Skip to contentSkip to conversation

pte_modify fix backport...

PATCH Daniel J Blueman 2 participants 3 messages Aug 5, 2004

lore
Share & tools
lore

Daniel J Blueman

author
#0 lore raw

This patch [1] corrects the behaviour of pte_modify() on ia64 to not clear page protection flags it shouldn't touch.

Without this patch, it clears the uncacheable flag on UC memory regions, which can cause MCAs with device I/O.

It was taken into 2.6.0 a while ago, but is yet to be included in 2.4 - the patch here is rediffed against 2.4.26-rc5.

Is there chance of it being taken in?

--- [1]

include/asm-ia64/pgtable.h +3 -2
diff -durN linux-2.4.26-rc5-orig/include/asm-ia64/pgtable.h linux-2.4.26-rc5-patched/include/asm-ia64/pgtable.h
@@ -60,7 +60,8 @@
 #define _PAGE_PROTNONE		(__IA64_UL(1) << 63)
 
 #define _PFN_MASK		_PAGE_PPN_MASK
-#define _PAGE_CHG_MASK		(_PFN_MASK | _PAGE_A | _PAGE_D)
+/* Mask of bits which may be changed by pte_modify(); the odd bits are there for _PAGE_PROTNONE */
+#define _PAGE_CHG_MASK		(_PAGE_P | _PAGE_PROTNONE | _PAGE_PL_MASK | _PAGE_AR_MASK | _PAGE_ED)
 
 #define _PAGE_SIZE_4K	12
 #define _PAGE_SIZE_8K	13

@@ -216,7 +217,7 @@
 ({ pte_t __pte; pte_val(__pte) = physpage + pgprot_val(pgprot); __pte; })
 
 #define pte_modify(_pte, newprot) \
-	(__pte((pte_val(_pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)))
+	(__pte((pte_val(_pte) & ~_PAGE_CHG_MASK) | (pgprot_val(newprot) & _PAGE_CHG_MASK)))
 
 #define page_pte_prot(page,prot)	mk_pte(page, prot)
 #define page_pte(page)			page_pte_prot(page, __pgprot(0))
Signature · 2 lines
Daniel J Blueman
Software Engineer, Quadrics Ltd
#1 lore raw
Quoted 10 lines · Daniel J Blueman

This patch [1] corrects the behaviour of pte_modify() on ia64 to not clear page protection flags it shouldn't touch.

Without this patch, it clears the uncacheable flag on UC memory regions, which can cause MCAs with device I/O.

It was taken into 2.6.0 a while ago, but is yet to be included in 2.4 - the patch here is rediffed against 2.4.26-rc5.

Is there chance of it being taken in?

I put this in the 2.4 ia64 BK tree a couple days ago. Can you check
here: http://lia64.bkbits.net:8080/linux-ia64-2.4 and make sure that it works for you?

The plain patch is also available here, if that works better for you:
ftp://ftp.kernel.org/pub/linux/kernel/ports/ia64/v2.4/testing/cset/index.html

Quoted 26 lines

diff -durN linux-2.4.26-rc5-orig/include/asm-ia64/pgtable.h linux-2.4.26-rc5-patched/include/asm-ia64/pgtable.h

include/asm-ia64/pgtable.h +3 -2
@@ -60,7 +60,8 @@
 #define _PAGE_PROTNONE		(__IA64_UL(1) << 63)
 
 #define _PFN_MASK		_PAGE_PPN_MASK
-#define _PAGE_CHG_MASK		(_PFN_MASK | _PAGE_A | _PAGE_D)
+/* Mask of bits which may be changed by pte_modify(); the odd bits are there for _PAGE_PROTNONE */
+#define _PAGE_CHG_MASK		(_PAGE_P | _PAGE_PROTNONE | _PAGE_PL_MASK | _PAGE_AR_MASK | _PAGE_ED)
 
 #define _PAGE_SIZE_4K	12
 #define _PAGE_SIZE_8K	13

@@ -216,7 +217,7 @@
 ({ pte_t __pte; pte_val(__pte) = physpage + pgprot_val(pgprot); __pte; })
 
 #define pte_modify(_pte, newprot) \
-	(__pte((pte_val(_pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)))
+	(__pte((pte_val(_pte) & ~_PAGE_CHG_MASK) | (pgprot_val(newprot) & _PAGE_CHG_MASK)))
 
 #define page_pte_prot(page,prot)	mk_pte(page, prot)
 #define page_pte(page)			page_pte_prot(page, __pgprot(0))
Signature · 3 lines
-- 
Daniel J Blueman
Software Engineer, Quadrics Ltd
author
#2 lore raw
Quoted 35 lines · Bjorn Helgaas
Quoted 10 lines · Daniel J Blueman

This patch [1] corrects the behaviour of pte_modify() on ia64 to not clear page protection flags it shouldn't touch.

Without this patch, it clears the uncacheable flag on UC memory regions, which can cause MCAs with device I/O.

It was taken into 2.6.0 a while ago, but is yet to be included in 2.4 - the patch here is rediffed against 2.4.26-rc5.

Is there chance of it being taken in?

I put this in the 2.4 ia64 BK tree a couple days ago. Can you check
here: http://lia64.bkbits.net:8080/linux-ia64-2.4 and make sure that it works for you?

The plain patch is also available here, if that works better for you:
ftp://ftp.kernel.org/pub/linux/kernel/ports/ia64/v2.4/testing/cset/index.html

Quoted 16 lines

diff -durN linux-2.4.26-rc5-orig/include/asm-ia64/pgtable.h linux-2.4.26-rc5-patched/include/asm-ia64/pgtable.h

include/asm-ia64/pgtable.h +2 -1
@@ -60,7 +60,8 @@
 #define _PAGE_PROTNONE		(__IA64_UL(1) << 63)
 
 #define _PFN_MASK		_PAGE_PPN_MASK
-#define _PAGE_CHG_MASK		(_PFN_MASK | _PAGE_A | _PAGE_D)
+/* Mask of bits which may be changed by pte_modify(); the odd bits are there for _PAGE_PROTNONE */
+#define _PAGE_CHG_MASK		(_PAGE_P | _PAGE_PROTNONE | _PAGE_PL_MASK | _PAGE_AR_MASK | _PAGE_ED)
 
 #define _PAGE_SIZE_4K	12
 #define _PAGE_SIZE_8K	13

@@ -216,7 +217,7 @@
 ({ pte_t __pte; pte_val(__pte) = physpage + pgprot_val(pgprot); __pte; })
Quoted 6 lines

include/asm-ia64/pgtable.h line 223

Quoted 6 lines
include/asm-ia64/pgtable.h +1 -1
 #define pte_modify(_pte, newprot) \
-	(__pte((pte_val(_pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)))
+	(__pte((pte_val(_pte) & ~_PAGE_CHG_MASK) | (pgprot_val(newprot) & _PAGE_CHG_MASK)))
 
 #define page_pte_prot(page,prot)	mk_pte(page, prot)
 #define page_pte(page)			page_pte_prot(page, __pgprot(0))

Bjorn,

The two changesets are good. Thanks!

Signature · 2 lines
Daniel J Blueman
Software Engineer, Quadrics Ltd