summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/boot/crt0.S
blob: 121cab9d579bf08ef9785fb1616c258ca1792d77 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) Paul Mackerras 1997.
 *
 * Adapted for 64 bit LE PowerPC by Andrew Tauferner
 */

#include "ppc_asm.h"

RELA = 7
RELASZ = 8
RELAENT = 9

	.data
	/* A procedure descriptor used when booting this as a COFF file.
	 * When making COFF, this comes first in the link and we're
	 * linked at 0x500000.
	 */
	.globl	_zimage_start_opd
_zimage_start_opd:
	.long	0x500000, 0, 0, 0
	.text
	b	_zimage_start

#ifdef __powerpc64__
.balign 8
p_start:	.8byte	_start
p_etext:	.8byte	_etext
p_bss_start:	.8byte	__bss_start
p_end:		.8byte	_end

p_toc:		.8byte	.TOC. - p_base
p_dyn:		.8byte	__dynamic_start - p_base
p_rela:		.8byte	__rela_dyn_start - p_base
p_prom:		.8byte	0
	.weak	_platform_stack_top
p_pstack:	.8byte	_platform_stack_top
#else
p_start:	.long	_start
p_etext:	.long	_etext
p_bss_start:	.long	__bss_start
p_end:		.long	_end

	.weak	_platform_stack_top
p_pstack:	.long	_platform_stack_top
#endif

	.weak	_zimage_start
_zimage_start:
	.globl	_zimage_start_lib
_zimage_start_lib:
	/* Work out the offset between the address we were linked at
	   and the address where we're running. */
	bcl	20,31,.+4
p_base:	mflr	r10		/* r10 now points to runtime addr of p_base */
#ifndef __powerpc64__
	/* grab the link address of the dynamic section in r11 */
	addis	r11,r10,(_GLOBAL_OFFSET_TABLE_-p_base)@ha
	lwz	r11,(_GLOBAL_OFFSET_TABLE_-p_base)@l(r11)
	cmpwi	r11,0
	beq	3f		/* if not linked -pie */
	/* get the runtime address of the dynamic section in r12 */
	.weak	__dynamic_start
	addis	r12,r10,(__dynamic_start-p_base)@ha
	addi	r12,r12,(__dynamic_start-p_base)@l
	subf	r11,r11,r12	/* runtime - linktime offset */

	/* The dynamic section contains a series of tagged entries.
	 * We need the RELA and RELACOUNT entries. */
	li	r9,0
	li	r0,0
9:	lwz	r8,0(r12)	/* get tag */
	cmpwi	r8,0
	beq	10f		/* end of list */
	cmpwi	r8,RELA
	bne	11f
	lwz	r9,4(r12)	/* get RELA pointer in r9 */
	b	12f
11:	cmpwi	r8,RELASZ
	bne	.Lcheck_for_relaent
	lwz	r0,4(r12)       /* get RELASZ value in r0 */
	b	12f
.Lcheck_for_relaent:
	cmpwi	r8,RELAENT
	bne	12f
	lwz     r14,4(r12)      /* get RELAENT value in r14 */
12:	addi	r12,r12,8
	b	9b

	/* The relocation section contains a list of relocations.
	 * We now do the R_PPC_RELATIVE ones, which point to words
	 * which need to be initialized with addend + offset */
10:	/* skip relocation if we don't have both */
	cmpwi	r0,0
	beq	3f
	cmpwi	r9,0
	beq	3f
	cmpwi	r14,0
	beq	3f

	add	r9,r9,r11	/* Relocate RELA pointer */
	divwu   r0,r0,r14       /* RELASZ / RELAENT */
	mtctr	r0
2:	lbz	r0,4+3(r9)	/* ELF32_R_INFO(reloc->r_info) */
	cmpwi	r0,22		/* R_PPC_RELATIVE */
	bne	.Lnext
	lwz	r12,0(r9)	/* reloc->r_offset */
	lwz	r0,8(r9)	/* reloc->r_addend */
	add	r0,r0,r11
	stwx	r0,r11,r12
.Lnext:	add	r9,r9,r14
	bdnz	2b

	/* Do a cache flush for our text, in case the loader didn't */
3:	lwz	r9,p_start-p_base(r10)	/* note: these are relocated now */
	lwz	r8,p_etext-p_base(r10)
4:	dcbf	r0,r9
	icbi	r0,r9
	addi	r9,r9,0x20
	cmplw	cr0,r9,r8
	blt	4b
	sync
	isync

	/* Clear the BSS */
	lwz	r9,p_bss_start-p_base(r10)
	lwz	r8,p_end-p_base(r10)
	li	r0,0
5:	stw	r0,0(r9)
	addi	r9,r9,4
	cmplw	cr0,r9,r8
	blt	5b

	/* Possibly set up a custom stack */
	lwz	r8,p_pstack-p_base(r10)
	cmpwi	r8,0
	beq	6f
	lwz	r1,0(r8)
	li	r0,0
	stwu	r0,-16(r1)	/* establish a stack frame */
6:
#else /* __powerpc64__ */
	/* Save the prom pointer at p_prom. */
	std	r5,(p_prom-p_base)(r10)

