[PATCH] Rework ptep_set_access_flags and fix sun4c
Benjamin Herrenschmidt
benh at kernel.crashing.org
Wed May 23 14:20:03 EST 2007
Some changes done a while ago to avoid pounding on ptep_set_access_flags
and update_mmu_cache in some race situations break sun4c which requires
update_mmu_cache() to always be called on minor faults.
This patch reworks ptep_set_access_flags() semantics, implementations
and callers so that it's now responsible for returning whether an update
is necessary or not (basically whether the PTE actually changed). This
allow fixing the sparc implementation to always return 1 on sun4c.
Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
This version adds the missing ia64 bits and fixes the i386 bit (compile
tested this time) according to Hugh's comments. I also updated
set_huge_ptep_writable() to do the same as do_wp_page().
---
include/asm-generic/pgtable.h | 17 ++++++++++++-----
include/asm-i386/pgtable.h | 8 +++++---
include/asm-ia64/pgtable.h | 25 ++++++++++++++++---------
include/asm-powerpc/pgtable-ppc32.h | 12 ++++++++----
include/asm-powerpc/pgtable-ppc64.h | 12 ++++++++----
include/asm-ppc/pgtable.h | 12 ++++++++----
include/asm-s390/pgtable.h | 7 ++++++-
include/asm-sparc/pgtable.h | 11 +++++++++++
include/asm-x86_64/pgtable.h | 14 ++++++++------
mm/hugetlb.c | 7 ++++---
mm/memory.c | 13 ++++++-------
11 files changed, 92 insertions(+), 46 deletions(-)
Index: linux-work/include/asm-generic/pgtable.h
===================================================================
--- linux-work.orig/include/asm-generic/pgtable.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-generic/pgtable.h 2007-05-23 14:00:32.000000000 +1000
@@ -27,13 +27,20 @@ do { \
* Largely same as above, but only sets the access flags (dirty,
* accessed, and writable). Furthermore, we know it always gets set
* to a "more permissive" setting, which allows most architectures
- * to optimize this.
+ * to optimize this. We return whether the PTE actually changed, which
+ * in turn instructs the caller to do things like update__mmu_cache.
+ * This used to be done in the caller, but sparc needs minor faults to
+ * force that call on sun4c so we changed this macro slightly
*/
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
-do { \
- set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \
- flush_tlb_page(__vma, __address); \
-} while (0)
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) { \
+ set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \
+ flush_tlb_page(__vma, __address); \
+ } \
+ __changed; \
+})
#endif
#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
Index: linux-work/include/asm-powerpc/pgtable-ppc64.h
===================================================================
--- linux-work.orig/include/asm-powerpc/pgtable-ppc64.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-powerpc/pgtable-ppc64.h 2007-05-22 16:03:09.000000000 +1000
@@ -413,10 +413,14 @@ static inline void __ptep_set_access_fla
:"cc");
}
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
- do { \
- __ptep_set_access_flags(__ptep, __entry, __dirty); \
- flush_tlb_page_nohash(__vma, __address); \
- } while(0)
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) { \
+ __ptep_set_access_flags(__ptep, __entry, __dirty); \
+ flush_tlb_page_nohash(__vma, __address); \
+ } \
+ __changed; \
+})
/*
* Macro to mark a page protection value as "uncacheable".
