From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Improve the code to upgrade the standard 2K page tables to 4K page tables
with PGSTEs to allow the operation to happen when the program is already
multi-threaded.
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/include/asm/mmu.h | 2 -
arch/s390/include/asm/mmu_context.h | 19 +---
arch/s390/include/asm/pgtable.h | 11 +++
arch/s390/mm/pgtable.c | 181 +++++++++++++++++++++++-------------
4 files changed, 129 insertions(+), 84 deletions(-)
diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
index 6340178..ff132ac 100644
--- a/arch/s390/include/asm/mmu.h
+++ b/arch/s390/include/asm/mmu.h
@@ -12,8 +12,6 @@ typedef struct {
unsigned long asce_bits;
unsigned long asce_limit;
unsigned long vdso_base;
- /* Cloned contexts will be created with extended page tables. */
- unsigned int alloc_pgste:1;
/* The mmu context has extended page tables. */
unsigned int has_pgste:1;
} mm_context_t;
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index 084e775..4fb67a0 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -21,24 +21,7 @@ static inline int init_new_context(struct task_struct *tsk,
#ifdef CONFIG_64BIT
mm->context.asce_bits |= _ASCE_TYPE_REGION3;
#endif
- if (current->mm && current->mm->context.alloc_pgste) {
- /*
- * alloc_pgste indicates, that any NEW context will be created
- * with extended page tables. The old context is unchanged. The
- * page table allocation and the page table operations will
- * look at has_pgste to distinguish normal and extended page
- * tables. The only way to create extended page tables is to
- * set alloc_pgste and then create a new context (e.g. dup_mm).
- * The page table allocation is called after init_new_context
- * and if has_pgste is set, it will create extended page
- * tables.
- */
- mm->context.has_pgste = 1;
- mm->context.alloc_pgste = 1;
- } else {
- mm->context.has_pgste = 0;
- mm->context.alloc_pgste = 0;
- }
+ mm->context.has_pgste = 0;
mm->context.asce_limit = STACK_TOP_MAX;
crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
return 0;
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 75fb726..7a60bb9 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1361,6 +1361,17 @@ static inline pmd_t pmd_mkwrite(pmd_t pmd)
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLB_PAGE */
+static inline void pmdp_flush_lazy(struct mm_struct *mm,
+ unsigned long address, pmd_t *pmdp)
+{
+ int active = (mm == current->active_mm) ? 1 : 0;
+
+ if ((atomic_read(&mm->context.attach_count) & 0xffff) > active)
+ __pmd_idte(address, pmdp);
+ else
+ mm->context.flush_mm = 1;
+}
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define __HAVE_ARCH_PGTABLE_DEPOSIT
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index a8154a1..6d33248 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -731,6 +731,11 @@ void gmap_do_ipte_notify(struct mm_struct *mm, unsigned long addr, pte_t *pte)
spin_unlock(&gmap_notifier_lock);
}
+static inline int page_table_with_pgste(struct page *page)
+{
+ return atomic_read(&page->_mapcount) == 0;
+}
+
static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
unsigned long vmaddr)
{
@@ -750,7 +755,7 @@ static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
mp->vmaddr = vmaddr & PMD_MASK;
INIT_LIST_HEAD(&mp->mapper);
page->index = (unsigned long) mp;
- atomic_set(&page->_mapcount, 3);
+ atomic_set(&page->_mapcount, 0);
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);
@@ -821,6 +826,11 @@ EXPORT_SYMBOL(set_guest_storage_key);
#else /* CONFIG_PGSTE */
+static inline int page_table_with_pgste(struct page *page)
+{
+ return 0;
+}
+
static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm,
unsigned long vmaddr)
{
@@ -897,12 +907,12 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
struct page *page;
unsigned int bit, mask;
- if (mm_has_pgste(mm)) {
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ if (page_table_with_pgste(page)) {
gmap_disconnect_pgtable(mm, table);
return page_table_free_pgste(table);
}
/* 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);
if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
@@ -940,14 +950,14 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table)
unsigned int bit, mask;
mm = tlb->mm;
- if (mm_has_pgste(mm)) {
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ if (page_table_with_pgste(page)) {
gmap_disconnect_pgtable(mm, table);
table = (unsigned long *) (__pa(table) | FRAG_MASK);
tlb_remove_table(tlb, table);
return;
}
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);
if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK)
list_del(&page->lru);
@@ -1033,36 +1043,120 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-void thp_split_vma(struct vm_area_struct *vma)
+static inline void thp_split_vma(struct vm_area_struct *vma)
{
unsigned long addr;
- struct page *page;
- for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) {
