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, 46 int signo, int si_code, void __user *addr) 47 { 48 if (user_mode(regs)) { 49 struct task_struct *tsk = current; 50 51 tsk->thread.fault_address = (__force unsigned int)addr; 52 53 force_sig_fault(signo, si_code, addr, 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)addr); 61 } 62 63 return 1; 64 } 65 66 #define DO_ERROR_INFO(signr, str, name, sicode) \ 67 int name(unsigned long address, struct pt_regs *regs) \ 68 { \ 69 return unhandled_exception(str, regs, signr, sicode, \ 70 (void __user *)address); \ 71 } 72 73 /* 74 * Entry points for exceptions NOT needing specific handling 75 */ 76 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC) 77 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC) 78 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 79 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR) 80 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT) 81 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN) 82 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0) 83 84 /* 85 * Entry Point for Misaligned Data access Exception, for emulating in software 86 */ 87 int do_misaligned_access(unsigned long address, struct pt_regs *regs, 88 struct callee_regs *cregs) 89 { 90 /* If emulation not enabled, or failed, kill the task */ 91 if (misaligned_fixup(address, regs, cregs) != 0) 92 return do_misaligned_error(address, regs); 93 94 return 0; 95 } 96 97 /* 98 * Entry point for miscll errors such as Nested Exceptions 99 * -Duplicate TLB entry is handled seperately though 100 */ 101 void do_machine_check_fault(unsigned long address, struct pt_regs *regs) 102 { 103 die("Unhandled Machine Check Exception", regs, address); 104 } 105 106 107 /* 108 * Entry point for traps induced by ARCompact TRAP_S <n> insn 109 * This is same family as TRAP0/SWI insn (use the same vector). 110 * The only difference being SWI insn take no operand, while TRAP_S does 111 * which reflects in ECR Reg as 8 bit param. 112 * Thus TRAP_S <n> can be used for specific purpose 113 * -1 used for software breakpointing (gdb) 114 * -2 used by kprobes 115 * -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as 116 * -fno-isolate-erroneous-paths-dereference 117 */ 118 void do_non_swi_trap(unsigned long address, struct pt_regs *regs) 119 { 120 unsigned int param = regs->ecr_param; 121 122 switch (param) { 123 case 1: 124 trap_is_brkpt(address, regs); 125 break; 126 127 case 2: 128 trap_is_kprobe(address, regs); 129 break; 130 131 case 3: 132 case 4: 133 kgdb_trap(regs); 134 break; 135 136 case 5: 137 do_trap5_error(address, regs); 138 break; 139 default: 140 break; 141 } 142 } 143 144 /* 145 * Entry point for Instruction Error Exception 146 * -For a corner case, ARC kprobes implementation resorts to using 147 * this exception, hence the check 148 */ 149 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs) 150 { 151 int rc; 152 153 /* Check if this exception is caused by kprobes */ 154 rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL); 155 if (rc == NOTIFY_STOP) 156 return; 157 158 insterror_is_error(address, regs); 159 } 160 161 /* 162 * abort() call generated by older gcc for __builtin_trap() 163 */ 164 void abort(void) 165 { 166 __asm__ __volatile__("trap_s 5\n"); 167 } 168