On 2009-06-08, at 14:56, Stanislav Sedov wrote:
On Mon, 8 Jun 2009 12:15:39 +0000 (UTC)
Rafal Jaworowski <r...@freebsd.org> mentioned:
Author: raj
Date: Mon Jun 8 12:15:39 2009
New Revision: 193712
URL: http://svn.freebsd.org/changeset/base/193712
Log:
Invalidate cache in pmap_remove_all() on ARM.
When pages are removed from virtual address space by calling
pmap_remove_all()
CPU caches were not invalidated, which led to read corruption when
another
page got mapped at this same virtual address at later time (the
CPU was
retrieving stale contents).
Submitted by: Piotr Ziecik
Obtained from: Semihalf
Modified:
head/sys/arm/arm/pmap.c
Modified: head/sys/arm/arm/pmap.c
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--- head/sys/arm/arm/pmap.c Mon Jun 8 12:10:42 2009 (r193711)
+++ head/sys/arm/arm/pmap.c Mon Jun 8 12:15:39 2009 (r193712)
@@ -3124,7 +3124,19 @@ pmap_remove_all(vm_page_t m)
if (flush == FALSE && (pv->pv_pmap == curpm ||
pv->pv_pmap == pmap_kernel()))
flush = TRUE;
+
PMAP_LOCK(pv->pv_pmap);
+ /*
+ * Cached contents were written-back in pmap_remove_write(),
+ * but we still have to invalidate the cache entry to make
+ * sure stale data are not retrieved when another page will be
+ * mapped under this virtual address.
+ */
+ if (pmap_is_current(pv->pv_pmap)) {
+ cpu_dcache_inv_range(pv->pv_va, PAGE_SIZE);
+ cpu_l2cache_inv_range(pv->pv_va, PAGE_SIZE);
+ }
+
Hi, Rafal!
What about calling the pmap_dcache_wb_range function for each
mapping in
the cycle instead of calling cpu_XXX_inv_range functions directly?
I think
something like this would do the trick:
% pmap_dcache_wb_range(pv->pv_pmap, pv->pv_va, PAGE_SIZE, FALSE,
% (pv->pv_flags & PVF_WRITE) == 0)
This will also take care of the writeback cache. I don't know if it
is really
needed, though.
Do you see anything wrong with calling cpu_xxx_inv_range directly?
Writing back (if required) was already performed by
pmap_remove_write(), and what we only need at this point is
invalidation. pmap_dcache_wb_range would also eventually call
cpu_XXX_inv_range if given a proper combination of flags (BTW: the
do_inv flag in your example should be TRUE for our context to work),
so it wouldn't be any simpler. I'd rather prefer doing explicitly what
is needed without extra wrapping.
Rafal
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