[S390] use generic RCU page-table freeing code
Replace the s390 specific rcu page-table freeing code with the
generic variant. This requires to duplicate the definition for the
struct mmu_table_batch as s390 does not use the generic tlb flush
code.
While we are at it remove the restriction that page table fragments
can not be reused after a single fragment has been freed with rcu
and split out allocation and freeing of page tables with pgstes.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 9fab2aa..90d77bd 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -89,6 +89,7 @@
select HAVE_GET_USER_PAGES_FAST
select HAVE_ARCH_MUTEX_CPU_RELAX
select HAVE_ARCH_JUMP_LABEL if !MARCH_G5
+ select HAVE_RCU_TABLE_FREE if SMP
select ARCH_INLINE_SPIN_TRYLOCK
select ARCH_INLINE_SPIN_TRYLOCK_BH
select ARCH_INLINE_SPIN_LOCK
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index f6314af..38e71eb 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -17,15 +17,15 @@
#include <linux/gfp.h>
#include <linux/mm.h>
-#define check_pgt_cache() do {} while (0)
-
unsigned long *crst_table_alloc(struct mm_struct *);
void crst_table_free(struct mm_struct *, unsigned long *);
-void crst_table_free_rcu(struct mm_struct *, unsigned long *);
unsigned long *page_table_alloc(struct mm_struct *);
void page_table_free(struct mm_struct *, unsigned long *);
-void page_table_free_rcu(struct mm_struct *, unsigned long *);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+void page_table_free_rcu(struct mmu_gather *, unsigned long *);
+void __tlb_remove_table(void *_table);
+#endif
static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
{
diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
index 77eee54..c687a2c 100644
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -26,67 +26,60 @@
#include <linux/swap.h>
#include <asm/processor.h>
#include <asm/pgalloc.h>
-#include <asm/smp.h>
#include <asm/tlbflush.h>
struct mmu_gather {
struct mm_struct *mm;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ struct mmu_table_batch *batch;
+#endif
unsigned int fullmm;
- unsigned int nr_ptes;
- unsigned int nr_pxds;
- unsigned int max;
- void **array;
- void *local[8];
+ unsigned int need_flush;
};
-static inline void __tlb_alloc_page(struct mmu_gather *tlb)
-{
- unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+struct mmu_table_batch {
+ struct rcu_head rcu;
+ unsigned int nr;
+ void *tables[0];
+};
- if (addr) {
- tlb->array = (void *) addr;
- tlb->max = PAGE_SIZE / sizeof(void *);
- }
-}
+#define MAX_TABLE_BATCH \
+ ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
+
+extern void tlb_table_flush(struct mmu_gather *tlb);
+extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
+#endif
static inline void tlb_gather_mmu(struct mmu_gather *tlb,
struct mm_struct *mm,
unsigned int full_mm_flush)
{
tlb->mm = mm;
- tlb->max = ARRAY_SIZE(tlb->local);
- tlb->array = tlb->local;
tlb->fullmm = full_mm_flush;
+ tlb->need_flush = 0;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ tlb->batch = NULL;
+#endif
if (tlb->fullmm)
__tlb_flush_mm(mm);
- else
- __tlb_alloc_page(tlb);
- tlb->nr_ptes = 0;
- tlb->nr_pxds = tlb->max;
}
static inline void tlb_flush_mmu(struct mmu_gather *tlb)
{
- if (!tlb->fullmm && (tlb->nr_ptes > 0 || tlb->nr_pxds < tlb->max))
- __tlb_flush_mm(tlb->mm);
- while (tlb->nr_ptes > 0)
- page_table_free_rcu(tlb->mm, tlb->array[--tlb->nr_ptes]);
- while (tlb->nr_pxds < tlb->max)
- crst_table_free_rcu(tlb->mm, tlb->array[tlb->nr_pxds++]);
+ if (!tlb->need_flush)
+ return;
+ tlb->need_flush = 0;
+ __tlb_flush_mm(tlb->mm);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ tlb_table_flush(tlb);
+#endif
}
static inline void tlb_finish_mmu(struct mmu_gather *tlb,
unsigned long start, unsigned long end)
{
tlb_flush_mmu(tlb);
-
- rcu_table_freelist_finish();
-
- /* keep the page table cache within bounds */
- check_pgt_cache();
-
- if (tlb->array != tlb->local)
- free_pages((unsigned long) tlb->array, 0);
