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 #include <linux/kexec.h>
19
20 #include <asm/processor.h>
21 #include <asm/ptrace.h>
22 #include <asm/csr.h>
23
24 int show_unhandled_signals = 1;
25
26 extern asmlinkage void handle_exception(void);
27
28 static DEFINE_SPINLOCK(die_lock);
29
die(struct pt_regs * regs,const char * str)30 void die(struct pt_regs *regs, const char *str)
31 {
32 static int die_counter;
33 int ret;
34
35 oops_enter();
36
37 spin_lock_irq(&die_lock);
38 console_verbose();
39 bust_spinlocks(1);
40
41 pr_emerg("%s [#%d]\n", str, ++die_counter);
42 print_modules();
43 show_regs(regs);
44
45 ret = notify_die(DIE_OOPS, str, regs, 0, regs->scause, SIGSEGV);
46
47 if (regs && kexec_should_crash(current))
48 crash_kexec(regs);
49
50 bust_spinlocks(0);
51 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
52 spin_unlock_irq(&die_lock);
53 oops_exit();
54
55 if (in_interrupt())
56 panic("Fatal exception in interrupt");
57 if (panic_on_oops)
58 panic("Fatal exception");
59 if (ret != NOTIFY_STOP)
60 make_task_dead(SIGSEGV);
61 }
62
do_trap(struct pt_regs * regs,int signo,int code,unsigned long addr)63 void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
64 {
65 struct task_struct *tsk = current;
66
67 if (show_unhandled_signals && unhandled_signal(tsk, signo)
68 && printk_ratelimit()) {
69 pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
70 tsk->comm, task_pid_nr(tsk), signo, code, addr);
71 print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
72 pr_cont("\n");
73 show_regs(regs);
74 }
75
76 force_sig_fault(signo, code, (void __user *)addr);
77 }
78
do_trap_error(struct pt_regs * regs,int signo,int code,unsigned long addr,const char * str)79 static void do_trap_error(struct pt_regs *regs, int signo, int code,
80 unsigned long addr, const char *str)
81 {
82 if (user_mode(regs)) {
83 do_trap(regs, signo, code, addr);
84 } else {
85 if (!fixup_exception(regs))
86 die(regs, str);
87 }
88 }
89
90 #define DO_ERROR_INFO(name, signo, code, str) \
91 asmlinkage __visible void name(struct pt_regs *regs) \
92 { \
93 do_trap_error(regs, signo, code, regs->sepc, "Oops - " str); \
94 }
95
96 DO_ERROR_INFO(do_trap_unknown,
97 SIGILL, ILL_ILLTRP, "unknown exception");
98 DO_ERROR_INFO(do_trap_insn_misaligned,
99 SIGBUS, BUS_ADRALN, "instruction address misaligned");
100 DO_ERROR_INFO(do_trap_insn_fault,
101 SIGSEGV, SEGV_ACCERR, "instruction access fault");
102 DO_ERROR_INFO(do_trap_insn_illegal,
103 SIGILL, ILL_ILLOPC, "illegal instruction");
104 DO_ERROR_INFO(do_trap_load_misaligned,
105 SIGBUS, BUS_ADRALN, "load address misaligned");
106 DO_ERROR_INFO(do_trap_load_fault,
107 SIGSEGV, SEGV_ACCERR, "load access fault");
108 DO_ERROR_INFO(do_trap_store_misaligned,
109 SIGBUS, BUS_ADRALN, "store (or AMO) address misaligned");
110 DO_ERROR_INFO(do_trap_store_fault,
111 SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
112 DO_ERROR_INFO(do_trap_ecall_u,
113 SIGILL, ILL_ILLTRP, "environment call from U-mode");
114 DO_ERROR_INFO(do_trap_ecall_s,
115 SIGILL, ILL_ILLTRP, "environment call from S-mode");
116 DO_ERROR_INFO(do_trap_ecall_m,
117 SIGILL, ILL_ILLTRP, "environment call from M-mode");
118
get_break_insn_length(unsigned long pc)119 static inline unsigned long get_break_insn_length(unsigned long pc)
120 {
121 bug_insn_t insn;
122
123 if (probe_kernel_address((bug_insn_t *)pc, insn))
124 return 0;
125 return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
126 }
127
do_trap_break(struct pt_regs * regs)128 asmlinkage __visible void do_trap_break(struct pt_regs *regs)
129 {
130 if (user_mode(regs))
131 force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->sepc);
132 else if (report_bug(regs->sepc, regs) == BUG_TRAP_TYPE_WARN)
133 regs->sepc += get_break_insn_length(regs->sepc);
134 else
135 die(regs, "Kernel BUG");
136 }
137
138 #ifdef CONFIG_GENERIC_BUG
is_valid_bugaddr(unsigned long pc)139 int is_valid_bugaddr(unsigned long pc)
140 {
141 bug_insn_t insn;
142
143 if (pc < VMALLOC_START)
144 return 0;
145 if (probe_kernel_address((bug_insn_t *)pc, insn))
146 return 0;
147 if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
148 return (insn == __BUG_INSN_32);
149 else
150 return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
151 }
152 #endif /* CONFIG_GENERIC_BUG */
153
trap_init(void)154 void __init trap_init(void)
155 {
156 /*
157 * Set sup0 scratch register to 0, indicating to exception vector
158 * that we are presently executing in the kernel
159 */
160 csr_write(CSR_SSCRATCH, 0);
161 /* Set the exception vector address */
162 csr_write(CSR_STVEC, &handle_exception);
163 /* Enable all interrupts */
164 csr_write(CSR_SIE, -1);
165 }
166