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Commit 92f842ea authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Martin Schwidefsky
Browse files

[S390] store indication fault optimization 



Use the store indication bit in the translation exception code on
page faults to avoid the protection faults that immediatly follow
the page fault if the access has been a write.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 6931be08

arch/s390/include/asm/pgtable.h

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 
extern pgd_t swapper_pg_dir[] __attribute__ ((aligned (4096)));

extern void paging_init(void);

extern void vmem_map_init(void);

extern void fault_init(void);



/*

 * The S390 doesn't have any external MMU info: the kernel page

arch/s390/mm/fault.c

+18 −3
Original line number Diff line number Diff line
@@ -52,6 +52,19 @@ 
#define VM_FAULT_BADMAP		0x020000

#define VM_FAULT_BADACCESS	0x040000



static unsigned long store_indication;



void fault_init(void)

{

	unsigned long long facility_list[2];



	if (stfle(facility_list, 2) < 2)

		return;

	if ((facility_list[0] & (1ULL << 61)) &&

	    (facility_list[1] & (1ULL << 52)))

		store_indication = 0xc00;

}



static inline int notify_page_fault(struct pt_regs *regs)

{

	int ret = 0;
@@ -294,7 +307,7 @@ static inline int do_exception(struct pt_regs *regs, int access, 
	struct mm_struct *mm;

	struct vm_area_struct *vma;

	unsigned long address;

	int fault;

	int fault, write;



	if (notify_page_fault(regs))

		return 0;
@@ -348,8 +361,10 @@ static inline int do_exception(struct pt_regs *regs, int access, 
	 * make sure we exit gracefully rather than endlessly redo

	 * the fault.

	 */

	fault = handle_mm_fault(mm, vma, address,

				(access == VM_WRITE) ? FAULT_FLAG_WRITE : 0);

	write = (access == VM_WRITE ||

		 (trans_exc_code & store_indication) == 0x400) ?

		FAULT_FLAG_WRITE : 0;

	fault = handle_mm_fault(mm, vma, address, write);

	if (unlikely(fault & VM_FAULT_ERROR))

		goto out_up;

arch/s390/mm/init.c

+1 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ void __init paging_init(void) 
#endif

	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;

	free_area_init_nodes(max_zone_pfns);

	fault_init();

}



void __init mem_init(void)