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