// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OpenRISC traps.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 *
 *  Here we handle the break vectors not used by the system call
 *  mechanism, as well as some general stack/register dumping
 *  things.
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/extable.h>
#include <linux/kmod.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>

#include <asm/bug.h>
#include <asm/fpu.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/unwinder.h>
#include <asm/sections.h>

int lwa_flag;
static unsigned long __user *lwa_addr;

asmlinkage void unhandled_exception(struct pt_regs *regs, int ea, int vector);
asmlinkage void do_trap(struct pt_regs *regs, unsigned long address);
asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address);
asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address);
asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address);
asmlinkage void do_illegal_instruction(struct pt_regs *regs,
                                       unsigned long address);

static void print_trace(void *data, unsigned long addr, int reliable)
{
        const char *loglvl = data;

        pr_info("%s[<%p>] %s%pS\n", loglvl, (void *) addr, reliable ? "" : "? ",
                (void *) addr);
}

static void print_data(unsigned long base_addr, unsigned long word, int i)
{
        if (i == 0)
                pr_info("(%08lx:)\t%08lx", base_addr + (i * 4), word);
        else
                pr_info(" %08lx:\t%08lx", base_addr + (i * 4), word);
}

/* displays a short stack trace */
void show_stack(struct task_struct *task, unsigned long *esp, const char *loglvl)
{
        if (esp == NULL)
                esp = (unsigned long *)&esp;

        pr_info("%sCall trace:\n", loglvl);
        unwind_stack((void *)loglvl, esp, print_trace);
}

void show_registers(struct pt_regs *regs)
{
        int i;
        int in_kernel = 1;
        unsigned long esp;

        esp = (unsigned long)(regs->sp);
        if (user_mode(regs))
                in_kernel = 0;

        pr_info("CPU #: %d\n"
                "   PC: %08lx    SR: %08lx    SP: %08lx\n",
                smp_processor_id(), regs->pc, regs->sr, regs->sp);
        pr_info("GPR00: %08lx GPR01: %08lx GPR02: %08lx GPR03: %08lx\n",
                0L, regs->gpr[1], regs->gpr[2], regs->gpr[3]);
        pr_info("GPR04: %08lx GPR05: %08lx GPR06: %08lx GPR07: %08lx\n",
                regs->gpr[4], regs->gpr[5], regs->gpr[6], regs->gpr[7]);
        pr_info("GPR08: %08lx GPR09: %08lx GPR10: %08lx GPR11: %08lx\n",
                regs->gpr[8], regs->gpr[9], regs->gpr[10], regs->gpr[11]);
        pr_info("GPR12: %08lx GPR13: %08lx GPR14: %08lx GPR15: %08lx\n",
                regs->gpr[12], regs->gpr[13], regs->gpr[14], regs->gpr[15]);
        pr_info("GPR16: %08lx GPR17: %08lx GPR18: %08lx GPR19: %08lx\n",
                regs->gpr[16], regs->gpr[17], regs->gpr[18], regs->gpr[19]);
        pr_info("GPR20: %08lx GPR21: %08lx GPR22: %08lx GPR23: %08lx\n",
                regs->gpr[20], regs->gpr[21], regs->gpr[22], regs->gpr[23]);
        pr_info("GPR24: %08lx GPR25: %08lx GPR26: %08lx GPR27: %08lx\n",
                regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
        pr_info("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
                regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
        pr_info("  RES: %08lx oGPR11: %08lx\n",
                regs->gpr[11], regs->orig_gpr11);

        pr_info("Process %s (pid: %d, stackpage=%08lx)\n",
                current->comm, current->pid, (unsigned long)current);
        /*
         * When in-kernel, we also print out the stack and code at the
         * time of the fault..
         */
        if (in_kernel) {

                pr_info("\nStack: ");
                show_stack(NULL, (unsigned long *)esp, KERN_EMERG);

                if (esp < PAGE_OFFSET)
                        goto bad_stack;

                pr_info("\n");
                for (i = -8; i < 24; i += 1) {
                        unsigned long word;

                        if (__get_user(word, &((unsigned long *)esp)[i])) {
bad_stack:
                                pr_info(" Bad Stack value.");
                                break;
                        }

                        print_data(esp, word, i);
                }

                pr_info("\nCode: ");
                if (regs->pc < PAGE_OFFSET)
                        goto bad;

                for (i = -6; i < 6; i += 1) {
                        unsigned long word;

