_IBM405_ERR77
dcbt 0,r12
#endif
stwcx. r8,0,r12
bne- 3b
subi r12,r12,TI_FLAGS
4: /* Anything which requires enabling interrupts? */
andi. r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SINGLESTEP)
beq ret_from_except
/* Re-enable interrupts */
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10)
/* Save NVGPRS if they're not saved already */
lwz r4,TRAP(r1)
andi. r4,r4,1
beq 5f
SAVE_NVGPRS(r1)
li r4,0xc00
stw r4,TRAP(r1)
5:
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_syscall_trace_leave
b ret_from_except_full
#ifdef SHOW_SYSCALLS
do_show_syscall:
#ifdef SHOW_SYSCALLS_TASK
lis r11,show_syscalls_task@ha
lwz r11,show_syscalls_task@l(r11)
cmp 0,r2,r11
bnelr
#endif
stw r31,GPR31(r1)
mflr r31
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)
mr r5,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)
mtlr r31
lwz r31,GPR31(r1)
blr
do_show_syscall_exit:
#ifdef SHOW_SYSCALLS_TASK
lis r11,show_syscalls_task@ha
lwz r11,show_syscalls_task@l(r11)
cmp 0,r2,r11
bnelr
#endif
stw r31,GPR31(r1)
mflr r31
stw r3,RESULT(r1) /* Save result */
mr r4,r3
lis r3,79f@ha
addi r3,r3,79f@l
bl printk
lwz r3,RESULT(r1)
mtlr r31
lwz r31,GPR31(r1)
blr
7: .string "syscall %d(%x, %x, %x, %x, %x, "
77: .string "%x), current=%p\n"
79: .string " -> %x\n"
.align 2,0
#ifdef SHOW_SYSCALLS_TASK
.data
.globl show_syscalls_task
show_syscalls_task:
.long -1
.text
#endif
#endif /* SHOW_SYSCALLS */
/*
* The fork/clone functions need to copy the full register set into
* the child process. Therefore we need to save all the nonvolatile
* registers (r13 - r31) before calling the C code.
*/
.globl ppc_fork
ppc_fork:
SAVE_NVGPRS(r1)
lwz r0,TRAP(r1)
rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
stw r0,TRAP(r1) /* register set saved */
b sys_fork
.globl ppc_vfork
ppc_vfork:
SAVE_NVGPRS(r1)
lwz r0,TRAP(r1)
rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
stw r0,TRAP(r1) /* register set saved */
b sys_vfork
.globl ppc_clone
ppc_clone:
SAVE_NVGPRS(r1)
lwz r0,TRAP(r1)
rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
stw r0,TRAP(r1) /* register set saved */
b sys_clone
.globl ppc_swapcontext
ppc_swapcontext:
SAVE_NVGPRS(r1)
lwz r0,TRAP(r1)
rlwinm r0,r0,0,0,30 /* clear LSB to indicate full */
stw r0,TRAP(r1) /* register set saved */
b sys_swapcontext
/*
* Top-level page fault handling.
* This is in assembler because if do_page_fault tells us that
* it is a bad kernel page fault, we want to save the non-volatile
* registers before calling bad_page_fault.
*/
.globl handle_page_fault
handle_page_fault:
stw r4,_DAR(r1)
addi r3,r1,STACK_FRAME_OVERHEAD
bl do_page_fault
cmpwi r3,0
beq+ ret_from_except
SAVE_NVGPRS(r1)
lwz r0,TRAP(r1)
clrrwi r0,r0,1
stw r0,TRAP(r1)
mr r5,r3
addi r3,r1,STACK_FRAME_OVERHEAD
lwz r4,_DAR(r1)
bl bad_page_fault
b ret_from_except_full
/*
* 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.
* On entry, r3 points to the THREAD for the current task, r4
* points to the THREAD for the new task.
*
* This routine is always called with interrupts disabled.
