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-rw-r--r--arch/s390/mm/pgalloc.c714
1 files changed, 714 insertions, 0 deletions
diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
new file mode 100644
index 000000000..2de48b2c1
--- /dev/null
+++ b/arch/s390/mm/pgalloc.c
@@ -0,0 +1,714 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Page table allocation functions
+ *
+ * Copyright IBM Corp. 2016
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/sysctl.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <asm/mmu_context.h>
+#include <asm/pgalloc.h>
+#include <asm/gmap.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+
+#ifdef CONFIG_PGSTE
+
+int page_table_allocate_pgste = 0;
+EXPORT_SYMBOL(page_table_allocate_pgste);
+
+static struct ctl_table page_table_sysctl[] = {
+ {
+ .procname = "allocate_pgste",
+ .data = &page_table_allocate_pgste,
+ .maxlen = sizeof(int),
+ .mode = S_IRUGO | S_IWUSR,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+ { }
+};
+
+static struct ctl_table page_table_sysctl_dir[] = {
+ {
+ .procname = "vm",
+ .maxlen = 0,
+ .mode = 0555,
+ .child = page_table_sysctl,
+ },
+ { }
+};
+
+static int __init page_table_register_sysctl(void)
+{
+ return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
+}
+__initcall(page_table_register_sysctl);
+
+#endif /* CONFIG_PGSTE */
+
+unsigned long *crst_table_alloc(struct mm_struct *mm)
+{
+ struct page *page = alloc_pages(GFP_KERNEL, CRST_ALLOC_ORDER);
+
+ if (!page)
+ return NULL;
+ arch_set_page_dat(page, CRST_ALLOC_ORDER);
+ return (unsigned long *) page_to_virt(page);
+}
+
+void crst_table_free(struct mm_struct *mm, unsigned long *table)
+{
+ free_pages((unsigned long)table, CRST_ALLOC_ORDER);
+}
+
+static void __crst_table_upgrade(void *arg)
+{
+ struct mm_struct *mm = arg;
+
+ /* change all active ASCEs to avoid the creation of new TLBs */
+ if (current->active_mm == mm) {
+ S390_lowcore.user_asce = mm->context.asce;
+ __ctl_load(S390_lowcore.user_asce, 7, 7);
+ }
+ __tlb_flush_local();
+}
+
+int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
+{
+ unsigned long *pgd = NULL, *p4d = NULL, *__pgd;
+ unsigned long asce_limit = mm->context.asce_limit;
+
+ /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
+ VM_BUG_ON(asce_limit < _REGION2_SIZE);
+
+ if (end <= asce_limit)
+ return 0;
+
+ if (asce_limit == _REGION2_SIZE) {
+ p4d = crst_table_alloc(mm);
+ if (unlikely(!p4d))
+ goto err_p4d;
+ crst_table_init(p4d, _REGION2_ENTRY_EMPTY);
+ }
+ if (end > _REGION1_SIZE) {
+ pgd = crst_table_alloc(mm);
+ if (unlikely(!pgd))
+ goto err_pgd;
+ crst_table_init(pgd, _REGION1_ENTRY_EMPTY);
+ }
+
+ spin_lock_bh(&mm->page_table_lock);
+
+ /*
+ * This routine gets called with mmap_lock lock held and there is
+ * no reason to optimize for the case of otherwise. However, if
+ * that would ever change, the below check will let us know.