}
/*
@@ -112,12 +105,11 @@
static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
unsigned long address)
{
- if (!tlb->fullmm) {
- tlb->array[tlb->nr_ptes++] = pte;
- if (tlb->nr_ptes >= tlb->nr_pxds)
- tlb_flush_mmu(tlb);
- } else
- page_table_free(tlb->mm, (unsigned long *) pte);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ if (!tlb->fullmm)
+ return page_table_free_rcu(tlb, (unsigned long *) pte);
+#endif
+ page_table_free(tlb->mm, (unsigned long *) pte);
}
/*
@@ -133,12 +125,11 @@
#ifdef __s390x__
if (tlb->mm->context.asce_limit <= (1UL << 31))
return;
- if (!tlb->fullmm) {
- tlb->array[--tlb->nr_pxds] = pmd;
- if (tlb->nr_ptes >= tlb->nr_pxds)
- tlb_flush_mmu(tlb);
- } else
- crst_table_free(tlb->mm, (unsigned long *) pmd);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ if (!tlb->fullmm)
+ return tlb_remove_table(tlb, pmd);
+#endif
+ crst_table_free(tlb->mm, (unsigned long *) pmd);
#endif
}
@@ -155,12 +146,11 @@
#ifdef __s390x__
if (tlb->mm->context.asce_limit <= (1UL << 42))
return;
- if (!tlb->fullmm) {
- tlb->array[--tlb->nr_pxds] = pud;
- if (tlb->nr_ptes >= tlb->nr_pxds)
- tlb_flush_mmu(tlb);
- } else
- crst_table_free(tlb->mm, (unsigned long *) pud);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ if (!tlb->fullmm)
+ return tlb_remove_table(tlb, pud);
+#endif
+ crst_table_free(tlb->mm, (unsigned long *) pud);
#endif
}
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index b09763f..37a23c22 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -24,94 +24,12 @@
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
-struct rcu_table_freelist {
- struct rcu_head rcu;
- struct mm_struct *mm;
- unsigned int pgt_index;
- unsigned int crst_index;
- unsigned long *table[0];
-};
-
-#define RCU_FREELIST_SIZE \
- ((PAGE_SIZE - sizeof(struct rcu_table_freelist)) \
- / sizeof(unsigned long))
-
-static DEFINE_PER_CPU(struct rcu_table_freelist *, rcu_table_freelist);
-
-static void __page_table_free(struct mm_struct *mm, unsigned long *table);
-
-static struct rcu_table_freelist *rcu_table_freelist_get(struct mm_struct *mm)
-{
- struct rcu_table_freelist **batchp = &__get_cpu_var(rcu_table_freelist);
- struct rcu_table_freelist *batch = *batchp;
-
- if (batch)
- return batch;
- batch = (struct rcu_table_freelist *) __get_free_page(GFP_ATOMIC);
- if (batch) {
- batch->mm = mm;
- batch->pgt_index = 0;
- batch->crst_index = RCU_FREELIST_SIZE;
- *batchp = batch;
- }
- return batch;
-}
-
-static void rcu_table_freelist_callback(struct rcu_head *head)
-{
- struct rcu_table_freelist *batch =
- container_of(head, struct rcu_table_freelist, rcu);
-
- while (batch->pgt_index > 0)
- __page_table_free(batch->mm, batch->table[--batch->pgt_index]);
- while (batch->crst_index < RCU_FREELIST_SIZE)
- crst_table_free(batch->mm, batch->table[batch->crst_index++]);
- free_page((unsigned long) batch);
-}
-
-void rcu_table_freelist_finish(void)
-{
- struct rcu_table_freelist **batchp = &get_cpu_var(rcu_table_freelist);
- struct rcu_table_freelist *batch = *batchp;
-
- if (!batch)
- goto out;
- call_rcu(&batch->rcu, rcu_table_freelist_callback);
- *batchp = NULL;
-out:
- put_cpu_var(rcu_table_freelist);
-}
-
-static void smp_sync(void *arg)
-{
-}
-
#ifndef CONFIG_64BIT
#define ALLOC_ORDER 1
-#define TABLES_PER_PAGE 4
-#define FRAG_MASK 15UL
-#define SECOND_HALVES 10UL
-
-void clear_table_pgstes(unsigned long *table)
-{
- clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/4);
- memset(table + 256, 0, PAGE_SIZE/4);
- clear_table(table + 512, _PAGE_TYPE_EMPTY, PAGE_SIZE/4);
- memset(table + 768, 0, PAGE_SIZE/4);
-}
-
+#define FRAG_MASK 0x0f
#else
#define ALLOC_ORDER 2
-#define TABLES_PER_PAGE 2
-#define FRAG_MASK 3UL
-#define SECOND_HALVES 2UL
-
-void clear_table_pgstes(unsigned long *table)
-{
- clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2);
- memset(table + 256, 0, PAGE_SIZE/2);
-}
-
+#define FRAG_MASK 0x03
#endif
