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Intel describes the behavior of their processors as "undefined" if two or

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more mappings to the same physical page have different memory types, i.e.,
PAT settings.  Consequently, if pmap_change_attr() is applied to a virtual
address range within the kernel map, then the corresponding ranges of the
direct map also need to be changed.  Enhance pmap_change_attr() to handle
this case automatically.

Add a comment describing what pmap_change_attr() does.

Discussed with:	jhb
This commit is contained in:
Alan Cox 2008-08-09 05:46:13 +00:00
parent 3dfff737f3
commit b09485a336
1 changed files with 84 additions and 2 deletions
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86
sys/amd64/amd64/pmap.c
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@ -4417,6 +4417,25 @@ pmap_demote_pdpe(pmap_t pmap, pdp_entry_t *pdpe, vm_offset_t va)
return (TRUE);
}
/*
* Changes the specified virtual address range's memory type to that given by
* the parameter "mode". The specified virtual address range must be
* completely contained within either the direct map or the kernel map. If
* the virtual address range is contained within the kernel map, then the
* memory type for each of the corresponding ranges of the direct map is also
* changed. (The corresponding ranges of the direct map are those ranges that
* map the same physical pages as the specified virtual address range.) These
* changes to the direct map are necessary because Intel describes the
* behavior of their processors as "undefined" if two or more mappings to the
* same physical page have different memory types.
*
* Returns zero if the change completed successfully, and either EINVAL or
* ENOMEM if the change failed. Specifically, EINVAL is returned if some part
* of the virtual address range was not mapped, and ENOMEM is returned if
* there was insufficient memory available to complete the change. In the
* latter case, the memory type may have been changed on some part of the
* virtual address range or the direct map.
*/
int
pmap_change_attr(vm_offset_t va, vm_size_t size, int mode)
{
@ -4432,10 +4451,11 @@ static int
pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
{
vm_offset_t base, offset, tmpva;
vm_paddr_t pa_start, pa_end;
pdp_entry_t *pdpe;
pd_entry_t *pde;
pt_entry_t *pte;
int cache_bits_pte, cache_bits_pde;
int cache_bits_pte, cache_bits_pde, error;
boolean_t changed;
PMAP_LOCK_ASSERT(kernel_pmap, MA_OWNED);
@ -4521,11 +4541,13 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
return (EINVAL);
tmpva += PAGE_SIZE;
}
error = 0;
/*
* Ok, all the pages exist, so run through them updating their
* cache mode if required.
*/
pa_start = pa_end = 0;
for (tmpva = base; tmpva < base + size; ) {
pdpe = pmap_pdpe(kernel_pmap, tmpva);
if (*pdpe & PG_PS) {
@ -4536,6 +4558,25 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
if (!changed)
changed = TRUE;
}
if (tmpva >= VM_MIN_KERNEL_ADDRESS) {
if (pa_start == pa_end) {
/* Start physical address run. */
pa_start = *pdpe & PG_PS_FRAME;
pa_end = pa_start + NBPDP;
} else if (pa_end == (*pdpe & PG_PS_FRAME))
pa_end += NBPDP;
else {
/* Run ended, update direct map. */
error = pmap_change_attr_locked(
PHYS_TO_DMAP(pa_start),
pa_end - pa_start, mode);
if (error != 0)
break;
/* Start physical address run. */
pa_start = *pdpe & PG_PS_FRAME;
pa_end = pa_start + NBPDP;
}
}
tmpva = trunc_1gpage(tmpva) + NBPDP;
continue;
}
@ -4548,6 +4589,25 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
if (!changed)
changed = TRUE;
}
if (tmpva >= VM_MIN_KERNEL_ADDRESS) {
if (pa_start == pa_end) {
/* Start physical address run. */
pa_start = *pde & PG_PS_FRAME;
pa_end = pa_start + NBPDR;
} else if (pa_end == (*pde & PG_PS_FRAME))
pa_end += NBPDR;
else {
/* Run ended, update direct map. */
error = pmap_change_attr_locked(
PHYS_TO_DMAP(pa_start),
pa_end - pa_start, mode);
if (error != 0)
break;
/* Start physical address run. */
pa_start = *pde & PG_PS_FRAME;
pa_end = pa_start + NBPDR;
}
}
tmpva = trunc_2mpage(tmpva) + NBPDR;
} else {
if (cache_bits_pte < 0)
@ -4558,9 +4618,31 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
if (!changed)
changed = TRUE;
}
if (tmpva >= VM_MIN_KERNEL_ADDRESS) {
if (pa_start == pa_end) {
/* Start physical address run. */
pa_start = *pte & PG_FRAME;
pa_end = pa_start + PAGE_SIZE;
} else if (pa_end == (*pte & PG_FRAME))
pa_end += PAGE_SIZE;
else {
/* Run ended, update direct map. */
error = pmap_change_attr_locked(
PHYS_TO_DMAP(pa_start),
pa_end - pa_start, mode);
if (error != 0)
break;
/* Start physical address run. */
pa_start = *pte & PG_FRAME;
pa_end = pa_start + PAGE_SIZE;
}
}
tmpva += PAGE_SIZE;
}
}
if (error == 0 && pa_start != pa_end)
error = pmap_change_attr_locked(PHYS_TO_DMAP(pa_start),
pa_end - pa_start, mode);
/*
* Flush CPU caches if required to make sure any data isn't cached that
@ -4570,7 +4652,7 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
pmap_invalidate_range(kernel_pmap, base, tmpva);
pmap_invalidate_cache();
}
return (0);
return (error);
}
/*