*
* 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 , 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)
mflr r0
stw r0,INT_FRAME_SIZE+4(r1)
/* r3-r12 are caller saved -- Cort */
SAVE_NVGPRS(r1)
stw r0,_NIP(r1) /* Return to switch caller */
mfmsr r11
li r0,MSR_FP /* Disable floating-point */
#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
oris r0,r0,MSR_VEC@h /* Disable altivec */
mfspr r12,SPRN_VRSAVE /* save vrsave register value */
stw r12,THREAD+THREAD_VRSAVE(r2)
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
oris r0,r0,MSR_SPE@h /* Disable SPE */
mfspr r12,SPRN_SPEFSCR /* save spefscr register value */
stw r12,THREAD+THREAD_SPEFSCR(r2)
#endif /* CONFIG_SPE */
and. r0,r0,r11 /* FP or altivec or SPE enabled? */
beq+ 1f
andc r11,r11,r0
MTMSRD(r11)
isync
1: stw r11,_MSR(r1)
mfcr r10
stw r10,_CCR(r1)
stw r1,KSP(r3) /* Set old stack pointer */
#ifdef CONFIG_SMP
/* We need a sync somewhere here to make sure that if the
* previous task gets rescheduled on another CPU, it sees all
* stores it has performed on this one.
*/
sync
#endif /* CONFIG_SMP */
tophys(r0,r4)
CLR_TOP32(r0)
mtspr SPRN_SPRG3,r0 /* Update current THREAD phys addr */
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 */
#ifdef CONFIG_ALTIVEC
BEGIN_FTR_SECTION
lwz r0,THREAD+THREAD_VRSAVE(r2)
mtspr SPRN_VRSAVE,r0 /* if G4, restore VRSAVE reg */
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
lwz r0,THREAD+THREAD_SPEFSCR(r2)
mtspr SPRN_SPEFSCR,r0 /* restore SPEFSCR reg */
#endif /* CONFIG_SPE */
lwz r0,_CCR(r1)
mtcrf 0xFF,r0
/* r3-r12 are destroyed -- Cort */
REST_NVGPRS(r1)
lwz r4,_NIP(r1) /* Return to _switch caller in new task */
mtlr r4
addi r1,r1,INT_FRAME_SIZE
blr
.globl fast_exception_return
fast_exception_return:
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
andi. r10,r9,MSR_RI /* check for recoverable interrupt */
beq 1f /* if not, we've got problems */
#endif
2: REST_4GPRS(3, r11)
lwz r10,_CCR(r11)
REST_GPR(1, r11)
mtcr r10
lwz r10,_LINK(r11)
mtlr r10
REST_GPR(10, r11)
mtspr SPRN_SRR1,r9
mtspr SPRN_SRR0,r12
REST_GPR(9, r11)
REST_GPR(12, r11)
lwz r11,GPR11(r11)
SYNC
RFI
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
/* check if the exception happened in a restartable section */
1: lis r3,exc_exit_restart_end@ha
addi r3,r3,exc_exit_restart_end@l
cmplw r12,r3
bge 3f
lis r4,exc_exit_restart@ha
addi r4,r4,exc_exit_restart@l
cmplw r12,r4
blt 3f
lis r3,fee_restarts@ha
tophys(r3,r3)
lwz r5,fee_restarts@l(r3)
addi r5,r5,1
stw r5,fee_restarts@l(r3)
mr r12,r4 /* restart at exc_exit_restart */
b 2b
.comm fee_restarts,4
/* aargh, a nonrecoverable interrupt, panic */
/* aargh, we don't know which trap this is */
/* but the 601 doesn't implement the RI bit, so assume it's OK */
3:
BEGIN_FTR_SECTION
b 2b
END_FTR_SECTION_IFSET(CPU_FTR_601)
li r10,-1
stw r10,TRAP(r11)
addi r3,r1,STACK_FRAME_OVERHEAD
lis r10,MSR_KERNEL@h
ori r10,r10,MSR_KERNEL@l
bl transfer_to_handler_full
.long nonrecoverable_exception
.long ret_from_except
#endif
.globl ret_from_except_full
ret_from_except_full:
REST_NVGPRS(r1)
/* fall through */
.globl ret_from_except
ret_from_except:
/* Hard-disable interrupts so that current_thread_info()->flags
* can't change between when we test it and when we return
* from the interrupt. */
LOAD_MSR_KERNEL(r10,MSR_KERNEL)
SYNC /* Some chip revs have problems here... */
MTMSRD(r10) /* disable interrupts */
lwz r3,_MSR(r1) /* Returning to user mode? */
