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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] [IA64] fix p2m traversing race
# HG changeset patch
# User awilliam@xxxxxxxxxxx
# Node ID 439051df45f3d43793e4b0370da0b55ef0b3dc75
# Parent 4fae646d60daedc9ced751064509884043cb15fd
[IA64] fix p2m traversing race
Fixed by adding volatile to pgd_t, pud_t, pmd_t where necessary.
The Xen/IA64 p2m table is lockless so that acquire semantics is
necessary when traversing the p2m in order to prevent memory-reodering
the following memory load.
Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
xen/arch/ia64/xen/mm.c | 138 +++++--------
xen/include/asm-ia64/domain.h | 2
xen/include/asm-ia64/linux-xen/asm-generic/pgtable-nopud.h | 8
xen/include/asm-ia64/linux-xen/asm/pgalloc.h | 27 ++
xen/include/asm-ia64/linux-xen/asm/pgtable.h | 13 +
5 files changed, 100 insertions(+), 88 deletions(-)
diff -r 4fae646d60da -r 439051df45f3 xen/arch/ia64/xen/mm.c
--- a/xen/arch/ia64/xen/mm.c Thu Nov 30 15:57:37 2006 -0700
+++ b/xen/arch/ia64/xen/mm.c Thu Nov 30 15:57:42 2006 -0700
@@ -249,7 +249,7 @@ try_to_clear_PGC_allocate(struct domain*
}
static void
-mm_teardown_pte(struct domain* d, pte_t* pte, unsigned long offset)
+mm_teardown_pte(struct domain* d, volatile pte_t* pte, unsigned long offset)
{
pte_t old_pte;
unsigned long mfn;
@@ -286,39 +286,39 @@ mm_teardown_pte(struct domain* d, pte_t*
}
static void
-mm_teardown_pmd(struct domain* d, pmd_t* pmd, unsigned long offset)
+mm_teardown_pmd(struct domain* d, volatile pmd_t* pmd, unsigned long offset)
{
unsigned long i;
- pte_t* pte = pte_offset_map(pmd, offset);
+ volatile pte_t* pte = pte_offset_map(pmd, offset);
for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
- if (!pte_present(*pte))
+ if (!pte_present(*pte)) // acquire semantics
continue;
mm_teardown_pte(d, pte, offset + (i << PAGE_SHIFT));
}
}
static void
-mm_teardown_pud(struct domain* d, pud_t *pud, unsigned long offset)
+mm_teardown_pud(struct domain* d, volatile pud_t *pud, unsigned long offset)
{
unsigned long i;
- pmd_t *pmd = pmd_offset(pud, offset);
+ volatile pmd_t *pmd = pmd_offset(pud, offset);
for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
- if (!pmd_present(*pmd))
+ if (!pmd_present(*pmd)) // acquire semantics
continue;
mm_teardown_pmd(d, pmd, offset + (i << PMD_SHIFT));
}
}
static void
-mm_teardown_pgd(struct domain* d, pgd_t *pgd, unsigned long offset)
+mm_teardown_pgd(struct domain* d, volatile pgd_t *pgd, unsigned long offset)
{
unsigned long i;
- pud_t *pud = pud_offset(pgd, offset);
+ volatile pud_t *pud = pud_offset(pgd, offset);
for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
- if (!pud_present(*pud))
+ if (!pud_present(*pud)) // acquire semantics
continue;
mm_teardown_pud(d, pud, offset + (i << PUD_SHIFT));
}
@@ -329,30 +329,32 @@ mm_teardown(struct domain* d)
{
struct mm_struct* mm = &d->arch.mm;
unsigned long i;
- pgd_t* pgd;
+ volatile pgd_t* pgd;
if (mm->pgd == NULL)
return;
pgd = pgd_offset(mm, 0);
for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
- if (!pgd_present(*pgd))
+ if (!pgd_present(*pgd)) // acquire semantics
continue;
mm_teardown_pgd(d, pgd, i << PGDIR_SHIFT);
}
}
static void
-mm_p2m_teardown_pmd(struct domain* d, pmd_t* pmd, unsigned long offset)
+mm_p2m_teardown_pmd(struct domain* d, volatile pmd_t* pmd,
+ unsigned long offset)
{
pte_free_kernel(pte_offset_map(pmd, offset));
}
static void
-mm_p2m_teardown_pud(struct domain* d, pud_t *pud, unsigned long offset)
