Le 18/12/2014 03:14, Scott Wood a écrit :
On Wed, 2014-12-17 at 10:14 +0100, Christophe Leroy wrote:
Some powerpc like the 8xx don't have a RW bit in PTE bits but a RO (Read Only)
bit.
This patch implements the handling of a _PAGE_RO flag to be used in place of
_PAGE_RW
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
v2 is a complete rework compared to v1
arch/powerpc/include/asm/pgtable-ppc32.h | 11 ++++++-----
arch/powerpc/include/asm/pgtable.h | 10 +++++++---
arch/powerpc/include/asm/pte-common.h | 27 ++++++++++++++++++---------
arch/powerpc/mm/gup.c | 2 ++
arch/powerpc/mm/mem.c | 2 +-
arch/powerpc/mm/pgtable_32.c | 24 ++++++++++++++++++++----
6 files changed, 54 insertions(+), 22 deletions(-)
diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h
b/arch/powerpc/include/asm/pgtable-ppc32.h
index 543bb8e..64ed9e1 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -125,7 +125,7 @@ extern int icache_44x_need_flush;
#ifndef __ASSEMBLY__
#define pte_clear(mm, addr, ptep) \
- do { pte_update(ptep, ~_PAGE_HASHPTE, 0); } while (0)
+ do { pte_update(ptep, ~_PAGE_HASHPTE, _PAGE_RO); } while (0)
Is this really necessary? It's already clearing the valid bit.
Likewise in several other places that set or check for _PAGE_RO on pages
for which no access is permitted.
You are right, this is not needed. I needed it because I had defined
pte_none() as requiring _PAGE_RO set. But we can keep value 0 as
pte_none. Taken into account in v3
Christophe
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