andi. r0,r3,MSR_PR
beq resume_kernel
user_exc_return: /* r10 contains MSR_KERNEL here */
/* Check current_thread_info()->flags */
rlwinm r9,r1,0,0,18
lwz r9,TI_FLAGS(r9)
andi. r0,r9,(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK|_TIF_NEED_RESCHED)
bne do_work
restore_user:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
/* Check whether this process has its own DBCR0 value. The single
step bit tells us that dbcr0 should be loaded. */
lwz r0,THREAD+THREAD_DBCR0(r2)
andis. r10,r0,DBCR0_IC@h
bnel- load_dbcr0
#endif
#ifdef CONFIG_PREEMPT
b restore
/* N.B. the only way to get here is from the beq following ret_from_except. */
resume_kernel:
/* check current_thread_info->preempt_count */
rlwinm r9,r1,0,0,18
lwz r0,TI_PREEMPT(r9)
cmpwi 0,r0,0 /* if non-zero, just restore regs and return */
bne restore
lwz r0,TI_FLAGS(r9)
andi. r0,r0,_TIF_NEED_RESCHED
beq+ restore
andi. r0,r3,MSR_EE /* interrupts off? */
beq restore /* don't schedule if so */
1: bl preempt_schedule_irq
rlwinm r9,r1,0,0,18
lwz r3,TI_FLAGS(r9)
andi. r0,r3,_TIF_NEED_RESCHED
bne- 1b
#else
resume_kernel:
#endif /* CONFIG_PREEMPT */
/* interrupts are hard-disabled at this point */
restore:
lwz r0,GPR0(r1)
lwz r2,GPR2(r1)
REST_4GPRS(3, r1)
REST_2GPRS(7, r1)
lwz r10,_XER(r1)
lwz r11,_CTR(r1)
mtspr SPRN_XER,r10
mtctr r11
PPC405_ERR77(0,r1)
stwcx. r0,0,r1 /* to clear the reservation */
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
lwz r9,_MSR(r1)
andi. r10,r9,MSR_RI /* check if this exception occurred */
beql nonrecoverable /* at a bad place (MSR:RI = 0) */
lwz r10,_CCR(r1)
lwz r11,_LINK(r1)
mtcrf 0xFF,r10
mtlr r11
/*
* Once we put values in SRR0 and SRR1, we are in a state
* where exceptions are not recoverable, since taking an
* exception will trash SRR0 and SRR1. Therefore we clear the
* MSR:RI bit to indicate this. If we do take an exception,
* we can't return to the point of the exception but we
* can restart the exception exit path at the label
* exc_exit_restart below. -- paulus
*/
LOAD_MSR_KERNEL(r10,MSR_KERNEL & ~MSR_RI)
SYNC
MTMSRD(r10) /* clear the RI bit */
.globl exc_exit_restart
exc_exit_restart:
lwz r9,_MSR(r1)
lwz r12,_NIP(r1)
FIX_SRR1(r9,r10)
mtspr SPRN_SRR0,r12
mtspr SPRN_SRR1,r9
REST_4GPRS(9, r1)
lwz r1,GPR1(r1)
.globl exc_exit_restart_end
exc_exit_restart_end:
SYNC
RFI
#else /* !(CONFIG_4xx || CONFIG_BOOKE) */
/*
* This is a bit different on 4xx/Book-E because it doesn't have
* the RI bit in the MSR.
* The TLB miss handler checks if we have interrupted
* the exception exit path and restarts it if so
* (well maybe one day it will... :).
*/
lwz r11,_LINK(r1)
mtlr r11
lwz r10,_CCR(r1)
mtcrf 0xff,r10
REST_2GPRS(9, r1)
.globl exc_exit_restart
exc_exit_restart:
lwz r11,_NIP(r1)
lwz r12,_MSR(r1)
exc_exit_start:
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
REST_2GPRS(11, r1)
lwz r1,GPR1(r1)
.globl exc_exit_restart_end
exc_exit_restart_end:
PPC405_ERR77_SYNC
rfi
b . /* prevent prefetch past rfi */
/*
* Returning from a critical interrupt in user mode doesn't need
* to be any different from a normal exception. For a critical
* interrupt in the kernel, we just return (without checking for
* preemption) since the interrupt may have happened at some crucial
* place (e.g. inside the TLB miss handler), and because we will be
* running with r1 pointing into critical_stack, not the current
* process's kernel stack (and therefore current_thread_info() will
* give the wrong answer).
