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/*
* linux/arch/nios2/kernel/entry.S
*
* Copyright (C) 2013-2014 Altera Corporation
* Copyright (C) 2009, Wind River Systems Inc
*
* Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
*
* Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com)
* Copyright (C) 1998 D. Jeff Dionne <jeff@lineo.ca>,
* Kenneth Albanowski <kjahds@kjahds.com>,
* Copyright (C) 2000 Lineo Inc. (www.lineo.com)
* Copyright (C) 2004 Microtronix Datacom Ltd.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Linux/m68k support by Hamish Macdonald
*
* 68060 fixes by Jesper Skov
* ColdFire support by Greg Ungerer (gerg@snapgear.com)
* 5307 fixes by David W. Miller
* linux 2.4 support David McCullough <davidm@snapgear.com>
*/
#include <linux/sys.h>
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/asm-macros.h>
#include <asm/thread_info.h>
#include <asm/errno.h>
#include <asm/setup.h>
#include <asm/entry.h>
#include <asm/unistd.h>
#include <asm/processor.h>
.macro GET_THREAD_INFO reg
.if THREAD_SIZE & 0xffff0000
andhi \reg, sp, %hi(~(THREAD_SIZE-1))
.else
addi \reg, r0, %lo(~(THREAD_SIZE-1))
and \reg, \reg, sp
.endif
.endm
.macro kuser_cmpxchg_check
/*
* Make sure our user space atomic helper is restarted if it was
* interrupted in a critical region.
* ea-4 = address of interrupted insn (ea must be preserved).
* sp = saved regs.
* cmpxchg_ldw = first critical insn, cmpxchg_stw = last critical insn.
* If ea <= cmpxchg_stw and ea > cmpxchg_ldw then saved EA is set to
* cmpxchg_ldw + 4.
*/
/* et = cmpxchg_stw + 4 */
movui et, (KUSER_BASE + 4 + (cmpxchg_stw - __kuser_helper_start))
bgtu ea, et, 1f
subi et, et, (cmpxchg_stw - cmpxchg_ldw) /* et = cmpxchg_ldw + 4 */
bltu ea, et, 1f
stw et, PT_EA(sp) /* fix up EA */
mov ea, et
1:
.endm
.section .rodata
.align 4
exception_table:
.word unhandled_exception /* 0 - Reset */
.word unhandled_exception /* 1 - Processor-only Reset */
.word external_interrupt /* 2 - Interrupt */
.word handle_trap /* 3 - Trap Instruction */
.word instruction_trap /* 4 - Unimplemented instruction */
.word handle_illegal /* 5 - Illegal instruction */
.word handle_unaligned /* 6 - Misaligned data access */
.word handle_unaligned /* 7 - Misaligned destination address */
.word handle_diverror /* 8 - Division error */
.word protection_exception_ba /* 9 - Supervisor-only instr. address */
.word protection_exception_instr /* 10 - Supervisor only instruction */
.word protection_exception_ba /* 11 - Supervisor only data address */
.word unhandled_exception /* 12 - Double TLB miss (data) */
.word protection_exception_pte /* 13 - TLB permission violation (x) */
.word protection_exception_pte /* 14 - TLB permission violation (r) */
.word protection_exception_pte /* 15 - TLB permission violation (w) */
.word unhandled_exception /* 16 - MPU region violation */
trap_table:
.word handle_system_call /* 0 */
.word handle_trap_1 /* 1 */
.word handle_trap_2 /* 2 */
.word handle_trap_3 /* 3 */
.word handle_trap_reserved /* 4 */
.word handle_trap_reserved /* 5 */
.word handle_trap_reserved /* 6 */
.word handle_trap_reserved /* 7 */
.word handle_trap_reserved /* 8 */
.word handle_trap_reserved /* 9 */
.word handle_trap_reserved /* 10 */
.word handle_trap_reserved /* 11 */
.word handle_trap_reserved /* 12 */
.word handle_trap_reserved /* 13 */
.word handle_trap_reserved /* 14 */
.word handle_trap_reserved /* 15 */
.word handle_trap_reserved /* 16 */
.word handle_trap_reserved /* 17 */
.word handle_trap_reserved /* 18 */
.word handle_trap_reserved /* 19 */
.word handle_trap_reserved /* 20 */
.word handle_trap_reserved /* 21 */
.word handle_trap_reserved /* 22 */
.word handle_trap_reserved /* 23 */
.word handle_trap_reserved /* 24 */
.word handle_trap_reserved /* 25 */
.word handle_trap_reserved /* 26 */
.word handle_trap_reserved /* 27 */
.word handle_trap_reserved /* 28 */
.word handle_trap_reserved /* 29 */
#ifdef CONFIG_KGDB
.word handle_kgdb_breakpoint /* 30 KGDB breakpoint */
#else
.word instruction_trap /* 30 */
#endif
.word handle_breakpoint /* 31 */
.text
.set noat
.set nobreak
ENTRY(inthandler)
SAVE_ALL
kuser_cmpxchg_check
/* Clear EH bit before we get a new excpetion in the kernel
* and after we have saved it to the exception frame. This is done
* whether it's trap, tlb-miss or interrupt. If we don't do this
* estatus is not updated the next exception.
