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 <linux/unaligned.h> 22 #include <asm/kprobes.h> 23 #include "unaligned.h" 24 25 void die(const char *str, struct pt_regs *regs, unsigned long address) 26 { 27 show_kernel_fault_diag(str, regs, address); 28 29 /* DEAD END */ 30 __asm__("flag 1"); 31 } 32 33 /* 34 * Helper called for bulk of exceptions NOT needing specific handling 35 * -for user faults enqueues requested signal 36 * -for kernel, chk if due to copy_(to|from)_user, otherwise die() 37 */ 38 static noinline int 39 unhandled_exception(const char *str, struct pt_regs *regs, 40 int signo, int si_code, void __user *addr) 41 { 42 if (user_mode(regs)) { 43 struct task_struct *tsk = current; 44 45 tsk->thread.fault_address = (__force unsigned int)addr; 46 47 force_sig_fault(signo, si_code, addr); 48 49 } else { 50 /* If not due to copy_(to|from)_user, we are doomed */ 51 if (fixup_exception(regs)) 52 return 0; 53 54 die(str, regs, (unsigned long)addr); 55 } 56 57 return 1; 58 } 59 60 #define DO_ERROR_INFO(signr, str, name, sicode) \ 61 int name(unsigned long address, struct pt_regs *regs) \ 62 { \ 63 return unhandled_exception(str, regs, signr, sicode, \ 64 (void __user *)address); \ 65 } 66 67 /* 68 * Entry points for exceptions NOT needing specific handling 69 */ 70 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC) 71 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC) 72 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 73 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR) 74 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT) 75 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN) 76 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0) 77 78 /* 79 * Entry Point for Misaligned Data access Exception, for emulating in software 80 */ 81 int do_misaligned_access(unsigned long address, struct pt_regs *regs, 82 struct callee_regs *cregs) 83 { 84 /* If emulation not enabled, or failed, kill the task */ 85 if (misaligned_fixup(address, regs, cregs) != 0) 86 return do_misaligned_error(address, regs); 87 88 return 0; 89 } 90 91 /* 92 * Entry point for miscll errors such as Nested Exceptions 93 * -Duplicate TLB entry is handled separately though 94 */ 95 void do_machine_check_fault(unsigned long address, struct pt_regs *regs) 96 { 97 die("Unhandled Machine Check Exception", regs, address); 98 } 99 100 101 /* 102 * Entry point for traps induced by ARCompact TRAP_S <n> insn 103 * This is same family as TRAP0/SWI insn (use the same vector). 104 * The only difference being SWI insn take no operand, while TRAP_S does 105 * which reflects in ECR Reg as 8 bit param. 106 * Thus TRAP_S <n> can be used for specific purpose 107 * -1 used for software breakpointing (gdb) 108 * -2 used by kprobes 109 * -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as 110 * -fno-isolate-erroneous-paths-dereference 111 */ 112 void do_non_swi_trap(unsigned long address, struct pt_regs *regs) 113 { 114 switch (regs->ecr.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