+mm_p2m_teardown_pud(struct domain* d, volatile pud_t *pud,
+ unsigned long offset)
{
unsigned long i;
- pmd_t *pmd = pmd_offset(pud, offset);
+ volatile pmd_t *pmd = pmd_offset(pud, offset);
for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
if (!pmd_present(*pmd))
@@ -363,10 +365,11 @@ mm_p2m_teardown_pud(struct domain* d, pu
}
static void
-mm_p2m_teardown_pgd(struct domain* d, pgd_t *pgd, unsigned long offset)
+mm_p2m_teardown_pgd(struct domain* d, volatile pgd_t *pgd,
+ unsigned long offset)
{
unsigned long i;
- pud_t *pud = pud_offset(pgd, offset);
+ volatile pud_t *pud = pud_offset(pgd, offset);
for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
if (!pud_present(*pud))
@@ -381,7 +384,7 @@ mm_p2m_teardown(struct domain* d)
{
struct mm_struct* mm = &d->arch.mm;
unsigned long i;
- pgd_t* pgd;
+ volatile pgd_t* pgd;
BUG_ON(mm->pgd == NULL);
pgd = pgd_offset(mm, 0);
@@ -565,38 +568,6 @@ unsigned long translate_domain_mpaddr(un
}
//XXX !xxx_present() should be used instread of !xxx_none()?
-// __assign_new_domain_page(), assign_new_domain_page() and
-// assign_new_domain0_page() are used only when domain creation.
-// their accesses aren't racy so that returned pte_t doesn't need
-// volatile qualifier
-static pte_t*
-__lookup_alloc_domain_pte(struct domain* d, unsigned long mpaddr)
-{
- struct mm_struct *mm = &d->arch.mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
-
- BUG_ON(mm->pgd == NULL);
- pgd = pgd_offset(mm, mpaddr);
- if (pgd_none(*pgd)) {
- pgd_populate(mm, pgd, pud_alloc_one(mm,mpaddr));
- }
-
- pud = pud_offset(pgd, mpaddr);
- if (pud_none(*pud)) {
- pud_populate(mm, pud, pmd_alloc_one(mm,mpaddr));
- }
-
- pmd = pmd_offset(pud, mpaddr);
- if (pmd_none(*pmd)) {
- pmd_populate_kernel(mm, pmd, pte_alloc_one_kernel(mm, mpaddr));
- }
-
- return pte_offset_map(pmd, mpaddr);
-}
-
-//XXX !xxx_present() should be used instread of !xxx_none()?
// pud, pmd, pte page is zero cleared when they are allocated.
// Their area must be visible before population so that
// cmpxchg must have release semantics.
@@ -604,15 +575,15 @@ lookup_alloc_domain_pte(struct domain* d
lookup_alloc_domain_pte(struct domain* d, unsigned long mpaddr)
{
struct mm_struct *mm = &d->arch.mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
+ volatile pgd_t *pgd;
+ volatile pud_t *pud;
+ volatile pmd_t *pmd;
BUG_ON(mm->pgd == NULL);
pgd = pgd_offset(mm, mpaddr);
again_pgd:
- if (unlikely(pgd_none(*pgd))) {
+ if (unlikely(pgd_none(*pgd))) { // acquire semantics
pud_t *old_pud = NULL;
pud = pud_alloc_one(mm, mpaddr);
if (unlikely(!pgd_cmpxchg_rel(mm, pgd, old_pud, pud))) {
@@ -623,7 +594,7 @@ lookup_alloc_domain_pte(struct domain* d
pud = pud_offset(pgd, mpaddr);
again_pud:
- if (unlikely(pud_none(*pud))) {
+ if (unlikely(pud_none(*pud))) { // acquire semantics
pmd_t* old_pmd = NULL;
pmd = pmd_alloc_one(mm, mpaddr);
if (unlikely(!pud_cmpxchg_rel(mm, pud, old_pmd, pmd))) {
@@ -634,7 +605,7 @@ lookup_alloc_domain_pte(struct domain* d
pmd = pmd_offset(pud, mpaddr);
again_pmd:
- if (unlikely(pmd_none(*pmd))) {
+ if (unlikely(pmd_none(*pmd))) { // acquire semantics
pte_t* old_pte = NULL;
pte_t* pte = pte_alloc_one_kernel(mm, mpaddr);
if (unlikely(!pmd_cmpxchg_kernel_rel(mm, pmd, old_pte, pte))) {
@@ -643,7 +614,7 @@ lookup_alloc_domain_pte(struct domain* d
}
}
- return (volatile pte_t*)pte_offset_map(pmd, mpaddr);
+ return pte_offset_map(pmd, mpaddr);
}
//XXX xxx_none() should be used instread of !xxx_present()?
