From a9809407f6b6b4b55df7b6cf5522e39476b7e5e6 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 6 Jun 2016 10:30:45 +0200 Subject: s390/mm: fix vunmap vs finish_arch_post_lock_switch The vunmap_pte_range() function calls ptep_get_and_clear() without any locking. ptep_get_and_clear() uses ptep_xchg_lazy()/ptep_flush_direct() for the page table update. ptep_flush_direct requires that preemption is disabled, but without any locking this is not the case. If the kernel preempts the task while the attach_counter is increased an endless loop in finish_arch_post_lock_switch() will occur the next time the task is scheduled. Add explicit preempt_disable()/preempt_enable() calls to the relevant functions in arch/s390/mm/pgtable.c. Signed-off-by: Martin Schwidefsky --- arch/s390/mm/pgtable.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'arch/s390/mm/pgtable.c') diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 9f0ce0e6eeb4..67111ccbb5e0 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -70,7 +70,6 @@ static inline pgste_t pgste_get_lock(pte_t *ptep) #ifdef CONFIG_PGSTE unsigned long old; - preempt_disable(); asm( " lg %0,%2\n" "0: lgr %1,%0\n" @@ -93,7 +92,6 @@ static inline void pgste_set_unlock(pte_t *ptep, pgste_t pgste) : "=Q" (ptep[PTRS_PER_PTE]) : "d" (pgste_val(pgste)), "Q" (ptep[PTRS_PER_PTE]) : "cc", "memory"); - preempt_enable(); #endif } @@ -230,9 +228,11 @@ pte_t ptep_xchg_direct(struct mm_struct *mm, unsigned long addr, pgste_t pgste; pte_t old; + preempt_disable(); pgste = ptep_xchg_start(mm, addr, ptep); old = ptep_flush_direct(mm, addr, ptep); ptep_xchg_commit(mm, addr, ptep, pgste, old, new); + preempt_enable(); return old; } EXPORT_SYMBOL(ptep_xchg_direct); @@ -243,9 +243,11 @@ pte_t ptep_xchg_lazy(struct mm_struct *mm, unsigned long addr, pgste_t pgste; pte_t old; + preempt_disable(); pgste = ptep_xchg_start(mm, addr, ptep); old = ptep_flush_lazy(mm, addr, ptep); ptep_xchg_commit(mm, addr, ptep, pgste, old, new); + preempt_enable(); return old; } EXPORT_SYMBOL(ptep_xchg_lazy); @@ -256,6 +258,7 @@ pte_t ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr, pgste_t pgste; pte_t old; + preempt_disable(); pgste = ptep_xchg_start(mm, addr, ptep); old = ptep_flush_lazy(mm, addr, ptep); if (mm_has_pgste(mm)) { @@ -279,6 +282,7 @@ void ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr, } else { *ptep = pte; } + preempt_enable(); } EXPORT_SYMBOL(ptep_modify_prot_commit); @@ -333,8 +337,10 @@ pmd_t pmdp_xchg_direct(struct mm_struct *mm, unsigned long addr, { pmd_t old; + preempt_disable(); old = pmdp_flush_direct(mm, addr, pmdp); *pmdp = new; + preempt_enable(); return old; } EXPORT_SYMBOL(pmdp_xchg_direct); @@ -344,8 +350,10 @@ pmd_t pmdp_xchg_lazy(struct mm_struct *mm, unsigned long addr, { pmd_t old; + preempt_disable(); old = pmdp_flush_lazy(mm, addr, pmdp); *pmdp = new; + preempt_enable(); return old; } EXPORT_SYMBOL(pmdp_xchg_lazy); @@ -398,20 +406,24 @@ void ptep_set_pte_at(struct mm_struct *mm, unsigned long addr, pgste_t pgste; /* the mm_has_pgste() check is done in set_pte_at() */ + preempt_disable(); 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); + preempt_enable(); } void ptep_set_notify(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { pgste_t pgste; + preempt_disable(); pgste = pgste_get_lock(ptep); pgste_val(pgste) |= PGSTE_IN_BIT; pgste_set_unlock(ptep, pgste); + preempt_enable(); } static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry) @@ -434,6 +446,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr, pte_t pte; /* Zap unused and logically-zero pages */ + preempt_disable(); pgste = pgste_get_lock(ptep); pgstev = pgste_val(pgste); pte = *ptep; @@ -446,6 +459,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr, if (reset) pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK; pgste_set_unlock(ptep, pgste); + preempt_enable(); } void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep) @@ -454,6 +468,7 @@ void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep) pgste_t pgste; /* Clear storage key */ + preempt_disable(); pgste = pgste_get_lock(ptep); pgste_val(pgste) &= ~(PGSTE_ACC_BITS | PGSTE_FP_BIT | PGSTE_GR_BIT | PGSTE_GC_BIT); @@ -461,6 +476,7 @@ void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep) if (!(ptev & _PAGE_INVALID) && (ptev & _PAGE_WRITE)) page_set_storage_key(ptev & PAGE_MASK, PAGE_DEFAULT_KEY, 1); pgste_set_unlock(ptep, pgste); + preempt_enable(); } /* -- cgit