                        if (__get_user(word, &((unsigned long *)regs->pc)[i])) {
bad:
                                pr_info(" Bad PC value.");
                                break;
                        }

                        print_data(regs->pc, word, i);
                }
        }
        pr_info("\n");
}

/* This is normally the 'Oops' routine */
void __noreturn die(const char *str, struct pt_regs *regs, long err)
{

        console_verbose();
        pr_emerg("\n%s#: %04lx\n", str, err & 0xffff);
        show_registers(regs);
#ifdef CONFIG_JUMP_UPON_UNHANDLED_EXCEPTION
        pr_emerg("\n\nUNHANDLED_EXCEPTION: entering infinite loop\n");

        /* shut down interrupts */
        local_irq_disable();

        __asm__ __volatile__("l.nop   1");
        do {} while (1);
#endif
        make_task_dead(SIGSEGV);
}

asmlinkage void unhandled_exception(struct pt_regs *regs, int ea, int vector)
{
        pr_emerg("Unable to handle exception at EA =0x%x, vector 0x%x",
                 ea, vector);
        die("Oops", regs, 9);
}

asmlinkage void do_fpe_trap(struct pt_regs *regs, unsigned long address)
{
        if (user_mode(regs)) {
                int code = FPE_FLTUNK;
#ifdef CONFIG_FPU
                unsigned long fpcsr;

                save_fpu(current);
                fpcsr = current->thread.fpcsr;

                if (fpcsr & SPR_FPCSR_IVF)
                        code = FPE_FLTINV;
                else if (fpcsr & SPR_FPCSR_OVF)
                        code = FPE_FLTOVF;
                else if (fpcsr & SPR_FPCSR_UNF)
                        code = FPE_FLTUND;
                else if (fpcsr & SPR_FPCSR_DZF)
                        code = FPE_FLTDIV;
                else if (fpcsr & SPR_FPCSR_IXF)
                        code = FPE_FLTRES;

                /* Clear all flags */
                current->thread.fpcsr &= ~SPR_FPCSR_ALLF;
                restore_fpu(current);
#endif
                force_sig_fault(SIGFPE, code, (void __user *)regs->pc);
        } else {
                pr_emerg("KERNEL: Illegal fpe exception 0x%.8lx\n", regs->pc);
                die("Die:", regs, SIGFPE);
        }
}

asmlinkage void do_trap(struct pt_regs *regs, unsigned long address)
{
        if (user_mode(regs)) {
                force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);
        } else {
                pr_emerg("KERNEL: Illegal trap exception 0x%.8lx\n", regs->pc);
                die("Die:", regs, SIGILL);
        }
}

asmlinkage void do_unaligned_access(struct pt_regs *regs, unsigned long address)
{
        if (user_mode(regs)) {
                /* Send a SIGBUS */
                force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)address);
        } else {
                pr_emerg("KERNEL: Unaligned Access 0x%.8lx\n", address);
                die("Die:", regs, address);
        }

}

asmlinkage void do_bus_fault(struct pt_regs *regs, unsigned long address)
{
        if (user_mode(regs)) {
                /* Send a SIGBUS */
                force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
        } else {                /* Kernel mode */
                pr_emerg("KERNEL: Bus error (SIGBUS) 0x%.8lx\n", address);
                die("Die:", regs, address);
        }
}

static inline int in_delay_slot(struct pt_regs *regs)
{
#ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX
        /* No delay slot flag, do the old way */
        unsigned int op, insn;

        insn = *((unsigned int *)regs->pc);
        op = insn >> 26;
        switch (op) {
        case 0x00: /* l.j */
        case 0x01: /* l.jal */
        case 0x03: /* l.bnf */
        case 0x04: /* l.bf */
        case 0x11: /* l.jr */
        case 0x12: /* l.jalr */
                return 1;
        default:
                return 0;
        }
#else
        return mfspr(SPR_SR) & SPR_SR_DSX;
#endif
}

static inline void adjust_pc(struct pt_regs *regs, unsigned long address)
{
        int displacement;
        unsigned int rb, op, jmp;

        if (unlikely(in_delay_slot(regs))) {
                /* In delay slot, instruction at pc is a branch, simulate it */
                jmp = *((unsigned int *)regs->pc);

