// SPDX-License-Identifier: GPL-2.0
/*
 * arch/sparc/kernel/traps.c
 *
 * Copyright 1995, 2008 David S. Miller (davem@davemloft.net)
 * Copyright 2000 Jakub Jelinek (jakub@redhat.com)
 */

/*
 * I hate traps on the sparc, grrr...
 */

#include <linux/cpu.h>
#include <linux/sched/mm.h>
#include <linux/sched/debug.h>
#include <linux/mm_types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/kdebug.h>
#include <linux/export.h>
#include <linux/pgtable.h>

#include <asm/delay.h>
#include <asm/ptrace.h>
#include <asm/oplib.h>
#include <asm/page.h>
#include <asm/unistd.h>
#include <asm/traps.h>

#include "entry.h"
#include "kernel.h"

/* #define TRAP_DEBUG */

static void instruction_dump(unsigned long *pc)
{
        int i;
        
        if((((unsigned long) pc) & 3))
                return;

        for(i = -3; i < 6; i++)
                printk("%c%08lx%c",i?' ':'<',pc[i],i?' ':'>');
        printk("\n");
}

#define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
#define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")

void __noreturn die_if_kernel(char *str, struct pt_regs *regs)
{
        static int die_counter;
        int count = 0;

        /* Amuse the user. */
        printk(
"              \\|/ ____ \\|/\n"
"              \"@'/ ,. \\`@\"\n"
"              /_| \\__/ |_\\\n"
"                 \\__U_/\n");

        printk("%s(%d): %s [#%d]\n", current->comm, task_pid_nr(current), str, ++die_counter);
        show_regs(regs);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);

        __SAVE; __SAVE; __SAVE; __SAVE;
        __SAVE; __SAVE; __SAVE; __SAVE;
        __RESTORE; __RESTORE; __RESTORE; __RESTORE;
        __RESTORE; __RESTORE; __RESTORE; __RESTORE;

        {
                struct reg_window32 *rw = (struct reg_window32 *)regs->u_regs[UREG_FP];

                /* Stop the back trace when we hit userland or we
                 * find some badly aligned kernel stack. Set an upper
                 * bound in case our stack is trashed and we loop.
                 */
                while(rw                                        &&
                      count++ < 30                              &&
                      (((unsigned long) rw) >= PAGE_OFFSET)     &&
                      !(((unsigned long) rw) & 0x7)) {
                        printk("Caller[%08lx]: %pS\n", rw->ins[7],
                               (void *) rw->ins[7]);
                        rw = (struct reg_window32 *)rw->ins[6];
                }
        }
        printk("Instruction DUMP:");
        instruction_dump ((unsigned long *) regs->pc);
        make_task_dead((regs->psr & PSR_PS) ? SIGKILL : SIGSEGV);
}

void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
{
        if(type < 0x80) {
                /* Sun OS's puke from bad traps, Linux survives! */
                printk("Unimplemented Sparc TRAP, type = %02lx\n", type);
                die_if_kernel("Whee... Hello Mr. Penguin", regs);
        }       

        if(regs->psr & PSR_PS)
                die_if_kernel("Kernel bad trap", regs);

        force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
                               (void __user *)regs->pc, type - 0x80);
}

void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                            unsigned long psr)
{
        if(psr & PSR_PS)
                die_if_kernel("Kernel illegal instruction", regs);
#ifdef TRAP_DEBUG
        printk("Ill instr. at pc=%08lx instruction is %08lx\n",
               regs->pc, *(unsigned long *)regs->pc);
#endif

        send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
}

void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                         unsigned long psr)
{
        if(psr & PSR_PS)
                die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
        send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
}

