root/arch/csky/kernel/traps.c
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/user.h>
#include <linux/string.h>
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/ptrace.h>
#include <linux/kallsyms.h>
#include <linux/rtc.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/sched/debug.h>

#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/pgalloc.h>
#include <asm/siginfo.h>

#include <asm/mmu_context.h>

#ifdef CONFIG_CPU_HAS_FPU
#include <abi/fpu.h>
#endif

int show_unhandled_signals = 1;

/* Defined in entry.S */
asmlinkage void csky_trap(void);

asmlinkage void csky_systemcall(void);
asmlinkage void csky_cmpxchg(void);
asmlinkage void csky_get_tls(void);
asmlinkage void csky_irq(void);

asmlinkage void csky_pagefault(void);

/* Defined in head.S */
asmlinkage void _start_smp_secondary(void);

void __init pre_trap_init(void)
{
        int i;

        mtcr("vbr", vec_base);

        for (i = 1; i < 128; i++)
                VEC_INIT(i, csky_trap);
}

void __init trap_init(void)
{
        VEC_INIT(VEC_AUTOVEC, csky_irq);

        /* setup trap0 trap2 trap3 */
        VEC_INIT(VEC_TRAP0, csky_systemcall);
        VEC_INIT(VEC_TRAP2, csky_cmpxchg);
        VEC_INIT(VEC_TRAP3, csky_get_tls);

        /* setup MMU TLB exception */
        VEC_INIT(VEC_TLBINVALIDL, csky_pagefault);
        VEC_INIT(VEC_TLBINVALIDS, csky_pagefault);
        VEC_INIT(VEC_TLBMODIFIED, csky_pagefault);

#ifdef CONFIG_CPU_HAS_FPU
        init_fpu();
#endif

#ifdef CONFIG_SMP
        mtcr("cr<28, 0>", virt_to_phys(vec_base));

        VEC_INIT(VEC_RESET, (void *)virt_to_phys(_start_smp_secondary));
#endif
}

static DEFINE_SPINLOCK(die_lock);

void die(struct pt_regs *regs, const char *str)
{
        static int die_counter;
        int ret;

        oops_enter();

        spin_lock_irq(&die_lock);
        console_verbose();
        bust_spinlocks(1);

        pr_emerg("%s [#%d]\n", str, ++die_counter);
        print_modules();
        show_regs(regs);
        show_stack(current, (unsigned long *)regs->regs[4], KERN_INFO);

        ret = notify_die(DIE_OOPS, str, regs, 0, trap_no(regs), SIGSEGV);

        bust_spinlocks(0);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
        spin_unlock_irq(&die_lock);
        oops_exit();

        if (in_interrupt())
                panic("Fatal exception in interrupt");
        if (panic_on_oops)
                panic("Fatal exception");
        if (ret != NOTIFY_STOP)
                make_task_dead(SIGSEGV);
}

void do_trap(struct pt_regs *regs, int signo, int code, unsigned long addr)
{
        struct task_struct *tsk = current;

        if (show_unhandled_signals && unhandled_signal(tsk, signo)
            && printk_ratelimit()) {
                pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x%08lx",
                        tsk->comm, task_pid_nr(tsk), signo, code, addr);
                print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
                pr_cont("\n");
                show_regs(regs);
        }

        force_sig_fault(signo, code, (void __user *)addr);
}

static void do_trap_error(struct pt_regs *regs, int signo, int code,
        unsigned long addr, const char *str)
{
        current->thread.trap_no = trap_no(regs);

        if (user_mode(regs)) {
                do_trap(regs, signo, code, addr);
        } else {
                if (!fixup_exception(regs))
                        die(regs, str);
        }
}

#define DO_ERROR_INFO(name, signo, code, str)                           \
asmlinkage __visible void name(struct pt_regs *regs)                    \
{                                                                       \
        do_trap_error(regs, signo, code, regs->pc, "Oops - " str);      \
}

DO_ERROR_INFO(do_trap_unknown,
        SIGILL, ILL_ILLTRP, "unknown exception");
DO_ERROR_INFO(do_trap_zdiv,
        SIGFPE, FPE_INTDIV, "error zero div exception");
DO_ERROR_INFO(do_trap_buserr,
        SIGSEGV, ILL_ILLADR, "error bus error exception");

asmlinkage void do_trap_misaligned(struct pt_regs *regs)
{
#ifdef CONFIG_CPU_NEED_SOFTALIGN
        csky_alignment(regs);
#else
        current->thread.trap_no = trap_no(regs);
        do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->pc,
                      "Oops - load/store address misaligned");
#endif
}

asmlinkage void do_trap_bkpt(struct pt_regs *regs)
{
#ifdef CONFIG_KPROBES
        if (kprobe_single_step_handler(regs))
                return;
#endif
#ifdef CONFIG_UPROBES
        if (uprobe_single_step_handler(regs))
                return;
#endif
        if (user_mode(regs)) {
                send_sig(SIGTRAP, current, 0);
                return;
        }

        do_trap_error(regs, SIGILL, ILL_ILLTRP, regs->pc,
                      "Oops - illegal trap exception");
}

asmlinkage void do_trap_illinsn(struct pt_regs *regs)
{
        current->thread.trap_no = trap_no(regs);

#ifdef CONFIG_KPROBES
        if (kprobe_breakpoint_handler(regs))
                return;
#endif
#ifdef CONFIG_UPROBES
        if (uprobe_breakpoint_handler(regs))
                return;
#endif
#ifndef CONFIG_CPU_NO_USER_BKPT
        if (*(uint16_t *)instruction_pointer(regs) != USR_BKPT) {
                send_sig(SIGTRAP, current, 0);
                return;
        }
#endif

        do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->pc,
                      "Oops - illegal instruction exception");
}

asmlinkage void do_trap_fpe(struct pt_regs *regs)
{
#ifdef CONFIG_CPU_HAS_FPU
        return fpu_fpe(regs);
#else
        do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->pc,
                      "Oops - fpu instruction exception");
#endif
}

asmlinkage void do_trap_priv(struct pt_regs *regs)
{
#ifdef CONFIG_CPU_HAS_FPU
        if (user_mode(regs) && fpu_libc_helper(regs))
                return;
#endif
        do_trap_error(regs, SIGILL, ILL_PRVOPC, regs->pc,
                      "Oops - illegal privileged exception");
}

asmlinkage void trap_c(struct pt_regs *regs)
{
        switch (trap_no(regs)) {
        case VEC_ZERODIV:
                do_trap_zdiv(regs);
                break;
        case VEC_TRACE:
                do_trap_bkpt(regs);
                break;
        case VEC_ILLEGAL:
                do_trap_illinsn(regs);
                break;
        case VEC_TRAP1:
        case VEC_BREAKPOINT:
                do_trap_bkpt(regs);
                break;
        case VEC_ACCESS:
                do_trap_buserr(regs);
                break;
        case VEC_ALIGN:
                do_trap_misaligned(regs);
                break;
        case VEC_FPE:
                do_trap_fpe(regs);
                break;
        case VEC_PRIV:
                do_trap_priv(regs);
                break;
        default:
                do_trap_unknown(regs);
                break;
        }
}