+ */
+ VM_BUG_ON(asce_limit != mm->context.asce_limit);
+
+ if (p4d) {
+ __pgd = (unsigned long *) mm->pgd;
+ p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd);
+ mm->pgd = (pgd_t *) p4d;
+ mm->context.asce_limit = _REGION1_SIZE;
+ mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+ _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
+ mm_inc_nr_puds(mm);
+ }
+ if (pgd) {
+ __pgd = (unsigned long *) mm->pgd;
+ pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd);
+ mm->pgd = (pgd_t *) pgd;
+ mm->context.asce_limit = TASK_SIZE_MAX;
+ mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+ _ASCE_USER_BITS | _ASCE_TYPE_REGION1;
+ }
+
+ spin_unlock_bh(&mm->page_table_lock);
+
+ on_each_cpu(__crst_table_upgrade, mm, 0);
+
+ return 0;
+
+err_pgd:
+ crst_table_free(mm, p4d);
+err_p4d:
+ return -ENOMEM;
+}
+
+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;
+}
+
+#ifdef CONFIG_PGSTE
+
+struct page *page_table_alloc_pgste(struct mm_struct *mm)
+{
+ struct page *page;
+ u64 *table;
+
+ page = alloc_page(GFP_KERNEL);
+ if (page) {
+ table = (u64 *)page_to_virt(page);
+ memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
+ memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
+ }
+ return page;
+}
+
+void page_table_free_pgste(struct page *page)
+{
+ __free_page(page);
+}
+
+#endif /* CONFIG_PGSTE */
+
+/*
+ * A 2KB-pgtable is either upper or lower half of a normal page.
+ * The second half of the page may be unused or used as another
+ * 2KB-pgtable.
+ *
+ * Whenever possible the parent page for a new 2KB-pgtable is picked
+ * from the list of partially allocated pages mm_context_t::pgtable_list.
+ * In case the list is empty a new parent page is allocated and added to
+ * the list.
+ *
+ * When a parent page gets fully allocated it contains 2KB-pgtables in both
+ * upper and lower halves and is removed from mm_context_t::pgtable_list.
+ *
+ * When 2KB-pgtable is freed from to fully allocated parent page that
+ * page turns partially allocated and added to mm_context_t::pgtable_list.
+ *
+ * If 2KB-pgtable is freed from the partially allocated parent page that
+ * page turns unused and gets removed from mm_context_t::pgtable_list.
+ * Furthermore, the unused parent page is released.
+ *
+ * As follows from the above, no unallocated or fully allocated parent
+ * pages are contained in mm_context_t::pgtable_list.
+ *
+ * The upper byte (bits 24-31) of the parent page _refcount is used
+ * for tracking contained 2KB-pgtables and has the following format:
+ *
+ * PP AA
+ * 01234567 upper byte (bits 24-31) of struct page::_refcount
+ * || ||
+ * || |+--- upper 2KB-pgtable is allocated
+ * || +---- lower 2KB-pgtable is allocated
+ * |+------- upper 2KB-pgtable is pending for removal
+ * +-------- lower 2KB-pgtable is pending for removal
+ *
+ * (See commit 620b4e903179 ("s390: use _refcount for pgtables") on why
+ * using _refcount is possible).
+ *
+ * When 2KB-pgtable is allocated the corresponding AA bit is set to 1.
+ * The parent page is either:
+ * - added to mm_context_t::pgtable_list in case the second half of the
+ * parent page is still unallocated;
+ * - removed from mm_context_t::pgtable_list in case both hales of the
+ * parent page are allocated;
+ * These operations are protected with mm_context_t::lock.
+ *
+ * When 2KB-pgtable is deallocated the corresponding AA bit is set to 0
+ * and the corresponding PP bit is set to 1 in a single atomic operation.
+ * Thus, PP and AA bits corresponding to the same 2KB-pgtable are mutually
+ * exclusive and may never be both set to 1!
+ * The parent page is either:
+ * - added to mm_context_t::pgtable_list in case the second half of the
+ * parent page is still allocated;
+ * - removed from mm_context_t::pgtable_list in case the second half of
+ * the parent page is unallocated;
+ * These operations are protected with mm_context_t::lock.
+ *
+ * It is important to understand that mm_context_t::lock only protects
+ * mm_context_t::pgtable_list and AA bits, but not the parent page itself
+ * and PP bits.
+ *
+ * Releasing the parent page happens whenever the PP bit turns from 1 to 0,
+ * while both AA bits and the second PP bit are already unset. Then the
+ * parent page does not contain any 2KB-pgtable fragment anymore, and it has
+ * also been removed from mm_context_t::pgtable_list. It is safe to release
+ * the page therefore.