unsigned long VMALLOC_START = VMALLOC_END - VMALLOC_SIZE;
@@ -140,29 +58,6 @@
free_pages((unsigned long) table, ALLOC_ORDER);
}
-void crst_table_free_rcu(struct mm_struct *mm, unsigned long *table)
-{
- struct rcu_table_freelist *batch;
-
- preempt_disable();
- if (atomic_read(&mm->mm_users) < 2 &&
- cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {
- crst_table_free(mm, table);
- goto out;
- }
- batch = rcu_table_freelist_get(mm);
- if (!batch) {
- smp_call_function(smp_sync, NULL, 1);
- crst_table_free(mm, table);
- goto out;
- }
- batch->table[--batch->crst_index] = table;
- if (batch->pgt_index >= batch->crst_index)
- rcu_table_freelist_finish();
-out:
- preempt_enable();
-}
-
#ifdef CONFIG_64BIT
int crst_table_upgrade(struct mm_struct *mm, unsigned long limit)
{
@@ -238,124 +133,175 @@
}
#endif
+static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
+{
+ unsigned int old, new;
+
+ do {
+ old = atomic_read(v);
+ new = old ^ bits;
+ } while (atomic_cmpxchg(v, old, new) != old);
+ return new;
+}
+
/*
* page table entry allocation/free routines.
*/
+#ifdef CONFIG_PGSTE
+static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm)
+{
+ struct page *page;
+ unsigned long *table;
+
+ page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
+ if (!page)
+ return NULL;
+ pgtable_page_ctor(page);
+ atomic_set(&page->_mapcount, 3);
+ table = (unsigned long *) page_to_phys(page);
+ clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2);
+ clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
+ return table;
+}
+
+static inline void page_table_free_pgste(unsigned long *table)
+{
+ struct page *page;
+
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ pgtable_page_ctor(page);
+ atomic_set(&page->_mapcount, -1);
+ __free_page(page);
+}
+#endif
+
unsigned long *page_table_alloc(struct mm_struct *mm)
{
struct page *page;
unsigned long *table;
- unsigned long bits;
+ unsigned int mask, bit;
- bits = (mm->context.has_pgste) ? 3UL : 1UL;
+#ifdef CONFIG_PGSTE
+ if (mm_has_pgste(mm))
+ return page_table_alloc_pgste(mm);
+#endif
+ /* Allocate fragments of a 4K page as 1K/2K page table */
spin_lock_bh(&mm->context.list_lock);
- page = NULL;
+ mask = FRAG_MASK;
if (!list_empty(&mm->context.pgtable_list)) {
page = list_first_entry(&mm->context.pgtable_list,
struct page, lru);
- if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
- page = NULL;
+ table = (unsigned long *) page_to_phys(page);
+ mask = atomic_read(&page->_mapcount);
+ mask = mask | (mask >> 4);
}
- if (!page) {
+ if ((mask & FRAG_MASK) == FRAG_MASK) {
spin_unlock_bh(&mm->context.list_lock);
page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
if (!page)
return NULL;
pgtable_page_ctor(page);
- page->flags &= ~FRAG_MASK;
+ atomic_set(&page->_mapcount, 1);
table = (unsigned long *) page_to_phys(page);
- if (mm->context.has_pgste)
- clear_table_pgstes(table);
- else
- clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
+ clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
spin_lock_bh(&mm->context.list_lock);
list_add(&page->lru, &mm->context.pgtable_list);
+ } else {
+ for (bit = 1; mask & bit; bit <<= 1)
+ table += PTRS_PER_PTE;
+ mask = atomic_xor_bits(&page->_mapcount, bit);
+ if ((mask & FRAG_MASK) == FRAG_MASK)
+ list_del(&page->lru);
}
- table = (unsigned long *) page_to_phys(page);
- while (page->flags & bits) {
- table += 256;
- bits <<= 1;
- }
- page->flags |= bits;
- if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
- list_move_tail(&page->lru, &mm->context.pgtable_list);
spin_unlock_bh(&mm->context.list_lock);
return table;
}
-static void __page_table_free(struct mm_struct *mm, unsigned long *table)
-{
- struct page *page;
- unsigned long bits;
-
- bits = ((unsigned long) table) & 15;
- table = (unsigned long *)(((unsigned long) table) ^ bits);
- page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
- page->flags ^= bits;
- if (!(page->flags & FRAG_MASK)) {
- pgtable_page_dtor(page);
