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Commit 837cd0bd authored by Robin Holt's avatar Robin Holt Committed by Tony Luck
Browse files

[IA64] 4-level page tables 



This patch introduces 4-level page tables to ia64.  I have run
some benchmarks and found nothing interesting.  Performance has
consistently fallen within the noise range.

It also introduces a config option (setting the default to 3
levels).  The config option prevents having 4 level page
tables with 64k base page size.

Signed-off-by: default avatarRobin Holt <holt@sgi.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent d12eb7e1

arch/ia64/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -164,6 +164,19 @@ config IA64_PAGE_SIZE_64KB 


endchoice



choice

	prompt "Page Table Levels"

	default PGTABLE_3



config PGTABLE_3

	bool "3 Levels"



config PGTABLE_4

	depends on !IA64_PAGE_SIZE_64KB

	bool "4 Levels"



endchoice



source kernel/Kconfig.hz



config IA64_BRL_EMU

arch/ia64/configs/sn2_defconfig

+2 −0
Original line number Diff line number Diff line
@@ -80,6 +80,8 @@ CONFIG_MCKINLEY=y 
# CONFIG_IA64_PAGE_SIZE_8KB is not set

CONFIG_IA64_PAGE_SIZE_16KB=y

# CONFIG_IA64_PAGE_SIZE_64KB is not set

# CONFIG_PGTABLE_3 is not set

CONFIG_PGTABLE_4=y

# CONFIG_HZ_100 is not set

CONFIG_HZ_250=y

# CONFIG_HZ_1000 is not set

arch/ia64/defconfig

+2 −0
Original line number Diff line number Diff line
@@ -82,6 +82,8 @@ CONFIG_MCKINLEY=y 
# CONFIG_IA64_PAGE_SIZE_8KB is not set

CONFIG_IA64_PAGE_SIZE_16KB=y

# CONFIG_IA64_PAGE_SIZE_64KB is not set

CONFIG_PGTABLE_3=y

# CONFIG_PGTABLE_4 is not set

# CONFIG_HZ_100 is not set

CONFIG_HZ_250=y

# CONFIG_HZ_1000 is not set

arch/ia64/kernel/ivt.S

+48 −15
Original line number Diff line number Diff line
@@ -114,7 +114,7 @@ ENTRY(vhpt_miss) 
	shl r21=r16,3				// shift bit 60 into sign bit

	shr.u r17=r16,61			// get the region number into r17

	;;

	shr r22=r21,3

	shr.u r22=r21,3

#ifdef CONFIG_HUGETLB_PAGE

	extr.u r26=r25,2,6

	;;
@@ -140,20 +140,34 @@ ENTRY(vhpt_miss) 
(p6)	dep r17=r18,r19,3,(PAGE_SHIFT-3)	// r17=PTA + IFA(33,42)*8

(p7)	dep r17=r18,r17,3,(PAGE_SHIFT-6)	// r17=PTA + (((IFA(61,63) << 7) | IFA(33,39))*8)

	cmp.eq p7,p6=0,r21			// unused address bits all zeroes?

	shr.u r18=r22,PMD_SHIFT			// shift L2 index into position

#ifdef CONFIG_PGTABLE_4

	shr.u r28=r22,PUD_SHIFT			// shift L2 index into position

#else

	shr.u r18=r22,PMD_SHIFT			// shift L3 index into position

#endif

	;;

	ld8 r17=[r17]				// fetch the L1 entry (may be 0)

	;;

(p7)	cmp.eq p6,p7=r17,r0			// was L1 entry NULL?

	dep r17=r18,r17,3,(PAGE_SHIFT-3)	// compute address of L2 page table entry

#ifdef CONFIG_PGTABLE_4

	dep r28=r28,r17,3,(PAGE_SHIFT-3)	// compute address of L2 page table entry

	;;

	shr.u r18=r22,PMD_SHIFT			// shift L3 index into position

(p7)	ld8 r29=[r28]				// fetch the L2 entry (may be 0)

	;;

(p7)	ld8 r20=[r17]				// fetch the L2 entry (may be 0)

	shr.u r19=r22,PAGE_SHIFT		// shift L3 index into position

(p7)	cmp.eq.or.andcm p6,p7=r29,r0		// was L2 entry NULL?

	dep r17=r18,r29,3,(PAGE_SHIFT-3)	// compute address of L3 page table entry

#else

	dep r17=r18,r17,3,(PAGE_SHIFT-3)	// compute address of L3 page table entry

#endif

	;;

(p7)	cmp.eq.or.andcm p6,p7=r20,r0		// was L2 entry NULL?

	dep r21=r19,r20,3,(PAGE_SHIFT-3)	// compute address of L3 page table entry

(p7)	ld8 r20=[r17]				// fetch the L3 entry (may be 0)

	shr.u r19=r22,PAGE_SHIFT		// shift L4 index into position

	;;

(p7)	ld8 r18=[r21]				// read the L3 PTE

(p7)	cmp.eq.or.andcm p6,p7=r20,r0		// was L3 entry NULL?

	dep r21=r19,r20,3,(PAGE_SHIFT-3)	// compute address of L4 page table entry

	;;

(p7)	ld8 r18=[r21]				// read the L4 PTE

	mov r19=cr.isr				// cr.isr bit 0 tells us if this is an insn miss

	;;

(p7)	tbit.z p6,p7=r18,_PAGE_P_BIT		// page present bit cleared?
@@ -192,14 +206,21 @@ ENTRY(vhpt_miss) 
	 * between reading the pagetable and the "itc".  If so, flush the entry we

	 * inserted and retry.

