1 /* 2 * Traps/Non-MMU Exception handling for ARC 3 * 4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * vineetg: May 2011 11 * -user-space unaligned access emulation 12 * 13 * Rahul Trivedi: Codito Technologies 2004 14 */ 15 16 #include <linux/sched.h> 17 #include <linux/kdebug.h> 18 #include <linux/uaccess.h> 19 #include <linux/ptrace.h> 20 #include <linux/kprobes.h> 21 #include <linux/kgdb.h> 22 #include <asm/setup.h> 23 #include <asm/unaligned.h> 24 #include <asm/kprobes.h> 25 26 void __init trap_init(void) 27 { 28 return; 29 } 30 31 void die(const char *str, struct pt_regs *regs, unsigned long address, 32 unsigned long cause_reg) 33 { 34 show_kernel_fault_diag(str, regs, address, cause_reg); 35 36 /* DEAD END */ 37 __asm__("flag 1"); 38 } 39 40 /* 41 * Helper called for bulk of exceptions NOT needing specific handling 42 * -for user faults enqueues requested signal 43 * -for kernel, chk if due to copy_(to|from)_user, otherwise die() 44 */ 45 static noinline int handle_exception(unsigned long cause, char *str, 46 struct pt_regs *regs, siginfo_t *info) 47 { 48 if (user_mode(regs)) { 49 struct task_struct *tsk = current; 50 51 tsk->thread.fault_address = (__force unsigned int)info->si_addr; 52 tsk->thread.cause_code = cause; 53 54 force_sig_info(info->si_signo, info, tsk); 55 56 } else { 57 /* If not due to copy_(to|from)_user, we are doomed */ 58 if (fixup_exception(regs)) 59 return 0; 60 61 die(str, regs, (unsigned long)info->si_addr, cause); 62 } 63 64 return 1; 65 } 66 67 #define DO_ERROR_INFO(signr, str, name, sicode) \ 68 int name(unsigned long cause, unsigned long address, struct pt_regs *regs) \ 69 { \ 70 siginfo_t info = { \ 71 .si_signo = signr, \ 72 .si_errno = 0, \ 73 .si_code = sicode, \ 74 .si_addr = (void __user *)address, \ 75 }; \ 76 return handle_exception(cause, str, regs, &info);\ 77 } 78 79 /* 80 * Entry points for exceptions NOT needing specific handling 81 */ 82 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC) 83 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC) 84 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 85 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR) 86 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT) 87 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN) 88 89 #ifdef CONFIG_ARC_MISALIGN_ACCESS 90 /* 91 * Entry Point for Misaligned Data access Exception, for emulating in software 92 */ 93 int do_misaligned_access(unsigned long cause, unsigned long address, 94 struct pt_regs *regs, struct callee_regs *cregs) 95 { 96 if (misaligned_fixup(address, regs, cause, cregs) != 0) 97 return do_misaligned_error(cause, address, regs); 98 99 return 0; 100 } 101 #endif 102 103 /* 104 * Entry point for miscll errors such as Nested Exceptions 105 * -Duplicate TLB entry is handled seperately though 106 */ 107 void do_machine_check_fault(unsigned long cause, unsigned long address, 108 struct pt_regs *regs) 109 { 110 die("Machine Check Exception", regs, address, cause); 111 } 112 113 114 /* 115 * Entry point for traps induced by ARCompact TRAP_S <n> insn 116 * This is same family as TRAP0/SWI insn (use the same vector). 117 * The only difference being SWI insn take no operand, while TRAP_S does 118 * which reflects in ECR Reg as 8 bit param. 119 * Thus TRAP_S <n> can be used for specific purpose 120 * -1 used for software breakpointing (gdb) 121 * -2 used by kprobes 122 */ 123 void do_non_swi_trap(unsigned long cause, unsigned long address, 124 struct pt_regs *regs) 125 { 126 unsigned int param = cause & 0xff; 127 128 switch (param) { 129 case 1: 130 trap_is_brkpt(cause, address, regs); 131 break; 132 133 case 2: 134 trap_is_kprobe(param, address, regs); 135 break; 136 137 case 3: 138 case 4: 139 kgdb_trap(regs, param); 140 break; 141 142 default: 143 break; 144 } 145 } 146 147 /* 148 * Entry point for Instruction Error Exception 149 * -For a corner case, ARC kprobes implementation resorts to using 150 * this exception, hence the check 151 */ 152 void do_insterror_or_kprobe(unsigned long cause, 153 unsigned long address, 154 struct pt_regs *regs) 155 { 156 /* Check if this exception is caused by kprobes */ 157 if (notify_die(DIE_IERR, "kprobe_ierr", regs, address, 158 cause, SIGILL) == NOTIFY_STOP) 159 return; 160 161 insterror_is_error(cause, address, regs); 162 } 163