// SPDX-License-Identifier: GPL-2.0
/*  arch/sparc64/kernel/process.c
 *
 *  Copyright (C) 1995, 1996, 2008 David S. Miller (davem@davemloft.net)
 *  Copyright (C) 1996       Eddie C. Dost   (ecd@skynet.be)
 *  Copyright (C) 1997, 1998 Jakub Jelinek   (jj@sunsite.mff.cuni.cz)
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#include <stdarg.h>

#include <linux/errno.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/delay.h>
#include <linux/compat.h>
#include <linux/tick.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/perf_event.h>
#include <linux/elfcore.h>
#include <linux/sysrq.h>
#include <linux/nmi.h>
#include <linux/context_tracking.h>
#include <linux/signal.h>

#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/pstate.h>
#include <asm/elf.h>
#include <asm/fpumacro.h>
#include <asm/head.h>
#include <asm/cpudata.h>
#include <asm/mmu_context.h>
#include <asm/unistd.h>
#include <asm/hypervisor.h>
#include <asm/syscalls.h>
#include <asm/irq_regs.h>
#include <asm/smp.h>
#include <asm/pcr.h>

#include "kstack.h"

/* Idle loop support on sparc64. */
void arch_cpu_idle(void)
{
        if (tlb_type != hypervisor) {
                touch_nmi_watchdog();
                local_irq_enable();
        } else {
                unsigned long pstate;

                local_irq_enable();

                /* The sun4v sleeping code requires that we have PSTATE.IE cleared over
                 * the cpu sleep hypervisor call.
                 */
                __asm__ __volatile__(
                        "rdpr %%pstate, %0\n\t"
                        "andn %0, %1, %0\n\t"
                        "wrpr %0, %%g0, %%pstate"
                        : "=&r" (pstate)
                        : "i" (PSTATE_IE));

                if (!need_resched() && !cpu_is_offline(smp_processor_id())) {
                        sun4v_cpu_yield();
                        /* If resumed by cpu_poke then we need to explicitly
                         * call scheduler_ipi().
                         */
                        scheduler_poke();
                }

                /* Re-enable interrupts. */
                __asm__ __volatile__(
                        "rdpr %%pstate, %0\n\t"
                        "or %0, %1, %0\n\t"
                        "wrpr %0, %%g0, %%pstate"
                        : "=&r" (pstate)
                        : "i" (PSTATE_IE));
        }
}

#ifdef CONFIG_HOTPLUG_CPU
void arch_cpu_idle_dead(void)
{
        sched_preempt_enable_no_resched();
        cpu_play_dead();
}
#endif

#ifdef CONFIG_COMPAT
static void show_regwindow32(struct pt_regs *regs)
{
        struct reg_window32 __user *rw;
        struct reg_window32 r_w;
        mm_segment_t old_fs;
        
        __asm__ __volatile__ ("flushw");
        rw = compat_ptr((unsigned int)regs->u_regs[14]);
        old_fs = get_fs();
        set_fs (USER_DS);
        if (copy_from_user (&r_w, rw, sizeof(r_w))) {
                set_fs (old_fs);
                return;
        }

        set_fs (old_fs);                        
        printk("l0: %08x l1: %08x l2: %08x l3: %08x "
               "l4: %08x l5: %08x l6: %08x l7: %08x\n",
               r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3],
               r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]);
        printk("i0: %08x i1: %08x i2: %08x i3: %08x "
               "i4: %08x i5: %08x i6: %08x i7: %08x\n",
               r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3],
               r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]);
}
#else
#define show_regwindow32(regs)  do { } while (0)
#endif

static void show_regwindow(struct pt_regs *regs)
{
        struct reg_window __user *rw;
        struct reg_window *rwk;
        struct reg_window r_w;
        mm_segment_t old_fs;

