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