Index: linux-work/mm/memory.c
===================================================================
--- linux-work.orig/mm/memory.c 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/mm/memory.c 2007-05-22 16:03:09.000000000 +1000
@@ -1691,9 +1691,10 @@ static int do_wp_page(struct mm_struct *
flush_cache_page(vma, address, pte_pfn(orig_pte));
entry = pte_mkyoung(orig_pte);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- ptep_set_access_flags(vma, address, page_table, entry, 1);
- update_mmu_cache(vma, address, entry);
- lazy_mmu_prot_update(entry);
+ if (ptep_set_access_flags(vma, address, page_table, entry,1)) {
+ update_mmu_cache(vma, address, entry);
+ lazy_mmu_prot_update(entry);
+ }
ret |= VM_FAULT_WRITE;
goto unlock;
}
@@ -2525,10 +2526,9 @@ static inline int handle_pte_fault(struc
pte_t *pte, pmd_t *pmd, int write_access)
{
pte_t entry;
- pte_t old_entry;
spinlock_t *ptl;
- old_entry = entry = *pte;
+ entry = *pte;
if (!pte_present(entry)) {
if (pte_none(entry)) {
if (vma->vm_ops) {
@@ -2561,8 +2561,7 @@ static inline int handle_pte_fault(struc
entry = pte_mkdirty(entry);
}
entry = pte_mkyoung(entry);
- if (!pte_same(old_entry, entry)) {
- ptep_set_access_flags(vma, address, pte, entry, write_access);
+ if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
update_mmu_cache(vma, address, entry);
lazy_mmu_prot_update(entry);
} else {
Index: linux-work/include/asm-powerpc/pgtable-ppc32.h
===================================================================
--- linux-work.orig/include/asm-powerpc/pgtable-ppc32.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-powerpc/pgtable-ppc32.h 2007-05-22 16:03:09.000000000 +1000
@@ -673,10 +673,14 @@ static inline void __ptep_set_access_fla
}
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
- do { \
- __ptep_set_access_flags(__ptep, __entry, __dirty); \
- flush_tlb_page_nohash(__vma, __address); \
- } while(0)
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) { \
+ __ptep_set_access_flags(__ptep, __entry, __dirty); \
+ flush_tlb_page_nohash(__vma, __address); \
+ } \
+ __changed; \
+})
/*
* Macro to mark a page protection value as "uncacheable".
Index: linux-work/include/asm-i386/pgtable.h
===================================================================
--- linux-work.orig/include/asm-i386/pgtable.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-i386/pgtable.h 2007-05-23 11:54:33.000000000 +1000
@@ -285,13 +285,15 @@ static inline pte_t native_local_ptep_ge
*/
#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
#define ptep_set_access_flags(vma, address, ptep, entry, dirty) \
-do { \
- if (dirty) { \
+({ \
+ int __changed = !pte_same(*(ptep), entry); \
+ if (__changed && dirty) { \
(ptep)->pte_low = (entry).pte_low; \
pte_update_defer((vma)->vm_mm, (address), (ptep)); \
flush_tlb_page(vma, address); \
} \
-} while (0)
+ __changed; \
+})
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
#define ptep_test_and_clear_dirty(vma, addr, ptep) ({ \
Index: linux-work/include/asm-ppc/pgtable.h
===================================================================
--- linux-work.orig/include/asm-ppc/pgtable.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-ppc/pgtable.h 2007-05-22 16:03:09.000000000 +1000
@@ -694,10 +694,14 @@ static inline void __ptep_set_access_fla
}
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
- do { \
- __ptep_set_access_flags(__ptep, __entry, __dirty); \
- flush_tlb_page_nohash(__vma, __address); \
- } while(0)
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) { \
+ __ptep_set_access_flags(__ptep, __entry, __dirty); \
+ flush_tlb_page_nohash(__vma, __address); \
+ } \
+ __changed; \
+})
/*
* Macro to mark a page protection value as "uncacheable".
Index: linux-work/include/asm-s390/pgtable.h
===================================================================
--- linux-work.orig/include/asm-s390/pgtable.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-s390/pgtable.h 2007-05-22 16:03:09.000000000 +1000
@@ -744,7 +744,12 @@ ptep_establish(struct vm_area_struct *vm
}
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
- ptep_establish(__vma, __address, __ptep, __entry)
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) \
+ ptep_establish(__vma, __address, __ptep, __entry); \
+ __changed; \
+})
/*
* Test and clear dirty bit in storage key.
