Author: kib
Date: Mon Jan 26 10:11:55 2015
New Revision: 277743
URL: https://svnweb.freebsd.org/changeset/base/277743
Log:
Ensure that _tmppt KVA is used exclusively by providing exclusive sx
lock around the mapping and uiomove(). Before r277643, it was
partially protected by Giant (but potential sleeping in fault from
uiomove() would still allow other thread to reuse the mapping).
Noted by: ian
Reviewed by: alc, ian
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
Modified:
head/sys/arm/arm/mem.c
Modified: head/sys/arm/arm/mem.c
==============================================================================
--- head/sys/arm/arm/mem.c Mon Jan 26 09:53:41 2015 (r277742)
+++ head/sys/arm/arm/mem.c Mon Jan 26 10:11:55 2015 (r277743)
@@ -55,6 +55,7 @@ __FBSDID("$FreeBSD$");
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
+#include <sys/sx.h>
#include <sys/systm.h>
#include <sys/uio.h>
@@ -72,6 +73,9 @@ MALLOC_DEFINE(M_MEMDESC, "memdesc", "mem
struct mem_range_softc mem_range_softc;
+static struct sx tmppt_lock;
+SX_SYSINIT(tmppt, &tmppt_lock, "mem4map");
+
/* ARGSUSED */
int
memrw(struct cdev *dev, struct uio *uio, int flags)
@@ -107,6 +111,7 @@ memrw(struct cdev *dev, struct uio *uio,
}
if (!address_valid)
return (EINVAL);
+ sx_xlock(&tmppt_lock);
pmap_kenter((vm_offset_t)_tmppt, v);
o = (int)uio->uio_offset & PAGE_MASK;
c = (u_int)(PAGE_SIZE - ((int)iov->iov_base &
PAGE_MASK));
@@ -114,6 +119,7 @@ memrw(struct cdev *dev, struct uio *uio,
c = min(c, (u_int)iov->iov_len);
error = uiomove((caddr_t)&_tmppt[o], (int)c, uio);
pmap_qremove((vm_offset_t)_tmppt, 1);
+ sx_xunlock(&tmppt_lock);
continue;
}
else if (dev2unit(dev) == CDEV_MINOR_KMEM) {
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