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c427c42cd6
linux/arch/s390/mm/pgtable.c
David Hildenbrand c427c42cd6 s390/mm: don't drop errors in get_guest_storage_key 
Commit 1e133ab296 ("s390/mm: split arch/s390/mm/pgtable.c") changed
the return value of get_guest_storage_key to an unsigned char, resulting
in -EFAULT getting interpreted as a valid storage key.

Cc: stable@vger.kernel.org # 4.6+
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2016-06-10 12:07:26 +02:00

583 lines
14 KiB
C
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/*
* Copyright IBM Corp. 2007, 2011
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/sysctl.h>
#include <linux/ksm.h>
#include <linux/mman.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
static inline pte_t ptep_flush_direct(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
int active, count;
pte_t old;
old = *ptep;
if (unlikely(pte_val(old) & _PAGE_INVALID))
return old;
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&
cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
__ptep_ipte_local(addr, ptep);
else
__ptep_ipte(addr, ptep);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
static inline pte_t ptep_flush_lazy(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
int active, count;
pte_t old;
old = *ptep;
if (unlikely(pte_val(old) & _PAGE_INVALID))
return old;
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if ((count & 0xffff) <= active) {
pte_val(*ptep) |= _PAGE_INVALID;
mm->context.flush_mm = 1;
} else
__ptep_ipte(addr, ptep);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
static inline pgste_t pgste_get_lock(pte_t *ptep)
{
unsigned long new = 0;
#ifdef CONFIG_PGSTE
unsigned long old;
preempt_disable();
asm(
" lg %0,%2\n"
"0: lgr %1,%0\n"
" nihh %0,0xff7f\n" /* clear PCL bit in old */
" oihh %1,0x0080\n" /* set PCL bit in new */
" csg %0,%1,%2\n"
" jl 0b\n"
: "=&d" (old), "=&d" (new), "=Q" (ptep[PTRS_PER_PTE])
: "Q" (ptep[PTRS_PER_PTE]) : "cc", "memory");
#endif
return __pgste(new);
}
static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
asm(
" nihh %1,0xff7f\n" /* clear PCL bit */
" stg %1,%0\n"
: "=Q" (ptep[PTRS_PER_PTE])
: "d" (pgste_val(pgste)), "Q" (ptep[PTRS_PER_PTE])
: "cc", "memory");
preempt_enable();
#endif
}
static inline pgste_t pgste_get(pte_t *ptep)
{
unsigned long pgste = 0;
#ifdef CONFIG_PGSTE
pgste = *(unsigned long *)(ptep + PTRS_PER_PTE);
#endif
return __pgste(pgste);
}
static inline void pgste_set(pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
*(pgste_t *)(ptep + PTRS_PER_PTE) = pgste;
#endif
}
static inline pgste_t pgste_update_all(pte_t pte, pgste_t pgste,
struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
unsigned long address, bits, skey;
if (!mm_use_skey(mm) || pte_val(pte) & _PAGE_INVALID)
return pgste;
address = pte_val(pte) & PAGE_MASK;
skey = (unsigned long) page_get_storage_key(address);
bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
/* Transfer page changed & referenced bit to guest bits in pgste */
pgste_val(pgste) |= bits << 48; /* GR bit & GC bit */
/* Copy page access key and fetch protection bit to pgste */
pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT);
pgste_val(pgste) |= (skey & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
#endif
return pgste;
}
static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry,
struct mm_struct *mm)
{
#ifdef CONFIG_PGSTE
unsigned long address;
unsigned long nkey;
if (!mm_use_skey(mm) || pte_val(entry) & _PAGE_INVALID)
return;
VM_BUG_ON(!(pte_val(*ptep) & _PAGE_INVALID));
address = pte_val(entry) & PAGE_MASK;
/*
* Set page access key and fetch protection bit from pgste.
* The guest C/R information is still in the PGSTE, set real
* key C/R to 0.