        if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) {
                __asm__ __volatile__ ("flushw");
                rw = (struct reg_window __user *)
                        (regs->u_regs[14] + STACK_BIAS);
                rwk = (struct reg_window *)
                        (regs->u_regs[14] + STACK_BIAS);
                if (!(regs->tstate & TSTATE_PRIV)) {
                        old_fs = get_fs();
                        set_fs (USER_DS);
                        if (copy_from_user (&r_w, rw, sizeof(r_w))) {
                                set_fs (old_fs);
                                return;
                        }
                        rwk = &r_w;
                        set_fs (old_fs);                        
                }
        } else {
                show_regwindow32(regs);
                return;
        }
        printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n",
               rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]);
        printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
               rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]);
        printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n",
               rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]);
        printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n",
               rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]);
        if (regs->tstate & TSTATE_PRIV)
                printk("I7: <%pS>\n", (void *) rwk->ins[7]);
}

void show_regs(struct pt_regs *regs)
{
        show_regs_print_info(KERN_DEFAULT);

        printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x    %s\n", regs->tstate,
               regs->tpc, regs->tnpc, regs->y, print_tainted());
        printk("TPC: <%pS>\n", (void *) regs->tpc);
        printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n",
               regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
               regs->u_regs[3]);
        printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n",
               regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
               regs->u_regs[7]);
        printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n",
               regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
               regs->u_regs[11]);
        printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n",
               regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
               regs->u_regs[15]);
        printk("RPC: <%pS>\n", (void *) regs->u_regs[15]);
        show_regwindow(regs);
        show_stack(current, (unsigned long *)regs->u_regs[UREG_FP], KERN_DEFAULT);
}

union global_cpu_snapshot global_cpu_snapshot[NR_CPUS];
static DEFINE_SPINLOCK(global_cpu_snapshot_lock);

static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs,
                              int this_cpu)
{
        struct global_reg_snapshot *rp;

        flushw_all();

        rp = &global_cpu_snapshot[this_cpu].reg;

        rp->tstate = regs->tstate;
        rp->tpc = regs->tpc;
        rp->tnpc = regs->tnpc;
        rp->o7 = regs->u_regs[UREG_I7];

        if (regs->tstate & TSTATE_PRIV) {
                struct reg_window *rw;

                rw = (struct reg_window *)
                        (regs->u_regs[UREG_FP] + STACK_BIAS);
                if (kstack_valid(tp, (unsigned long) rw)) {
                        rp->i7 = rw->ins[7];
                        rw = (struct reg_window *)
                                (rw->ins[6] + STACK_BIAS);
                        if (kstack_valid(tp, (unsigned long) rw))
                                rp->rpc = rw->ins[7];
                }
        } else {
                rp->i7 = 0;
                rp->rpc = 0;
        }
        rp->thread = tp;
}

/* In order to avoid hangs we do not try to synchronize with the
 * global register dump client cpus.  The last store they make is to
 * the thread pointer, so do a short poll waiting for that to become
 * non-NULL.
 */
static void __global_reg_poll(struct global_reg_snapshot *gp)
{
        int limit = 0;

        while (!gp->thread && ++limit < 100) {
                barrier();
                udelay(1);
        }
}

void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
{
        struct thread_info *tp = current_thread_info();
        struct pt_regs *regs = get_irq_regs();
        unsigned long flags;
        int this_cpu, cpu;

        if (!regs)
                regs = tp->kregs;

        spin_lock_irqsave(&global_cpu_snapshot_lock, flags);

        this_cpu = raw_smp_processor_id();

        memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

        if (cpumask_test_cpu(this_cpu, mask) && !exclude_self)
                __global_reg_self(tp, regs, this_cpu);

        smp_fetch_global_regs();

        for_each_cpu(cpu, mask) {
                struct global_reg_snapshot *gp;

                if (exclude_self && cpu == this_cpu)
                        continue;

                gp = &global_cpu_snapshot[cpu].reg;

