1/*
  2 * Copyright (C) 2012 Regents of the University of California
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful,
  9 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11 *   GNU General Public License for more details.
 12 */
 13
 14#include <linux/kernel.h>
 15#include <linux/init.h>
 16#include <linux/sched.h>
 17#include <linux/sched/debug.h>
 18#include <linux/sched/signal.h>
 19#include <linux/signal.h>
 20#include <linux/kdebug.h>
 21#include <linux/uaccess.h>
 22#include <linux/mm.h>
 23#include <linux/module.h>
 24#include <linux/irq.h>
 25
 26#include <asm/processor.h>
 27#include <asm/ptrace.h>
 28#include <asm/csr.h>
 29
 30int show_unhandled_signals = 1;
 31
 32extern asmlinkage void handle_exception(void);
 33
 34static DEFINE_SPINLOCK(die_lock);
 35
 36void die(struct pt_regs *regs, const char *str)
 37{
 38	static int die_counter;
 39	int ret;
 40
 41	oops_enter();
 42
 43	spin_lock_irq(&die_lock);
 44	console_verbose();
 45	bust_spinlocks(1);
 46
 47	pr_emerg("%s [#%d]\n", str, ++die_counter);
 48	print_modules();
 49	show_regs(regs);
 50
 51	ret = notify_die(DIE_OOPS, str, regs, 0, regs->scause, SIGSEGV);
 52
 53	bust_spinlocks(0);
 54	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 55	spin_unlock_irq(&die_lock);
 56	oops_exit();
 57
 58	if (in_interrupt())
 59		panic("Fatal exception in interrupt");
 60	if (panic_on_oops)
 61		panic("Fatal exception");
 62	if (ret != NOTIFY_STOP)
 63		do_exit(SIGSEGV);
 64}
 65
 66static inline void do_trap_siginfo(int signo, int code,
 67	unsigned long addr, struct task_struct *tsk)
 68{
 69	siginfo_t info;
 70
 71	info.si_signo = signo;
 72	info.si_errno = 0;
 73	info.si_code = code;
 74	info.si_addr = (void __user *)addr;
 75	force_sig_info(signo, &info, tsk);
 76}
 77
 78void do_trap(struct pt_regs *regs, int signo, int code,
 79	unsigned long addr, struct task_struct *tsk)
 80{
 81	if (show_unhandled_signals && unhandled_signal(tsk, signo)
 82	    && printk_ratelimit()) {
 83		pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
 84			tsk->comm, task_pid_nr(tsk), signo, code, addr);
 85		print_vma_addr(KERN_CONT " in ", GET_IP(regs));
 86		pr_cont("\n");
 87		show_regs(regs);
 88	}
 89
 90	do_trap_siginfo(signo, code, addr, tsk);
 91}
 92
 93static void do_trap_error(struct pt_regs *regs, int signo, int code,
 94	unsigned long addr, const char *str)
 95{
 96	if (user_mode(regs)) {
 97		do_trap(regs, signo, code, addr, current);
 98	} else {
 99		if (!fixup_exception(regs))
100			die(regs, str);
101	}
102}
103
104#define DO_ERROR_INFO(name, signo, code, str)				\
105asmlinkage void name(struct pt_regs *regs)				\
106{									\
107	do_trap_error(regs, signo, code, regs->sepc, "Oops - " str);	\
108}
109
110DO_ERROR_INFO(do_trap_unknown,
111	SIGILL, ILL_ILLTRP, "unknown exception");
112DO_ERROR_INFO(do_trap_insn_misaligned,
113	SIGBUS, BUS_ADRALN, "instruction address misaligned");
114DO_ERROR_INFO(do_trap_insn_fault,
115	SIGSEGV, SEGV_ACCERR, "instruction access fault");
116DO_ERROR_INFO(do_trap_insn_illegal,
117	SIGILL, ILL_ILLOPC, "illegal instruction");
118DO_ERROR_INFO(do_trap_load_misaligned,
119	SIGBUS, BUS_ADRALN, "load address misaligned");
120DO_ERROR_INFO(do_trap_load_fault,
121	SIGSEGV, SEGV_ACCERR, "load access fault");
122DO_ERROR_INFO(do_trap_store_misaligned,
123	SIGBUS, BUS_ADRALN, "store (or AMO) address misaligned");
124DO_ERROR_INFO(do_trap_store_fault,
125	SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
126DO_ERROR_INFO(do_trap_ecall_u,
127	SIGILL, ILL_ILLTRP, "environment call from U-mode");
128DO_ERROR_INFO(do_trap_ecall_s,
129	SIGILL, ILL_ILLTRP, "environment call from S-mode");
130DO_ERROR_INFO(do_trap_ecall_m,
131	SIGILL, ILL_ILLTRP, "environment call from M-mode");
132
133asmlinkage void do_trap_break(struct pt_regs *regs)
134{
135#ifdef CONFIG_GENERIC_BUG
136	if (!user_mode(regs)) {
137		enum bug_trap_type type;
138
139		type = report_bug(regs->sepc, regs);
140		switch (type) {
141		case BUG_TRAP_TYPE_NONE:
142			break;
143		case BUG_TRAP_TYPE_WARN:
144			regs->sepc += sizeof(bug_insn_t);
145			return;
146		case BUG_TRAP_TYPE_BUG:
147			die(regs, "Kernel BUG");
148		}
149	}
150#endif /* CONFIG_GENERIC_BUG */
151
152	do_trap_siginfo(SIGTRAP, TRAP_BRKPT, regs->sepc, current);
153	regs->sepc += 0x4;
154}
155
156#ifdef CONFIG_GENERIC_BUG
157int is_valid_bugaddr(unsigned long pc)
158{
159	bug_insn_t insn;
160
161	if (pc < PAGE_OFFSET)
162		return 0;
163	if (probe_kernel_address((bug_insn_t __user *)pc, insn))
164		return 0;
165	return (insn == __BUG_INSN);
166}
167#endif /* CONFIG_GENERIC_BUG */
168
169void __init trap_init(void)
170{
171	/*
172	 * Set sup0 scratch register to 0, indicating to exception vector
173	 * that we are presently executing in the kernel
174	 */
175	csr_write(sscratch, 0);
176	/* Set the exception vector address */
177	csr_write(stvec, &handle_exception);
178	/* Enable all interrupts */
179	csr_write(sie, -1);
180}