*/
nkey = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
nkey |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
page_set_storage_key(address, nkey, 0);
#endif
}
static inline pgste_t pgste_set_pte(pte_t *ptep, pgste_t pgste, pte_t entry)
{
#ifdef CONFIG_PGSTE
if ((pte_val(entry) & _PAGE_PRESENT) &&
(pte_val(entry) & _PAGE_WRITE) &&
!(pte_val(entry) & _PAGE_INVALID)) {
if (!MACHINE_HAS_ESOP) {
/*
* Without enhanced suppression-on-protection force
* the dirty bit on for all writable ptes.
*/
pte_val(entry) |= _PAGE_DIRTY;
pte_val(entry) &= ~_PAGE_PROTECT;
}
if (!(pte_val(entry) & _PAGE_PROTECT))
/* This pte allows write access, set user-dirty */
pgste_val(pgste) |= PGSTE_UC_BIT;
}
#endif
*ptep = entry;
return pgste;
}
static inline pgste_t pgste_ipte_notify(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep, pgste_t pgste)
{
#ifdef CONFIG_PGSTE
if (pgste_val(pgste) & PGSTE_IN_BIT) {
pgste_val(pgste) &= ~PGSTE_IN_BIT;
ptep_notify(mm, addr, ptep);
}
#endif
return pgste;
}
static inline pgste_t ptep_xchg_start(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
pgste_t pgste = __pgste(0);
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste = pgste_ipte_notify(mm, addr, ptep, pgste);
}
return pgste;
}
static inline void ptep_xchg_commit(struct mm_struct *mm,
unsigned long addr, pte_t *ptep,
pgste_t pgste, pte_t old, pte_t new)
{
if (mm_has_pgste(mm)) {
if (pte_val(old) & _PAGE_INVALID)
pgste_set_key(ptep, pgste, new, mm);
if (pte_val(new) & _PAGE_INVALID) {
pgste = pgste_update_all(old, pgste, mm);
if ((pgste_val(pgste) & _PGSTE_GPS_USAGE_MASK) ==
_PGSTE_GPS_USAGE_UNUSED)
pte_val(old) |= _PAGE_UNUSED;
}
pgste = pgste_set_pte(ptep, pgste, new);
pgste_set_unlock(ptep, pgste);
} else {
*ptep = new;
}
}
pte_t ptep_xchg_direct(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t new)
{
pgste_t pgste;
pte_t old;
pgste = ptep_xchg_start(mm, addr, ptep);
old = ptep_flush_direct(mm, addr, ptep);
ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
return old;
}
EXPORT_SYMBOL(ptep_xchg_direct);
pte_t ptep_xchg_lazy(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t new)
{
pgste_t pgste;
pte_t old;
pgste = ptep_xchg_start(mm, addr, ptep);
old = ptep_flush_lazy(mm, addr, ptep);
ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
return old;
}
EXPORT_SYMBOL(ptep_xchg_lazy);
pte_t ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
pgste_t pgste;
pte_t old;
pgste = ptep_xchg_start(mm, addr, ptep);
old = ptep_flush_lazy(mm, addr, ptep);
if (mm_has_pgste(mm)) {
pgste = pgste_update_all(old, pgste, mm);
pgste_set(ptep, pgste);
}
return old;
}
EXPORT_SYMBOL(ptep_modify_prot_start);
void ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
pgste_t pgste;
if (mm_has_pgste(mm)) {
pgste = pgste_get(ptep);
pgste_set_key(ptep, pgste, pte, mm);
pgste = pgste_set_pte(ptep, pgste, pte);
pgste_set_unlock(ptep, pgste);
} else {
*ptep = pte;
}
}
EXPORT_SYMBOL(ptep_modify_prot_commit);
static inline pmd_t pmdp_flush_direct(struct mm_struct *mm,
unsigned long addr, pmd_t *pmdp)
{
int active, count;
pmd_t old;
old = *pmdp;
if (pmd_val(old) & _SEGMENT_ENTRY_INVALID)
return old;
if (!MACHINE_HAS_IDTE) {
__pmdp_csp(pmdp);
return old;
}
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if (MACHINE_HAS_TLB_LC && (count & 0xffff) <= active &&
cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
