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Diffstat (limited to 'arch/nios2/kernel/entry.S')
| -rw-r--r-- | arch/nios2/kernel/entry.S | 568 |
1 files changed, 568 insertions, 0 deletions
diff --git a/arch/nios2/kernel/entry.S b/arch/nios2/kernel/entry.S new file mode 100644 index 000000000..99f0a65e6 --- /dev/null +++ b/arch/nios2/kernel/entry.S @@ -0,0 +1,568 @@ +/* + * 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: |