+ *
+ * PGSTE memory spaces use full 4KB-pgtables and do not need most of the
+ * logic described above. Both AA bits are set to 1 to denote a 4KB-pgtable
+ * while the PP bits are never used, nor such a page is added to or removed
+ * from mm_context_t::pgtable_list.
+ */
+unsigned long *page_table_alloc(struct mm_struct *mm)
+{
+ unsigned long *table;
+ struct page *page;
+ unsigned int mask, bit;
+
+ /* Try to get a fragment of a 4K page as a 2K page table */
+ if (!mm_alloc_pgste(mm)) {
+ table = NULL;
+ spin_lock_bh(&mm->context.lock);
+ if (!list_empty(&mm->context.pgtable_list)) {
+ page = list_first_entry(&mm->context.pgtable_list,
+ struct page, lru);
+ mask = atomic_read(&page->_refcount) >> 24;
+ /*
+ * The pending removal bits must also be checked.
+ * Failure to do so might lead to an impossible
+ * value of (i.e 0x13 or 0x23) written to _refcount.
+ * Such values violate the assumption that pending and
+ * allocation bits are mutually exclusive, and the rest
+ * of the code unrails as result. That could lead to
+ * a whole bunch of races and corruptions.
+ */
+ mask = (mask | (mask >> 4)) & 0x03U;
+ if (mask != 0x03U) {
+ table = (unsigned long *) page_to_virt(page);
+ bit = mask & 1; /* =1 -> second 2K */
+ if (bit)
+ table += PTRS_PER_PTE;
+ atomic_xor_bits(&page->_refcount,
+ 0x01U << (bit + 24));
+ list_del(&page->lru);
+ }
+ }
+ spin_unlock_bh(&mm->context.lock);
+ if (table)
+ return table;
+ }
+ /* Allocate a fresh page */
+ page = alloc_page(GFP_KERNEL);
+ if (!page)
+ return NULL;
+ if (!pgtable_pte_page_ctor(page)) {
+ __free_page(page);
+ return NULL;
+ }
+ arch_set_page_dat(page, 0);
+ /* Initialize page table */
+ table = (unsigned long *) page_to_virt(page);
+ if (mm_alloc_pgste(mm)) {
+ /* Return 4K page table with PGSTEs */
+ atomic_xor_bits(&page->_refcount, 0x03U << 24);
+ memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
+ memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
+ } else {
+ /* Return the first 2K fragment of the page */
+ atomic_xor_bits(&page->_refcount, 0x01U << 24);
+ memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE);
+ spin_lock_bh(&mm->context.lock);
+ list_add(&page->lru, &mm->context.pgtable_list);
+ spin_unlock_bh(&mm->context.lock);
+ }
+ return table;
+}
+
+static void page_table_release_check(struct page *page, void *table,
+ unsigned int half, unsigned int mask)
+{
+ char msg[128];
+
+ if (!IS_ENABLED(CONFIG_DEBUG_VM) || !mask)
+ return;
+ snprintf(msg, sizeof(msg),
+ "Invalid pgtable %p release half 0x%02x mask 0x%02x",
+ table, half, mask);
+ dump_page(page, msg);
+}
+
+void page_table_free(struct mm_struct *mm, unsigned long *table)
+{
+ unsigned int mask, bit, half;
+ struct page *page;
+
+ page = virt_to_page(table);
+ if (!mm_alloc_pgste(mm)) {
+ /* Free 2K page table fragment of a 4K page */