	 */

	ld8 r25=[r21]				// read L3 PTE again

	ld8 r26=[r17]				// read L2 entry again

	ld8 r25=[r21]				// read L4 entry again

	ld8 r26=[r17]				// read L3 PTE again

#ifdef CONFIG_PGTABLE_4

	ld8 r18=[r28]				// read L2 entry again

#endif

	cmp.ne p6,p7=r0,r0

	;;

	cmp.ne p6,p7=r26,r20			// did L2 entry change

	cmp.ne.or.andcm p6,p7=r26,r20		// did L3 entry change

#ifdef CONFIG_PGTABLE_4

	cmp.ne.or.andcm p6,p7=r29,r18		// did L4 PTE change

#endif

	mov r27=PAGE_SHIFT<<2

	;;

(p6)	ptc.l r22,r27				// purge PTE page translation

(p7)	cmp.ne.or.andcm p6,p7=r25,r18		// did L3 PTE change

(p7)	cmp.ne.or.andcm p6,p7=r25,r18		// did L4 PTE change

	;;

(p6)	ptc.l r16,r27				// purge translation

#endif
@@ -432,18 +453,30 @@ ENTRY(nested_dtlb_miss) 
(p6)	dep r17=r18,r19,3,(PAGE_SHIFT-3)	// r17=PTA + IFA(33,42)*8

(p7)	dep r17=r18,r17,3,(PAGE_SHIFT-6)	// r17=PTA + (((IFA(61,63) << 7) | IFA(33,39))*8)

	cmp.eq p7,p6=0,r21			// unused address bits all zeroes?

	shr.u r18=r22,PMD_SHIFT			// shift L2 index into position

#ifdef CONFIG_PGTABLE_4

	shr.u r18=r22,PUD_SHIFT			// shift L2 index into position

#else

	shr.u r18=r22,PMD_SHIFT			// shift L3 index into position

#endif

	;;

	ld8 r17=[r17]				// fetch the L1 entry (may be 0)

	;;

(p7)	cmp.eq p6,p7=r17,r0			// was L1 entry NULL?

	dep r17=r18,r17,3,(PAGE_SHIFT-3)	// compute address of L2 page table entry

	;;

#ifdef CONFIG_PGTABLE_4

(p7)	ld8 r17=[r17]				// fetch the L2 entry (may be 0)

	shr.u r19=r22,PAGE_SHIFT		// shift L3 index into position

	shr.u r18=r22,PMD_SHIFT			// shift L3 index into position

	;;

(p7)	cmp.eq.or.andcm p6,p7=r17,r0		// was L2 entry NULL?

	dep r17=r19,r17,3,(PAGE_SHIFT-3)	// compute address of L3 page table entry

	dep r17=r18,r17,3,(PAGE_SHIFT-3)	// compute address of L2 page table entry

	;;

#endif

(p7)	ld8 r17=[r17]				// fetch the L3 entry (may be 0)

	shr.u r19=r22,PAGE_SHIFT		// shift L4 index into position

	;;

(p7)	cmp.eq.or.andcm p6,p7=r17,r0		// was L3 entry NULL?

	dep r17=r19,r17,3,(PAGE_SHIFT-3)	// compute address of L4 page table entry

(p6)	br.cond.spnt page_fault

	mov b0=r30

	br.sptk.many b0				// return to continuation point

include/asm-ia64/page.h

+6 −2
Original line number Diff line number Diff line
@@ -47,8 +47,6 @@ 
#define PERCPU_PAGE_SHIFT	16	/* log2() of max. size of per-CPU area */

#define PERCPU_PAGE_SIZE	(__IA64_UL_CONST(1) << PERCPU_PAGE_SHIFT)



#define RGN_MAP_LIMIT	((1UL << (4*PAGE_SHIFT - 12)) - PAGE_SIZE)	/* per region addr limit */





#ifdef CONFIG_HUGETLB_PAGE

# define HPAGE_REGION_BASE	RGN_BASE(RGN_HPAGE)
@@ -175,11 +173,17 @@ get_order (unsigned long size) 
   */

  typedef struct { unsigned long pte; } pte_t;

  typedef struct { unsigned long pmd; } pmd_t;

#ifdef CONFIG_PGTABLE_4

  typedef struct { unsigned long pud; } pud_t;

#endif

  typedef struct { unsigned long pgd; } pgd_t;

  typedef struct { unsigned long pgprot; } pgprot_t;



# define pte_val(x)	((x).pte)

# define pmd_val(x)	((x).pmd)

#ifdef CONFIG_PGTABLE_4

# define pud_val(x)	((x).pud)

#endif

# define pgd_val(x)	((x).pgd)

# define pgprot_val(x)	((x).pgprot)