Commit 7139bc15 authored by John David Anglin's avatar John David Anglin Committed by James Bottomley
Browse files

[PARISC] Purge existing TLB entries in set_pte_at and ptep_set_wrprotect 



This patch goes a long way toward fixing the minifail bug, and
it  significantly improves the stability of SMP machines such as
the rp3440.  When write  protecting a page for COW, we need to
purge the existing translation.  Otherwise, the COW break
doesn't occur as expected because the TLB may still have a stale entry
which allows writes.

[jejb: fix up checkpatch errors]
Signed-off-by: default avatarJohn David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 5da1f88b

arch/parisc/include/asm/pgtable.h

+10 −3
Original line number Diff line number Diff line
@@ -12,11 +12,10 @@ 


#include <linux/bitops.h>

#include <linux/spinlock.h>

#include <linux/mm_types.h>

#include <asm/processor.h>

#include <asm/cache.h>



struct vm_area_struct;



/*

 * kern_addr_valid(ADDR) tests if ADDR is pointing to valid kernel

 * memory.  For the return value to be meaningful, ADDR must be >=
@@ -40,7 +39,14 @@ struct vm_area_struct; 
        do{                                                     \

                *(pteptr) = (pteval);                           \

        } while(0)

#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)



extern void purge_tlb_entries(struct mm_struct *, unsigned long);



#define set_pte_at(mm, addr, ptep, pteval)                      \

	do {                                                    \

		set_pte(ptep, pteval);                          \

		purge_tlb_entries(mm, addr);                    \

	} while (0)



#endif /* !__ASSEMBLY__ */
@@ -466,6 +472,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, 
		old = pte_val(*ptep);

		new = pte_val(pte_wrprotect(__pte (old)));

	} while (cmpxchg((unsigned long *) ptep, old, new) != old);

	purge_tlb_entries(mm, addr);

#else

	pte_t old_pte = *ptep;

	set_pte_at(mm, addr, ptep, pte_wrprotect(old_pte));

arch/parisc/kernel/cache.c

+18 −0
Original line number Diff line number Diff line
@@ -419,6 +419,24 @@ void kunmap_parisc(void *addr) 
EXPORT_SYMBOL(kunmap_parisc);

#endif



void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)

{

	unsigned long flags;



	/* Note: purge_tlb_entries can be called at startup with

	   no context.  */



	/* Disable preemption while we play with %sr1.  */

	preempt_disable();

	mtsp(mm->context, 1);

	purge_tlb_start(flags);

	pdtlb(addr);

	pitlb(addr);

	purge_tlb_end(flags);

	preempt_enable();

}

EXPORT_SYMBOL(purge_tlb_entries);



void __flush_tlb_range(unsigned long sid, unsigned long start,

		       unsigned long end)

{

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