- __free_page(page);
- }
-}
-
void page_table_free(struct mm_struct *mm, unsigned long *table)
{
struct page *page;
- unsigned long bits;
+ unsigned int bit, mask;
- bits = (mm->context.has_pgste) ? 3UL : 1UL;
- bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long);
+#ifdef CONFIG_PGSTE
+ if (mm_has_pgste(mm))
+ return page_table_free_pgste(table);
+#endif
+ /* Free 1K/2K page table fragment of a 4K page */
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ bit = 1 << ((__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)));
spin_lock_bh(&mm->context.list_lock);
- page->flags ^= bits;
- if (page->flags & FRAG_MASK) {
- /* Page now has some free pgtable fragments. */
- if (!list_empty(&page->lru))
- list_move(&page->lru, &mm->context.pgtable_list);
- page = NULL;
- } else
- /* All fragments of the 4K page have been freed. */
+ if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
list_del(&page->lru);
+ mask = atomic_xor_bits(&page->_mapcount, bit);
+ if (mask & FRAG_MASK)
+ list_add(&page->lru, &mm->context.pgtable_list);
spin_unlock_bh(&mm->context.list_lock);
- if (page) {
+ if (mask == 0) {
pgtable_page_dtor(page);
+ atomic_set(&page->_mapcount, -1);
__free_page(page);
}
}
-void page_table_free_rcu(struct mm_struct *mm, unsigned long *table)
-{
- struct rcu_table_freelist *batch;
- struct page *page;
- unsigned long bits;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
- preempt_disable();
- if (atomic_read(&mm->mm_users) < 2 &&
- cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) {
- page_table_free(mm, table);
- goto out;
+static void __page_table_free_rcu(void *table, unsigned bit)
+{
+ struct page *page;
+
+#ifdef CONFIG_PGSTE
+ if (bit == FRAG_MASK)
+ return page_table_free_pgste(table);
+#endif
+ /* Free 1K/2K page table fragment of a 4K page */
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ if (atomic_xor_bits(&page->_mapcount, bit) == 0) {
+ pgtable_page_dtor(page);
+ atomic_set(&page->_mapcount, -1);
+ __free_page(page);
}
- batch = rcu_table_freelist_get(mm);
- if (!batch) {
- smp_call_function(smp_sync, NULL, 1);
- page_table_free(mm, table);
- goto out;
+}
+
+void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table)
+{
+ struct mm_struct *mm;
+ struct page *page;
+ unsigned int bit, mask;
+
+ mm = tlb->mm;
+#ifdef CONFIG_PGSTE
+ if (mm_has_pgste(mm)) {
+ table = (unsigned long *) (__pa(table) | FRAG_MASK);
+ tlb_remove_table(tlb, table);
+ return;
}
- bits = (mm->context.has_pgste) ? 3UL : 1UL;
- bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long);
+#endif
+ bit = 1 << ((__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)));
page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
spin_lock_bh(&mm->context.list_lock);
- /* Delayed freeing with rcu prevents reuse of pgtable fragments */
- list_del_init(&page->lru);
+ if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
+ list_del(&page->lru);
+ mask = atomic_xor_bits(&page->_mapcount, bit | (bit << 4));
+ if (mask & FRAG_MASK)
+ list_add_tail(&page->lru, &mm->context.pgtable_list);
spin_unlock_bh(&mm->context.list_lock);
- table = (unsigned long *)(((unsigned long) table) | bits);
- batch->table[batch->pgt_index++] = table;
- if (batch->pgt_index >= batch->crst_index)
- rcu_table_freelist_finish();
-out:
- preempt_enable();
+ table = (unsigned long *) (__pa(table) | (bit << 4));
+ tlb_remove_table(tlb, table);
}
+void __tlb_remove_table(void *_table)
+{
+ void *table = (void *)((unsigned long) _table & PAGE_MASK);
+ unsigned type = (unsigned long) _table & ~PAGE_MASK;
+
+ if (type)
+ __page_table_free_rcu(table, type);
+ else
+ free_pages((unsigned long) table, ALLOC_ORDER);
+}
+
+#endif
+
/*
* switch on pgstes for its userspace process (for kvm)
*/
@@ -369,7 +315,7 @@
return -EINVAL;
/* Do we have pgstes? if yes, we are done */
- if (tsk->mm->context.has_pgste)
+ if (mm_has_pgste(tsk->mm))
return 0;
/* lets check if we are allowed to replace the mm */