                displacement = sign_extend32(((jmp) & 0x3ffffff) << 2, 27);
                rb = (jmp & 0x0000ffff) >> 11;
                op = jmp >> 26;

                switch (op) {
                case 0x00: /* l.j */
                        regs->pc += displacement;
                        return;
                case 0x01: /* l.jal */
                        regs->pc += displacement;
                        regs->gpr[9] = regs->pc + 8;
                        return;
                case 0x03: /* l.bnf */
                        if (regs->sr & SPR_SR_F)
                                regs->pc += 8;
                        else
                                regs->pc += displacement;
                        return;
                case 0x04: /* l.bf */
                        if (regs->sr & SPR_SR_F)
                                regs->pc += displacement;
                        else
                                regs->pc += 8;
                        return;
                case 0x11: /* l.jr */
                        regs->pc = regs->gpr[rb];
                        return;
                case 0x12: /* l.jalr */
                        regs->pc = regs->gpr[rb];
                        regs->gpr[9] = regs->pc + 8;
                        return;
                default:
                        break;
                }
        } else {
                regs->pc += 4;
        }
}

static inline void simulate_lwa(struct pt_regs *regs, unsigned long address,
                                unsigned int insn)
{
        unsigned int ra, rd;
        unsigned long value;
        unsigned long orig_pc;
        long imm;

        const struct exception_table_entry *entry;

        orig_pc = regs->pc;
        adjust_pc(regs, address);

        ra = (insn >> 16) & 0x1f;
        rd = (insn >> 21) & 0x1f;
        imm = (short)insn;
        lwa_addr = (unsigned long __user *)(regs->gpr[ra] + imm);

        if ((unsigned long)lwa_addr & 0x3) {
                do_unaligned_access(regs, address);
                return;
        }

        if (get_user(value, lwa_addr)) {
                if (user_mode(regs)) {
                        force_sig(SIGSEGV);
                        return;
                }

                if ((entry = search_exception_tables(orig_pc))) {
                        regs->pc = entry->fixup;
                        return;
                }

                /* kernel access in kernel space, load it directly */
                value = *((unsigned long *)lwa_addr);
        }

        lwa_flag = 1;
        regs->gpr[rd] = value;
}

static inline void simulate_swa(struct pt_regs *regs, unsigned long address,
                                unsigned int insn)
{
        unsigned long __user *vaddr;
        unsigned long orig_pc;
        unsigned int ra, rb;
        long imm;

        const struct exception_table_entry *entry;

        orig_pc = regs->pc;
        adjust_pc(regs, address);

        ra = (insn >> 16) & 0x1f;
        rb = (insn >> 11) & 0x1f;
        imm = (short)(((insn & 0x2200000) >> 10) | (insn & 0x7ff));
        vaddr = (unsigned long __user *)(regs->gpr[ra] + imm);

        if (!lwa_flag || vaddr != lwa_addr) {
                regs->sr &= ~SPR_SR_F;
                return;
        }

        if ((unsigned long)vaddr & 0x3) {
                do_unaligned_access(regs, address);
                return;
        }

        if (put_user(regs->gpr[rb], vaddr)) {
                if (user_mode(regs)) {
                        force_sig(SIGSEGV);
                        return;
                }

                if ((entry = search_exception_tables(orig_pc))) {
                        regs->pc = entry->fixup;
                        return;
                }

                /* kernel access in kernel space, store it directly */
                *((unsigned long *)vaddr) = regs->gpr[rb];
        }

        lwa_flag = 0;
        regs->sr |= SPR_SR_F;
}

#define INSN_LWA        0x1b
#define INSN_SWA        0x33

asmlinkage void do_illegal_instruction(struct pt_regs *regs,
                                       unsigned long address)
{
        unsigned int op;
        unsigned int insn = *((unsigned int *)address);

        op = insn >> 26;

        switch (op) {
        case INSN_LWA:
                simulate_lwa(regs, address, insn);
                return;

        case INSN_SWA:
                simulate_swa(regs, address, insn);
                return;

        default:
                break;
        }

        if (user_mode(regs)) {
                /* Send a SIGILL */
                force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)address);
        } else {                /* Kernel mode */
                pr_emerg("KERNEL: Illegal instruction (SIGILL) 0x%.8lx\n",
                         address);
                die("Die:", regs, address);
        }
}