@@ -651,48 +622,48 @@ lookup_noalloc_domain_pte(struct domain*
lookup_noalloc_domain_pte(struct domain* d, unsigned long mpaddr)
{
struct mm_struct *mm = &d->arch.mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
+ volatile pgd_t *pgd;
+ volatile pud_t *pud;
+ volatile pmd_t *pmd;
BUG_ON(mm->pgd == NULL);
pgd = pgd_offset(mm, mpaddr);
- if (unlikely(!pgd_present(*pgd)))
+ if (unlikely(!pgd_present(*pgd))) // acquire semantics
return NULL;
pud = pud_offset(pgd, mpaddr);
- if (unlikely(!pud_present(*pud)))
+ if (unlikely(!pud_present(*pud))) // acquire semantics
return NULL;
pmd = pmd_offset(pud, mpaddr);
- if (unlikely(!pmd_present(*pmd)))
+ if (unlikely(!pmd_present(*pmd))) // acquire semantics
return NULL;
- return (volatile pte_t*)pte_offset_map(pmd, mpaddr);
+ return pte_offset_map(pmd, mpaddr);
}
static volatile pte_t*
lookup_noalloc_domain_pte_none(struct domain* d, unsigned long mpaddr)
{
struct mm_struct *mm = &d->arch.mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
+ volatile pgd_t *pgd;
+ volatile pud_t *pud;
+ volatile pmd_t *pmd;
BUG_ON(mm->pgd == NULL);
pgd = pgd_offset(mm, mpaddr);
- if (unlikely(pgd_none(*pgd)))
+ if (unlikely(pgd_none(*pgd))) // acquire semantics
return NULL;
pud = pud_offset(pgd, mpaddr);
- if (unlikely(pud_none(*pud)))
+ if (unlikely(pud_none(*pud))) // acquire semantics
return NULL;
pmd = pmd_offset(pud, mpaddr);
- if (unlikely(pmd_none(*pmd)))
+ if (unlikely(pmd_none(*pmd))) // acquire semantics
return NULL;
- return (volatile pte_t*)pte_offset_map(pmd, mpaddr);
+ return pte_offset_map(pmd, mpaddr);
}
unsigned long
@@ -783,7 +754,8 @@ xencomm_paddr_to_maddr(unsigned long pad
/* Allocate a new page for domain and map it to the specified metaphysical
address. */
static struct page_info *
-__assign_new_domain_page(struct domain *d, unsigned long mpaddr, pte_t* pte)
+__assign_new_domain_page(struct domain *d, unsigned long mpaddr,
+ volatile pte_t* pte)
{
struct page_info *p;
unsigned long maddr;
@@ -825,7 +797,7 @@ struct page_info *
struct page_info *
assign_new_domain_page(struct domain *d, unsigned long mpaddr)
{
- pte_t *pte = __lookup_alloc_domain_pte(d, mpaddr);
+ volatile pte_t *pte = lookup_alloc_domain_pte(d, mpaddr);
if (!pte_none(*pte))
return NULL;
@@ -836,10 +808,10 @@ void
void
assign_new_domain0_page(struct domain *d, unsigned long mpaddr)
{
- pte_t *pte;
+ volatile pte_t *pte;
BUG_ON(d != dom0);
- pte = __lookup_alloc_domain_pte(d, mpaddr);
+ pte = lookup_alloc_domain_pte(d, mpaddr);
if (pte_none(*pte)) {
struct page_info *p = __assign_new_domain_page(d, mpaddr, pte);
if (p == NULL) {
@@ -1816,7 +1788,7 @@ void domain_cache_flush (struct domain *
void domain_cache_flush (struct domain *d, int sync_only)
{
struct mm_struct *mm = &d->arch.mm;
- pgd_t *pgd = mm->pgd;
+ volatile pgd_t *pgd = mm->pgd;
unsigned long maddr;
int i,j,k, l;
int nbr_page = 0;
