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