linux/arch/riscv/kernel/traps.c
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   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/kprobes.h>
  16#include <linux/mm.h>
  17#include <linux/module.h>
  18#include <linux/irq.h>
  19
  20#include <asm/asm-prototypes.h>
  21#include <asm/bug.h>
  22#include <asm/processor.h>
  23#include <asm/ptrace.h>
  24#include <asm/csr.h>
  25
  26int show_unhandled_signals = 1;
  27
  28static DEFINE_SPINLOCK(die_lock);
  29
  30void 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->cause, SIGSEGV);
  46
  47        bust_spinlocks(0);
  48        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
  49        spin_unlock_irq(&die_lock);
  50        oops_exit();
  51
  52        if (in_interrupt())
  53                panic("Fatal exception in interrupt");
  54        if (panic_on_oops)
  55                panic("Fatal exception");
  56        if (ret != NOTIFY_STOP)
  57                do_exit(SIGSEGV);
  58}
  59
  60void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
  61{
  62        struct task_struct *tsk = current;
  63
  64        if (show_unhandled_signals && unhandled_signal(tsk, signo)
  65            && printk_ratelimit()) {
  66                pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
  67                        tsk->comm, task_pid_nr(tsk), signo, code, addr);
  68                print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
  69                pr_cont("\n");
  70                __show_regs(regs);
  71        }
  72
  73        force_sig_fault(signo, code, (void __user *)addr);
  74}
  75
  76static void do_trap_error(struct pt_regs *regs, int signo, int code,
  77        unsigned long addr, const char *str)
  78{
  79        current->thread.bad_cause = regs->cause;
  80
  81        if (user_mode(regs)) {
  82                do_trap(regs, signo, code, addr);
  83        } else {
  84                if (!fixup_exception(regs))
  85                        die(regs, str);
  86        }
  87}
  88
  89#if defined (CONFIG_XIP_KERNEL) && defined (CONFIG_RISCV_ERRATA_ALTERNATIVE)
  90#define __trap_section          __section(".xip.traps")
  91#else
  92#define __trap_section
  93#endif
  94#define DO_ERROR_INFO(name, signo, code, str)                           \
  95asmlinkage __visible __trap_section void name(struct pt_regs *regs)     \
  96{                                                                       \
  97        do_trap_error(regs, signo, code, regs->epc, "Oops - " str);     \
  98}
  99
 100DO_ERROR_INFO(do_trap_unknown,
 101        SIGILL, ILL_ILLTRP, "unknown exception");
 102DO_ERROR_INFO(do_trap_insn_misaligned,
 103        SIGBUS, BUS_ADRALN, "instruction address misaligned");
 104DO_ERROR_INFO(do_trap_insn_fault,
 105        SIGSEGV, SEGV_ACCERR, "instruction access fault");
 106DO_ERROR_INFO(do_trap_insn_illegal,
 107        SIGILL, ILL_ILLOPC, "illegal instruction");
 108DO_ERROR_INFO(do_trap_load_fault,
 109        SIGSEGV, SEGV_ACCERR, "load access fault");
 110#ifndef CONFIG_RISCV_M_MODE
 111DO_ERROR_INFO(do_trap_load_misaligned,
 112        SIGBUS, BUS_ADRALN, "Oops - load address misaligned");
 113DO_ERROR_INFO(do_trap_store_misaligned,
 114        SIGBUS, BUS_ADRALN, "Oops - store (or AMO) address misaligned");
 115#else
 116int handle_misaligned_load(struct pt_regs *regs);
 117int handle_misaligned_store(struct pt_regs *regs);
 118
 119asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
 120{
 121        if (!handle_misaligned_load(regs))
 122                return;
 123        do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
 124                      "Oops - load address misaligned");
 125}
 126
 127asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
 128{
 129        if (!handle_misaligned_store(regs))
 130                return;