*/
rdctl r24, status
movi r9, %lo(~STATUS_EH)
and r24, r24, r9
wrctl status, r24
/* Read cause and vector and branch to the associated handler */
mov r4, sp
rdctl r5, exception
movia r9, exception_table
add r24, r9, r5
ldw r24, 0(r24)
jmp r24
/***********************************************************************
* Handle traps
***********************************************************************
*/
ENTRY(handle_trap)
ldwio r24, -4(ea) /* instruction that caused the exception */
srli r24, r24, 4
andi r24, r24, 0x7c
movia r9,trap_table
add r24, r24, r9
ldw r24, 0(r24)
jmp r24
/***********************************************************************
* Handle system calls
***********************************************************************
*/
ENTRY(handle_system_call)
/* Enable interrupts */
rdctl r10, status
ori r10, r10, STATUS_PIE
wrctl status, r10
/* Reload registers destroyed by common code. */
ldw r4, PT_R4(sp)
ldw r5, PT_R5(sp)
local_restart:
stw r2, PT_ORIG_R2(sp)
/* Check that the requested system call is within limits */
movui r1, __NR_syscalls
bgeu r2, r1, ret_invsyscall
slli r1, r2, 2
movhi r11, %hiadj(sys_call_table)
add r1, r1, r11
ldw r1, %lo(sys_call_table)(r1)
/* Check if we are being traced */
GET_THREAD_INFO r11
ldw r11,TI_FLAGS(r11)
BTBNZ r11,r11,TIF_SYSCALL_TRACE,traced_system_call
/* Execute the system call */
callr r1
/* If the syscall returns a negative result:
* Set r7 to 1 to indicate error,
* Negate r2 to get a positive error code
* If the syscall returns zero or a positive value:
* Set r7 to 0.
* The sigreturn system calls will skip the code below by
* adding to register ra. To avoid destroying registers
*/
translate_rc_and_ret:
movi r1, 0
bge r2, zero, 3f
ldw r1, PT_ORIG_R2(sp)
addi r1, r1, 1
beq r1, zero, 3f
sub r2, zero, r2
movi r1, 1
3:
stw r2, PT_R2(sp)
stw r1, PT_R7(sp)
end_translate_rc_and_ret:
ret_from_exception:
ldw r1, PT_ESTATUS(sp)
/* if so, skip resched, signals */
TSTBNZ r1, r1, ESTATUS_EU, Luser_return
restore_all:
rdctl r10, status /* disable intrs */
andi r10, r10, %lo(~STATUS_PIE)
wrctl status, r10
RESTORE_ALL
eret
/* If the syscall number was invalid return ENOSYS */
ret_invsyscall:
movi r2, -ENOSYS
br translate_rc_and_ret
/* This implements the same as above, except it calls
* do_syscall_trace_enter and do_syscall_trace_exit before and after the
* syscall in order for utilities like strace and gdb to work.
*/
traced_system_call:
SAVE_SWITCH_STACK
call do_syscall_trace_enter
RESTORE_SWITCH_STACK
/* Create system call register arguments. The 5th and 6th
arguments on stack are already in place at the beginning
of pt_regs. */
ldw r2, PT_R2(sp)
ldw r4, PT_R4(sp)
ldw r5, PT_R5(sp)
ldw r6, PT_R6(sp)
ldw r7, PT_R7(sp)
/* Fetch the syscall function. */
movui r1, __NR_syscalls
bgeu r2, r1, traced_invsyscall
slli r1, r2, 2
movhi r11,%hiadj(sys_call_table)
add r1, r1, r11
ldw r1, %lo(sys_call_table)(r1)
callr r1
/* If the syscall returns a negative result:
* Set r7 to 1 to indicate error,
* Negate r2 to get a positive error code
* If the syscall returns zero or a positive value:
* Set r7 to 0.
