1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2012 Regents of the University of California
  4 */
  5
  6#include <linux/cpu.h>
  7#include <linux/kernel.h>
  8#include <linux/init.h>
  9#include <linux/sched.h>
 10#include <linux/sched/debug.h>
 11#include <linux/sched/signal.h>
 12#include <linux/signal.h>
 13#include <linux/kdebug.h>
 14#include <linux/uaccess.h>
 15#include <linux/mm.h>
 16#include <linux/module.h>
 17#include <linux/irq.h>
 18
 19#include <asm/processor.h>
 20#include <asm/ptrace.h>
 21#include <asm/csr.h>
 22
 23int show_unhandled_signals = 1;
 24
 25extern asmlinkage void handle_exception(void);
 26
 27static DEFINE_SPINLOCK(die_lock);
 28
 29void die(struct pt_regs *regs, const char *str)
 30{
 31	static int die_counter;
 32	int ret;
 33
 34	oops_enter();
 35
 36	spin_lock_irq(&die_lock);
 37	console_verbose();
 38	bust_spinlocks(1);
 39
 40	pr_emerg("%s [#%d]\n", str, ++die_counter);
 41	print_modules();
 42	show_regs(regs);
 43
 44	ret = notify_die(DIE_OOPS, str, regs, 0, regs->scause, SIGSEGV);
 45
 46	bust_spinlocks(0);
 47	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 48	spin_unlock_irq(&die_lock);
 49	oops_exit();
 50
 51	if (in_interrupt())
 52		panic("Fatal exception in interrupt");
 53	if (panic_on_oops)
 54		panic("Fatal exception");
 55	if (ret != NOTIFY_STOP)
 56		do_exit(SIGSEGV);
 57}
 58
 59void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
 60{
 61	struct task_struct *tsk = current;
 62
 63	if (show_unhandled_signals && unhandled_signal(tsk, signo)
 64	    && printk_ratelimit()) {
 65		pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
 66			tsk->comm, task_pid_nr(tsk), signo, code, addr);
 67		print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
 68		pr_cont("\n");
 69		show_regs(regs);
 70	}
 71
 72	force_sig_fault(signo, code, (void __user *)addr);
 73}
 74
 75static void do_trap_error(struct pt_regs *regs, int signo, int code,
 76	unsigned long addr, const char *str)
 77{
 78	if (user_mode(regs)) {
 79		do_trap(regs, signo, code, addr);
 80	} else {
 81		if (!fixup_exception(regs))
 82			die(regs, str);
 83	}
 84}
 85
 86#define DO_ERROR_INFO(name, signo, code, str)				\
 87asmlinkage __visible void name(struct pt_regs *regs)			\
 88{									\
 89	do_trap_error(regs, signo, code, regs->sepc, "Oops - " str);	\
 90}
 91
 92DO_ERROR_INFO(do_trap_unknown,
 93	SIGILL, ILL_ILLTRP, "unknown exception");
 94DO_ERROR_INFO(do_trap_insn_misaligned,
 95	SIGBUS, BUS_ADRALN, "instruction address misaligned");
 96DO_ERROR_INFO(do_trap_insn_fault,
 97	SIGSEGV, SEGV_ACCERR, "instruction access fault");
 98DO_ERROR_INFO(do_trap_insn_illegal,
 99	SIGILL, ILL_ILLOPC, "illegal instruction");
100DO_ERROR_INFO(do_trap_load_misaligned,
101	SIGBUS, BUS_ADRALN, "load address misaligned");
102DO_ERROR_INFO(do_trap_load_fault,
103	SIGSEGV, SEGV_ACCERR, "load access fault");
104DO_ERROR_INFO(do_trap_store_misaligned,
105	SIGBUS, BUS_ADRALN, "store (or AMO) address misaligned");
106DO_ERROR_INFO(do_trap_store_fault,
107	SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
108DO_ERROR_INFO(do_trap_ecall_u,
109	SIGILL, ILL_ILLTRP, "environment call from U-mode");
110DO_ERROR_INFO(do_trap_ecall_s,
111	SIGILL, ILL_ILLTRP, "environment call from S-mode");
112DO_ERROR_INFO(do_trap_ecall_m,
113	SIGILL, ILL_ILLTRP, "environment call from M-mode");
114
115static inline unsigned long get_break_insn_length(unsigned long pc)
116{
117	bug_insn_t insn;
118
119	if (probe_kernel_address((bug_insn_t *)pc, insn))
120		return 0;
121	return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
122}
123
124asmlinkage __visible void do_trap_break(struct pt_regs *regs)
125{
126	if (user_mode(regs))
127		force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->sepc);
128	else if (report_bug(regs->sepc, regs) == BUG_TRAP_TYPE_WARN)
129		regs->sepc += get_break_insn_length(regs->sepc);
130	else
131		die(regs, "Kernel BUG");
132}
133
134#ifdef CONFIG_GENERIC_BUG
135int is_valid_bugaddr(unsigned long pc)
136{
137	bug_insn_t insn;
138
139	if (pc < VMALLOC_START)
140		return 0;
141	if (probe_kernel_address((bug_insn_t *)pc, insn))
142		return 0;
143	if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
144		return (insn == __BUG_INSN_32);
145	else
146		return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
147}
148#endif /* CONFIG_GENERIC_BUG */
149
150void __init trap_init(void)
151{
152	/*
153	 * Set sup0 scratch register to 0, indicating to exception vector
154	 * that we are presently executing in the kernel
155	 */
156	csr_write(CSR_SSCRATCH, 0);
157	/* Set the exception vector address */
158	csr_write(CSR_STVEC, &handle_exception);
159	/* Enable all interrupts */
160	csr_write(CSR_SIE, -1);
161}