                __global_reg_poll(gp);

                tp = gp->thread;
                printk("%c CPU[%3d]: TSTATE[%016lx] TPC[%016lx] TNPC[%016lx] TASK[%s:%d]\n",
                       (cpu == this_cpu ? '*' : ' '), cpu,
                       gp->tstate, gp->tpc, gp->tnpc,
                       ((tp && tp->task) ? tp->task->comm : "NULL"),
                       ((tp && tp->task) ? tp->task->pid : -1));

                if (gp->tstate & TSTATE_PRIV) {
                        printk("             TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n",
                               (void *) gp->tpc,
                               (void *) gp->o7,
                               (void *) gp->i7,
                               (void *) gp->rpc);
                } else {
                        printk("             TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n",
                               gp->tpc, gp->o7, gp->i7, gp->rpc);
                }

                touch_nmi_watchdog();
        }

        memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

        spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags);
}

#ifdef CONFIG_MAGIC_SYSRQ

static void sysrq_handle_globreg(int key)
{
        trigger_all_cpu_backtrace();
}

static const struct sysrq_key_op sparc_globalreg_op = {
        .handler        = sysrq_handle_globreg,
        .help_msg       = "global-regs(y)",
        .action_msg     = "Show Global CPU Regs",
};

static void __global_pmu_self(int this_cpu)
{
        struct global_pmu_snapshot *pp;
        int i, num;

        if (!pcr_ops)
                return;

        pp = &global_cpu_snapshot[this_cpu].pmu;

        num = 1;
        if (tlb_type == hypervisor &&
            sun4v_chip_type >= SUN4V_CHIP_NIAGARA4)
                num = 4;

        for (i = 0; i < num; i++) {
                pp->pcr[i] = pcr_ops->read_pcr(i);
                pp->pic[i] = pcr_ops->read_pic(i);
        }
}

static void __global_pmu_poll(struct global_pmu_snapshot *pp)
{
        int limit = 0;

        while (!pp->pcr[0] && ++limit < 100) {
                barrier();
                udelay(1);
        }
}

static void pmu_snapshot_all_cpus(void)
{
        unsigned long flags;
        int this_cpu, cpu;

        spin_lock_irqsave(&global_cpu_snapshot_lock, flags);

        memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

        this_cpu = raw_smp_processor_id();

        __global_pmu_self(this_cpu);

        smp_fetch_global_pmu();

        for_each_online_cpu(cpu) {
                struct global_pmu_snapshot *pp = &global_cpu_snapshot[cpu].pmu;

                __global_pmu_poll(pp);

                printk("%c CPU[%3d]: PCR[%08lx:%08lx:%08lx:%08lx] PIC[%08lx:%08lx:%08lx:%08lx]\n",
                       (cpu == this_cpu ? '*' : ' '), cpu,
                       pp->pcr[0], pp->pcr[1], pp->pcr[2], pp->pcr[3],
                       pp->pic[0], pp->pic[1], pp->pic[2], pp->pic[3]);

                touch_nmi_watchdog();
        }

        memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot));

        spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags);
}

static void sysrq_handle_globpmu(int key)
{
        pmu_snapshot_all_cpus();
}

static const struct sysrq_key_op sparc_globalpmu_op = {
        .handler        = sysrq_handle_globpmu,
        .help_msg       = "global-pmu(x)",
        .action_msg     = "Show Global PMU Regs",
};

static int __init sparc_sysrq_init(void)
{
        int ret = register_sysrq_key('y', &sparc_globalreg_op);

        if (!ret)
                ret = register_sysrq_key('x', &sparc_globalpmu_op);
        return ret;
}

core_initcall(sparc_sysrq_init);

#endif

/* Free current thread data structures etc.. */
void exit_thread(struct task_struct *tsk)
{
        struct thread_info *t = task_thread_info(tsk);

        if (t->utraps) {
                if (t->utraps[0] < 2)
                        kfree (t->utraps);
                else
                        t->utraps[0]--;
        }
}

void flush_thread(void)
{
        struct thread_info *t = current_thread_info();
        struct mm_struct *mm;

        mm = t->task->mm;
        if (mm)
                tsb_context_switch(mm);

        set_thread_wsaved(0);