+ bit = ((unsigned long) table & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
+ spin_lock_bh(&mm->context.lock);
+ /*
+ * Mark the page for delayed release. The actual release
+ * will happen outside of the critical section from this
+ * function or from __tlb_remove_table()
+ */
+ mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24));
+ mask >>= 24;
+ if (mask & 0x03U)
+ list_add(&page->lru, &mm->context.pgtable_list);
+ else
+ list_del(&page->lru);
+ spin_unlock_bh(&mm->context.lock);
+ mask = atomic_xor_bits(&page->_refcount, 0x10U << (bit + 24));
+ mask >>= 24;
+ if (mask != 0x00U)
+ return;
+ half = 0x01U << bit;
+ } else {
+ half = 0x03U;
+ mask = atomic_xor_bits(&page->_refcount, 0x03U << 24);
+ mask >>= 24;
+ }
+
+ page_table_release_check(page, table, half, mask);
+ pgtable_pte_page_dtor(page);
+ __free_page(page);
+}
+
+void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
+ unsigned long vmaddr)
+{
+ struct mm_struct *mm;
+ struct page *page;
+ unsigned int bit, mask;
+
+ mm = tlb->mm;
+ page = virt_to_page(table);
+ if (mm_alloc_pgste(mm)) {
+ gmap_unlink(mm, table, vmaddr);
+ table = (unsigned long *) ((unsigned long)table | 0x03U);
+ tlb_remove_table(tlb, table);
+ return;
+ }
+ bit = ((unsigned long) table & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
+ spin_lock_bh(&mm->context.lock);
+ /*
+ * Mark the page for delayed release. The actual release will happen
+ * outside of the critical section from __tlb_remove_table() or from
+ * page_table_free()
+ */
+ mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24));
+ mask >>= 24;
+ if (mask & 0x03U)
+ list_add_tail(&page->lru, &mm->context.pgtable_list);
+ else
+ list_del(&page->lru);
+ spin_unlock_bh(&mm->context.lock);
+ table = (unsigned long *) ((unsigned long) table | (0x01U << bit));
+ tlb_remove_table(tlb, table);
+}
+
+void __tlb_remove_table(void *_table)
+{
+ unsigned int mask = (unsigned long) _table & 0x03U, half = mask;
+ void *table = (void *)((unsigned long) _table ^ mask);
+ struct page *page = virt_to_page(table);
+
+ switch (half) {
+ case 0x00U: /* pmd, pud, or p4d */
+ free_pages((unsigned long)table, CRST_ALLOC_ORDER);
+ return;
+ case 0x01U: /* lower 2K of a 4K page table */
+ case 0x02U: /* higher 2K of a 4K page table */
+ mask = atomic_xor_bits(&page->_refcount, mask << (4 + 24));
+ mask >>= 24;
+ if (mask != 0x00U)
+ return;
+ break;
+ case 0x03U: /* 4K page table with pgstes */
+ mask = atomic_xor_bits(&page->_refcount, 0x03U << 24);
+ mask >>= 24;
+ break;
+ }
+
+ page_table_release_check(page, table, half, mask);
+ pgtable_pte_page_dtor(page);
+ __free_page(page);
+}
+
+/*
+ * Base infrastructure required to generate basic asces, region, segment,
+ * and page tables that do not make use of enhanced features like EDAT1.
