/*
 *  linux/arch/alpha/kernel/process.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 */

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

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/utsname.h>
#include <linux/time.h>
#include <linux/major.h>
#include <linux/stat.h>
#include <linux/mman.h>
#include <linux/elfcore.h>
#include <linux/reboot.h>
#include <linux/tty.h>
#include <linux/console.h>

#include <asm/reg.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/hwrpb.h>
#include <asm/fpu.h>

#include "proto.h"
#include "pci_impl.h"

/*
 * Initial task structure. Make this a per-architecture thing,
 * because different architectures tend to have different
 * alignment requirements and potentially different initial
 * setup.
 */

unsigned long init_user_stack[1024] = { STACK_MAGIC, };
static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS;
struct mm_struct init_mm = INIT_MM(init_mm);

union task_union init_task_union __attribute__((section("init_task")))
         = { task: INIT_TASK(init_task_union.task) };

/*
 * No need to acquire the kernel lock, we're entirely local..
 */
asmlinkage int
sys_sethae(unsigned long hae, unsigned long a1, unsigned long a2,
           unsigned long a3, unsigned long a4, unsigned long a5,
           struct pt_regs regs)
{
        (&regs)->hae = hae;
        return 0;
}

void
cpu_idle(void)
{
        /* An endless idle loop with no priority at all.  */
        current->nice = 20;
        current->counter = -100;

        while (1) {
                /* FIXME -- EV6 and LCA45 know how to power down
                   the CPU.  */

                /* Although we are an idle CPU, we do not want to 
                   get into the scheduler unnecessarily.  */
                long oldval = xchg(&current->need_resched, -1UL);
                if (!oldval)
                        while (current->need_resched < 0);
                schedule();
                check_pgt_cache();
        }
}


struct halt_info {
        int mode;
        char *restart_cmd;
};

static void
common_shutdown_1(void *generic_ptr)
{
        struct halt_info *how = (struct halt_info *)generic_ptr;
        struct percpu_struct *cpup;
        unsigned long *pflags, flags;
        int cpuid = smp_processor_id();

        /* No point in taking interrupts anymore. */
        __cli();

        cpup = (struct percpu_struct *)
                        ((unsigned long)hwrpb + hwrpb->processor_offset
                         + hwrpb->processor_size * cpuid);
        pflags = &cpup->flags;
        flags = *pflags;

        /* Clear reason to "default"; clear "bootstrap in progress". */
        flags &= ~0x00ff0001UL;

#ifdef CONFIG_SMP
        /* Secondaries halt here. */
        if (cpuid != boot_cpuid) {
                flags |= 0x00040000UL; /* "remain halted" */
                *pflags = flags;
                clear_bit(cpuid, &cpu_present_mask);
                halt();
        }
#endif

        if (how->mode == LINUX_REBOOT_CMD_RESTART) {
                if (!how->restart_cmd) {
                        flags |= 0x00020000UL; /* "cold bootstrap" */
                } else {
                        /* For SRM, we could probably set environment
                           variables to get this to work.  We'd have to
                           delay this until after srm_paging_stop unless
                           we ever got srm_fixup working.

                           At the moment, SRM will use the last boot device,
                           but the file and flags will be the defaults, when
                           doing a "warm" bootstrap.  */
                        flags |= 0x00030000UL; /* "warm bootstrap" */
                }
        } else {
                flags |= 0x00040000UL; /* "remain halted" */
        }
        *pflags = flags;

#ifdef CONFIG_SMP
        /* Wait for the secondaries to halt. */
        clear_bit(boot_cpuid, &cpu_present_mask);
        while (cpu_present_mask)
                barrier();
#endif

        /* If booted from SRM, reset some of the original environment. */
        if (alpha_using_srm) {
#ifdef CONFIG_DUMMY_CONSOLE
                /* This has the effect of resetting the VGA video origin.  */
                take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
#endif
                /* reset_for_srm(); */
                set_hae(srm_hae);
        }

        if (alpha_mv.kill_arch)
                alpha_mv.kill_arch(how->mode);

        if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
                /* Unfortunately, since MILO doesn't currently understand
                   the hwrpb bits above, we can't reliably halt the 
                   processor and keep it halted.  So just loop.  */
                return;
        }

        if (alpha_using_srm)
                srm_paging_stop();

        halt();
}

static void
common_shutdown(int mode, char *restart_cmd)
{
        struct halt_info args;
        args.mode = mode;
        args.restart_cmd = restart_cmd;
#ifdef CONFIG_SMP
        smp_call_function(common_shutdown_1, &args, 1, 0);
#endif
        common_shutdown_1(&args);
}

void
machine_restart(char *restart_cmd)
{
        common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
}