        /* Clear FPU register state. */
        t->fpsaved[0] = 0;
}

/* It's a bit more tricky when 64-bit tasks are involved... */
static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
{
        bool stack_64bit = test_thread_64bit_stack(psp);
        unsigned long fp, distance, rval;

        if (stack_64bit) {
                csp += STACK_BIAS;
                psp += STACK_BIAS;
                __get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
                fp += STACK_BIAS;
                if (test_thread_flag(TIF_32BIT))
                        fp &= 0xffffffff;
        } else
                __get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));

        /* Now align the stack as this is mandatory in the Sparc ABI
         * due to how register windows work.  This hides the
         * restriction from thread libraries etc.
         */
        csp &= ~15UL;

        distance = fp - psp;
        rval = (csp - distance);
        if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
                rval = 0;
        else if (!stack_64bit) {
                if (put_user(((u32)csp),
                             &(((struct reg_window32 __user *)rval)->ins[6])))
                        rval = 0;
        } else {
                if (put_user(((u64)csp - STACK_BIAS),
                             &(((struct reg_window __user *)rval)->ins[6])))
                        rval = 0;
                else
                        rval = rval - STACK_BIAS;
        }

        return rval;
}

/* Standard stuff. */
static inline void shift_window_buffer(int first_win, int last_win,
                                       struct thread_info *t)
{
        int i;

        for (i = first_win; i < last_win; i++) {
                t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1];
                memcpy(&t->reg_window[i], &t->reg_window[i+1],
                       sizeof(struct reg_window));
        }
}

void synchronize_user_stack(void)
{
        struct thread_info *t = current_thread_info();
        unsigned long window;

        flush_user_windows();
        if ((window = get_thread_wsaved()) != 0) {
                window -= 1;
                do {
                        struct reg_window *rwin = &t->reg_window[window];
                        int winsize = sizeof(struct reg_window);
                        unsigned long sp;

                        sp = t->rwbuf_stkptrs[window];

                        if (test_thread_64bit_stack(sp))
                                sp += STACK_BIAS;
                        else
                                winsize = sizeof(struct reg_window32);

                        if (!copy_to_user((char __user *)sp, rwin, winsize)) {
                                shift_window_buffer(window, get_thread_wsaved() - 1, t);
                                set_thread_wsaved(get_thread_wsaved() - 1);
                        }
                } while (window--);
        }
}

static void stack_unaligned(unsigned long sp)
{
        force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp, 0);
}

static const char uwfault32[] = KERN_INFO \
        "%s[%d]: bad register window fault: SP %08lx (orig_sp %08lx) TPC %08lx O7 %08lx\n";
static const char uwfault64[] = KERN_INFO \
        "%s[%d]: bad register window fault: SP %016lx (orig_sp %016lx) TPC %08lx O7 %016lx\n";

void fault_in_user_windows(struct pt_regs *regs)
{
        struct thread_info *t = current_thread_info();
        unsigned long window;

        flush_user_windows();
        window = get_thread_wsaved();

        if (likely(window != 0)) {
                window -= 1;
                do {
                        struct reg_window *rwin = &t->reg_window[window];
                        int winsize = sizeof(struct reg_window);
                        unsigned long sp, orig_sp;

                        orig_sp = sp = t->rwbuf_stkptrs[window];

                        if (test_thread_64bit_stack(sp))
                                sp += STACK_BIAS;
                        else
                                winsize = sizeof(struct reg_window32);

                        if (unlikely(sp & 0x7UL))
                                stack_unaligned(sp);

                        if (unlikely(copy_to_user((char __user *)sp,
                                                  rwin, winsize))) {
                                if (show_unhandled_signals)
                                        printk_ratelimited(is_compat_task() ?
                                                           uwfault32 : uwfault64,
                                                           current->comm, current->pid,
                                                           sp, orig_sp,
                                                           regs->tpc,
                                                           regs->u_regs[UREG_I7]);
                                goto barf;
                        }
                } while (window--);
        }
        set_thread_wsaved(0);
        return;

barf:
        set_thread_wsaved(window + 1);
        force_sig(SIGSEGV);
}

/* Copy a Sparc thread.  The fork() return value conventions
 * under SunOS are nothing short of bletcherous:
 * Parent -->  %o0 == childs  pid, %o1 == 0
 * Child  -->  %o0 == parents pid, %o1 == 1
 */
int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
                struct task_struct *p, unsigned long tls)
{
        struct thread_info *t = task_thread_info(p);
        struct pt_regs *regs = current_pt_regs();
        struct sparc_stackf *parent_sf;
        unsigned long child_stack_sz;
        char *child_trap_frame;