+ */
+
+static struct kmem_cache *base_pgt_cache;
+
+static unsigned long *base_pgt_alloc(void)
+{
+ unsigned long *table;
+
+ table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL);
+ if (table)
+ memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
+ return table;
+}
+
+static void base_pgt_free(unsigned long *table)
+{
+ kmem_cache_free(base_pgt_cache, table);
+}
+
+static unsigned long *base_crst_alloc(unsigned long val)
+{
+ unsigned long *table;
+
+ table = (unsigned long *)__get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER);
+ if (table)
+ crst_table_init(table, val);
+ return table;
+}
+
+static void base_crst_free(unsigned long *table)
+{
+ free_pages((unsigned long)table, CRST_ALLOC_ORDER);
+}
+
+#define BASE_ADDR_END_FUNC(NAME, SIZE) \
+static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \
+ unsigned long end) \
+{ \
+ unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \
+ \
+ return (next - 1) < (end - 1) ? next : end; \
+}
+
+BASE_ADDR_END_FUNC(page, _PAGE_SIZE)
+BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE)
+BASE_ADDR_END_FUNC(region3, _REGION3_SIZE)
+BASE_ADDR_END_FUNC(region2, _REGION2_SIZE)
+BASE_ADDR_END_FUNC(region1, _REGION1_SIZE)
+
+static inline unsigned long base_lra(unsigned long address)
+{
+ unsigned long real;
+
+ asm volatile(
+ " lra %0,0(%1)\n"
+ : "=d" (real) : "a" (address) : "cc");
+ return real;
+}
+
+static int base_page_walk(unsigned long *origin, unsigned long addr,
+ unsigned long end, int alloc)
+{
+ unsigned long *pte, next;
+
+ if (!alloc)
+ return 0;
+ pte = origin;
+ pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT;
+ do {
+ next = base_page_addr_end(addr, end);
+ *pte = base_lra(addr);
+ } while (pte++, addr = next, addr < end);
+ return 0;
+}
+
+static int base_segment_walk(unsigned long *origin, unsigned long addr,
+ unsigned long end, int alloc)
+{
+ unsigned long *ste, next, *table;
+ int rc;
+
+ ste = origin;
+ ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
+ do {
+ next = base_segment_addr_end(addr, end);
+ if (*ste & _SEGMENT_ENTRY_INVALID) {
+ if (!alloc)
+ continue;
+ table = base_pgt_alloc();
+ if (!table)
+ return -ENOMEM;
+ *ste = __pa(table) | _SEGMENT_ENTRY;
+ }
+ table = __va(*ste & _SEGMENT_ENTRY_ORIGIN);
+ rc = base_page_walk(table, addr, next, alloc);
+ if (rc)
+ return rc;
+ if (!alloc)
+ base_pgt_free(table);
+ cond_resched();
+ } while (ste++, addr = next, addr < end);
+ return 0;
+}
+
+static int base_region3_walk(unsigned long *origin, unsigned long addr,
+ unsigned long end, int alloc)
+{
+ unsigned long *rtte, next, *table;
+ int rc;
+
+ rtte = origin;
+ rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT;
+ do {
+ next = base_region3_addr_end(addr, end);
+ if (*rtte & _REGION_ENTRY_INVALID) {
+ if (!alloc)
+ continue;
+ table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
+ if (!table)
+ return -ENOMEM;
+ *rtte = __pa(table) | _REGION3_ENTRY;
+ }
+ table = __va(*rtte & _REGION_ENTRY_ORIGIN);
+ rc = base_segment_walk(table, addr, next, alloc);
+ if (rc)
+ return rc;
+ if (!alloc)
+ base_crst_free(table);
+ } while (rtte++, addr = next, addr < end);
+ return 0;
+}
+
+static int base_region2_walk(unsigned long *origin, unsigned long addr,
+ unsigned long end, int alloc)
+{
+ unsigned long *rste, next, *table;
+ int rc;
+
+ rste = origin;
+ rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT;
+ do {
+ next = base_region2_addr_end(addr, end);
+ if (*rste & _REGION_ENTRY_INVALID) {
+ if (!alloc)
+ continue;
+ table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
+ if (!table)
+ return -ENOMEM;
+ *rste = __pa(table) | _REGION2_ENTRY;
+ }
+ table = __va(*rste & _REGION_ENTRY_ORIGIN);
+ rc = base_region3_walk(table, addr, next, alloc);
+ if (rc)
+ return rc;
+ if (!alloc)
+ base_crst_free(table);
+ } while (rste++, addr = next, addr < end);
+ return 0;
+}
+
+static int base_region1_walk(unsigned long *origin, unsigned long addr,
+ unsigned long end, int alloc)
+{
+ unsigned long *rfte, next, *table;
+ int rc;
+
+ rfte = origin;
+ rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT;
+ do {
+ next = base_region1_addr_end(addr, end);
+ if (*rfte & _REGION_ENTRY_INVALID) {
+ if (!alloc)
+ continue;
+ table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
+ if (!table)
+ return -ENOMEM;
+ *rfte = __pa(table) | _REGION1_ENTRY;
+ }
+ table = __va(*rfte & _REGION_ENTRY_ORIGIN);
+ rc = base_region2_walk(table, addr, next, alloc);
+ if (rc)
+ return rc;
+ if (!alloc)
+ base_crst_free(table);
+ } while (rfte++, addr = next, addr < end);
+ return 0;
+}
+
+/**
+ * base_asce_free - free asce and tables returned from base_asce_alloc()
+ * @asce: asce to be freed
+ *
+ * Frees all region, segment, and page tables that were allocated with a
+ * corresponding base_asce_alloc() call.
