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[PowerPC] fix panic reading /dev/kmem on !DMAP machines

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This fixes /dev/kmem causing panic on machines not using DMAP.

Found when running libkvm Kyua test case on QEMU VM with no
Huge Pages support.

Reviewed by:	jhibbits, luporl
Approved by:	jhibbits (mentor)
Sponsored by:	Eldorado Research Institute (eldorado.org.br)
Differential Revision:	https://reviews.freebsd.org/D23776
This commit is contained in:
Alfredo Dal'Ava Junior 2020-03-20 11:51:08 +00:00
parent aa301e5ffe
commit d2d06767b5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=359160
1 changed files with 23 additions and 10 deletions
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33
sys/powerpc/powerpc/mem.c
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@ -98,9 +98,11 @@ memrw(struct cdev *dev, struct uio *uio, int flags)
struct vm_page m;
vm_page_t marr;
vm_size_t cnt;
ssize_t orig_resid;
cnt = 0;
error = 0;
orig_resid = uio->uio_resid;
while (uio->uio_resid > 0 && !error) {
iov = uio->uio_iov;
@ -137,7 +139,8 @@ kmem_direct_mapped: off = v & PAGE_MASK;
else if (dev2unit(dev) == CDEV_MINOR_KMEM) {
va = uio->uio_offset;
if ((va < VM_MIN_KERNEL_ADDRESS) || (va > virtual_end)) {
if (hw_direct_map &&
((va < VM_MIN_KERNEL_ADDRESS) || (va > virtual_end))) {
v = DMAP_TO_PHYS(va);
goto kmem_direct_mapped;
}
@ -151,24 +154,34 @@ kmem_direct_mapped: off = v & PAGE_MASK;
* so that we don't create any zero-fill pages.
*/
for (; va < eva; va += PAGE_SIZE)
if (pmap_extract(kernel_pmap, va) == 0)
return (EFAULT);
for (; va < eva; va += PAGE_SIZE) {
if (pmap_extract(kernel_pmap, va) == 0) {
error = EFAULT;
break;
}
}
if (error != 0)
break;
prot = (uio->uio_rw == UIO_READ)
? VM_PROT_READ : VM_PROT_WRITE;
va = uio->uio_offset;
if (kernacc((void *) va, iov->iov_len, prot)
== FALSE)
return (EFAULT);
if (((va >= VM_MIN_KERNEL_ADDRESS) && (va <= virtual_end)) &&
!kernacc((void *) va, iov->iov_len, prot)) {
error = EFAULT;
break;
}
error = uiomove((void *)va, iov->iov_len, uio);
continue;
}
}
/*
* 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);
}