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

/*
 * arch/xtensa/kernel/process.c
 *
 * Xtensa Processor version.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001 - 2005 Tensilica Inc.
 *
 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
 * Chris Zankel <chris@zankel.net>
 * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
 * Kevin Chea
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/elf.h>
#include <linux/init.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
#include <linux/module.h>
#include <linux/mqueue.h>
#include <linux/fs.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/platform.h>
#include <asm/mmu.h>
#include <asm/irq.h>
#include <asm/atomic.h>
#include <asm/asm-offsets.h>
#include <asm/regs.h>

extern void ret_from_fork(void);

struct task_struct *current_set[NR_CPUS] = {&init_task, };

void (*pm_power_off)(void) = NULL;
EXPORT_SYMBOL(pm_power_off);


/*
 * Powermanagement idle function, if any is provided by the platform.
 */

void cpu_idle(void)
{
        local_irq_enable();

        /* endless idle loop with no priority at all */
        while (1) {
                while (!need_resched())
                        platform_idle();
                preempt_enable_no_resched();
                schedule();
                preempt_disable();
        }
}

/*
 * Free current thread data structures etc..
 */

void exit_thread(void)
{
}

void flush_thread(void)
{
}

/*
 * Copy thread.
 *
 * The stack layout for the new thread looks like this:
 *
 *      +------------------------+ <- sp in childregs (= tos)
 *      |       childregs        |
 *      +------------------------+ <- thread.sp = sp in dummy-frame
 *      |      dummy-frame       |    (saved in dummy-frame spill-area)
 *      +------------------------+
 *
 * We create a dummy frame to return to ret_from_fork:
 *   a0 points to ret_from_fork (simulating a call4)
 *   sp points to itself (thread.sp)
 *   a2, a3 are unused.
 *
 * Note: This is a pristine frame, so we don't need any spill region on top of
 *       childregs.
 */

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
                unsigned long unused,
                struct task_struct * p, struct pt_regs * regs)
{
        struct pt_regs *childregs;
        unsigned long tos;
        int user_mode = user_mode(regs);

        /* Set up new TSS. */
        tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
        if (user_mode)
                childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
        else
                childregs = (struct pt_regs*)tos - 1;

        *childregs = *regs;

        /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
        *((int*)childregs - 3) = (unsigned long)childregs;
        *((int*)childregs - 4) = 0;

        childregs->areg[1] = tos;
        childregs->areg[2] = 0;
        p->set_child_tid = p->clear_child_tid = NULL;
        p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
        p->thread.sp = (unsigned long)childregs;
        if (user_mode(regs)) {

                int len = childregs->wmask & ~0xf;
                childregs->areg[1] = usp;
                memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
                       &regs->areg[XCHAL_NUM_AREGS - len/4], len);

                if (clone_flags & CLONE_SETTLS)
                        childregs->areg[2] = childregs->areg[6];

        } else {
                /* In kernel space, we start a new thread with a new stack. */
                childregs->wmask = 1;
        }
        return 0;
}


/*
 * These bracket the sleeping functions..
 */

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long sp, pc;
        unsigned long stack_page = (unsigned long) task_stack_page(p);
        int count = 0;

        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        sp = p->thread.sp;
        pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);

        do {
                if (sp < stack_page + sizeof(struct task_struct) ||
                    sp >= (stack_page + THREAD_SIZE) ||
                    pc == 0)
                        return 0;
                if (!in_sched_functions(pc))
                        return pc;

                /* Stack layout: sp-4: ra, sp-3: sp' */

                pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
                sp = *(unsigned long *)sp - 3;
        } while (count++ < 16);
        return 0;
}

/*
 * do_copy_regs() gathers information from 'struct pt_regs' and
 * 'current->thread.areg[]' to fill in the xtensa_gregset_t
 * structure.
 *
 * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
 * of processor registers.  Besides different ordering,
 * xtensa_gregset_t contains non-live register information that
 * 'struct pt_regs' does not.  Exception handling (primarily) uses
 * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
 *
 */

void do_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
                   struct task_struct *tsk)
{
        /* Note:  PS.EXCM is not set while user task is running; its
         * being set in regs->ps is for exception handling convenience.
         */

        elfregs->pc             = regs->pc;
        elfregs->ps             = (regs->ps & ~(1 << PS_EXCM_BIT));
        elfregs->lbeg           = regs->lbeg;
        elfregs->lend           = regs->lend;
        elfregs->lcount         = regs->lcount;
        elfregs->sar            = regs->sar;

        memcpy (elfregs->a, regs->areg, sizeof(elfregs->a));
}

void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
{
        do_copy_regs ((xtensa_gregset_t *)elfregs, regs, current);
}


/* The inverse of do_copy_regs().  No error or sanity checking. */

void do_restore_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
                      struct task_struct *tsk)
{
        const unsigned long ps_mask = PS_CALLINC_MASK | PS_OWB_MASK;
        unsigned long ps;

