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 <asm/ptrace.h> 20 #include <asm/setup.h> 21 #include <asm/kprobes.h> 22 #include <asm/unaligned.h> 23 #include <asm/kgdb.h> 24 25 void __init trap_init(void) 26 { 27 return; 28 } 29 30 void die(const char *str, struct pt_regs *regs, unsigned long address, 31 unsigned long cause_reg) 32 { 33 show_kernel_fault_diag(str, regs, address, cause_reg); 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 handle_exception(unsigned long cause, char *str, 45 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 tsk->thread.cause_code = cause; 52 53 force_sig_info(info->si_signo, info, tsk); 54 55 } else { 56 /* If not due to copy_(to|from)_user, we are doomed */ 57 if (fixup_exception(regs)) 58 return 0; 59 60 die(str, regs, (unsigned long)info->si_addr, cause); 61 } 62 63 return 1; 64 } 65 66 #define DO_ERROR_INFO(signr, str, name, sicode) \ 67 int name(unsigned long cause, unsigned long address, struct pt_regs *regs) \ 68 { \ 69 siginfo_t info = { \ 70 .si_signo = signr, \ 71 .si_errno = 0, \ 72 .si_code = sicode, \ 73 .si_addr = (void __user *)address, \ 74 }; \ 75 return handle_exception(cause, str, regs, &info);\ 76 } 77 78 /* 79 * Entry points for exceptions NOT needing specific handling 80 */ 81 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC) 82 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC) 83 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 84 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR) 85 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT) 86 87 #ifdef CONFIG_ARC_MISALIGN_ACCESS 88 /* 89 * Entry Point for Misaligned Data access Exception, for emulating in software 90 */ 91 int do_misaligned_access(unsigned long cause, unsigned long address, 92 struct pt_regs *regs, struct callee_regs *cregs) 93 { 94 if (misaligned_fixup(address, regs, cause, cregs) != 0) { 95 siginfo_t info; 96 97 info.si_signo = SIGBUS; 98 info.si_errno = 0; 99 info.si_code = BUS_ADRALN; 100 info.si_addr = (void __user *)address; 101 return handle_exception(cause, "Misaligned Access", regs, 102 &info); 103 } 104 return 0; 105 } 106 107 #else 108 DO_ERROR_INFO(SIGSEGV, "Misaligned Access", do_misaligned_access, SEGV_ACCERR) 109 #endif 110 111 /* 112 * Entry point for miscll errors such as Nested Exceptions 113 * -Duplicate TLB entry is handled seperately though 114 */ 115 void do_machine_check_fault(unsigned long cause, unsigned long address, 116 struct pt_regs *regs) 117 { 118 die("Machine Check Exception", regs, address, cause); 119 } 120 121 122 /* 123 * Entry point for traps induced by ARCompact TRAP_S <n> insn 124 * This is same family as TRAP0/SWI insn (use the same vector). 125 * The only difference being SWI insn take no operand, while TRAP_S does 126 * which reflects in ECR Reg as 8 bit param. 127 * Thus TRAP_S <n> can be used for specific purpose 128 * -1 used for software breakpointing (gdb) 129 * -2 used by kprobes 130 */ 131 void do_non_swi_trap(unsigned long cause, unsigned long address, 132 struct pt_regs *regs) 133 { 134 unsigned int param = cause & 0xff; 135 136 switch (param) { 137 case 1: 138 trap_is_brkpt(cause, address, regs); 139 break; 140 141 case 2: 142 trap_is_kprobe(param, address, regs); 143 break; 144 145 case 3: 146 case 4: 147 kgdb_trap(regs, param); 148 break; 149 150 default: 151 break; 152 } 153 } 154 155 /* 156 * Entry point for Instruction Error Exception 157 * -For a corner case, ARC kprobes implementation resorts to using 158 * this exception, hence the check 159 */ 160 void do_insterror_or_kprobe(unsigned long cause, 161 unsigned long address, 162 struct pt_regs *regs) 163 { 164 /* Check if this exception is caused by kprobes */ 165 if (notify_die(DIE_IERR, "kprobe_ierr", regs, address, 166 cause, SIGILL) == NOTIFY_STOP) 167 return; 168 169 insterror_is_error(cause, address, regs); 170 } 171