* The sigreturn system calls will skip the code below by
* adding to register ra. To avoid destroying registers
*/
translate_rc_and_ret2:
movi r1, 0
bge r2, zero, 4f
ldw r1, PT_ORIG_R2(sp)
addi r1, r1, 1
beq r1, zero, 4f
sub r2, zero, r2
movi r1, 1
4:
stw r2, PT_R2(sp)
stw r1, PT_R7(sp)
end_translate_rc_and_ret2:
SAVE_SWITCH_STACK
call do_syscall_trace_exit
RESTORE_SWITCH_STACK
br ret_from_exception
/* If the syscall number was invalid return ENOSYS */
traced_invsyscall:
movi r2, -ENOSYS
br translate_rc_and_ret2
Luser_return:
GET_THREAD_INFO r11 /* get thread_info pointer */
ldw r10, TI_FLAGS(r11) /* get thread_info->flags */
ANDI32 r11, r10, _TIF_WORK_MASK
beq r11, r0, restore_all /* Nothing to do */
BTBZ r1, r10, TIF_NEED_RESCHED, Lsignal_return
/* Reschedule work */
call schedule
br ret_from_exception
Lsignal_return:
ANDI32 r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME
beq r1, r0, restore_all
mov r4, sp /* pt_regs */
SAVE_SWITCH_STACK
call do_notify_resume
beq r2, r0, no_work_pending
RESTORE_SWITCH_STACK
/* prepare restart syscall here without leaving kernel */
ldw r2, PT_R2(sp) /* reload syscall number in r2 */
ldw r4, PT_R4(sp) /* reload syscall arguments r4-r9 */
ldw r5, PT_R5(sp)
ldw r6, PT_R6(sp)
ldw r7, PT_R7(sp)
ldw r8, PT_R8(sp)
ldw r9, PT_R9(sp)
br local_restart /* restart syscall */
no_work_pending:
RESTORE_SWITCH_STACK
br ret_from_exception
/***********************************************************************
* Handle external interrupts.
***********************************************************************
*/
/*
* This is the generic interrupt handler (for all hardware interrupt
* sources). It figures out the vector number and calls the appropriate
* interrupt service routine directly.
*/
external_interrupt:
rdctl r12, ipending
rdctl r9, ienable
and r12, r12, r9
/* skip if no interrupt is pending */
beq r12, r0, ret_from_interrupt
/*
* Process an external hardware interrupt.
*/
addi ea, ea, -4 /* re-issue the interrupted instruction */
stw ea, PT_EA(sp)
2: movi r4, %lo(-1) /* Start from bit position 0,
highest priority */
/* This is the IRQ # for handler call */
1: andi r10, r12, 1 /* Isolate bit we are interested in */
srli r12, r12, 1 /* shift count is costly without hardware
multiplier */
addi r4, r4, 1
beq r10, r0, 1b
mov r5, sp /* Setup pt_regs pointer for handler call */
call do_IRQ
rdctl r12, ipending /* check again if irq still pending */
rdctl r9, ienable /* Isolate possible interrupts */
and r12, r12, r9
bne r12, r0, 2b
/* br ret_from_interrupt */ /* fall through to ret_from_interrupt */
ENTRY(ret_from_interrupt)
ldw r1, PT_ESTATUS(sp) /* check if returning to kernel */
TSTBNZ r1, r1, ESTATUS_EU, Luser_return
#ifdef CONFIG_PREEMPTION
GET_THREAD_INFO r1
ldw r4, TI_PREEMPT_COUNT(r1)
bne r4, r0, restore_all
ldw r4, TI_FLAGS(r1) /* ? Need resched set */
BTBZ r10, r4, TIF_NEED_RESCHED, restore_all
ldw r4, PT_ESTATUS(sp) /* ? Interrupts off */
andi r10, r4, ESTATUS_EPIE
beq r10, r0, restore_all
call preempt_schedule_irq
#endif
br restore_all
/***********************************************************************
* A few syscall wrappers
***********************************************************************
*/
/*
* int clone(unsigned long clone_flags, unsigned long newsp,
* int __user * parent_tidptr, int __user * child_tidptr,
* int tls_val)
*/
ENTRY(sys_clone)
SAVE_SWITCH_STACK
subi sp, sp, 4 /* make space for tls pointer */
