linux/arch/s390/include/asm/tlbflush.h
Martin Schwidefsky 050eef364a [S390] fix tlb flushing vs. concurrent /proc accesses
The tlb flushing code uses the mm_users field of the mm_struct to
decide if each page table entry needs to be flushed individually with
IPTE or if a global flush for the mm_struct is sufficient after all page
table updates have been done. The comment for mm_users says "How many
users with user space?" but the /proc code increases mm_users after it
found the process structure by pid without creating a new user process.
Which makes mm_users useless for the decision between the two tlb
flusing methods. The current code can be confused to not flush tlb
entries by a concurrent access to /proc files if e.g. a fork is in
progres. The solution for this problem is to make the tlb flushing
logic independent from the mm_users field.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-08-24 09:26:34 +02:00

145 lines
3.4 KiB
C

#ifndef _S390_TLBFLUSH_H
#define _S390_TLBFLUSH_H
#include <linux/mm.h>
#include <linux/sched.h>
#include <asm/processor.h>
#include <asm/pgalloc.h>
/*
* Flush all tlb entries on the local cpu.
*/
static inline void __tlb_flush_local(void)
{
asm volatile("ptlb" : : : "memory");
}
#ifdef CONFIG_SMP
/*
* Flush all tlb entries on all cpus.
*/
void smp_ptlb_all(void);
static inline void __tlb_flush_global(void)
{
register unsigned long reg2 asm("2");
register unsigned long reg3 asm("3");
register unsigned long reg4 asm("4");
long dummy;
#ifndef __s390x__
if (!MACHINE_HAS_CSP) {
smp_ptlb_all();
return;
}
#endif /* __s390x__ */
dummy = 0;
reg2 = reg3 = 0;
reg4 = ((unsigned long) &dummy) + 1;
asm volatile(
" csp %0,%2"
: : "d" (reg2), "d" (reg3), "d" (reg4), "m" (dummy) : "cc" );
}
static inline void __tlb_flush_full(struct mm_struct *mm)
{
cpumask_t local_cpumask;
preempt_disable();
/*
* If the process only ran on the local cpu, do a local flush.
*/
local_cpumask = cpumask_of_cpu(smp_processor_id());
if (cpumask_equal(mm_cpumask(mm), &local_cpumask))
__tlb_flush_local();
else
__tlb_flush_global();
preempt_enable();
}
#else
#define __tlb_flush_full(mm) __tlb_flush_local()
#endif
/*
* Flush all tlb entries of a page table on all cpus.
*/
static inline void __tlb_flush_idte(unsigned long asce)
{
asm volatile(
" .insn rrf,0xb98e0000,0,%0,%1,0"
: : "a" (2048), "a" (asce) : "cc" );
}
static inline void __tlb_flush_mm(struct mm_struct * mm)
{
if (unlikely(cpumask_empty(mm_cpumask(mm))))
return;
/*
* If the machine has IDTE we prefer to do a per mm flush
* on all cpus instead of doing a local flush if the mm
* only ran on the local cpu.
*/
if (MACHINE_HAS_IDTE) {
if (mm->context.noexec)
__tlb_flush_idte((unsigned long)
get_shadow_table(mm->pgd) |
mm->context.asce_bits);
__tlb_flush_idte((unsigned long) mm->pgd |
mm->context.asce_bits);
return;
}
__tlb_flush_full(mm);
}
static inline void __tlb_flush_mm_cond(struct mm_struct * mm)
{
spin_lock(&mm->page_table_lock);
if (mm->context.flush_mm) {
__tlb_flush_mm(mm);
mm->context.flush_mm = 0;
}
spin_unlock(&mm->page_table_lock);
}
/*
* TLB flushing:
* flush_tlb() - flushes the current mm struct TLBs
* flush_tlb_all() - flushes all processes TLBs
* flush_tlb_mm(mm) - flushes the specified mm context TLB's
* flush_tlb_page(vma, vmaddr) - flushes one page
* flush_tlb_range(vma, start, end) - flushes a range of pages
* flush_tlb_kernel_range(start, end) - flushes a range of kernel pages
*/
/*
* flush_tlb_mm goes together with ptep_set_wrprotect for the
* copy_page_range operation and flush_tlb_range is related to
* ptep_get_and_clear for change_protection. ptep_set_wrprotect and
* ptep_get_and_clear do not flush the TLBs directly if the mm has
* only one user. At the end of the update the flush_tlb_mm and
* flush_tlb_range functions need to do the flush.
*/
#define flush_tlb() do { } while (0)
#define flush_tlb_all() do { } while (0)
#define flush_tlb_page(vma, addr) do { } while (0)
static inline void flush_tlb_mm(struct mm_struct *mm)
{
__tlb_flush_mm_cond(mm);
}
static inline void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
__tlb_flush_mm_cond(vma->vm_mm);
}
static inline void flush_tlb_kernel_range(unsigned long start,
unsigned long end)
{
__tlb_flush_mm(&init_mm);
}
#endif /* _S390_TLBFLUSH_H */