xref: /openbmc/linux/arch/arm/lib/copy_template.S (revision 8dd3cdea) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 *  linux/arch/arm/lib/copy_template.s
4 *
5 *  Code template for optimized memory copy functions
6 *
7 *  Author:	Nicolas Pitre
8 *  Created:	Sep 28, 2005
9 *  Copyright:	MontaVista Software, Inc.
10 */
11
12/*
13 * Theory of operation
14 * -------------------
15 *
16 * This file provides the core code for a forward memory copy used in
17 * the implementation of memcopy(), copy_to_user() and copy_from_user().
18 *
19 * The including file must define the following accessor macros
20 * according to the need of the given function:
21 *
22 * ldr1w ptr reg abort
23 *
24 *	This loads one word from 'ptr', stores it in 'reg' and increments
25 *	'ptr' to the next word. The 'abort' argument is used for fixup tables.
26 *
27 * ldr4w ptr reg1 reg2 reg3 reg4 abort
28 * ldr8w ptr, reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
29 *
30 *	This loads four or eight words starting from 'ptr', stores them
31 *	in provided registers and increments 'ptr' past those words.
32 *	The'abort' argument is used for fixup tables.
33 *
34 * ldr1b ptr reg cond abort
35 *
36 *	Similar to ldr1w, but it loads a byte and increments 'ptr' one byte.
37 *	It also must apply the condition code if provided, otherwise the
38 *	"al" condition is assumed by default.
39 *
40 * str1w ptr reg abort
41 * str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
42 * str1b ptr reg cond abort
43 *
44 *	Same as their ldr* counterparts, but data is stored to 'ptr' location
45 *	rather than being loaded.
46 *
47 * enter reg1 reg2
48 *
49 *	Preserve the provided registers on the stack plus any additional
50 *	data as needed by the implementation including this code. Called
51 *	upon code entry.
52 *
53 * usave reg1 reg2
54 *
55 *	Unwind annotation macro is corresponding for 'enter' macro.
56 *	It tell unwinder that preserved some provided registers on the stack
57 *	and additional data by a prior 'enter' macro.
58 *
59 * exit reg1 reg2
60 *
61 *	Restore registers with the values previously saved with the
62 *	'preserv' macro. Called upon code termination.
63 *
64 * LDR1W_SHIFT
65 * STR1W_SHIFT
66 *
67 *	Correction to be applied to the "ip" register when branching into
68 *	the ldr1w or str1w instructions (some of these macros may expand to
69 *	than one 32bit instruction in Thumb-2)
70 */
71
72	UNWIND(	.fnstart			)
73		enter	r4, UNWIND(fpreg,) lr
74	UNWIND(	.setfp	fpreg, sp		)
75	UNWIND(	mov	fpreg, sp		)
76
77		subs	r2, r2, #4
78		blt	8f
79		ands	ip, r0, #3
80	PLD(	pld	[r1, #0]		)
81		bne	9f
82		ands	ip, r1, #3
83		bne	10f
84
851:		subs	r2, r2, #(28)
86		stmfd	sp!, {r5, r6, r8, r9}
87		blt	5f
88
89	CALGN(	ands	ip, r0, #31		)
90	CALGN(	rsb	r3, ip, #32		)
91	CALGN(	sbcsne	r4, r3, r2		)  @ C is always set here
92	CALGN(	bcs	2f			)
93	CALGN(	adr	r4, 6f			)
94	CALGN(	subs	r2, r2, r3		)  @ C gets set
95	CALGN(	add	pc, r4, ip		)
96
97	PLD(	pld	[r1, #0]		)
982:	PLD(	subs	r2, r2, #96		)
99	PLD(	pld	[r1, #28]		)
100	PLD(	blt	4f			)
101	PLD(	pld	[r1, #60]		)
102	PLD(	pld	[r1, #92]		)
103
1043:	PLD(	pld	[r1, #124]		)
1054:		ldr8w	r1, r3, r4, r5, r6, r8, r9, ip, lr, abort=20f
106		subs	r2, r2, #32
107		str8w	r0, r3, r4, r5, r6, r8, r9, ip, lr, abort=20f
108		bge	3b
109	PLD(	cmn	r2, #96			)
110	PLD(	bge	4b			)
111
1125:		ands	ip, r2, #28
113		rsb	ip, ip, #32
114#if LDR1W_SHIFT > 0
115		lsl	ip, ip, #LDR1W_SHIFT
116#endif
117		addne	pc, pc, ip		@ C is always clear here
118		b	7f
1196:
120		.rept	(1 << LDR1W_SHIFT)
121		W(nop)
122		.endr
123		ldr1w	r1, r3, abort=20f