 131        do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc,
 132                      "Oops - store (or AMO) address misaligned");
 133}
 134#endif
 135DO_ERROR_INFO(do_trap_store_fault,
 136        SIGSEGV, SEGV_ACCERR, "store (or AMO) access fault");
 137DO_ERROR_INFO(do_trap_ecall_u,
 138        SIGILL, ILL_ILLTRP, "environment call from U-mode");
 139DO_ERROR_INFO(do_trap_ecall_s,
 140        SIGILL, ILL_ILLTRP, "environment call from S-mode");
 141DO_ERROR_INFO(do_trap_ecall_m,
 142        SIGILL, ILL_ILLTRP, "environment call from M-mode");
 143
 144static inline unsigned long get_break_insn_length(unsigned long pc)
 145{
 146        bug_insn_t insn;
 147
 148        if (get_kernel_nofault(insn, (bug_insn_t *)pc))
 149                return 0;
 150
 151        return GET_INSN_LENGTH(insn);
 152}
 153
 154asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
 155{
 156#ifdef CONFIG_KPROBES
 157        if (kprobe_single_step_handler(regs))
 158                return;
 159
 160        if (kprobe_breakpoint_handler(regs))
 161                return;
 162#endif
 163#ifdef CONFIG_UPROBES
 164        if (uprobe_single_step_handler(regs))
 165                return;
 166
 167        if (uprobe_breakpoint_handler(regs))
 168                return;
 169#endif
 170        current->thread.bad_cause = regs->cause;
 171
 172        if (user_mode(regs))
 173                force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->epc);
 174#ifdef CONFIG_KGDB
 175        else if (notify_die(DIE_TRAP, "EBREAK", regs, 0, regs->cause, SIGTRAP)
 176                                                                == NOTIFY_STOP)
 177                return;
 178#endif
 179        else if (report_bug(regs->epc, regs) == BUG_TRAP_TYPE_WARN)
 180                regs->epc += get_break_insn_length(regs->epc);
 181        else
 182                die(regs, "Kernel BUG");
 183}
 184NOKPROBE_SYMBOL(do_trap_break);
 185
 186#ifdef CONFIG_GENERIC_BUG
 187int is_valid_bugaddr(unsigned long pc)
 188{
 189        bug_insn_t insn;
 190
 191        if (pc < VMALLOC_START)
 192                return 0;
 193        if (get_kernel_nofault(insn, (bug_insn_t *)pc))
 194                return 0;
 195        if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
 196                return (insn == __BUG_INSN_32);
 197        else
 198                return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
 199}
 200#endif /* CONFIG_GENERIC_BUG */
 201
 202/* stvec & scratch is already set from head.S */
 203void __init trap_init(void)
 204{
 205}
 206
 207#ifdef CONFIG_VMAP_STACK
 208static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)],
 209                overflow_stack)__aligned(16);
 210/*
 211 * shadow stack, handled_ kernel_ stack_ overflow(in kernel/entry.S) is used
 212 * to get per-cpu overflow stack(get_overflow_stack).
 213 */
 214long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)];
 215asmlinkage unsigned long get_overflow_stack(void)
 216{
 217        return (unsigned long)this_cpu_ptr(overflow_stack) +
 218                OVERFLOW_STACK_SIZE;
 219}
 220
 221asmlinkage void handle_bad_stack(struct pt_regs *regs)
 222{
 223        unsigned long tsk_stk = (unsigned long)current->stack;
 224        unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack);
 225
 226        console_verbose();
 227
 228        pr_emerg("Insufficient stack space to handle exception!\n");
 229        pr_emerg("Task stack:     [0x%016lx..0x%016lx]\n",
 230                        tsk_stk, tsk_stk + THREAD_SIZE);
 231        pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n",
 232                        ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE);
 233
 234        __show_regs(regs);
 235        panic("Kernel stack overflow");
 236
 237        for (;;)
 238                wait_for_interrupt();
 239}
 240#endif
 241