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
|
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "arm/asm.h"
// using frame size $-4 means do not save LR on stack.
TEXT _rt0_arm(SB),7,$-4
MOVW $setR12(SB), R12
// copy arguments forward on an even stack
// use R13 instead of SP to avoid linker rewriting the offsets
MOVW 0(R13), R0 // argc
MOVW $4(R13), R1 // argv
SUB $128, R13 // plenty of scratch
AND $~7, R13
MOVW R0, 120(R13) // save argc, argv away
MOVW R1, 124(R13)
// set up m and g registers
// g is R10, m is R9
MOVW $g0(SB), g
MOVW $m0(SB), m
// save m->g0 = g0
MOVW g, m_g0(m)
// create istack out of the OS stack
MOVW $(-8192+104)(R13), R0
MOVW R0, g_stackguard(g) // (w 104b guard)
MOVW R13, g_stackbase(g)
BL emptyfunc(SB) // fault if stack check is wrong
BL check(SB)
// saved argc, argv
MOVW 120(R13), R0
MOVW R0, 4(R13)
MOVW 124(R13), R1
MOVW R1, 8(R13)
BL args(SB)
BL osinit(SB)
BL schedinit(SB)
// create a new goroutine to start program
MOVW $mainstart(SB), R0
MOVW.W R0, -4(R13)
MOVW $8, R0
MOVW.W R0, -4(R13)
MOVW $0, R0
MOVW.W R0, -4(R13) // push $0 as guard
BL ·newproc(SB)
MOVW $12(R13), R13 // pop args and LR
// start this M
BL mstart(SB)
MOVW $1234, R0
MOVW $1000, R1
MOVW R0, (R1) // fail hard
B _dep_dummy(SB) // Never reached
TEXT mainstart(SB),7,$4
BL main·init(SB)
BL initdone(SB)
BL main·main(SB)
MOVW $0, R0
MOVW R0, 4(SP)
BL exit(SB)
MOVW $1234, R0
MOVW $1001, R1
MOVW R0, (R1) // fail hard
RET
// TODO(kaib): remove these once i actually understand how the linker removes symbols
// pull in dummy dependencies
TEXT _dep_dummy(SB),7,$0
BL _div(SB)
BL _divu(SB)
BL _mod(SB)
BL _modu(SB)
BL _modu(SB)
BL _sfloat(SB)
TEXT breakpoint(SB),7,$0
BL abort(SB)
RET
/*
* go-routine
*/
// uintptr gosave(Gobuf*)
// save state in Gobuf; setjmp
TEXT gosave(SB), 7, $-4
MOVW 0(FP), R0
MOVW SP, gobuf_sp(R0)
MOVW LR, gobuf_pc(R0)
MOVW g, gobuf_g(R0)
MOVW $0, R0 // return 0
RET
// void gogo(Gobuf*, uintptr)
// restore state from Gobuf; longjmp
TEXT gogo(SB), 7, $-4
MOVW 0(FP), R1 // gobuf
MOVW 4(FP), R0 // return 2nd arg
MOVW gobuf_g(R1), g
MOVW 0(g), R2 // make sure g != nil
MOVW gobuf_sp(R1), SP // restore SP
MOVW gobuf_pc(R1), PC
// void gogocall(Gobuf*, void (*fn)(void))
// restore state from Gobuf but then call fn.
// (call fn, returning to state in Gobuf)
// using frame size $-4 means do not save LR on stack.
TEXT gogocall(SB), 7, $-4
MOVW 0(FP), R0
MOVW 4(FP), R1 // fn
MOVW gobuf_g(R0), g
MOVW 0(g), R2 // make sure g != nil
MOVW gobuf_sp(R0), SP // restore SP
MOVW gobuf_pc(R0), LR
MOVW R1, PC
/*
* support for morestack
*/
// Called during function prolog when more stack is needed.
// R1 frame size
// R2 arg size
// R3 prolog's LR
// NB. we do not save R0 because we've forced 5c to pass all arguments
// on the stack.
// using frame size $-4 means do not save LR on stack.
TEXT ·morestack(SB),7,$-4
// Cannot grow scheduler stack (m->g0).
MOVW m_g0(m), R4
CMP g, R4
BNE 2(PC)
BL abort(SB)
// Save in m.