/* XXX User may want to be allowed to do this. XXX */

void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                            unsigned long psr)
{
        if(regs->psr & PSR_PS) {
                printk("KERNEL MNA at pc %08lx npc %08lx called by %08lx\n", pc, npc,
                       regs->u_regs[UREG_RETPC]);
                die_if_kernel("BOGUS", regs);
                /* die_if_kernel("Kernel MNA access", regs); */
        }
#if 0
        show_regs (regs);
        instruction_dump ((unsigned long *) regs->pc);
        printk ("do_MNA!\n");
#endif
        send_sig_fault(SIGBUS, BUS_ADRALN,
                       /* FIXME: Should dig out mna address */ (void *)0,
                       current);
}

static unsigned long init_fsr = 0x0UL;
static unsigned long init_fregs[32] __attribute__ ((aligned (8))) =
                { ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
                  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
                  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
                  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL };

void do_fpd_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                 unsigned long psr)
{
        /* Sanity check... */
        if(psr & PSR_PS)
                die_if_kernel("Kernel gets FloatingPenguinUnit disabled trap", regs);

        put_psr(get_psr() | PSR_EF);    /* Allow FPU ops. */
        regs->psr |= PSR_EF;
#ifndef CONFIG_SMP
        if(last_task_used_math == current)
                return;
        if(last_task_used_math) {
                /* Other processes fpu state, save away */
                struct task_struct *fptask = last_task_used_math;
                fpsave(&fptask->thread.float_regs[0], &fptask->thread.fsr,
                       &fptask->thread.fpqueue[0], &fptask->thread.fpqdepth);
        }
        last_task_used_math = current;
        if(used_math()) {
                fpload(&current->thread.float_regs[0], &current->thread.fsr);
        } else {
                /* Set initial sane state. */
                fpload(&init_fregs[0], &init_fsr);
                set_used_math();
        }
#else
        if(!used_math()) {
                fpload(&init_fregs[0], &init_fsr);
                set_used_math();
        } else {
                fpload(&current->thread.float_regs[0], &current->thread.fsr);
        }
        set_thread_flag(TIF_USEDFPU);
#endif
}

static unsigned long fake_regs[32] __attribute__ ((aligned (8)));
static unsigned long fake_fsr;
static unsigned long fake_queue[32] __attribute__ ((aligned (8)));
static unsigned long fake_depth;

void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                 unsigned long psr)
{
        static int calls;
        unsigned long fsr;
        int ret = 0;
        int code;
#ifndef CONFIG_SMP
        struct task_struct *fpt = last_task_used_math;
#else
        struct task_struct *fpt = current;
#endif
        put_psr(get_psr() | PSR_EF);
        /* If nobody owns the fpu right now, just clear the
         * error into our fake static buffer and hope it don't
         * happen again.  Thank you crashme...
         */
#ifndef CONFIG_SMP
        if(!fpt) {
#else
        if (!test_tsk_thread_flag(fpt, TIF_USEDFPU)) {
#endif
                fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth);
                regs->psr &= ~PSR_EF;
                return;
        }
        fpsave(&fpt->thread.float_regs[0], &fpt->thread.fsr,
               &fpt->thread.fpqueue[0], &fpt->thread.fpqdepth);
#ifdef DEBUG_FPU
        printk("Hmm, FP exception, fsr was %016lx\n", fpt->thread.fsr);
#endif

        switch ((fpt->thread.fsr & 0x1c000)) {
        /* switch on the contents of the ftt [floating point trap type] field */
#ifdef DEBUG_FPU
        case (1 << 14):
                printk("IEEE_754_exception\n");
                break;
#endif
        case (2 << 14):  /* unfinished_FPop (underflow & co) */
        case (3 << 14):  /* unimplemented_FPop (quad stuff, maybe sqrt) */
                ret = do_mathemu(regs, fpt);
                break;
#ifdef DEBUG_FPU
        case (4 << 14):
                printk("sequence_error (OS bug...)\n");
                break;
        case (5 << 14):
                printk("hardware_error (uhoh!)\n");
                break;
        case (6 << 14):
                printk("invalid_fp_register (user error)\n");
                break;
#endif /* DEBUG_FPU */
        }
        /* If we successfully emulated the FPop, we pretend the trap never happened :-> */
        if (ret) {
                fpload(&current->thread.float_regs[0], &current->thread.fsr);
                return;
        }
        /* nope, better SIGFPE the offending process... */
               