+ */
+void base_asce_free(unsigned long asce)
+{
+ unsigned long *table = __va(asce & _ASCE_ORIGIN);
+
+ if (!asce)
+ return;
+ switch (asce & _ASCE_TYPE_MASK) {
+ case _ASCE_TYPE_SEGMENT:
+ base_segment_walk(table, 0, _REGION3_SIZE, 0);
+ break;
+ case _ASCE_TYPE_REGION3:
+ base_region3_walk(table, 0, _REGION2_SIZE, 0);
+ break;
+ case _ASCE_TYPE_REGION2:
+ base_region2_walk(table, 0, _REGION1_SIZE, 0);
+ break;
+ case _ASCE_TYPE_REGION1:
+ base_region1_walk(table, 0, TASK_SIZE_MAX, 0);
+ break;
+ }
+ base_crst_free(table);
+}
+
+static int base_pgt_cache_init(void)
+{
+ static DEFINE_MUTEX(base_pgt_cache_mutex);
+ unsigned long sz = _PAGE_TABLE_SIZE;
+
+ if (base_pgt_cache)
+ return 0;
+ mutex_lock(&base_pgt_cache_mutex);
+ if (!base_pgt_cache)
+ base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL);
+ mutex_unlock(&base_pgt_cache_mutex);
+ return base_pgt_cache ? 0 : -ENOMEM;
+}
+
+/**
+ * base_asce_alloc - create kernel mapping without enhanced DAT features
+ * @addr: virtual start address of kernel mapping
+ * @num_pages: number of consecutive pages
+ *
+ * Generate an asce, including all required region, segment and page tables,
+ * that can be used to access the virtual kernel mapping. The difference is
+ * that the returned asce does not make use of any enhanced DAT features like
+ * e.g. large pages. This is required for some I/O functions that pass an
+ * asce, like e.g. some service call requests.
+ *
+ * Note: the returned asce may NEVER be attached to any cpu. It may only be
+ * used for I/O requests. tlb entries that might result because the
+ * asce was attached to a cpu won't be cleared.
+ */
+unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages)
+{
+ unsigned long asce, *table, end;
+ int rc;
+
+ if (base_pgt_cache_init())
+ return 0;
+ end = addr + num_pages * PAGE_SIZE;
+ if (end <= _REGION3_SIZE) {
+ table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY);
+ if (!table)
+ return 0;
+ rc = base_segment_walk(table, addr, end, 1);
+ asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH;
+ } else if (end <= _REGION2_SIZE) {
+ table = base_crst_alloc(_REGION3_ENTRY_EMPTY);
+ if (!table)
+ return 0;
+ rc = base_region3_walk(table, addr, end, 1);
+ asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
+ } else if (end <= _REGION1_SIZE) {
+ table = base_crst_alloc(_REGION2_ENTRY_EMPTY);
+ if (!table)
+ return 0;
+ rc = base_region2_walk(table, addr, end, 1);
+ asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
+ } else {
+ table = base_crst_alloc(_REGION1_ENTRY_EMPTY);
+ if (!table)
+ return 0;
+ rc = base_region1_walk(table, addr, end, 1);
+ asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH;
+ }
+ if (rc) {
+ base_asce_free(asce);
+ asce = 0;
+ }
+ return asce;
+}