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
 23void __init trap_init(void)
 24{
 25	return;
 26}
 27
 28void 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 */
 41static noinline int
 42unhandled_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) \
 64int 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 */
 73DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
 74DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
 75DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
 76DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
 77DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
 78DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
 79DO_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 */
 84int 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 */
 98void 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 */
115void 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 */
146void 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 */
161void abort(void)
162{
163	__asm__ __volatile__("trap_s  5\n");
164}