@@ -1829,22 +1801,22 @@ void domain_cache_flush (struct domain *
flush_func = &flush_dcache_range;
for (i = 0; i < PTRS_PER_PGD; pgd++, i++) {
- pud_t *pud;
- if (!pgd_present(*pgd))
+ volatile pud_t *pud;
+ if (!pgd_present(*pgd)) // acquire semantics
continue;
pud = pud_offset(pgd, 0);
for (j = 0; j < PTRS_PER_PUD; pud++, j++) {
- pmd_t *pmd;
- if (!pud_present(*pud))
+ volatile pmd_t *pmd;
+ if (!pud_present(*pud)) // acquire semantics
continue;
pmd = pmd_offset(pud, 0);
for (k = 0; k < PTRS_PER_PMD; pmd++, k++) {
- pte_t *pte;
- if (!pmd_present(*pmd))
+ volatile pte_t *pte;
+ if (!pmd_present(*pmd)) // acquire semantics
continue;
pte = pte_offset_map(pmd, 0);
for (l = 0; l < PTRS_PER_PTE; pte++, l++) {
- if (!pte_present(*pte))
+ if (!pte_present(*pte)) // acquire semantics
continue;
/* Convert PTE to maddr. */
maddr = __va_ul (pte_val(*pte)
diff -r 4fae646d60da -r 439051df45f3 xen/include/asm-ia64/domain.h
--- a/xen/include/asm-ia64/domain.h Thu Nov 30 15:57:37 2006 -0700
+++ b/xen/include/asm-ia64/domain.h Thu Nov 30 15:57:42 2006 -0700
@@ -42,7 +42,7 @@ extern void panic_domain(struct pt_regs
__attribute__ ((noreturn, format (printf, 2, 3)));
struct mm_struct {
- pgd_t * pgd;
+ volatile pgd_t * pgd;
// atomic_t mm_users; /* How many users with user
space? */
};
diff -r 4fae646d60da -r 439051df45f3
xen/include/asm-ia64/linux-xen/asm-generic/pgtable-nopud.h
--- a/xen/include/asm-ia64/linux-xen/asm-generic/pgtable-nopud.h Thu Nov
30 15:57:37 2006 -0700
+++ b/xen/include/asm-ia64/linux-xen/asm-generic/pgtable-nopud.h Thu Nov
30 15:57:42 2006 -0700
@@ -35,10 +35,18 @@ static inline void pgd_clear(pgd_t *pgd)
*/
#define set_pgd(pgdptr, pgdval) set_pud((pud_t
*)(pgdptr), (pud_t) { pgdval })
+#ifndef XEN
static inline pud_t * pud_offset(pgd_t * pgd, unsigned long address)
{
return (pud_t *)pgd;
}
+#else
+static inline volatile pud_t *
+pud_offset(volatile pgd_t * pgd, unsigned long address)
+{
+ return (volatile pud_t *)pgd;
+}
+#endif
#define pud_val(x) (pgd_val((x).pgd))
#define __pud(x) ((pud_t) { __pgd(x) } )
diff -r 4fae646d60da -r 439051df45f3
xen/include/asm-ia64/linux-xen/asm/pgalloc.h
--- a/xen/include/asm-ia64/linux-xen/asm/pgalloc.h Thu Nov 30 15:57:37
2006 -0700
+++ b/xen/include/asm-ia64/linux-xen/asm/pgalloc.h Thu Nov 30 15:57:42
2006 -0700
@@ -92,10 +92,17 @@ static inline pgd_t *pgd_alloc(struct mm
return pgtable_quicklist_alloc();
}
+#ifndef XEN
static inline void pgd_free(pgd_t * pgd)
{
pgtable_quicklist_free(pgd);
}
+#else
+static inline void pgd_free(volatile pgd_t * pgd)
+{
+ pgtable_quicklist_free((void*)pgd);
+}
+#endif
static inline void
pud_populate(struct mm_struct *mm, pud_t * pud_entry, pmd_t * pmd)
@@ -105,8 +112,8 @@ pud_populate(struct mm_struct *mm, pud_t
#ifdef XEN
static inline int
-pud_cmpxchg_rel(struct mm_struct *mm, pud_t * pud_entry,
- pmd_t * old_pmd, pmd_t * new_pmd)
