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 { 33 show_kernel_fault_diag(str, regs, address); 34 35 /* DEAD END */ 36 __asm__("flag 1"); 37 } 38 39 /* 40 * Helper called for bulk of exceptions NOT needing specific handling 41 * -for user faults enqueues requested signal 42 * -for kernel, chk if due to copy_(to|from)_user, otherwise die() 43 */ 44 static noinline int 45 unhandled_exception(const char *str, struct pt_regs *regs, siginfo_t *info) 46 { 47 if (user_mode(regs)) { 48 struct task_struct *tsk = current; 49 50 tsk->thread.fault_address = (__force unsigned int)info->si_addr; 51 52 force_sig_info(info->si_signo, info, tsk); 53 54 } else { 55 /* If not due to copy_(to|from)_user, we are doomed */ 56 if (fixup_exception(regs)) 57 return 0; 58 59 die(str, regs, (unsigned long)info->si_addr); 60 } 61 62 return 1; 63 } 64 65 #define DO_ERROR_INFO(signr, str, name, sicode) \ 66 int name(unsigned long address, struct pt_regs *regs) \ 67 { \ 68 siginfo_t info = { \ 69 .si_signo = signr, \ 70 .si_errno = 0, \ 71 .si_code = sicode, \ 72 .si_addr = (void __user *)address, \ 73 }; \ 74 return unhandled_exception(str, regs, &info);\ 75 } 76 77 /* 78 * Entry points for exceptions NOT needing specific handling 79 */ 80 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC) 81 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC) 82 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 83 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR) 84 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT) 85 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN) 86 87 /* 88 * Entry Point for Misaligned Data access Exception, for emulating in software 89 */ 90 int do_misaligned_access(unsigned long address, struct pt_regs *regs, 91 struct callee_regs *cregs) 92 { 93 /* If emulation not enabled, or failed, kill the task */ 94 if (misaligned_fixup(address, regs, cregs) != 0) 95 return do_misaligned_error(address, regs); 96 97 return 0; 98 } 99 100 /* 101 * Entry point for miscll errors such as Nested Exceptions 102 * -Duplicate TLB entry is handled seperately though 103 */ 104 void do_machine_check_fault(unsigned long address, struct pt_regs *regs) 105 { 106 die("Machine Check Exception", regs, address); 107 } 108 109 110 /* 111 * Entry point for traps induced by ARCompact TRAP_S <n> insn 112 * This is same family as TRAP0/SWI insn (use the same vector). 113 * The only difference being SWI insn take no operand, while TRAP_S does 114 * which reflects in ECR Reg as 8 bit param. 115 * Thus TRAP_S <n> can be used for specific purpose 116 * -1 used for software breakpointing (gdb) 117 * -2 used by kprobes 118 */ 119 void do_non_swi_trap(unsigned long address, struct pt_regs *regs) 120 { 121 unsigned int param = regs->ecr_param; 122 123 switch (param) { 124 case 1: 125 trap_is_brkpt(address, regs); 126 break; 127 128 case 2: 129 trap_is_kprobe(address, regs); 130 break; 131 132 case 3: 133 case 4: 134 kgdb_trap(regs); 135 break; 136 137 default: 138 break; 139 } 140 } 141 142 /* 143 * Entry point for Instruction Error Exception 144 * -For a corner case, ARC kprobes implementation resorts to using 145 * this exception, hence the check 146 */ 147 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs) 148 { 149 int rc; 150 151 /* Check if this exception is caused by kprobes */ 152 rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL); 153 if (rc == NOTIFY_STOP) 154 return; 155 156 insterror_is_error(address, regs); 157 } 158