__pmdp_idte_local(addr, pmdp);
else
__pmdp_idte(addr, pmdp);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
static inline pmd_t pmdp_flush_lazy(struct mm_struct *mm,
unsigned long addr, pmd_t *pmdp)
{
int active, count;
pmd_t old;
old = *pmdp;
if (pmd_val(old) & _SEGMENT_ENTRY_INVALID)
return old;
active = (mm == current->active_mm) ? 1 : 0;
count = atomic_add_return(0x10000, &mm->context.attach_count);
if ((count & 0xffff) <= active) {
pmd_val(*pmdp) |= _SEGMENT_ENTRY_INVALID;
mm->context.flush_mm = 1;
} else if (MACHINE_HAS_IDTE)
__pmdp_idte(addr, pmdp);
else
__pmdp_csp(pmdp);
atomic_sub(0x10000, &mm->context.attach_count);
return old;
}
pmd_t pmdp_xchg_direct(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t new)
{
pmd_t old;
old = pmdp_flush_direct(mm, addr, pmdp);
*pmdp = new;
return old;
}
EXPORT_SYMBOL(pmdp_xchg_direct);
pmd_t pmdp_xchg_lazy(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t new)
{
pmd_t old;
old = pmdp_flush_lazy(mm, addr, pmdp);
*pmdp = new;
return old;
}
EXPORT_SYMBOL(pmdp_xchg_lazy);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable)
{
struct list_head *lh = (struct list_head *) pgtable;
assert_spin_locked(pmd_lockptr(mm, pmdp));
/* FIFO */
if (!pmd_huge_pte(mm, pmdp))
INIT_LIST_HEAD(lh);
else
list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
pmd_huge_pte(mm, pmdp) = pgtable;
}
pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
struct list_head *lh;
pgtable_t pgtable;
pte_t *ptep;
assert_spin_locked(pmd_lockptr(mm, pmdp));
/* FIFO */
pgtable = pmd_huge_pte(mm, pmdp);
lh = (struct list_head *) pgtable;
if (list_empty(lh))
pmd_huge_pte(mm, pmdp) = NULL;
else {
pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
list_del(lh);
}
ptep = (pte_t *) pgtable;
pte_val(*ptep) = _PAGE_INVALID;
ptep++;
pte_val(*ptep) = _PAGE_INVALID;
return pgtable;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#ifdef CONFIG_PGSTE
void ptep_set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t entry)
{
pgste_t pgste;
/* the mm_has_pgste() check is done in set_pte_at() */
pgste = pgste_get_lock(ptep);
pgste_val(pgste) &= ~_PGSTE_GPS_ZERO;
pgste_set_key(ptep, pgste, entry, mm);
pgste = pgste_set_pte(ptep, pgste, entry);
pgste_set_unlock(ptep, pgste);
}
void ptep_set_notify(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
pgste_t pgste;
pgste = pgste_get_lock(ptep);
pgste_val(pgste) |= PGSTE_IN_BIT;
pgste_set_unlock(ptep, pgste);
}
static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
{
if (!non_swap_entry(entry))
dec_mm_counter(mm, MM_SWAPENTS);
else if (is_migration_entry(entry)) {
struct page *page = migration_entry_to_page(entry);
dec_mm_counter(mm, mm_counter(page));
}
free_swap_and_cache(entry);
}
void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, int reset)
{
unsigned long pgstev;
pgste_t pgste;
pte_t pte;
/* Zap unused and logically-zero pages */
pgste = pgste_get_lock(ptep);
pgstev = pgste_val(pgste);
pte = *ptep;
if (pte_swap(pte) &&
((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED ||
(pgstev & _PGSTE_GPS_ZERO))) {
ptep_zap_swap_entry(mm, pte_to_swp_entry(pte));
pte_clear(mm, addr, ptep);
}
if (reset)
pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK;
pgste_set_unlock(ptep, pgste);
}
void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
unsigned long ptev;
pgste_t pgste;
/* Clear storage key */
