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MFC r277051:

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Fix several issues with /dev/mem and /dev/kmem devices on amd64.
This commit is contained in:
kib 2015-01-19 11:02:23 +00:00
parent 4337378f01
commit 762486d18f
1 changed files with 58 additions and 50 deletions
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108
sys/amd64/amd64/mem.c
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@ -58,6 +58,7 @@ __FBSDID("$FreeBSD$");
#include <sys/systm.h>
#include <sys/uio.h>
#include <machine/md_var.h>
#include <machine/specialreg.h>
#include <machine/vmparam.h>
@ -77,13 +78,15 @@ int
memrw(struct cdev *dev, struct uio *uio, int flags)
{
struct iovec *iov;
u_long c, v, vd;
int error, o, sflags;
vm_offset_t addr, eaddr;
void *p;
ssize_t orig_resid;
u_long v, vd;
u_int c;
int error, sflags;
error = 0;
c = 0;
sflags = curthread_pflags_set(TDP_DEVMEMIO);
orig_resid = uio->uio_resid;
while (uio->uio_resid > 0 && error == 0) {
iov = uio->uio_iov;
if (iov->iov_len == 0) {
@ -93,63 +96,68 @@ memrw(struct cdev *dev, struct uio *uio, int flags)
panic("memrw");
continue;
}
if (dev2unit(dev) == CDEV_MINOR_MEM) {
v = uio->uio_offset;
kmemphys:
o = v & PAGE_MASK;
c = min(uio->uio_resid, (u_int)(PAGE_SIZE - o));
vd = PHYS_TO_DMAP(v);
if (vd < DMAP_MIN_ADDRESS ||
(vd > DMAP_MIN_ADDRESS + dmaplimit &&
vd <= DMAP_MAX_ADDRESS) ||
(pmap_kextract(vd) == 0 && (v & PG_FRAME) != 0)) {
error = EFAULT;
goto ret;
}
error = uiomove((void *)vd, (int)c, uio);
continue;
} else if (dev2unit(dev) == CDEV_MINOR_KMEM) {
v = uio->uio_offset;
if (v >= DMAP_MIN_ADDRESS && v < DMAP_MAX_ADDRESS) {
v = DMAP_TO_PHYS(v);
goto kmemphys;
}
c = iov->iov_len;
v = uio->uio_offset;
c = ulmin(iov->iov_len, PAGE_SIZE - (u_int)(v & PAGE_MASK));
switch (dev2unit(dev)) {
case CDEV_MINOR_KMEM:
/*
* Make sure that all of the pages are currently
* resident so that we don't create any zero-fill
* pages.
* Since c is clamped to be less or equal than
* PAGE_SIZE, the uiomove() call does not
* access past the end of the direct map.
*/
addr = trunc_page(v);
eaddr = round_page(v + c);
if (v >= DMAP_MIN_ADDRESS &&
v < DMAP_MIN_ADDRESS + dmaplimit) {
error = uiomove((void *)v, c, uio);
break;
}
if (addr < VM_MIN_KERNEL_ADDRESS) {
error = EFAULT;
goto ret;
}
for (; addr < eaddr; addr += PAGE_SIZE) {
if (pmap_extract(kernel_pmap, addr) == 0) {
error = EFAULT;
goto ret;
}
}
if (!kernacc((caddr_t)(long)v, c,
uio->uio_rw == UIO_READ ?
if (!kernacc((void *)v, c, uio->uio_rw == UIO_READ ?
VM_PROT_READ : VM_PROT_WRITE)) {
error = EFAULT;
goto ret;
break;
}
error = uiomove((caddr_t)(long)v, (int)c, uio);
continue;
/*
* If the extracted address is not accessible
* through the direct map, then we make a
* private (uncached) mapping because we can't
* depend on the existing kernel mapping
* remaining valid until the completion of
* uiomove().
*
* XXX We cannot provide access to the
* physical page 0 mapped into KVA.
*/
v = pmap_extract(kernel_pmap, v);
if (v == 0) {
error = EFAULT;
break;
}
/* FALLTHROUGH */
case CDEV_MINOR_MEM:
if (v < dmaplimit) {
vd = PHYS_TO_DMAP(v);
error = uiomove((void *)vd, c, uio);
break;
}
if (v >= (1ULL << cpu_maxphyaddr)) {
error = EFAULT;
break;
}
p = pmap_mapdev(v, PAGE_SIZE);
error = uiomove(p, c, uio);
pmap_unmapdev((vm_offset_t)p, PAGE_SIZE);
break;
}
/* else panic! */
}
ret:
curthread_pflags_restore(sflags);
/*
* Don't return error if any byte was written. Read and write
* can return error only if no i/o was performed.
*/
if (uio->uio_resid != orig_resid)
error = 0;
return (error);
}