- page = follow_page(vma, addr, FOLL_SPLIT);
- }
+ for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE)
+ follow_page(vma, addr, FOLL_SPLIT);
}
-void thp_split_mm(struct mm_struct *mm)
+static inline void thp_split_mm(struct mm_struct *mm)
{
- struct vm_area_struct *vma = mm->mmap;
+ struct vm_area_struct *vma;
- while (vma != NULL) {
+ for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
thp_split_vma(vma);
vma->vm_flags &= ~VM_HUGEPAGE;
vma->vm_flags |= VM_NOHUGEPAGE;
- vma = vma->vm_next;
}
+ mm->def_flags |= VM_NOHUGEPAGE;
+}
+#else
+static inline void thp_split_mm(struct mm_struct *mm)
+{
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+static unsigned long page_table_realloc_pmd(struct mmu_gather *tlb,
+ struct mm_struct *mm, pud_t *pud,
+ unsigned long addr, unsigned long end)
+{
+ unsigned long next, *table, *new;
+ struct page *page;
+ pmd_t *pmd;
+
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+again:
+ if (pmd_none_or_clear_bad(pmd))
+ continue;
+ table = (unsigned long *) pmd_deref(*pmd);
+ page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
+ if (page_table_with_pgste(page))
+ continue;
+ /* Allocate new page table with pgstes */
+ new = page_table_alloc_pgste(mm, addr);
+ if (!new) {
+ mm->context.has_pgste = 0;
+ continue;
+ }
+ spin_lock(&mm->page_table_lock);
+ if (likely((unsigned long *) pmd_deref(*pmd) == table)) {
+ /* Nuke pmd entry pointing to the "short" page table */
+ pmdp_flush_lazy(mm, addr, pmd);
+ pmd_clear(pmd);
+ /* Copy ptes from old table to new table */
+ memcpy(new, table, PAGE_SIZE/2);
+ clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
+ /* Establish new table */
+ pmd_populate(mm, pmd, (pte_t *) new);
+ /* Free old table with rcu, there might be a walker! */
+ page_table_free_rcu(tlb, table);
+ new = NULL;
+ }
+ spin_unlock(&mm->page_table_lock);
+ if (new) {
+ page_table_free_pgste(new);
+ goto again;
+ }
+ } while (pmd++, addr = next, addr != end);
+
+ return addr;
+}
+
+static unsigned long page_table_realloc_pud(struct mmu_gather *tlb,
+ struct mm_struct *mm, pgd_t *pgd,
+ unsigned long addr, unsigned long end)
+{
+ unsigned long next;
+ pud_t *pud;
+
+ pud = pud_offset(pgd, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ next = page_table_realloc_pmd(tlb, mm, pud, addr, next);
+ } while (pud++, addr = next, addr != end);
+
+ return addr;
+}
+
+static void page_table_realloc(struct mmu_gather *tlb, struct mm_struct *mm,
+ unsigned long addr, unsigned long end)
+{
+ unsigned long next;
+ pgd_t *pgd;
+
+ pgd = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ next = page_table_realloc_pud(tlb, mm, pgd, addr, next);
+ } while (pgd++, addr = next, addr != end);
+}
+
/*
* switch on pgstes for its userspace process (for kvm)
*/
int s390_enable_sie(void)
{
struct task_struct *tsk = current;
- struct mm_struct *mm, *old_mm;
+ struct mm_struct *mm = tsk->mm;
+ struct mmu_gather tlb;
/* Do we have switched amode? If no, we cannot do sie */
if (s390_user_mode == HOME_SPACE_MODE)
@@ -1072,57 +1166,16 @@ int s390_enable_sie(void)
if (mm_has_pgste(tsk->mm))
return 0;
- /* lets check if we are allowed to replace the mm */
- task_lock(tsk);
- if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
-#ifdef CONFIG_AIO
- !hlist_empty(&tsk->mm->ioctx_list) ||
-#endif
- tsk->mm != tsk->active_mm) {
- task_unlock(tsk);
- return -EINVAL;
- }
- task_unlock(tsk);
-
- /* we copy the mm and let dup_mm create the page tables with_pgstes */
- tsk->mm->context.alloc_pgste = 1;
- /* make sure that both mms have a correct rss state */
- sync_mm_rss(tsk->mm);
- mm = dup_mm(tsk);
- tsk->mm->context.alloc_pgste = 0;
- if (!mm)
- return -ENOMEM;
-
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ down_write(&mm->mmap_sem);
/* split thp mappings and disable thp for future mappings */
thp_split_mm(mm);
- mm->def_flags |= VM_NOHUGEPAGE;
-#endif
-
- /* Now lets check again if something happened */
- task_lock(tsk);
- if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
-#ifdef CONFIG_AIO
- !hlist_empty(&tsk->mm->ioctx_list) ||
-#endif
- tsk->mm != tsk->active_mm) {
- mmput(mm);
- task_unlock(tsk);
- return -EINVAL;
- }
-
- /* ok, we are alone. No ptrace, no threads, etc. */
- old_mm = tsk->mm;
- tsk->mm = tsk->active_mm = mm;
- preempt_disable();
- update_mm(mm, tsk);
- atomic_inc(&mm->context.attach_count);
- atomic_dec(&old_mm->context.attach_count);
- cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
- preempt_enable();
- task_unlock(tsk);
- mmput(old_mm);
- return 0;
+ /* Reallocate the page tables with pgstes */
+ mm->context.has_pgste = 1;
+ tlb_gather_mmu(&tlb, mm, 0);
+ page_table_realloc(&tlb, mm, 0, TASK_SIZE);
+ tlb_finish_mmu(&tlb, 0, -1);
+ up_write(&mm->mmap_sem);
+ return mm->context.has_pgste ? 0 : -ENOMEM;
}
EXPORT_SYMBOL_GPL(s390_enable_sie);
--
1.8.3.1
--
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