void
machine_halt(void)
{
        common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
}

void
machine_power_off(void)
{
        common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
}

void
show_regs(struct pt_regs * regs)
{
        printk("\n");
        printk("Pid: %d, comm: %20s\n", current->pid, current->comm);
        printk("ps: %04lx pc: [<%016lx>] CPU %d    %s\n",
               regs->ps, regs->pc, smp_processor_id(), print_tainted());
        printk("rp: [<%016lx>] sp: %p\n", regs->r26, regs+1);
        printk(" r0: %016lx  r1: %016lx  r2: %016lx  r3: %016lx\n",
               regs->r0, regs->r1, regs->r2, regs->r3);
        printk(" r4: %016lx  r5: %016lx  r6: %016lx  r7: %016lx\n",
               regs->r4, regs->r5, regs->r6, regs->r7);
        printk(" r8: %016lx r16: %016lx r17: %016lx r18: %016lx\n",
               regs->r8, regs->r16, regs->r17, regs->r18);
        printk("r19: %016lx r20: %016lx r21: %016lx r22: %016lx\n",
               regs->r19, regs->r20, regs->r21, regs->r22);
        printk("r23: %016lx r24: %016lx r25: %016lx r26: %016lx\n",
               regs->r23, regs->r24, regs->r25, regs->r26);
        printk("r27: %016lx r28: %016lx r29: %016lx hae: %016lx\n",
               regs->r27, regs->r28, regs->gp, regs->hae);
}

/*
 * Re-start a thread when doing execve()
 */
void
start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
{
        set_fs(USER_DS);
        regs->pc = pc;
        regs->ps = 8;
        wrusp(sp);
}

/*
 * Free current thread data structures etc..
 */
void
exit_thread(void)
{
}

void
flush_thread(void)
{
        /* Arrange for each exec'ed process to start off with a clean slate
           with respect to the FPU.  This is all exceptions disabled.  */
        current->thread.flags &= ~IEEE_SW_MASK;
        wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
}

void
release_thread(struct task_struct *dead_task)
{
}

/*
 * "alpha_clone()".. By the time we get here, the
 * non-volatile registers have also been saved on the
 * stack. We do some ugly pointer stuff here.. (see
 * also copy_thread)
 *
 * Notice that "fork()" is implemented in terms of clone,
 * with parameters (SIGCHLD, 0).
 */
int
alpha_clone(unsigned long clone_flags, unsigned long usp,
            struct switch_stack * swstack)
{
        if (!usp)
                usp = rdusp();
        return do_fork(clone_flags, usp, (struct pt_regs *) (swstack+1), 0);
}

int
alpha_vfork(struct switch_stack * swstack)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(),
                        (struct pt_regs *) (swstack+1), 0);
}

/*
 * Copy an alpha thread..
 *
 * Note the "stack_offset" stuff: when returning to kernel mode, we need
 * to have some extra stack-space for the kernel stack that still exists
 * after the "ret_from_sys_call". When returning to user mode, we only
 * want the space needed by the syscall stack frame (ie "struct pt_regs").
 * Use the passed "regs" pointer to determine how much space we need
 * for a kernel fork().
 */

int
copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
            unsigned long unused,
            struct task_struct * p, struct pt_regs * regs)
{
        extern void ret_from_sys_call(void);
        extern void ret_from_fork(void);

        struct pt_regs * childregs;
        struct switch_stack * childstack, *stack;
        unsigned long stack_offset;

        stack_offset = PAGE_SIZE - sizeof(struct pt_regs);
        if (!(regs->ps & 8))
                stack_offset = (PAGE_SIZE-1) & (unsigned long) regs;
        childregs = (struct pt_regs *) (stack_offset + PAGE_SIZE + (long)p);
                
        *childregs = *regs;
        childregs->r0 = 0;
        childregs->r19 = 0;
        childregs->r20 = 1;     /* OSF/1 has some strange fork() semantics.  */
        regs->r20 = 0;
        stack = ((struct switch_stack *) regs) - 1;
        childstack = ((struct switch_stack *) childregs) - 1;
        *childstack = *stack;
        childstack->r26 = (unsigned long) ret_from_fork;
        p->thread.usp = usp;
        p->thread.ksp = (unsigned long) childstack;
        p->thread.pal_flags = 1;        /* set FEN, clear everything else */
        p->thread.flags = current->thread.flags;

        return 0;
}

/*
 * fill in the user structure for a core dump..
 */
void
dump_thread(struct pt_regs * pt, struct user * dump)
{
        /* switch stack follows right below pt_regs: */
        struct switch_stack * sw = ((struct switch_stack *) pt) - 1;

        dump->magic = CMAGIC;
        dump->start_code  = current->mm->start_code;
        dump->start_data  = current->mm->start_data;
        dump->start_stack = rdusp() & ~(PAGE_SIZE - 1);
        dump->u_tsize = ((current->mm->end_code - dump->start_code)
                         >> PAGE_SHIFT);
        dump->u_dsize = ((current->mm->brk + PAGE_SIZE-1 - dump->start_data)
                         >> PAGE_SHIFT);
        dump->u_ssize = (current->mm->start_stack - dump->start_stack
                         + PAGE_SIZE-1) >> PAGE_SHIFT;