        /* Note:  PS.EXCM is not set while user task is running; it
         * needs to be set in regs->ps is for exception handling convenience.
         */

        ps = (regs->ps & ~ps_mask) | (elfregs->ps & ps_mask) | (1<<PS_EXCM_BIT);
        regs->ps                = ps;
        regs->pc                = elfregs->pc;
        regs->lbeg              = elfregs->lbeg;
        regs->lend              = elfregs->lend;
        regs->lcount            = elfregs->lcount;
        regs->sar               = elfregs->sar;

        memcpy (regs->areg, elfregs->a, sizeof(regs->areg));
}

/*
 * do_save_fpregs() gathers information from 'struct pt_regs' and
 * 'current->thread' to fill in the elf_fpregset_t structure.
 *
 * Core files and ptrace use elf_fpregset_t.
 */

void do_save_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
                     struct task_struct *tsk)
{
#if XCHAL_HAVE_CP

        extern unsigned char    _xtensa_reginfo_tables[];
        extern unsigned         _xtensa_reginfo_table_size;
        int i;
        unsigned long flags;

        /* Before dumping coprocessor state from memory,
         * ensure any live coprocessor contents for this
         * task are first saved to memory:
         */
        local_irq_save(flags);

        for (i = 0; i < XCHAL_CP_MAX; i++) {
                if (tsk == coprocessor_info[i].owner) {
                        enable_coprocessor(i);
                        save_coprocessor_registers(
                            tsk->thread.cp_save+coprocessor_info[i].offset,i);
                        disable_coprocessor(i);
                }
        }

        local_irq_restore(flags);

        /* Now dump coprocessor & extra state: */
        memcpy((unsigned char*)fpregs,
                _xtensa_reginfo_tables, _xtensa_reginfo_table_size);
        memcpy((unsigned char*)fpregs + _xtensa_reginfo_table_size,
                tsk->thread.cp_save, XTENSA_CP_EXTRA_SIZE);
#endif
}

/*
 * The inverse of do_save_fpregs().
 * Copies coprocessor and extra state from fpregs into regs and tsk->thread.
 * Returns 0 on success, non-zero if layout doesn't match.
 */

int  do_restore_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
                        struct task_struct *tsk)
{
#if XCHAL_HAVE_CP

        extern unsigned char    _xtensa_reginfo_tables[];
        extern unsigned         _xtensa_reginfo_table_size;
        int i;
        unsigned long flags;

        /* Make sure save area layouts match.
         * FIXME:  in the future we could allow restoring from
         * a different layout of the same registers, by comparing
         * fpregs' table with _xtensa_reginfo_tables and matching
         * entries and copying registers one at a time.
         * Not too sure yet whether that's very useful.
         */

        if( memcmp((unsigned char*)fpregs,
                _xtensa_reginfo_tables, _xtensa_reginfo_table_size) ) {
            return -1;
        }

        /* Before restoring coprocessor state from memory,
         * ensure any live coprocessor contents for this
         * task are first invalidated.
         */

        local_irq_save(flags);

        for (i = 0; i < XCHAL_CP_MAX; i++) {
                if (tsk == coprocessor_info[i].owner) {
                        enable_coprocessor(i);
                        save_coprocessor_registers(
                            tsk->thread.cp_save+coprocessor_info[i].offset,i);
                        coprocessor_info[i].owner = 0;
                        disable_coprocessor(i);
                }
        }

        local_irq_restore(flags);

        /*  Now restore coprocessor & extra state:  */

        memcpy(tsk->thread.cp_save,
                (unsigned char*)fpregs + _xtensa_reginfo_table_size,
                XTENSA_CP_EXTRA_SIZE);
#endif
        return 0;
}
/*
 * Fill in the CP structure for a core dump for a particular task.
 */

int
dump_task_fpu(struct pt_regs *regs, struct task_struct *task, elf_fpregset_t *r)
{
        return 0;       /* no coprocessors active on this processor */
}

/*
 * Fill in the CP structure for a core dump.
 * This includes any FPU coprocessor.
 * Here, we dump all coprocessors, and other ("extra") custom state.
 *
 * This function is called by elf_core_dump() in fs/binfmt_elf.c
 * (in which case 'regs' comes from calls to do_coredump, see signals.c).
 */
int  dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
{
        return dump_task_fpu(regs, current, r);
}

asmlinkage
long xtensa_clone(unsigned long clone_flags, unsigned long newsp,
                  void __user *parent_tid, void *child_tls,
                  void __user *child_tid, long a5,
                  struct pt_regs *regs)
{
        if (!newsp)
                newsp = regs->areg[1];
        return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
}

/*
 *  * xtensa_execve() executes a new program.
 *   */

asmlinkage
long xtensa_execve(char __user *name, char __user * __user *argv,
                   char __user * __user *envp,
                   long a3, long a4, long a5,
                   struct pt_regs *regs)
{
        long error;
        char * filename;

        filename = getname(name);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        // FIXME: release coprocessor??
        error = do_execve(filename, argv, envp, regs);
        if (error == 0) {
                task_lock(current);
                current->ptrace &= ~PT_DTRACE;
                task_unlock(current);
        }
        putname(filename);
out:
        return error;
}