1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Traps/Non-MMU Exception handling for ARC 4 * 5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 6 * 7 * vineetg: May 2011 8 * -user-space unaligned access emulation 9 * 10 * Rahul Trivedi: Codito Technologies 2004 11 */ 12 13 #include <linux/sched/signal.h> 14 #include <linux/kdebug.h> 15 #include <linux/uaccess.h> 16 #include <linux/ptrace.h> 17 #include <linux/kprobes.h> 18 #include <linux/kgdb.h> 19 #include <asm/setup.h> 20 #include <asm/unaligned.h> 21 #include <asm/kprobes.h> 22 23 void __init trap_init(void) 24 { 25 return; 26 } 27 28 void die(const char *str, struct pt_regs *regs, unsigned long address) 29 { 30 show_kernel_fault_diag(str, regs, address); 31 32 /* DEAD END */ 33 __asm__("flag 1"); 34 } 35 36 /* 37 * Helper called for bulk of exceptions NOT needing specific handling 38 * -for user faults enqueues requested signal 39 * -for kernel, chk if due to copy_(to|from)_user, otherwise die() 40 */ 41 static noinline int 42 unhandled_exception(const char *str, struct pt_regs *regs, 43 int signo, int si_code, void __user *addr) 44 { 45 if (user_mode(regs)) { 46 struct task_struct *tsk = current; 47 48 tsk->thread.fault_address = (__force unsigned int)addr; 49 50 force_sig_fault(signo, si_code, addr); 51 52 } else { 53 /* If not due to copy_(to|from)_user, we are doomed */ 54 if (fixup_exception(regs)) 55 return 0; 56 57 die(str, regs, (unsigned long)addr); 58 } 59 60 return 1; 61 } 62 63 #define DO_ERROR_INFO(signr, str, name, sicode) \ 64 int name(unsigned long address, struct pt_regs *regs) \ 65 { \ 66 return unhandled_exception(str, regs, signr, sicode, \ 67 (void __user *)address); \ 68 } 69 70 /* 71 * Entry points for exceptions NOT needing specific handling 72 */ 73 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC) 74 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC) 75 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 76 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR) 77 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT) 78 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN) 79 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0) 80 81 /* 82 * Entry Point for Misaligned Data access Exception, for emulating in software 83 */ 84 int do_misaligned_access(unsigned long address, struct pt_regs *regs, 85 struct callee_regs *cregs) 86 { 87 /* If emulation not enabled, or failed, kill the task */ 88 if (misaligned_fixup(address, regs, cregs) != 0) 89 return do_misaligned_error(address, regs); 90 91 return 0; 92 } 93 94 /* 95 * Entry point for miscll errors such as Nested Exceptions 96 * -Duplicate TLB entry is handled seperately though 97 */ 98 void do_machine_check_fault(unsigned long address, struct pt_regs *regs) 99 { 100 die("Unhandled Machine Check Exception", regs, address); 101 } 102 103 104 /* 105 * Entry point for traps induced by ARCompact TRAP_S <n> insn 106 * This is same family as TRAP0/SWI insn (use the same vector). 107 * The only difference being SWI insn take no operand, while TRAP_S does 108 * which reflects in ECR Reg as 8 bit param. 109 * Thus TRAP_S <n> can be used for specific purpose 110 * -1 used for software breakpointing (gdb) 111 * -2 used by kprobes 112 * -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as 113 * -fno-isolate-erroneous-paths-dereference 114 */ 115 void do_non_swi_trap(unsigned long address, struct pt_regs *regs) 116 { 117 unsigned int param = regs->ecr_param; 118 119 switch (param) { 120 case 1: 121 trap_is_brkpt(address, regs); 122 break; 123 124 case 2: 125 trap_is_kprobe(address, regs); 126 break; 127 128 case 3: 129 case 4: 130 kgdb_trap(regs); 131 break; 132 133 case 5: 134 do_trap5_error(address, regs); 135 break; 136 default: 137 break; 138 } 139 } 140 141 /* 142 * Entry point for Instruction Error Exception 143 * -For a corner case, ARC kprobes implementation resorts to using 144 * this exception, hence the check 145 */ 146 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs) 147 { 148 int rc; 149 150 /* Check if this exception is caused by kprobes */ 151 rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL); 152 if (rc == NOTIFY_STOP) 153 return; 154 155 insterror_is_error(address, regs); 156 } 157 158 /* 159 * abort() call generated by older gcc for __builtin_trap() 160 */ 161 void abort(void) 162 { 163 __asm__ __volatile__("trap_s 5\n"); 164 } 165