#ifdef CONFIG_SMP
        clear_tsk_thread_flag(fpt, TIF_USEDFPU);
#endif
        if(psr & PSR_PS) {
                /* The first fsr store/load we tried trapped,
                 * the second one will not (we hope).
                 */
                printk("WARNING: FPU exception from kernel mode. at pc=%08lx\n",
                       regs->pc);
                regs->pc = regs->npc;
                regs->npc += 4;
                calls++;
                if(calls > 2)
                        die_if_kernel("Too many Penguin-FPU traps from kernel mode",
                                      regs);
                return;
        }

        fsr = fpt->thread.fsr;
        code = FPE_FLTUNK;
        if ((fsr & 0x1c000) == (1 << 14)) {
                if (fsr & 0x10)
                        code = FPE_FLTINV;
                else if (fsr & 0x08)
                        code = FPE_FLTOVF;
                else if (fsr & 0x04)
                        code = FPE_FLTUND;
                else if (fsr & 0x02)
                        code = FPE_FLTDIV;
                else if (fsr & 0x01)
                        code = FPE_FLTRES;
        }
        send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
#ifndef CONFIG_SMP
        last_task_used_math = NULL;
#endif
        regs->psr &= ~PSR_EF;
        if(calls > 0)
                calls=0;
}

void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                         unsigned long psr)
{
        if(psr & PSR_PS)
                die_if_kernel("Penguin overflow trap from kernel mode", regs);
        send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
}

void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                       unsigned long psr)
{
#ifdef TRAP_DEBUG
        printk("Watchpoint detected at PC %08lx NPC %08lx PSR %08lx\n",
               pc, npc, psr);
#endif
        if(psr & PSR_PS)
                panic("Tell me what a watchpoint trap is, and I'll then deal "
                      "with such a beast...");
}

void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                       unsigned long psr)
{
#ifdef TRAP_DEBUG
        printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
               pc, npc, psr);
#endif
        force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
}

void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                        unsigned long psr)
{
        send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
}

void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                         unsigned long psr)
{
#ifdef TRAP_DEBUG
        printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
               pc, npc, psr);
#endif
        send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
}

void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
                       unsigned long psr)
{
        send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
}

#ifdef CONFIG_DEBUG_BUGVERBOSE
void do_BUG(const char *file, int line)
{
        // bust_spinlocks(1);   XXX Not in our original BUG()
        printk("kernel BUG at %s:%d!\n", file, line);
}
EXPORT_SYMBOL(do_BUG);
#endif

/* Since we have our mappings set up, on multiprocessors we can spin them
 * up here so that timer interrupts work during initialization.
 */

void trap_init(void)
{
        extern void thread_info_offsets_are_bolixed_pete(void);

        /* Force linker to barf if mismatched */
        if (TI_UWINMASK    != offsetof(struct thread_info, uwinmask) ||
            TI_TASK        != offsetof(struct thread_info, task) ||
            TI_FLAGS       != offsetof(struct thread_info, flags) ||
            TI_CPU         != offsetof(struct thread_info, cpu) ||
            TI_PREEMPT     != offsetof(struct thread_info, preempt_count) ||
            TI_SOFTIRQ     != offsetof(struct thread_info, softirq_count) ||
            TI_HARDIRQ     != offsetof(struct thread_info, hardirq_count) ||
            TI_KSP         != offsetof(struct thread_info, ksp) ||
            TI_KPC         != offsetof(struct thread_info, kpc) ||
            TI_KPSR        != offsetof(struct thread_info, kpsr) ||
            TI_KWIM        != offsetof(struct thread_info, kwim) ||
            TI_REG_WINDOW  != offsetof(struct thread_info, reg_window) ||
            TI_RWIN_SPTRS  != offsetof(struct thread_info, rwbuf_stkptrs) ||
            TI_W_SAVED     != offsetof(struct thread_info, w_saved))
                thread_info_offsets_are_bolixed_pete();

        /* Attach to the address space of init_task. */
        mmgrab(&init_mm);
        current->active_mm = &init_mm;

        /* NOTE: Other cpus have this done as they are started
         *       up on SMP.
         */
}