1/* SPDX-License-Identifier: GPL-2.0 */
2/* clear_page.S: UltraSparc optimized clear page.
3 *
4 * Copyright (C) 1996, 1998, 1999, 2000, 2004 David S. Miller (davem@redhat.com)
5 * Copyright (C) 1997 Jakub Jelinek (jakub@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/pgtable.h>
10#include <asm/visasm.h>
11#include <asm/thread_info.h>
12#include <asm/page.h>
13#include <asm/spitfire.h>
14#include <asm/head.h>
15
16	/* What we used to do was lock a TLB entry into a specific
17	 * TLB slot, clear the page with interrupts disabled, then
18	 * restore the original TLB entry.  This was great for
19	 * disturbing the TLB as little as possible, but it meant
20	 * we had to keep interrupts disabled for a long time.
21	 *
22	 * Now, we simply use the normal TLB loading mechanism,
23	 * and this makes the cpu choose a slot all by itself.
24	 * Then we do a normal TLB flush on exit.  We need only
25	 * disable preemption during the clear.
26	 */
27
28	.text
29
30	.globl		_clear_page
31	EXPORT_SYMBOL(_clear_page)
32_clear_page:		/* %o0=dest */
33	ba,pt		%xcc, clear_page_common
34	 clr		%o4
35
36	/* This thing is pretty important, it shows up
37	 * on the profiles via do_anonymous_page().
38	 */
39	.align		32
40	.globl		clear_user_page
41	EXPORT_SYMBOL(clear_user_page)
42clear_user_page:	/* %o0=dest, %o1=vaddr */
43	lduw		[%g6 + TI_PRE_COUNT], %o2
44	sethi		%hi(PAGE_OFFSET), %g2
45	sethi		%hi(PAGE_SIZE), %o4
46
47	ldx		[%g2 + %lo(PAGE_OFFSET)], %g2
48	sethi		%hi(PAGE_KERNEL_LOCKED), %g3
49
50	ldx		[%g3 + %lo(PAGE_KERNEL_LOCKED)], %g3
51	sub		%o0, %g2, %g1		! paddr
52
53	and		%o1, %o4, %o0		! vaddr D-cache alias bit
54
55	or		%g1, %g3, %g1		! TTE data
56	sethi		%hi(TLBTEMP_BASE), %o3
57
58	add		%o2, 1, %o4
59	add		%o0, %o3, %o0		! TTE vaddr
60
61	/* Disable preemption.  */
62	mov		TLB_TAG_ACCESS, %g3
63	stw		%o4, [%g6 + TI_PRE_COUNT]
64
65	/* Load TLB entry.  */
66	rdpr		%pstate, %o4
67	wrpr		%o4, PSTATE_IE, %pstate
68	stxa		%o0, [%g3] ASI_DMMU
69	stxa		%g1, [%g0] ASI_DTLB_DATA_IN
70	sethi		%hi(KERNBASE), %g1
71	flush		%g1
72	wrpr		%o4, 0x0, %pstate
73
74	mov		1, %o4
75
76clear_page_common:
77	VISEntryHalf
78	membar		#StoreLoad | #StoreStore | #LoadStore
79	fzero		%f0
80	sethi		%hi(PAGE_SIZE/64), %o1
81	mov		%o0, %g1		! remember vaddr for tlbflush
82	fzero		%f2
83	or		%o1, %lo(PAGE_SIZE/64), %o1
84	faddd		%f0, %f2, %f4
85	fmuld		%f0, %f2, %f6
86	faddd		%f0, %f2, %f8
87	fmuld		%f0, %f2, %f10
88
89	faddd		%f0, %f2, %f12
90	fmuld		%f0, %f2, %f14
911:	stda		%f0, [%o0 + %g0] ASI_BLK_P
92	subcc		%o1, 1, %o1
93	bne,pt		%icc, 1b
94	 add		%o0, 0x40, %o0
95	membar		#Sync
96	VISExitHalf
97
98	brz,pn		%o4, out
99	 nop
100
101	stxa		%g0, [%g1] ASI_DMMU_DEMAP
102	membar		#Sync
103	stw		%o2, [%g6 + TI_PRE_COUNT]
104
105out:	retl
106	 nop
107
108