Index: linux-work/include/asm-sparc/pgtable.h
===================================================================
--- linux-work.orig/include/asm-sparc/pgtable.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-sparc/pgtable.h 2007-05-22 16:03:09.000000000 +1000
@@ -446,6 +446,17 @@ extern int io_remap_pfn_range(struct vm_
#define GET_IOSPACE(pfn) (pfn >> (BITS_PER_LONG - 4))
#define GET_PFN(pfn) (pfn & 0x0fffffffUL)
+#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
+#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) { \
+ set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \
+ flush_tlb_page(__vma, __address); \
+ } \
+ (sparc_cpu_model == sun4c) || __changed; \
+})
+
#include <asm-generic/pgtable.h>
#endif /* !(__ASSEMBLY__) */
Index: linux-work/include/asm-x86_64/pgtable.h
===================================================================
--- linux-work.orig/include/asm-x86_64/pgtable.h 2007-05-22 15:41:38.000000000 +1000
+++ linux-work/include/asm-x86_64/pgtable.h 2007-05-22 16:03:09.000000000 +1000
@@ -395,12 +395,14 @@ static inline pte_t pte_modify(pte_t pte
* bit at the same time. */
#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
#define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
- do { \
- if (__dirty) { \
- set_pte(__ptep, __entry); \
- flush_tlb_page(__vma, __address); \
- } \
- } while (0)
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed && __dirty) { \
+ set_pte(__ptep, __entry); \
+ flush_tlb_page(__vma, __address); \
+ } \
+ __changed; \
+})
/* Encode and de-code a swap entry */
#define __swp_type(x) (((x).val >> 1) & 0x3f)
Index: linux-work/include/asm-ia64/pgtable.h
===================================================================
--- linux-work.orig/include/asm-ia64/pgtable.h 2007-05-23 11:55:13.000000000 +1000
+++ linux-work/include/asm-ia64/pgtable.h 2007-05-23 11:57:23.000000000 +1000
@@ -533,16 +533,23 @@ extern void lazy_mmu_prot_update (pte_t
* daccess_bit in ivt.S).
*/
#ifdef CONFIG_SMP
-# define ptep_set_access_flags(__vma, __addr, __ptep, __entry, __safely_writable) \
-do { \
- if (__safely_writable) { \
- set_pte(__ptep, __entry); \
- flush_tlb_page(__vma, __addr); \
- } \
-} while (0)
+# define ptep_set_access_flags(__vma, __addr, __ptep, __entry, __safely_writable) \
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed && __safely_writable) { \
+ set_pte(__ptep, __entry); \
+ flush_tlb_page(__vma, __addr); \
+ } \
+ __changed; \
+})
#else
-# define ptep_set_access_flags(__vma, __addr, __ptep, __entry, __safely_writable) \
- ptep_establish(__vma, __addr, __ptep, __entry)
+# define ptep_set_access_flags(__vma, __addr, __ptep, __entry, __safely_writable) \
+({ \
+ int __changed = !pte_same(*(__ptep), __entry); \
+ if (__changed) { \
+ ptep_establish(__vma, __addr, __ptep, __entry) \
+ __changed; \
+})
#endif
# ifdef CONFIG_VIRTUAL_MEM_MAP
Index: linux-work/mm/hugetlb.c
===================================================================
--- linux-work.orig/mm/hugetlb.c 2007-05-23 13:59:25.000000000 +1000
+++ linux-work/mm/hugetlb.c 2007-05-23 13:59:32.000000000 +1000
@@ -326,9 +326,10 @@ static void set_huge_ptep_writable(struc
pte_t entry;
entry = pte_mkwrite(pte_mkdirty(*ptep));
- ptep_set_access_flags(vma, address, ptep, entry, 1);
- update_mmu_cache(vma, address, entry);
- lazy_mmu_prot_update(entry);
+ if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
+ update_mmu_cache(vma, address, entry);
+ lazy_mmu_prot_update(entry);
+ }
}
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