124		ldr1w	r1, r4, abort=20f
125		ldr1w	r1, r5, abort=20f
126		ldr1w	r1, r6, abort=20f
127		ldr1w	r1, r8, abort=20f
128		ldr1w	r1, r9, abort=20f
129		ldr1w	r1, lr, abort=20f
130
131#if LDR1W_SHIFT < STR1W_SHIFT
132		lsl	ip, ip, #STR1W_SHIFT - LDR1W_SHIFT
133#elif LDR1W_SHIFT > STR1W_SHIFT
134		lsr	ip, ip, #LDR1W_SHIFT - STR1W_SHIFT
135#endif
136		add	pc, pc, ip
137		nop
138		.rept	(1 << STR1W_SHIFT)
139		W(nop)
140		.endr
141		str1w	r0, r3, abort=20f
142		str1w	r0, r4, abort=20f
143		str1w	r0, r5, abort=20f
144		str1w	r0, r6, abort=20f
145		str1w	r0, r8, abort=20f
146		str1w	r0, r9, abort=20f
147		str1w	r0, lr, abort=20f
148
149	CALGN(	bcs	2b			)
150
1517:		ldmfd	sp!, {r5, r6, r8, r9}
152
1538:		movs	r2, r2, lsl #31
154		ldr1b	r1, r3, ne, abort=21f
155		ldr1b	r1, r4, cs, abort=21f
156		ldr1b	r1, ip, cs, abort=21f
157		str1b	r0, r3, ne, abort=21f
158		str1b	r0, r4, cs, abort=21f
159		str1b	r0, ip, cs, abort=21f
160
161		exit	r4, UNWIND(fpreg,) pc
162
1639:		rsb	ip, ip, #4
164		cmp	ip, #2
165		ldr1b	r1, r3, gt, abort=21f
166		ldr1b	r1, r4, ge, abort=21f
167		ldr1b	r1, lr, abort=21f
168		str1b	r0, r3, gt, abort=21f
169		str1b	r0, r4, ge, abort=21f
170		subs	r2, r2, ip
171		str1b	r0, lr, abort=21f
172		blt	8b
173		ands	ip, r1, #3
174		beq	1b
175
17610:		bic	r1, r1, #3
177		cmp	ip, #2
178		ldr1w	r1, lr, abort=21f
179		beq	17f
180		bgt	18f
181
182
183		.macro	forward_copy_shift pull push
184
185		subs	r2, r2, #28
186		blt	14f
187
188	CALGN(	ands	ip, r0, #31		)
189	CALGN(	rsb	ip, ip, #32		)
190	CALGN(	sbcsne	r4, ip, r2		)  @ C is always set here
191	CALGN(	subcc	r2, r2, ip		)
192	CALGN(	bcc	15f			)
193
19411:		stmfd	sp!, {r5, r6, r8 - r10}
195
196	PLD(	pld	[r1, #0]		)
197	PLD(	subs	r2, r2, #96		)
198	PLD(	pld	[r1, #28]		)
199	PLD(	blt	13f			)
200	PLD(	pld	[r1, #60]		)
201	PLD(	pld	[r1, #92]		)
202
20312:	PLD(	pld	[r1, #124]		)
20413:		ldr4w	r1, r4, r5, r6, r8, abort=19f
205		mov	r3, lr, lspull #\pull
206		subs	r2, r2, #32
207		ldr4w	r1, r9, r10, ip, lr, abort=19f
208		orr	r3, r3, r4, lspush #\push
209		mov	r4, r4, lspull #\pull
210		orr	r4, r4, r5, lspush #\push
211		mov	r5, r5, lspull #\pull
212		orr	r5, r5, r6, lspush #\push
213		mov	r6, r6, lspull #\pull
214		orr	r6, r6, r8, lspush #\push
215		mov	r8, r8, lspull #\pull
216		orr	r8, r8, r9, lspush #\push
217		mov	r9, r9, lspull #\pull
218		orr	r9, r9, r10, lspush #\push
219		mov	r10, r10, lspull #\pull
220		orr	r10, r10, ip, lspush #\push
221		mov	ip, ip, lspull #\pull
222		orr	ip, ip, lr, lspush #\push
223		str8w	r0, r3, r4, r5, r6, r8, r9, r10, ip, abort=19f
224		bge	12b
225	PLD(	cmn	r2, #96			)
226	PLD(	bge	13b			)
227
228		ldmfd	sp!, {r5, r6, r8 - r10}
229
23014:		ands	ip, r2, #28
231		beq	16f
232
23315:		mov	r3, lr, lspull #\pull
234		ldr1w	r1, lr, abort=21f
235		subs	ip, ip, #4
236		orr	r3, r3, lr, lspush #\push
237		str1w	r0, r3, abort=21f
238		bgt	15b
239	CALGN(	cmp	r2, #0			)
240	CALGN(	bge	11b			)
241
24216:		sub	r1, r1, #(\push / 8)
243		b	8b
244
245		.endm
246
247
248		forward_copy_shift	pull=8	push=24
249
25017:		forward_copy_shift	pull=16	push=16
251
25218:		forward_copy_shift	pull=24	push=8
253
254	UNWIND(	.fnend				)
255
256/*
257 * Abort preamble and completion macros.
258 * If a fixup handler is required then those macros must surround it.
259 * It is assumed that the fixup code will handle the private part of
260 * the exit macro.
261 */
262
263	.macro	copy_abort_preamble
26419:	ldmfd	sp!, {r5, r6, r8 - r10}
265	b	21f
26620:	ldmfd	sp!, {r5, r6, r8, r9}
26721:
268	.endm
269
270	.macro	copy_abort_end
271	ldmfd	sp!, {r4, UNWIND(fpreg,) pc}
272	.endm
273
274