+pud_cmpxchg_rel(struct mm_struct *mm, volatile pud_t * pud_entry,
+ pmd_t * old_pmd, volatile pmd_t * new_pmd)
{
#ifdef CONFIG_SMP
unsigned long r;
@@ -127,10 +134,17 @@ static inline pmd_t *pmd_alloc_one(struc
return pgtable_quicklist_alloc();
}
+#ifndef XEN
static inline void pmd_free(pmd_t * pmd)
{
pgtable_quicklist_free(pmd);
}
+#else
+static inline void pmd_free(volatile pmd_t * pmd)
+{
+ pgtable_quicklist_free((void*)pmd);
+}
+#endif
#define __pmd_free_tlb(tlb, pmd) pmd_free(pmd)
@@ -150,7 +164,7 @@ pmd_populate_kernel(struct mm_struct *mm
#ifdef XEN
static inline int
-pmd_cmpxchg_kernel_rel(struct mm_struct *mm, pmd_t * pmd_entry,
+pmd_cmpxchg_kernel_rel(struct mm_struct *mm, volatile pmd_t * pmd_entry,
pte_t * old_pte, pte_t * new_pte)
{
#ifdef CONFIG_SMP
@@ -186,12 +200,17 @@ static inline void pte_free(struct page
{
pgtable_quicklist_free(page_address(pte));
}
-#endif
static inline void pte_free_kernel(pte_t * pte)
{
pgtable_quicklist_free(pte);
}
+#else
+static inline void pte_free_kernel(volatile pte_t * pte)
+{
+ pgtable_quicklist_free((void*)pte);
+}
+#endif
#ifndef XEN
#define __pte_free_tlb(tlb, pte) pte_free(pte)
diff -r 4fae646d60da -r 439051df45f3
xen/include/asm-ia64/linux-xen/asm/pgtable.h
--- a/xen/include/asm-ia64/linux-xen/asm/pgtable.h Thu Nov 30 15:57:37
2006 -0700
+++ b/xen/include/asm-ia64/linux-xen/asm/pgtable.h Thu Nov 30 15:57:42
2006 -0700
@@ -380,7 +380,11 @@ pgd_index (unsigned long address)
/* The offset in the 1-level directory is given by the 3 region bits
(61..63) and the level-1 bits. */
+#ifndef XEN
static inline pgd_t*
+#else
+static inline volatile pgd_t*
+#endif
pgd_offset (struct mm_struct *mm, unsigned long address)
{
return mm->pgd + pgd_index(address);
@@ -397,15 +401,24 @@ pgd_offset (struct mm_struct *mm, unsign
#define pgd_offset_gate(mm, addr) pgd_offset_k(addr)
/* Find an entry in the second-level page table.. */
+#ifndef XEN
#define pmd_offset(dir,addr) \
((pmd_t *) pud_page(*(dir)) + (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD -
1)))
+#else
+#define pmd_offset(dir,addr) \
+ ((volatile pmd_t *) pud_page(*(dir)) + (((addr) >> PMD_SHIFT) &
(PTRS_PER_PMD - 1)))
+#endif
/*
* Find an entry in the third-level page table. This looks more complicated
than it
* should be because some platforms place page tables in high memory.
*/
#define pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE
- 1))
+#ifndef XEN
#define pte_offset_kernel(dir,addr) ((pte_t *) pmd_page_kernel(*(dir)) +
pte_index(addr))
+#else
+#define pte_offset_kernel(dir,addr) ((volatile pte_t *)
pmd_page_kernel(*(dir)) + pte_index(addr))
+#endif
#define pte_offset_map(dir,addr) pte_offset_kernel(dir, addr)
#define pte_offset_map_nested(dir,addr) pte_offset_map(dir, addr)
#define pte_unmap(pte) do { } while (0)
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