pgste = pgste_get_lock(ptep);
pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT |
PGSTE_GR_BIT | PGSTE_GC_BIT);
ptev = pte_val(*ptep);
if (!(ptev & _PAGE_INVALID) && (ptev & _PAGE_WRITE))
page_set_storage_key(ptev & PAGE_MASK, PAGE_DEFAULT_KEY, 1);
pgste_set_unlock(ptep, pgste);
}
/*
* Test and reset if a guest page is dirty
*/
bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long addr)
{
spinlock_t *ptl;
pgste_t pgste;
pte_t *ptep;
pte_t pte;
bool dirty;
ptep = get_locked_pte(mm, addr, &ptl);
if (unlikely(!ptep))
return false;
pgste = pgste_get_lock(ptep);
dirty = !!(pgste_val(pgste) & PGSTE_UC_BIT);
pgste_val(pgste) &= ~PGSTE_UC_BIT;
pte = *ptep;
if (dirty && (pte_val(pte) & _PAGE_PRESENT)) {
pgste = pgste_ipte_notify(mm, addr, ptep, pgste);
__ptep_ipte(addr, ptep);
if (MACHINE_HAS_ESOP || !(pte_val(pte) & _PAGE_WRITE))
pte_val(pte) |= _PAGE_PROTECT;
else
pte_val(pte) |= _PAGE_INVALID;
*ptep = pte;
}
pgste_set_unlock(ptep, pgste);
spin_unlock(ptl);
return dirty;
}
EXPORT_SYMBOL_GPL(test_and_clear_guest_dirty);
int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned char key, bool nq)
{
unsigned long keyul;
spinlock_t *ptl;
pgste_t old, new;
pte_t *ptep;
down_read(&mm->mmap_sem);
ptep = get_locked_pte(mm, addr, &ptl);
if (unlikely(!ptep)) {
up_read(&mm->mmap_sem);
return -EFAULT;
}
new = old = pgste_get_lock(ptep);
pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
PGSTE_ACC_BITS | PGSTE_FP_BIT);
keyul = (unsigned long) key;
pgste_val(new) |= (keyul & (_PAGE_CHANGED | _PAGE_REFERENCED)) << 48;
pgste_val(new) |= (keyul & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
if (!(pte_val(*ptep) & _PAGE_INVALID)) {
unsigned long address, bits, skey;
address = pte_val(*ptep) & PAGE_MASK;
skey = (unsigned long) page_get_storage_key(address);
bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
skey = key & (_PAGE_ACC_BITS | _PAGE_FP_BIT);
/* Set storage key ACC and FP */
page_set_storage_key(address, skey, !nq);
/* Merge host changed & referenced into pgste */
pgste_val(new) |= bits << 52;
}
/* changing the guest storage key is considered a change of the page */
if ((pgste_val(new) ^ pgste_val(old)) &
(PGSTE_ACC_BITS | PGSTE_FP_BIT | PGSTE_GR_BIT | PGSTE_GC_BIT))
pgste_val(new) |= PGSTE_UC_BIT;
pgste_set_unlock(ptep, new);
pte_unmap_unlock(ptep, ptl);
up_read(&mm->mmap_sem);
return 0;
}
EXPORT_SYMBOL(set_guest_storage_key);
unsigned long get_guest_storage_key(struct mm_struct *mm, unsigned long addr)
{
unsigned char key;
spinlock_t *ptl;
pgste_t pgste;
pte_t *ptep;
down_read(&mm->mmap_sem);
ptep = get_locked_pte(mm, addr, &ptl);
if (unlikely(!ptep)) {
up_read(&mm->mmap_sem);
return -EFAULT;
}
pgste = pgste_get_lock(ptep);
if (pte_val(*ptep) & _PAGE_INVALID) {
key = (pgste_val(pgste) & PGSTE_ACC_BITS) >> 56;
key |= (pgste_val(pgste) & PGSTE_FP_BIT) >> 56;
key |= (pgste_val(pgste) & PGSTE_GR_BIT) >> 48;
key |= (pgste_val(pgste) & PGSTE_GC_BIT) >> 48;
} else {
key = page_get_storage_key(pte_val(*ptep) & PAGE_MASK);
/* Reflect guest's logical view, not physical */
if (pgste_val(pgste) & PGSTE_GR_BIT)
key |= _PAGE_REFERENCED;
if (pgste_val(pgste) & PGSTE_GC_BIT)
key |= _PAGE_CHANGED;
}
pgste_set_unlock(ptep, pgste);
pte_unmap_unlock(ptep, ptl);
up_read(&mm->mmap_sem);
return key;
}
EXPORT_SYMBOL(get_guest_storage_key);
#endif
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