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// 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/page-states.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 int __init page_table_register_sysctl(void)
{
return register_sysctl("vm", page_table_sysctl) ? 0 : -ENOMEM;
}
__initcall(page_table_register_sysctl);
#endif /* CONFIG_PGSTE */
unsigned long *crst_table_alloc(struct mm_struct *mm)
{
struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER);
unsigned long *table;
if (!ptdesc)
return NULL;
table = ptdesc_to_virt(ptdesc);
__arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER);
return table;
}
void crst_table_free(struct mm_struct *mm, unsigned long *table)
{
pagetable_free(virt_to_ptdesc(table));
}
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.val = mm->context.asce;
local_ctl_load(7, &S390_lowcore.user_asce);
}
__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;
}
#ifdef CONFIG_PGSTE
struct ptdesc *page_table_alloc_pgste(struct mm_struct *mm)
{
struct ptdesc *ptdesc;
u64 *table;
ptdesc = pagetable_alloc(GFP_KERNEL, 0);
if (ptdesc) {
table = (u64 *)ptdesc_to_virt(ptdesc);
__arch_set_page_dat(table, 1);
memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
}
return ptdesc;
}
void page_table_free_pgste(struct ptdesc *ptdesc)
{
pagetable_free(ptdesc);
}
#endif /* CONFIG_PGSTE */
unsigned long *page_table_alloc(struct mm_struct *mm)
{
struct ptdesc *ptdesc;
unsigned long *table;
ptdesc = pagetable_alloc(GFP_KERNEL, 0);
if (!ptdesc)
return NULL;
if (!pagetable_pte_ctor(ptdesc)) {
pagetable_free(ptdesc);
return NULL;
}
table = ptdesc_to_virt(ptdesc);
__arch_set_page_dat(table, 1);
/* pt_list is used by gmap only */
INIT_LIST_HEAD(&ptdesc->pt_list);
memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
return table;
}
static void pagetable_pte_dtor_free(struct ptdesc *ptdesc)
{
pagetable_pte_dtor(ptdesc);
pagetable_free(ptdesc);
}
void page_table_free(struct mm_struct *mm, unsigned long *table)
{
struct ptdesc *ptdesc = virt_to_ptdesc(table);
pagetable_pte_dtor_free(ptdesc);
}
void __tlb_remove_table(void *table)
{
struct ptdesc *ptdesc = virt_to_ptdesc(table);
struct page *page = ptdesc_page(ptdesc);
if (compound_order(page) == CRST_ALLOC_ORDER) {
/* pmd, pud, or p4d */
pagetable_free(ptdesc);
return;
}
pagetable_pte_dtor_free(ptdesc);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void pte_free_now(struct rcu_head *head)
{
struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head);
pagetable_pte_dtor_free(ptdesc);
}
void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable)
{
struct ptdesc *ptdesc = virt_to_ptdesc(pgtable);
call_rcu(&ptdesc->pt_rcu_head, pte_free_now);
/*
* THPs are not allowed for KVM guests. Warn if pgste ever reaches here.
* Turn to the generic pte_free_defer() version once gmap is removed.
*/
WARN_ON_ONCE(mm_has_pgste(mm));
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/*
* 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;
struct ptdesc *ptdesc;
ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER);
if (!ptdesc)
return NULL;
table = ptdesc_address(ptdesc);
crst_table_init(table, val);
return table;
}
static void base_crst_free(unsigned long *table)
{
pagetable_free(virt_to_ptdesc(table));
}
#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;
}