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/*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; If not, see <http://www.gnu.org/licenses/>.
*
* Split out from xc_linus_osdep.c:
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
*/
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include "private.h"
#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#endif
int osdep_xencall_open(xencall_handle *xcall)
{
int fd;
/*
* Prefer the newer interface.
*/
fd = open("/dev/xen/privcmd", O_RDWR|O_CLOEXEC);
if ( fd == -1 && ( errno == ENOENT || errno == ENXIO || errno == ENODEV ))
{
/* Fallback to /proc/xen/privcmd */
fd = open("/proc/xen/privcmd", O_RDWR|O_CLOEXEC);
}
if ( fd == -1 )
{
PERROR("Could not obtain handle on privileged command interface");
return -1;
}
xcall->fd = fd;
/*
* Try the same for the hypercall buffer device.
*/
fd = open("/dev/xen/hypercall", O_RDWR|O_CLOEXEC);
if ( fd == -1 && errno != ENOENT )
{
PERROR("Error on trying to open hypercall buffer device");
return -1;
}
xcall->buf_fd = fd;
return 0;
}
int osdep_xencall_close(xencall_handle *xcall)
{
if ( xcall->buf_fd >= 0 )
close(xcall->buf_fd);
if ( xcall->fd >= 0 )
close(xcall->fd);
return 0;
}
long osdep_hypercall(xencall_handle *xcall, privcmd_hypercall_t *hypercall)
{
return ioctl(xcall->fd, IOCTL_PRIVCMD_HYPERCALL, hypercall);
}
static void *alloc_pages_bufdev(xencall_handle *xcall, size_t npages)
{
void *p;
p = mmap(NULL, npages * PAGE_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED,
xcall->buf_fd, 0);
if ( p == MAP_FAILED )
{
PERROR("alloc_pages: mmap (,%zu*%lu,...) [bufdev] failed",
npages, (unsigned long)PAGE_SIZE);
p = NULL;
}
return p;
}
static void *alloc_pages_nobufdev(xencall_handle *xcall, size_t npages)
{
size_t size = npages * PAGE_SIZE;
void *p;
int rc, i, saved_errno;
/* Address returned by mmap is page aligned. */
p = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_LOCKED, -1, 0);
if ( p == MAP_FAILED )
{
PERROR("alloc_pages: mmap(,%zu,...) [nobufdev] failed", size);
return NULL;
}
/* Do not copy the VMA to child process on fork. Avoid the page being COW
on hypercall. */
rc = madvise(p, npages * PAGE_SIZE, MADV_DONTFORK);
if ( rc < 0 )
{
PERROR("alloc_pages: madvise (,%zu*%lu,) [nobufdev] failed",
npages, (unsigned long)PAGE_SIZE);
goto out;
}
/*
* Touch each page in turn to force them to be un-CoWed, in case a
* fork happened in another thread at an inopportune moment
* above. The madvise() will prevent any subsequent fork calls from
* causing the same problem.
*/
for ( i = 0; i < npages ; i++ )
{
char *c = (char *)p + (i*PAGE_SIZE);
*c = 0;
}
return p;
out:
saved_errno = errno;
(void)munmap(p, size);
errno = saved_errno;
return NULL;
}
void *osdep_alloc_pages(xencall_handle *xcall, size_t npages)
{
void *p;
if ( xcall->buf_fd >= 0 )
p = alloc_pages_bufdev(xcall, npages);
else
p = alloc_pages_nobufdev(xcall, npages);
return p;
}
void osdep_free_pages(xencall_handle *xcall, void *ptr, size_t npages)
{
int saved_errno = errno;
if ( xcall->buf_fd < 0 )
{
/* Recover the VMA flags. Maybe it's not necessary */
madvise(ptr, npages * PAGE_SIZE, MADV_DOFORK);
}
munmap(ptr, npages * PAGE_SIZE);
/* We MUST propagate the hypercall errno, not unmap call's. */
errno = saved_errno;
}
int xencall_buffers_never_fault(xencall_handle *xcall)
{
return xcall->buf_fd >= 0;
}
/*
* Local variables:
* mode: C
* c-file-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
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