On Wed, 2008-07-09 at 13:46 +1000, Benjamin Herrenschmidt wrote:
> The old code looks bogus.. why clear M when G is set ? Only
> I should have mattered.
I can't find anywhere where G gets set without also setting I, so the
test seems redundant as well.
> I'll apply anyway as you aren't changing the existing behaviour here but
> maybe you can shoot me a fixup patch that removes the _PAGE_GUARDED
> condition completely here ?
No problem. There is code in cell/beat_htab.c doing the same thing.
I've gone ahead and fixed it there too.
> It's legal to have G=1 M=1 pages and can even be useful under some
> circumstances.
It doesn't look like anyone is trying to take advantage of that
currently.
Here's your patch:
powerpc: Remove unnecessary condition when sanity-checking WIMG bits
It is okay for both _PAGE_GUARDED and _PAGE_COHERENT (G and M) to be set
in the same pte. In fact, even if that were not the case, there doesn't
seem to be any place where G is set without also setting I (_PAGE_NO_CACHE),
so the test for I is sufficient.
Signed-off-by: Dave Kleikamp <[EMAIL PROTECTED]>
diff --git a/arch/powerpc/platforms/cell/beat_htab.c
b/arch/powerpc/platforms/cell/beat_htab.c
index 81467ff..2e67bd8 100644
--- a/arch/powerpc/platforms/cell/beat_htab.c
+++ b/arch/powerpc/platforms/cell/beat_htab.c
@@ -112,7 +112,7 @@ static long beat_lpar_hpte_insert(unsigned long hpte_group,
if (!(vflags & HPTE_V_BOLTED))
DBG_LOW(" hpte_v=%016lx, hpte_r=%016lx\n", hpte_v, hpte_r);
- if (rflags & (_PAGE_GUARDED|_PAGE_NO_CACHE))
+ if (rflags & _PAGE_NO_CACHE)
hpte_r &= ~_PAGE_COHERENT;
spin_lock(&beat_htab_lock);
@@ -334,7 +334,7 @@ static long beat_lpar_hpte_insert_v3(unsigned long
hpte_group,
if (!(vflags & HPTE_V_BOLTED))
DBG_LOW(" hpte_v=%016lx, hpte_r=%016lx\n", hpte_v, hpte_r);
- if (rflags & (_PAGE_GUARDED|_PAGE_NO_CACHE))
+ if (rflags & _PAGE_NO_CACHE)
hpte_r &= ~_PAGE_COHERENT;
/* insert into not-volted entry */
diff --git a/arch/powerpc/platforms/pseries/lpar.c
b/arch/powerpc/platforms/pseries/lpar.c
index 38b5927..52a80e5 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -305,8 +305,7 @@ static long pSeries_lpar_hpte_insert(unsigned long
hpte_group,
flags = 0;
/* Make pHyp happy */
- if ((rflags & _PAGE_GUARDED) ||
- ((rflags & _PAGE_NO_CACHE) & !(rflags & _PAGE_WRITETHRU)))
+ if ((rflags & _PAGE_NO_CACHE) & !(rflags & _PAGE_WRITETHRU))
hpte_r &= ~_PAGE_COHERENT;
lpar_rc = plpar_pte_enter(flags, hpte_group, hpte_v, hpte_r, &slot);
--
David Kleikamp
IBM Linux Technology Center
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