	/* Set r2 to the TOC. */
	ld	r2,(p_toc-p_base)(r10)
	add	r2,r2,r10

	/* Grab the link address of the dynamic section in r11. */
	ld	r11,-32768(r2)
	cmpwi	r11,0
	beq	3f              /* if not linked -pie then no dynamic section */

	ld	r11,(p_dyn-p_base)(r10)
	add	r11,r11,r10
	ld	r9,(p_rela-p_base)(r10)
	add	r9,r9,r10

	li	r13,0
	li	r8,0
9:	ld	r12,0(r11)       /* get tag */
	cmpdi	r12,0
	beq	12f              /* end of list */
	cmpdi	r12,RELA
	bne	10f
	ld	r13,8(r11)       /* get RELA pointer in r13 */
	b	11f
10:	cmpwi   r12,RELASZ
	bne	.Lcheck_for_relaent
	lwz	r8,8(r11)	/* get RELASZ pointer in r8 */
	b	11f
.Lcheck_for_relaent:
	cmpwi	r12,RELAENT
	bne     11f
	lwz     r14,8(r11)      /* get RELAENT pointer in r14 */
11:	addi	r11,r11,16
	b	9b
12:
	cmpdi	r13,0            /* check we have both RELA, RELASZ, RELAENT*/
	cmpdi	cr1,r8,0
	beq	3f
	beq	cr1,3f
	cmpdi	r14,0
	beq	3f

	/* Calcuate the runtime offset. */
	subf	r13,r13,r9

	/* Run through the list of relocations and process the
	 * R_PPC64_RELATIVE ones. */
	divdu   r8,r8,r14       /* RELASZ / RELAENT */
	mtctr	r8
13:	ld	r0,8(r9)        /* ELF64_R_TYPE(reloc->r_info) */
	cmpdi	r0,22           /* R_PPC64_RELATIVE */
	bne	.Lnext
	ld	r12,0(r9)        /* reloc->r_offset */
	ld	r0,16(r9)       /* reloc->r_addend */
	add	r0,r0,r13
	stdx	r0,r13,r12
.Lnext:	add	r9,r9,r14
	bdnz	13b

	/* Do a cache flush for our text, in case the loader didn't */
3:	ld	r9,p_start-p_base(r10)	/* note: these are relocated now */
	ld	r8,p_etext-p_base(r10)
4:	dcbf	r0,r9
	icbi	r0,r9
	addi	r9,r9,0x20
	cmpld	cr0,r9,r8
	blt	4b
	sync
	isync

	/* Clear the BSS */
	ld	r9,p_bss_start-p_base(r10)
	ld	r8,p_end-p_base(r10)
	li	r0,0
5:	std	r0,0(r9)
	addi	r9,r9,8
	cmpld	cr0,r9,r8
	blt	5b

	/* Possibly set up a custom stack */
	ld	r8,p_pstack-p_base(r10)
	cmpdi	r8,0
	beq	6f
	ld	r1,0(r8)
	li	r0,0
	stdu	r0,-112(r1)	/* establish a stack frame */
6:
#endif  /* __powerpc64__ */
	/* Call platform_init() */
	bl	platform_init

	/* Call start */
	b	start

#ifdef __powerpc64__

#define PROM_FRAME_SIZE 512

.macro OP_REGS op, width, start, end, base, offset
	.Lreg=\start
	.rept (\end - \start + 1)
	\op	.Lreg,\offset+\width*.Lreg(\base)
	.Lreg=.Lreg+1
	.endr
.endm

#define SAVE_GPRS(start, end, base)	OP_REGS std, 8, start, end, base, 0
#define REST_GPRS(start, end, base)	OP_REGS ld, 8, start, end, base, 0
#define SAVE_GPR(n, base)		SAVE_GPRS(n, n, base)
#define REST_GPR(n, base)		REST_GPRS(n, n, base)

/* prom handles the jump into and return from firmware.  The prom args pointer
   is loaded in r3. */
.globl prom
prom:
	mflr	r0
	std	r0,16(r1)
	stdu	r1,-PROM_FRAME_SIZE(r1) /* Save SP and create stack space */

	SAVE_GPR(2, r1)
	SAVE_GPRS(13, 31, r1)
	mfcr    r10
	std     r10,8*32(r1)
	mfmsr   r10
	std     r10,8*33(r1)

	/* remove MSR_LE from msr but keep MSR_SF */
	mfmsr	r10
	rldicr	r10,r10,0,62
	mtsrr1	r10

	/* Load FW address, set LR to label 1, and jump to FW */
	bcl	20,31,0f
0:	mflr	r10
	addi	r11,r10,(1f-0b)
	mtlr	r11

	ld	r10,(p_prom-0b)(r10)
	mtsrr0	r10

	rfid

1:	/* Return from OF */
	FIXUP_ENDIAN

	/* Restore registers and return. */
	rldicl  r1,r1,0,32

	/* Restore the MSR (back to 64 bits) */
	ld      r10,8*(33)(r1)
	mtmsr	r10
	isync

	/* Restore other registers */
	REST_GPR(2, r1)
	REST_GPRS(13, 31, r1)
	ld      r10,8*32(r1)
	mtcr	r10

	addi    r1,r1,PROM_FRAME_SIZE
	ld      r0,16(r1)
	mtlr    r0
	blr
#endif