1/* clear_page.S: UltraSparc optimized clear page.
2 *
3 * Copyright (C) 1996, 1998, 1999, 2000, 2004 David S. Miller (davem@redhat.com)
4 * Copyright (C) 1997 Jakub Jelinek (jakub@redhat.com)
5 */
6
7#include <asm/visasm.h>
8#include <asm/thread_info.h>
9#include <asm/page.h>
10#include <asm/pgtable.h>
11#include <asm/spitfire.h>
12#include <asm/head.h>
13
14	/* What we used to do was lock a TLB entry into a specific
15	 * TLB slot, clear the page with interrupts disabled, then
16	 * restore the original TLB entry.  This was great for
17	 * disturbing the TLB as little as possible, but it meant
18	 * we had to keep interrupts disabled for a long time.
19	 *
20	 * Now, we simply use the normal TLB loading mechanism,
21	 * and this makes the cpu choose a slot all by itself.
22	 * Then we do a normal TLB flush on exit.  We need only
23	 * disable preemption during the clear.
24	 */
25
26	.text
27
28	.globl		_clear_page
29_clear_page:		/* %o0=dest */
30	ba,pt		%xcc, clear_page_common
31	 clr		%o4
32
33	/* This thing is pretty important, it shows up
34	 * on the profiles via do_anonymous_page().
35	 */
36	.align		32
37	.globl		clear_user_page
38clear_user_page:	/* %o0=dest, %o1=vaddr */
39	lduw		[%g6 + TI_PRE_COUNT], %o2
40	sethi		%uhi(PAGE_OFFSET), %g2
41	sethi		%hi(PAGE_SIZE), %o4
42
43	sllx		%g2, 32, %g2
44	sethi		%hi(PAGE_KERNEL_LOCKED), %g3
45
46	ldx		[%g3 + %lo(PAGE_KERNEL_LOCKED)], %g3
47	sub		%o0, %g2, %g1		! paddr
48
49	and		%o1, %o4, %o0		! vaddr D-cache alias bit
50
51	or		%g1, %g3, %g1		! TTE data
52	sethi		%hi(TLBTEMP_BASE), %o3
53
54	add		%o2, 1, %o4
55	add		%o0, %o3, %o0		! TTE vaddr
56
57	/* Disable preemption.  */
58	mov		TLB_TAG_ACCESS, %g3
59	stw		%o4, [%g6 + TI_PRE_COUNT]
60
61	/* Load TLB entry.  */
62	rdpr		%pstate, %o4
63	wrpr		%o4, PSTATE_IE, %pstate
64	stxa		%o0, [%g3] ASI_DMMU
65	stxa		%g1, [%g0] ASI_DTLB_DATA_IN
66	sethi		%hi(KERNBASE), %g1
67	flush		%g1
68	wrpr		%o4, 0x0, %pstate
69
70	mov		1, %o4
71
72clear_page_common:
73	VISEntryHalf
74	membar		#StoreLoad | #StoreStore | #LoadStore
75	fzero		%f0
76	sethi		%hi(PAGE_SIZE/64), %o1
77	mov		%o0, %g1		! remember vaddr for tlbflush
78	fzero		%f2
79	or		%o1, %lo(PAGE_SIZE/64), %o1
80	faddd		%f0, %f2, %f4
81	fmuld		%f0, %f2, %f6
82	faddd		%f0, %f2, %f8
83	fmuld		%f0, %f2, %f10
84
85	faddd		%f0, %f2, %f12
86	fmuld		%f0, %f2, %f14
871:	stda		%f0, [%o0 + %g0] ASI_BLK_P
88	subcc		%o1, 1, %o1
89	bne,pt		%icc, 1b
90	 add		%o0, 0x40, %o0
91	membar		#Sync
92	VISExitHalf
93
94	brz,pn		%o4, out
95	 nop
96
97	stxa		%g0, [%g1] ASI_DMMU_DEMAP
98	membar		#Sync
99	stw		%o2, [%g6 + TI_PRE_COUNT]
100
101out:	retl
102	 nop
103