mirror of
https://github.com/xen-project/xen.git
synced 2026-10-28 10:11:27 +01:00
Ian Campbell
0831774c81
In some cases this replaces an FD_CLOEXEC dance, in others it is new. Linux has had O_CLOEXEC since 2.6.23 (October 2007), so we can rely on it from Xen 4.7 I think. Some libc headers may still lack the definition, so we take care of that if need be by defining to 0 (on the premise that such an old glibc might barf on O_CLOEXEC even if the kernel may or may not be so old). All stable versions of FreeBSD support O_CLOEXEC (10.2, 9.3 and 8.4), and we assume the libc there does too. Remove various comments about having to take responsibility for this (since really it is just hygiene, politeness, not a requirement) and the reasons for using O_CLOEXEC seem pretty straightforward. Backends for other OSes are untouched. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Acked-by: Wei Liu <wei.liu2@citrix.com> Cc: Roger.Pau@citrix.com Cc: jbeulich@suse.com
135 lines
3.2 KiB
C
135 lines
3.2 KiB
C
/*
|
|
* 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 <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;
|
|
return 0;
|
|
}
|
|
|
|
int osdep_xencall_close(xencall_handle *xcall)
|
|
{
|
|
int fd = xcall->fd;
|
|
if (fd == -1)
|
|
return 0;
|
|
return close(fd);
|
|
}
|
|
|
|
int osdep_hypercall(xencall_handle *xcall, privcmd_hypercall_t *hypercall)
|
|
{
|
|
return ioctl(xcall->fd, IOCTL_PRIVCMD_HYPERCALL, hypercall);
|
|
}
|
|
|
|
void *osdep_alloc_pages(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 failed");
|
|
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 failed");
|
|
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_free_pages(xencall_handle *xcall, void *ptr, size_t npages)
|
|
{
|
|
int saved_errno = errno;
|
|
/* 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;
|
|
}
|
|
|
|
/*
|
|
* Local variables:
|
|
* mode: C
|
|
* c-file-style: "BSD"
|
|
* c-basic-offset: 4
|
|
* tab-width: 4
|
|
* indent-tabs-mode: nil
|
|
* End:
|
|
*/
|