Linux-2.6.12-rc2

[mirror_ubuntu-bionic-kernel.git] / arch / s390 / kernel / process.c

/*
 *  arch/s390/kernel/process.c
 *
 *  S390 version
 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *               Hartmut Penner (hp@de.ibm.com),
 *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 *
 *  Derived from "arch/i386/kernel/process.c"
 *    Copyright (C) 1995, Linus Torvalds
 */

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

#include <linux/config.h>
#include <linux/compiler.h>
#include <linux/cpu.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/vmalloc.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/notifier.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/timer.h>

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

/*
 * Return saved PC of a blocked thread. used in kernel/sched.
 * resume in entry.S does not create a new stack frame, it
 * just stores the registers %r6-%r15 to the frame given by
 * schedule. We want to return the address of the caller of
 * schedule, so we have to walk the backchain one time to
 * find the frame schedule() store its return address.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
        struct stack_frame *sf;

        sf = (struct stack_frame *) tsk->thread.ksp;
        sf = (struct stack_frame *) sf->back_chain;
        return sf->gprs[8];
}

/*
 * Need to know about CPUs going idle?
 */
static struct notifier_block *idle_chain;

int register_idle_notifier(struct notifier_block *nb)
{
        return notifier_chain_register(&idle_chain, nb);
}
EXPORT_SYMBOL(register_idle_notifier);

int unregister_idle_notifier(struct notifier_block *nb)
{
        return notifier_chain_unregister(&idle_chain, nb);
}
EXPORT_SYMBOL(unregister_idle_notifier);

void do_monitor_call(struct pt_regs *regs, long interruption_code)
{
        /* disable monitor call class 0 */
        __ctl_clear_bit(8, 15);

        notifier_call_chain(&idle_chain, CPU_NOT_IDLE,
                            (void *)(long) smp_processor_id());
}

/*
 * The idle loop on a S390...
 */
void default_idle(void)
{
        psw_t wait_psw;
        unsigned long reg;
        int cpu, rc;

        local_irq_disable();
        if (need_resched()) {
                local_irq_enable();
                schedule();
                return;
        }

        /* CPU is going idle. */
        cpu = smp_processor_id();
        rc = notifier_call_chain(&idle_chain, CPU_IDLE, (void *)(long) cpu);
        if (rc != NOTIFY_OK && rc != NOTIFY_DONE)
                BUG();
        if (rc != NOTIFY_OK) {
                local_irq_enable();
                return;
        }

        /* enable monitor call class 0 */
        __ctl_set_bit(8, 15);

#ifdef CONFIG_HOTPLUG_CPU
        if (cpu_is_offline(smp_processor_id()))
                cpu_die();
#endif

        /* 
         * Wait for external, I/O or machine check interrupt and
         * switch off machine check bit after the wait has ended.
         */
        wait_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK | PSW_MASK_WAIT |
                PSW_MASK_IO | PSW_MASK_EXT;
#ifndef CONFIG_ARCH_S390X
        asm volatile (
                "    basr %0,0\n"
                "0:  la   %0,1f-0b(%0)\n"
                "    st   %0,4(%1)\n"
                "    oi   4(%1),0x80\n"
                "    lpsw 0(%1)\n"
                "1:  la   %0,2f-1b(%0)\n"
                "    st   %0,4(%1)\n"
                "    oi   4(%1),0x80\n"
                "    ni   1(%1),0xf9\n"
                "    lpsw 0(%1)\n"
                "2:"
                : "=&a" (reg) : "a" (&wait_psw) : "memory", "cc" );
#else /* CONFIG_ARCH_S390X */
        asm volatile (
                "    larl  %0,0f\n"
                "    stg   %0,8(%1)\n"
                "    lpswe 0(%1)\n"
                "0:  larl  %0,1f\n"
                "    stg   %0,8(%1)\n"
                "    ni    1(%1),0xf9\n"
                "    lpswe 0(%1)\n"
                "1:"
                : "=&a" (reg) : "a" (&wait_psw) : "memory", "cc" );
#endif /* CONFIG_ARCH_S390X */
}