stw r8, 0(sp) /* pass tls pointer (r8) via stack (5th argument) */
call nios2_clone
addi sp, sp, 4
RESTORE_SWITCH_STACK
ret
ENTRY(sys_rt_sigreturn)
SAVE_SWITCH_STACK
mov r4, sp
call do_rt_sigreturn
RESTORE_SWITCH_STACK
addi ra, ra, (end_translate_rc_and_ret - translate_rc_and_ret)
ret
/***********************************************************************
* A few other wrappers and stubs
***********************************************************************
*/
protection_exception_pte:
rdctl r6, pteaddr
slli r6, r6, 10
call do_page_fault
br ret_from_exception
protection_exception_ba:
rdctl r6, badaddr
call do_page_fault
br ret_from_exception
protection_exception_instr:
call handle_supervisor_instr
br ret_from_exception
handle_breakpoint:
call breakpoint_c
br ret_from_exception
#ifdef CONFIG_NIOS2_ALIGNMENT_TRAP
handle_unaligned:
SAVE_SWITCH_STACK
call handle_unaligned_c
RESTORE_SWITCH_STACK
br ret_from_exception
#else
handle_unaligned:
call handle_unaligned_c
br ret_from_exception
#endif
handle_illegal:
call handle_illegal_c
br ret_from_exception
handle_diverror:
call handle_diverror_c
br ret_from_exception
#ifdef CONFIG_KGDB
handle_kgdb_breakpoint:
call kgdb_breakpoint_c
br ret_from_exception
#endif
handle_trap_1:
call handle_trap_1_c
br ret_from_exception
handle_trap_2:
call handle_trap_2_c
br ret_from_exception
handle_trap_3:
handle_trap_reserved:
call handle_trap_3_c
br ret_from_exception
/*
* Beware - when entering resume, prev (the current task) is
* in r4, next (the new task) is in r5, don't change these
* registers.
*/
ENTRY(resume)
rdctl r7, status /* save thread status reg */
stw r7, TASK_THREAD + THREAD_KPSR(r4)
andi r7, r7, %lo(~STATUS_PIE) /* disable interrupts */
wrctl status, r7
SAVE_SWITCH_STACK
stw sp, TASK_THREAD + THREAD_KSP(r4)/* save kernel stack pointer */
ldw sp, TASK_THREAD + THREAD_KSP(r5)/* restore new thread stack */
movia r24, _current_thread /* save thread */
GET_THREAD_INFO r1
stw r1, 0(r24)
RESTORE_SWITCH_STACK
ldw r7, TASK_THREAD + THREAD_KPSR(r5)/* restore thread status reg */
wrctl status, r7
ret
ENTRY(ret_from_fork)
call schedule_tail
br ret_from_exception
ENTRY(ret_from_kernel_thread)
call schedule_tail
mov r4,r17 /* arg */
callr r16 /* function */
br ret_from_exception
/*
* Kernel user helpers.
*
* Each segment is 64-byte aligned and will be mapped to the <User space>.
* New segments (if ever needed) must be added after the existing ones.
* This mechanism should be used only for things that are really small and
* justified, and not be abused freely.
*
*/
/* Filling pads with undefined instructions. */
.macro kuser_pad sym size
.if ((. - \sym) & 3)
.rept (4 - (. - \sym) & 3)
.byte 0
.endr
.endif
.rept ((\size - (. - \sym)) / 4)
.word 0xdeadbeef
.endr
.endm
.align 6
.globl __kuser_helper_start
__kuser_helper_start:
__kuser_helper_version: /* @ 0x1000 */
.word ((__kuser_helper_end - __kuser_helper_start) >> 6)
__kuser_cmpxchg: /* @ 0x1004 */
/*
* r4 pointer to exchange variable
* r5 old value
* r6 new value
*/
cmpxchg_ldw:
ldw r2, 0(r4) /* load current value */
sub r2, r2, r5 /* compare with old value */
bne r2, zero, cmpxchg_ret
/* We had a match, store the new value */
cmpxchg_stw:
stw r6, 0(r4)
cmpxchg_ret:
ret
kuser_pad __kuser_cmpxchg, 64
.globl __kuser_sigtramp
__kuser_sigtramp:
movi r2, __NR_rt_sigreturn
trap
kuser_pad __kuser_sigtramp, 64
.globl __kuser_helper_end
__kuser_helper_end:
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