* We have to restore various SPRs that may have been in use at the
* time of the critical interrupt.
*
*/
#ifdef CONFIG_40x
#define PPC_40x_TURN_OFF_MSR_DR \
/* avoid any possible TLB misses here by turning off MSR.DR, we \
* assume the instructions here are mapped by a pinned TLB entry */ \
li r10,MSR_IR; \
mtmsr r10; \
isync; \
tophys(r1, r1);
#else
#define PPC_40x_TURN_OFF_MSR_DR
#endif
#define RET_FROM_EXC_LEVEL(exc_lvl_srr0, exc_lvl_srr1, exc_lvl_rfi) \
REST_NVGPRS(r1); \
lwz r3,_MSR(r1); \
andi. r3,r3,MSR_PR; \
LOAD_MSR_KERNEL(r10,MSR_KERNEL); \
bne user_exc_return; \
lwz r0,GPR0(r1); \
lwz r2,GPR2(r1); \
REST_4GPRS(3, r1); \
REST_2GPRS(7, r1); \
lwz r10,_XER(r1); \
lwz r11,_CTR(r1); \
mtspr SPRN_XER,r10; \
mtctr r11; \
PPC405_ERR77(0,r1); \
stwcx. r0,0,r1; /* to clear the reservation */ \
lwz r11,_LINK(r1); \
mtlr r11; \
lwz r10,_CCR(r1); \
mtcrf 0xff,r10; \
PPC_40x_TURN_OFF_MSR_DR; \
lwz r9,_DEAR(r1); \
lwz r10,_ESR(r1); \
mtspr SPRN_DEAR,r9; \
mtspr SPRN_ESR,r10; \
lwz r11,_NIP(r1); \
lwz r12,_MSR(r1); \
mtspr exc_lvl_srr0,r11; \
mtspr exc_lvl_srr1,r12; \
lwz r9,GPR9(r1); \
lwz r12,GPR12(r1); \
lwz r10,GPR10(r1); \
lwz r11,GPR11(r1); \
lwz r1,GPR1(r1); \
PPC405_ERR77_SYNC; \
exc_lvl_rfi; \
b .; /* prevent prefetch past exc_lvl_rfi */
.globl ret_from_crit_exc
ret_from_crit_exc:
RET_FROM_EXC_LEVEL(SPRN_CSRR0, SPRN_CSRR1, RFCI)
#ifdef CONFIG_BOOKE
.globl ret_from_debug_exc
ret_from_debug_exc:
RET_FROM_EXC_LEVEL(SPRN_DSRR0, SPRN_DSRR1, RFDI)
.globl ret_from_mcheck_exc
ret_from_mcheck_exc:
RET_FROM_EXC_LEVEL(SPRN_MCSRR0, SPRN_MCSRR1, RFMCI)
#endif /* CONFIG_BOOKE */
/*
* Load the DBCR0 value for a task that is being ptraced,
* having first saved away the global DBCR0. Note that r0
* has the dbcr0 value to set upon entry to this.
