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/signal.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 \ 70 clear_siginfo(&info); \ 71 info.si_signo = signr; \ 72 info.si_errno = 0; \ 73 info.si_code = sicode; \ 74 info.si_addr = (void __user *)address; \ 75 \ 76 return unhandled_exception(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", __weak 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 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0) 89 90 /* 91 * Entry Point for Misaligned Data access Exception, for emulating in software 92 */ 93 int do_misaligned_access(unsigned long address, struct pt_regs *regs, 94 struct callee_regs *cregs) 95 { 96 /* If emulation not enabled, or failed, kill the task */ 97 if (misaligned_fixup(address, regs, cregs) != 0) 98 return do_misaligned_error(address, regs); 99 100 return 0; 101 } 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 address, struct pt_regs *regs) 108 { 109 die("Unhandled Machine Check Exception", regs, address); 110 } 111 112 113 /* 114 * Entry point for traps induced by ARCompact TRAP_S <n> insn 115 * This is same family as TRAP0/SWI insn (use the same vector). 116 * The only difference being SWI insn take no operand, while TRAP_S does 117 * which reflects in ECR Reg as 8 bit param. 118 * Thus TRAP_S <n> can be used for specific purpose 119 * -1 used for software breakpointing (gdb) 120 * -2 used by kprobes 121 * -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as 122 * -fno-isolate-erroneous-paths-dereference 123 */ 124 void do_non_swi_trap(unsigned long address, struct pt_regs *regs) 125 { 126 unsigned int param = regs->ecr_param; 127 128 switch (param) { 129 case 1: 130 trap_is_brkpt(address, regs); 131 break; 132 133 case 2: 134 trap_is_kprobe(address, regs); 135 break; 136 137 case 3: 138 case 4: 139 kgdb_trap(regs); 140 break; 141 142 case 5: 143 do_trap5_error(address, regs); 144 break; 145 default: 146 break; 147 } 148 } 149 150 /* 151 * Entry point for Instruction Error Exception 152 * -For a corner case, ARC kprobes implementation resorts to using 153 * this exception, hence the check 154 */ 155 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs) 156 { 157 int rc; 158 159 /* Check if this exception is caused by kprobes */ 160 rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL); 161 if (rc == NOTIFY_STOP) 162 return; 163 164 insterror_is_error(address, regs); 165 } 166 167 /* 168 * abort() call generated by older gcc for __builtin_trap() 169 */ 170 void abort(void) 171 { 172 __asm__ __volatile__("trap_s 5\n"); 173 } 174