        /* Calculate offset to stack_frame & pt_regs */
        child_stack_sz = (STACKFRAME_SZ + TRACEREG_SZ);
        child_trap_frame = (task_stack_page(p) +
                            (THREAD_SIZE - child_stack_sz));

        t->new_child = 1;
        t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
        t->kregs = (struct pt_regs *) (child_trap_frame +
                                       sizeof(struct sparc_stackf));
        t->fpsaved[0] = 0;

        if (unlikely(p->flags & PF_KTHREAD)) {
                memset(child_trap_frame, 0, child_stack_sz);
                __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 
                        (current_pt_regs()->tstate + 1) & TSTATE_CWP;
                t->current_ds = ASI_P;
                t->kregs->u_regs[UREG_G1] = sp; /* function */
                t->kregs->u_regs[UREG_G2] = arg;
                return 0;
        }

        parent_sf = ((struct sparc_stackf *) regs) - 1;
        memcpy(child_trap_frame, parent_sf, child_stack_sz);
        if (t->flags & _TIF_32BIT) {
                sp &= 0x00000000ffffffffUL;
                regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
        }
        t->kregs->u_regs[UREG_FP] = sp;
        __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 
                (regs->tstate + 1) & TSTATE_CWP;
        t->current_ds = ASI_AIUS;
        if (sp != regs->u_regs[UREG_FP]) {
                unsigned long csp;

                csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
                if (!csp)
                        return -EFAULT;
                t->kregs->u_regs[UREG_FP] = csp;
        }
        if (t->utraps)
                t->utraps[0]++;

        /* Set the return value for the child. */
        t->kregs->u_regs[UREG_I0] = current->pid;
        t->kregs->u_regs[UREG_I1] = 1;

        /* Set the second return value for the parent. */
        regs->u_regs[UREG_I1] = 0;

        if (clone_flags & CLONE_SETTLS)
                t->kregs->u_regs[UREG_G7] = tls;

        return 0;
}

/* TIF_MCDPER in thread info flags for current task is updated lazily upon
 * a context switch. Update this flag in current task's thread flags
 * before dup so the dup'd task will inherit the current TIF_MCDPER flag.
 */
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
        if (adi_capable()) {
                register unsigned long tmp_mcdper;

                __asm__ __volatile__(
                        ".word 0x83438000\n\t"  /* rd  %mcdper, %g1 */
                        "mov %%g1, %0\n\t"
                        : "=r" (tmp_mcdper)
                        :
                        : "g1");
                if (tmp_mcdper)
                        set_thread_flag(TIF_MCDPER);
                else
                        clear_thread_flag(TIF_MCDPER);
        }

        *dst = *src;
        return 0;
}

unsigned long get_wchan(struct task_struct *task)
{
        unsigned long pc, fp, bias = 0;
        struct thread_info *tp;
        struct reg_window *rw;
        unsigned long ret = 0;
        int count = 0; 

        if (!task || task == current ||
            task->state == TASK_RUNNING)
                goto out;

        tp = task_thread_info(task);
        bias = STACK_BIAS;
        fp = task_thread_info(task)->ksp + bias;

        do {
                if (!kstack_valid(tp, fp))
                        break;
                rw = (struct reg_window *) fp;
                pc = rw->ins[7];
                if (!in_sched_functions(pc)) {
                        ret = pc;
                        goto out;
                }
                fp = rw->ins[6] + bias;
        } while (++count < 16);

out:
        return ret;
}