MOVW R1, m_moreframe(m)
MOVW R2, m_moreargs(m)
// Called from f.
// Set m->morebuf to f's caller.
MOVW R3, (m_morebuf+gobuf_pc)(m) // f's caller's PC
MOVW SP, (m_morebuf+gobuf_sp)(m) // f's caller's SP
MOVW SP, m_morefp(m) // f's caller's SP
MOVW g, (m_morebuf+gobuf_g)(m)
// Set m->morepc to f's PC.
MOVW LR, m_morepc(m)
// Call newstack on m's scheduling stack.
MOVW m_g0(m), g
MOVW (m_sched+gobuf_sp)(m), SP
B newstack(SB)
// Called from reflection library. Mimics morestack,
// reuses stack growth code to create a frame
// with the desired args running the desired function.
//
// func call(fn *byte, arg *byte, argsize uint32).
TEXT reflect·call(SB), 7, $-4
// Save our caller's state as the PC and SP to
// restore when returning from f.
MOVW LR, (m_morebuf+gobuf_pc)(m) // our caller's PC
MOVW SP, (m_morebuf+gobuf_sp)(m) // our caller's SP
MOVW g, (m_morebuf+gobuf_g)(m)
// Set up morestack arguments to call f on a new stack.
// We set f's frame size to 1, as a hint to newstack
// that this is a call from reflect·call.
// If it turns out that f needs a larger frame than
// the default stack, f's usual stack growth prolog will
// allocate a new segment (and recopy the arguments).
MOVW 4(SP), R0 // fn
MOVW 8(SP), R1 // arg frame
MOVW 12(SP), R2 // arg size
MOVW R0, m_morepc(m) // f's PC
MOVW R1, m_morefp(m) // argument frame pointer
MOVW R2, m_moreargs(m) // f's argument size
MOVW $1, R3
MOVW R3, m_moreframe(m) // f's frame size
// Call newstack on m's scheduling stack.
MOVW m_g0(m), g
MOVW (m_sched+gobuf_sp)(m), SP
B newstack(SB)
// Return point when leaving stack.
// using frame size $-4 means do not save LR on stack.
TEXT ·lessstack(SB), 7, $-4
// Save return value in m->cret
MOVW R0, m_cret(m)
// Call oldstack on m's scheduling stack.
MOVW m_g0(m), g
MOVW (m_sched+gobuf_sp)(m), SP
B oldstack(SB)
// void jmpdefer(fn, sp);
// called from deferreturn.
// 1. grab stored LR for caller
// 2. sub 4 bytes to get back to BL deferreturn
// 3. B to fn
TEXT jmpdefer(SB), 7, $0
MOVW 0(SP), LR
MOVW $-4(LR), LR // BL deferreturn
MOVW 4(SP), R0 // fn
MOVW 8(SP), SP
B (R0)
TEXT ·memclr(SB),7,$20
MOVW 0(FP), R0
MOVW $0, R1 // c = 0
MOVW R1, -16(SP)
MOVW 4(FP), R1 // n
MOVW R1, -12(SP)
MOVW m, -8(SP) // Save m and g
MOVW g, -4(SP)
BL memset(SB)
MOVW -8(SP), m // Restore m and g, memset clobbers them
MOVW -4(SP), g
RET
TEXT ·getcallerpc+0(SB),7,$-4
MOVW 0(SP), R0
RET
TEXT ·setcallerpc+0(SB),7,$-4
MOVW x+4(FP), R0
MOVW R0, 0(SP)
RET
TEXT getcallersp(SB),7,$-4
MOVW 0(FP), R0
MOVW $-4(R0), R0
RET
// runcgo(void(*fn)(void*), void *arg)
// Just call fn(arg), but first align the stack
// appropriately for the gcc ABI.
// TODO(kaib): figure out the arm-gcc ABI
TEXT runcgo(SB),7,$16
BL abort(SB)
// MOVL fn+0(FP), AX
// MOVL arg+4(FP), BX
// MOVL SP, CX
// ANDL $~15, SP // alignment for gcc ABI
// MOVL CX, 4(SP)
// MOVL BX, 0(SP)
// CALL AX
// MOVL 4(SP), SP
// RET
TEXT emptyfunc(SB),0,$0
RET
TEXT abort(SB),7,$-4
MOVW $0, R0
MOVW (R0), R1
|