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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2016-05-25 10:45:26 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-06-13 16:58:22 +0300
commit64f31d5802af11fd87872b4bae07b35cf0acb358 (patch)
tree73f514c73762092fd6710efa6863a5a6124d86a3 /arch/s390/mm
parent7dd968163f7c12bcb2132792bf873133b397a2d2 (diff)
downloadlinux-64f31d5802af11fd87872b4bae07b35cf0acb358.tar.xz
s390/mm: simplify the TLB flushing code
ptep_flush_lazy and pmdp_flush_lazy use mm->context.attach_count to decide between a lazy TLB flush vs an immediate TLB flush. The field contains two 16-bit counters, the number of CPUs that have the mm attached and can create TLB entries for it and the number of CPUs in the middle of a page table update. The __tlb_flush_asce, ptep_flush_direct and pmdp_flush_direct functions use the attach counter and a mask check with mm_cpumask(mm) to decide between a local flush local of the current CPU and a global flush. For all these functions the decision between lazy vs immediate and local vs global TLB flush can be based on CPU masks. There are two masks: the mm->context.cpu_attach_mask with the CPUs that are actively using the mm, and the mm_cpumask(mm) with the CPUs that have used the mm since the last full flush. The decision between lazy vs immediate flush is based on the mm->context.cpu_attach_mask, to decide between local vs global flush the mm_cpumask(mm) is used. With this patch all checks will use the CPU masks, the old counter mm->context.attach_count with its two 16-bit values is turned into a single counter mm->context.flush_count that keeps track of the number of CPUs with incomplete page table updates. The sole user of this counter is finish_arch_post_lock_switch() which waits for the end of all page table updates. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm')
-rw-r--r--arch/s390/mm/init.c4
-rw-r--r--arch/s390/mm/pgtable.c34
2 files changed, 15 insertions, 23 deletions
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 44db60d9e519..de2cdf4fbb9a 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -118,10 +118,8 @@ void mark_rodata_ro(void)
void __init mem_init(void)
{
- if (MACHINE_HAS_TLB_LC)
- cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
+ cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
cpumask_set_cpu(0, mm_cpumask(&init_mm));
- atomic_set(&init_mm.context.attach_count, 1);
set_max_mapnr(max_low_pfn);
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 67111ccbb5e0..74f8f2a8a4e8 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -27,40 +27,37 @@
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 &&
+ atomic_inc(&mm->context.flush_count);
+ if (MACHINE_HAS_TLB_LC &&
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);
+ atomic_dec(&mm->context.flush_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) {
+ atomic_inc(&mm->context.flush_count);
+ if (cpumask_equal(&mm->context.cpu_attach_mask,
+ cpumask_of(smp_processor_id()))) {
pte_val(*ptep) |= _PAGE_INVALID;
mm->context.flush_mm = 1;
} else
__ptep_ipte(addr, ptep);
- atomic_sub(0x10000, &mm->context.attach_count);
+ atomic_dec(&mm->context.flush_count);
return old;
}
@@ -289,7 +286,6 @@ 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;
@@ -299,36 +295,34 @@ static inline pmd_t pmdp_flush_direct(struct mm_struct *mm,
__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 &&
+ atomic_inc(&mm->context.flush_count);
+ if (MACHINE_HAS_TLB_LC &&
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);
+ atomic_dec(&mm->context.flush_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) {
+ atomic_inc(&mm->context.flush_count);
+ if (cpumask_equal(&mm->context.cpu_attach_mask,
+ cpumask_of(smp_processor_id()))) {
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);
+ atomic_dec(&mm->context.flush_count);
return old;
}