        /*
         * We store the registers in an order/format that is
         * compatible with DEC Unix/OSF/1 as this makes life easier
         * for gdb.
         */
        dump->regs[EF_V0]  = pt->r0;
        dump->regs[EF_T0]  = pt->r1;
        dump->regs[EF_T1]  = pt->r2;
        dump->regs[EF_T2]  = pt->r3;
        dump->regs[EF_T3]  = pt->r4;
        dump->regs[EF_T4]  = pt->r5;
        dump->regs[EF_T5]  = pt->r6;
        dump->regs[EF_T6]  = pt->r7;
        dump->regs[EF_T7]  = pt->r8;
        dump->regs[EF_S0]  = sw->r9;
        dump->regs[EF_S1]  = sw->r10;
        dump->regs[EF_S2]  = sw->r11;
        dump->regs[EF_S3]  = sw->r12;
        dump->regs[EF_S4]  = sw->r13;
        dump->regs[EF_S5]  = sw->r14;
        dump->regs[EF_S6]  = sw->r15;
        dump->regs[EF_A3]  = pt->r19;
        dump->regs[EF_A4]  = pt->r20;
        dump->regs[EF_A5]  = pt->r21;
        dump->regs[EF_T8]  = pt->r22;
        dump->regs[EF_T9]  = pt->r23;
        dump->regs[EF_T10] = pt->r24;
        dump->regs[EF_T11] = pt->r25;
        dump->regs[EF_RA]  = pt->r26;
        dump->regs[EF_T12] = pt->r27;
        dump->regs[EF_AT]  = pt->r28;
        dump->regs[EF_SP]  = rdusp();
        dump->regs[EF_PS]  = pt->ps;
        dump->regs[EF_PC]  = pt->pc;
        dump->regs[EF_GP]  = pt->gp;
        dump->regs[EF_A0]  = pt->r16;
        dump->regs[EF_A1]  = pt->r17;
        dump->regs[EF_A2]  = pt->r18;
        memcpy((char *)dump->regs + EF_SIZE, sw->fp, 32 * 8);
}

int
dump_fpu(struct pt_regs * regs, elf_fpregset_t *r)
{
        /* switch stack follows right below pt_regs: */
        struct switch_stack * sw = ((struct switch_stack *) regs) - 1;
        memcpy(r, sw->fp, 32 * 8);
        return 1;
}

/*
 * sys_execve() executes a new program.
 *
 * This works due to the alpha calling sequence: the first 6 args
 * are gotten from registers, while the rest is on the stack, so
 * we get a0-a5 for free, and then magically find "struct pt_regs"
 * on the stack for us..
 *
 * Don't do this at home.
 */
asmlinkage int
sys_execve(char *ufilename, char **argv, char **envp,
           unsigned long a3, unsigned long a4, unsigned long a5,
           struct pt_regs regs)
{
        int error;
        char *filename;

        filename = getname(ufilename);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        error = do_execve(filename, argv, envp, &regs);
        putname(filename);
out:
        return error;
}

/*
 * These bracket the sleeping functions..
 */
extern void scheduling_functions_start_here(void);
extern void scheduling_functions_end_here(void);
#define first_sched     ((unsigned long) scheduling_functions_start_here)
#define last_sched      ((unsigned long) scheduling_functions_end_here)

unsigned long
get_wchan(struct task_struct *p)
{
        unsigned long schedule_frame;
        unsigned long pc;
        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;
        /*
         * This one depends on the frame size of schedule().  Do a
         * "disass schedule" in gdb to find the frame size.  Also, the
         * code assumes that sleep_on() follows immediately after
         * interruptible_sleep_on() and that add_timer() follows
         * immediately after interruptible_sleep().  Ugly, isn't it?
         * Maybe adding a wchan field to task_struct would be better,
         * after all...
         */

        pc = thread_saved_pc(&p->thread);
        if (pc >= first_sched && pc < last_sched) {
                schedule_frame = ((unsigned long *)p->thread.ksp)[6];
                return ((unsigned long *)schedule_frame)[12];
        }
        return pc;
}