void cpu_idle(void)
{
        for (;;)
                default_idle();
}

void show_regs(struct pt_regs *regs)
{
        struct task_struct *tsk = current;

        printk("CPU:    %d    %s\n", tsk->thread_info->cpu, print_tainted());
        printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
               current->comm, current->pid, (void *) tsk,
               (void *) tsk->thread.ksp);

        show_registers(regs);
        /* Show stack backtrace if pt_regs is from kernel mode */
        if (!(regs->psw.mask & PSW_MASK_PSTATE))
                show_trace(0,(unsigned long *) regs->gprs[15]);
}

extern void kernel_thread_starter(void);

__asm__(".align 4\n"
        "kernel_thread_starter:\n"
        "    la    2,0(10)\n"
        "    basr  14,9\n"
        "    la    2,0\n"
        "    br    11\n");

int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
        struct pt_regs regs;

        memset(&regs, 0, sizeof(regs));
        regs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO | PSW_MASK_EXT;
        regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
        regs.gprs[9] = (unsigned long) fn;
        regs.gprs[10] = (unsigned long) arg;
        regs.gprs[11] = (unsigned long) do_exit;
        regs.orig_gpr2 = -1;

        /* Ok, create the new process.. */
        return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
                       0, &regs, 0, NULL, NULL);
}

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

void flush_thread(void)
{
        clear_used_math();
        clear_tsk_thread_flag(current, TIF_USEDFPU);
}

void release_thread(struct task_struct *dead_task)
{
}

int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
        unsigned long unused,
        struct task_struct * p, struct pt_regs * regs)
{
        struct fake_frame
          {
            struct stack_frame sf;
            struct pt_regs childregs;
          } *frame;

        frame = ((struct fake_frame *)
                 (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
        p->thread.ksp = (unsigned long) frame;
        /* Store access registers to kernel stack of new process. */
        frame->childregs = *regs;
        frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
        frame->childregs.gprs[15] = new_stackp;
        frame->sf.back_chain = 0;

        /* new return point is ret_from_fork */
        frame->sf.gprs[8] = (unsigned long) ret_from_fork;

        /* fake return stack for resume(), don't go back to schedule */
        frame->sf.gprs[9] = (unsigned long) frame;

        /* Save access registers to new thread structure. */
        save_access_regs(&p->thread.acrs[0]);

#ifndef CONFIG_ARCH_S390X
        /*
         * save fprs to current->thread.fp_regs to merge them with
         * the emulated registers and then copy the result to the child.
         */
        save_fp_regs(&current->thread.fp_regs);
        memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
               sizeof(s390_fp_regs));
        p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _SEGMENT_TABLE;
        /* Set a new TLS ?  */
        if (clone_flags & CLONE_SETTLS)
                p->thread.acrs[0] = regs->gprs[6];
#else /* CONFIG_ARCH_S390X */
        /* Save the fpu registers to new thread structure. */
        save_fp_regs(&p->thread.fp_regs);
        p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _REGION_TABLE;
        /* Set a new TLS ?  */
        if (clone_flags & CLONE_SETTLS) {
                if (test_thread_flag(TIF_31BIT)) {
                        p->thread.acrs[0] = (unsigned int) regs->gprs[6];
                } else {
                        p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
                        p->thread.acrs[1] = (unsigned int) regs->gprs[6];
                }
        }
#endif /* CONFIG_ARCH_S390X */
        /* start new process with ar4 pointing to the correct address space */
        p->thread.mm_segment = get_fs();
        /* Don't copy debug registers */
        memset(&p->thread.per_info,0,sizeof(p->thread.per_info));

        return 0;
}

asmlinkage long sys_fork(struct pt_regs regs)
{
        return do_fork(SIGCHLD, regs.gprs[15], &regs, 0, NULL, NULL);
}