*/
load_dbcr0:
mfmsr r10 /* first disable debug exceptions */
rlwinm r10,r10,0,~MSR_DE
mtmsr r10
isync
mfspr r10,SPRN_DBCR0
lis r11,global_dbcr0@ha
addi r11,r11,global_dbcr0@l
stw r10,0(r11)
mtspr SPRN_DBCR0,r0
lwz r10,4(r11)
addi r10,r10,1
stw r10,4(r11)
li r11,-1
mtspr SPRN_DBSR,r11 /* clear all pending debug events */
blr
.comm global_dbcr0,8
#endif /* !(CONFIG_4xx || CONFIG_BOOKE) */
do_work: /* r10 contains MSR_KERNEL here */
andi. r0,r9,_TIF_NEED_RESCHED
beq do_user_signal
do_resched: /* r10 contains MSR_KERNEL here */
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10) /* hard-enable interrupts */
bl schedule
recheck:
LOAD_MSR_KERNEL(r10,MSR_KERNEL)
SYNC
MTMSRD(r10) /* disable interrupts */
rlwinm r9,r1,0,0,18
lwz r9,TI_FLAGS(r9)
andi. r0,r9,_TIF_NEED_RESCHED
bne- do_resched
andi. r0,r9,_TIF_SIGPENDING
beq restore_user
do_user_signal: /* r10 contains MSR_KERNEL here */
ori r10,r10,MSR_EE
SYNC
MTMSRD(r10) /* hard-enable interrupts */
/* save r13-r31 in the exception frame, if not already done */
lwz r3,TRAP(r1)
andi. r0,r3,1
beq 2f
SAVE_NVGPRS(r1)
rlwinm r3,r3,0,0,30
stw r3,TRAP(r1)
2: li r3,0
addi r4,r1,STACK_FRAME_OVERHEAD
bl do_signal
REST_NVGPRS(r1)
b recheck
/*
* We come here when we are at the end of handling an exception
* that occurred at a place where taking an exception will lose
* state information, such as the contents of SRR0 and SRR1.
*/
nonrecoverable:
lis r10,exc_exit_restart_end@ha
addi r10,r10,exc_exit_restart_end@l
cmplw r12,r10
bge 3f
lis r11,exc_exit_restart@ha
addi r11,r11,exc_exit_restart@l
cmplw r12,r11
blt 3f
lis r10,ee_restarts@ha
lwz r12,ee_restarts@l(r10)
addi r12,r12,1
stw r12,ee_restarts@l(r10)
mr r12,r11 /* restart at exc_exit_restart */
blr
3: /* OK, we can't recover, kill this process */
/* but the 601 doesn't implement the RI bit, so assume it's OK */
BEGIN_FTR_SECTION
blr
END_FTR_SECTION_IFSET(CPU_FTR_601)
lwz r3,TRAP(r1)
andi. r0,r3,1
beq 4f
SAVE_NVGPRS(r1)
rlwinm r3,r3,0,0,30
stw r3,TRAP(r1)
4: addi r3,r1,STACK_FRAME_OVERHEAD
bl nonrecoverable_exception
/* shouldn't return */
b 4b
.comm ee_restarts,4
/*
* PROM code for specific machines follows. Put it
* here so it's easy to add arch-specific sections later.
* -- Cort
*/
#ifdef CONFIG_PPC_OF
/*
* On CHRP, the Run-Time Abstraction Services (RTAS) have to be
* called with the MMU off.
*/
_GLOBAL(enter_rtas)
stwu r1,-INT_FRAME_SIZE(r1)
mflr r0
stw r0,INT_FRAME_SIZE+4(r1)
lis r4,rtas_data@ha
lwz r4,rtas_data@l(r4)
lis r6,1f@ha /* physical return address for rtas */
addi r6,r6,1f@l
tophys(r6,r6)
tophys(r7,r1)
lis r8,rtas_entry@ha
lwz r8,rtas_entry@l(r8)
mfmsr r9
stw r9,8(r1)
LOAD_MSR_KERNEL(r0,MSR_KERNEL)
SYNC /* disable interrupts so SRR0/1 */
MTMSRD(r0) /* don't get trashed */
li r9,MSR_KERNEL & ~(MSR_IR|MSR_DR)
mtlr r6
CLR_TOP32(r7)
mtspr SPRN_SPRG2,r7
mtspr SPRN_SRR0,r8
mtspr SPRN_SRR1,r9
RFI
1: tophys(r9,r1)
lwz r8,INT_FRAME_SIZE+4(r9) /* get return address */
lwz r9,8(r9) /* original msr value */
FIX_SRR1(r9,r0)
addi r1,r1,INT_FRAME_SIZE
li r0,0
mtspr SPRN_SPRG2,r0
mtspr SPRN_SRR0,r8
mtspr SPRN_SRR1,r9
RFI /* return to caller */
.globl machine_check_in_rtas
machine_check_in_rtas:
twi 31,0,0
/* XXX load up BATs and panic */
#endif /* CONFIG_PPC_OF */
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