mirror of
https://github.com/xen-project/xen.git
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Wei Liu
6b8ed03ccf
This reverts commit cf8e5f25a9.
It is not supposed to be committed.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
139 lines
3.3 KiB
C
139 lines
3.3 KiB
C
/*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; If not, see <http://www.gnu.org/licenses/>.
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*
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* Split out from xc_linus_osdep.c:
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*
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* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <stdio.h>
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#include <sys/mman.h>
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#include <sys/ioctl.h>
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#include "private.h"
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#ifndef O_CLOEXEC
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#define O_CLOEXEC 0
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#endif
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int osdep_xencall_open(xencall_handle *xcall)
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{
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int fd;
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/*
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* Prefer the newer interface.
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*/
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fd = open("/dev/xen/privcmd", O_RDWR|O_CLOEXEC);
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if ( fd == -1 && ( errno == ENOENT || errno == ENXIO || errno == ENODEV ))
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{
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/* Fallback to /proc/xen/privcmd */
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fd = open("/proc/xen/privcmd", O_RDWR|O_CLOEXEC);
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}
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if ( fd == -1 )
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{
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PERROR("Could not obtain handle on privileged command interface");
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return -1;
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}
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xcall->fd = fd;
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return 0;
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}
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int osdep_xencall_close(xencall_handle *xcall)
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{
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int fd = xcall->fd;
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if (fd == -1)
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return 0;
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return close(fd);
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}
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int osdep_hypercall(xencall_handle *xcall, privcmd_hypercall_t *hypercall)
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{
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return ioctl(xcall->fd, IOCTL_PRIVCMD_HYPERCALL, hypercall);
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}
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void *osdep_alloc_pages(xencall_handle *xcall, size_t npages)
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{
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size_t size = npages * PAGE_SIZE;
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void *p;
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int rc, i, saved_errno;
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/* Address returned by mmap is page aligned. */
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p = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_LOCKED, -1, 0);
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if ( p == MAP_FAILED )
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{
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PERROR("alloc_pages: mmap failed");
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return NULL;
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}
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/* Do not copy the VMA to child process on fork. Avoid the page being COW
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on hypercall. */
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rc = madvise(p, npages * PAGE_SIZE, MADV_DONTFORK);
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if ( rc < 0 )
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{
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PERROR("alloc_pages: madvise failed");
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goto out;
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}
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/*
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* Touch each page in turn to force them to be un-CoWed, in case a
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* fork happened in another thread at an inopportune moment
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* above. The madvise() will prevent any subsequent fork calls from
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* causing the same problem.
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*/
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for ( i = 0; i < npages ; i++ )
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{
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char *c = (char *)p + (i*PAGE_SIZE);
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*c = 0;
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}
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return p;
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out:
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saved_errno = errno;
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(void)munmap(p, size);
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errno = saved_errno;
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return NULL;
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}
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void osdep_free_pages(xencall_handle *xcall, void *ptr, size_t npages)
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{
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int saved_errno = errno;
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/* Recover the VMA flags. Maybe it's not necessary */
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madvise(ptr, npages * PAGE_SIZE, MADV_DOFORK);
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munmap(ptr, npages * PAGE_SIZE);
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/* We MUST propagate the hypercall errno, not unmap call's. */
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errno = saved_errno;
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}
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/*
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* Local variables:
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* mode: C
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* c-file-style: "BSD"
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* c-basic-offset: 4
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* tab-width: 4
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* indent-tabs-mode: nil
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* End:
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*/
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