asmlinkage long sys_clone(struct pt_regs regs)
{
        unsigned long clone_flags;
        unsigned long newsp;
        int __user *parent_tidptr, *child_tidptr;

        clone_flags = regs.gprs[3];
        newsp = regs.orig_gpr2;
        parent_tidptr = (int __user *) regs.gprs[4];
        child_tidptr = (int __user *) regs.gprs[5];
        if (!newsp)
                newsp = regs.gprs[15];
        return do_fork(clone_flags, newsp, &regs, 0,
                       parent_tidptr, child_tidptr);
}

/*
 * This is trivial, and on the face of it looks like it
 * could equally well be done in user mode.
 *
 * Not so, for quite unobvious reasons - register pressure.
 * In user mode vfork() cannot have a stack frame, and if
 * done by calling the "clone()" system call directly, you
 * do not have enough call-clobbered registers to hold all
 * the information you need.
 */
asmlinkage long sys_vfork(struct pt_regs regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
                       regs.gprs[15], &regs, 0, NULL, NULL);
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage long sys_execve(struct pt_regs regs)
{
        int error;
        char * filename;

        filename = getname((char __user *) regs.orig_gpr2);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        error = do_execve(filename, (char __user * __user *) regs.gprs[3],
                          (char __user * __user *) regs.gprs[4], &regs);
        if (error == 0) {
                task_lock(current);
                current->ptrace &= ~PT_DTRACE;
                task_unlock(current);
                current->thread.fp_regs.fpc = 0;
                if (MACHINE_HAS_IEEE)
                        asm volatile("sfpc %0,%0" : : "d" (0));
        }
        putname(filename);
out:
        return error;
}


/*
 * fill in the FPU structure for a core dump.
 */
int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
{
#ifndef CONFIG_ARCH_S390X
        /*
         * save fprs to current->thread.fp_regs to merge them with
         * the emulated registers and then copy the result to the dump.
         */
        save_fp_regs(&current->thread.fp_regs);
        memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
#else /* CONFIG_ARCH_S390X */
        save_fp_regs(fpregs);
#endif /* CONFIG_ARCH_S390X */
        return 1;
}

/*
 * fill in the user structure for a core dump..
 */
void dump_thread(struct pt_regs * regs, struct user * dump)
{

/* changed the size calculations - should hopefully work better. lbt */
        dump->magic = CMAGIC;
        dump->start_code = 0;
        dump->start_stack = regs->gprs[15] & ~(PAGE_SIZE - 1);
        dump->u_tsize = current->mm->end_code >> PAGE_SHIFT;
        dump->u_dsize = (current->mm->brk + PAGE_SIZE - 1) >> PAGE_SHIFT;
        dump->u_dsize -= dump->u_tsize;
        dump->u_ssize = 0;
        if (dump->start_stack < TASK_SIZE)
                dump->u_ssize = (TASK_SIZE - dump->start_stack) >> PAGE_SHIFT;
        memcpy(&dump->regs, regs, sizeof(s390_regs));
        dump_fpu (regs, &dump->regs.fp_regs);
        dump->regs.per_info = current->thread.per_info;
}

unsigned long get_wchan(struct task_struct *p)
{
        struct stack_frame *sf, *low, *high;
        unsigned long return_address;
        int count;

        if (!p || p == current || p->state == TASK_RUNNING || !p->thread_info)
                return 0;
        low = (struct stack_frame *) p->thread_info;
        high = (struct stack_frame *)
                ((unsigned long) p->thread_info + THREAD_SIZE) - 1;
        sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
        if (sf <= low || sf > high)
                return 0;
        for (count = 0; count < 16; count++) {
                sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
                if (sf <= low || sf > high)
                        return 0;
                return_address = sf->gprs[8] & PSW_ADDR_INSN;
                if (!in_sched_functions(return_address))
                        return return_address;
        }
        return 0;
}