source: trunk/kernel/syscalls/sys_madvise.c @ 39

/*
 * kern/sys_madvise.c - process memory management related advises
 * 
 * Copyright (c) 2008,2009,2010,2011,2012 Ghassan Almaless
 * Copyright (c) 2011,2012 UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-kernel.
 *
 * ALMOS-kernel is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-kernel 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 ALMOS-kernel; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <types.h>
#include <errno.h>
#include <bits.h>
#include <vmm.h>
#include <thread.h>
#include <task.h>
#include <cluster.h>
#include <page.h>
#include <ppm.h>
#include <pmm.h>

/* TODO: don't use locks to lookup region as if address has been accessed it must be in kyesdb */
static error_t check_args(struct vmm_s *vmm, uint_t start, uint_t len, struct vm_region_s **reg)
{
        error_t err;
        struct vm_region_s *region;
  
        err = 0;
        rwlock_rdlock(&vmm->rwlock);

        region = vmm->last_region;
  
        if((start >= region->vm_limit) || (start < region->vm_start))
        {
                region = vm_region_find(vmm, start);
  
                if((region == NULL) || (start < region->vm_start))
                        err = EINVAL;
        }

        if((err == 0) && ((start + len) >= region->vm_limit))
                err = EINVAL;
  
        rwlock_unlock(&vmm->rwlock);

        *reg = region;
        return 0;
}


/* TODO: compute other advices */
int sys_madvise(void *start, size_t length, uint_t advice)
{
        error_t err;
        struct vmm_s *vmm;
        struct vm_region_s *region;
        struct thread_s *this;

        err = 0;
        this = current_thread;

        if((start == NULL) || ((uint_t)start & PMM_PAGE_MASK))
        {
                err = EINVAL;
                goto SYS_MADVISE_ERR;
        }

        if(NOT_IN_USPACE((uint_t)start + length))
        {
                err = EPERM;
                goto SYS_MADVISE_ERR;
        }
   
        vmm = &this->task->vmm;
        err = check_args(vmm, (uint_t)start, length, &region);
  
        if(err) goto SYS_MADVISE_ERR;
  
        if((region->vm_flags & VM_REG_DEV) || (region->vm_flags & VM_REG_SHARED))
                return 0;

        switch(advice)
        {
        case MADV_NORMAL:
        case MADV_RANDOM:
        case MADV_SEQUENTIAL:
        case MADV_WILLNEED:
                err = vmm_madvise_willneed(vmm, (uint_t)start, (uint_t)length);
                break;
        case MADV_DONTNEED:
                return 0;
    
        case MADV_MIGRATE:
                err = vmm_madvise_migrate(vmm, (uint_t)start, (uint_t)length);
                break;
  
        default:
                err = EINVAL;
        }

SYS_MADVISE_ERR:
        this->info.errno = err;
        return err;
}