/* * 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 , * Kenneth Albanowski , * 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 */ #include #include #include #include #include #include #include #include #include #include .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: /* 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) beq r1, r0, ret_invsyscall /* 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 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, we don't need to check the boundaries * since this is already done. */ 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 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_tra