sys_compat.c

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/*
 * Based on arch/arm/kernel/sys_arm.c
 *
 * Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
 * Copyright (C) 1995, 1996 Russell King.
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/compat.h>
#include <linux/personality.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>

#include <asm/cacheflush.h>
#include <asm/unistd32.h>

asmlinkage int compat_sys_fork(struct pt_regs *regs)
{
    return do_fork(SIGCHLD, regs->compat_sp, regs, 0, NULL, NULL);
}

asmlinkage int compat_sys_clone(unsigned long clone_flags, unsigned long newsp,
              int __user *parent_tidptr, int tls_val,
              int __user *child_tidptr, struct pt_regs *regs)
{
    if (!newsp)
        newsp = regs->compat_sp;

    return do_fork(clone_flags, newsp, regs, 0, parent_tidptr, child_tidptr);
}

asmlinkage int compat_sys_vfork(struct pt_regs *regs)
{
    return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->compat_sp,
               regs, 0, NULL, NULL);
}

asmlinkage int compat_sys_execve(const char __user *filenamei,
                 compat_uptr_t argv, compat_uptr_t envp,
                 struct pt_regs *regs)
{
    int error;
    struct filename *filename;

    filename = getname(filenamei);
    error = PTR_ERR(filename);
    if (IS_ERR(filename))
        goto out;
    error = compat_do_execve(filename->name, compat_ptr(argv),
                    compat_ptr(envp), regs);
    putname(filename);
out:
    return error;
}

asmlinkage int compat_sys_sched_rr_get_interval(compat_pid_t pid,
                        struct compat_timespec __user *interval)
{
    struct timespec t;
    int ret;
    mm_segment_t old_fs = get_fs();

    set_fs(KERNEL_DS);
    ret = sys_sched_rr_get_interval(pid, (struct timespec __user *)&t);
    set_fs(old_fs);
    if (put_compat_timespec(&t, interval))
        return -EFAULT;
    return ret;
}

static inline void
do_compat_cache_op(unsigned long start, unsigned long end, int flags)
{
    struct mm_struct *mm = current->active_mm;
    struct vm_area_struct *vma;

    if (end < start || flags)
        return;

    down_read(&mm->mmap_sem);
    vma = find_vma(mm, start);
    if (vma && vma->vm_start < end) {
        if (start < vma->vm_start)
            start = vma->vm_start;
        if (end > vma->vm_end)
            end = vma->vm_end;
        up_read(&mm->mmap_sem);
        __flush_cache_user_range(start & PAGE_MASK, PAGE_ALIGN(end));
        return;
    }
    up_read(&mm->mmap_sem);
}

/*
 * Handle all unrecognised system calls.
 */
long compat_arm_syscall(struct pt_regs *regs)
{
    unsigned int no = regs->regs[7];

    switch (no) {
    /*
     * Flush a region from virtual address 'r0' to virtual address 'r1'
     * _exclusive_.  There is no alignment requirement on either address;
     * user space does not need to know the hardware cache layout.
     *
     * r2 contains flags.  It should ALWAYS be passed as ZERO until it
     * is defined to be something else.  For now we ignore it, but may
     * the fires of hell burn in your belly if you break this rule. ;)
     *
     * (at a later date, we may want to allow this call to not flush
     * various aspects of the cache.  Passing '0' will guarantee that
     * everything necessary gets flushed to maintain consistency in
     * the specified region).
     */
    case __ARM_NR_compat_cacheflush:
        do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
        return 0;

    case __ARM_NR_compat_set_tls:
        current->thread.tp_value = regs->regs[0];
        asm ("msr tpidrro_el0, %0" : : "r" (regs->regs[0]));
        return 0;

    default:
        return -ENOSYS;
    }
}