Text file
src/runtime/sys_windows_arm64.s
1 // Copyright 2018 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 #include "go_asm.h"
6 #include "go_tls.h"
7 #include "textflag.h"
8 #include "funcdata.h"
9 #include "time_windows.h"
10 #include "cgo/abi_arm64.h"
11
12 // Offsets into Thread Environment Block (pointer in R18)
13 #define TEB_error 0x68
14 #define TEB_TlsSlots 0x1480
15
16 // Note: R0-R7 are args, R8 is indirect return value address,
17 // R9-R15 are caller-save, R19-R29 are callee-save.
18 //
19 // load_g and save_g (in tls_arm64.s) clobber R27 (REGTMP) and R0.
20
21 // void runtime·asmstdcall(void *c);
22 TEXT runtime·asmstdcall(SB),NOSPLIT|NOFRAME,$0
23 STP.W (R29, R30), -32(RSP) // allocate C ABI stack frame
24 STP (R19, R20), 16(RSP) // save old R19, R20
25 MOVD R0, R19 // save libcall pointer
26 MOVD RSP, R20 // save stack pointer
27
28 // SetLastError(0)
29 MOVD $0, TEB_error(R18_PLATFORM)
30 MOVD libcall_args(R19), R12 // libcall->args
31
32 // Do we have more than 8 arguments?
33 MOVD libcall_n(R19), R0
34 CMP $0, R0; BEQ _0args
35 CMP $1, R0; BEQ _1args
36 CMP $2, R0; BEQ _2args
37 CMP $3, R0; BEQ _3args
38 CMP $4, R0; BEQ _4args
39 CMP $5, R0; BEQ _5args
40 CMP $6, R0; BEQ _6args
41 CMP $7, R0; BEQ _7args
42 CMP $8, R0; BEQ _8args
43
44 // Reserve stack space for remaining args
45 SUB $8, R0, R2
46 ADD $1, R2, R3 // make even number of words for stack alignment
47 AND $~1, R3
48 LSL $3, R3
49 SUB R3, RSP
50
51 // R4: size of stack arguments (n-8)*8
52 // R5: &args[8]
53 // R6: loop counter, from 0 to (n-8)*8
54 // R7: scratch
55 // R8: copy of RSP - (R2)(RSP) assembles as (R2)(ZR)
56 SUB $8, R0, R4
57 LSL $3, R4
58 ADD $(8*8), R12, R5
59 MOVD $0, R6
60 MOVD RSP, R8
61 stackargs:
62 MOVD (R6)(R5), R7
63 MOVD R7, (R6)(R8)
64 ADD $8, R6
65 CMP R6, R4
66 BNE stackargs
67
68 _8args:
69 MOVD (7*8)(R12), R7
70 _7args:
71 MOVD (6*8)(R12), R6
72 _6args:
73 MOVD (5*8)(R12), R5
74 _5args:
75 MOVD (4*8)(R12), R4
76 _4args:
77 MOVD (3*8)(R12), R3
78 _3args:
79 MOVD (2*8)(R12), R2
80 _2args:
81 MOVD (1*8)(R12), R1
82 _1args:
83 MOVD (0*8)(R12), R0
84 _0args:
85
86 MOVD libcall_fn(R19), R12 // branch to libcall->fn
87 BL (R12)
88
89 MOVD R20, RSP // free stack space
90 MOVD R0, libcall_r1(R19) // save return value to libcall->r1
91 // TODO(rsc) floating point like amd64 in libcall->r2?
92
93 // GetLastError
94 MOVD TEB_error(R18_PLATFORM), R0
95 MOVD R0, libcall_err(R19)
96
97 // Restore callee-saved registers.
98 LDP 16(RSP), (R19, R20)
99 LDP.P 32(RSP), (R29, R30)
100 RET
101
102 TEXT runtime·badsignal2(SB),NOSPLIT,$16-0
103 NO_LOCAL_POINTERS
104
105 // stderr
106 MOVD runtime·_GetStdHandle(SB), R1
107 MOVD $-12, R0
108 SUB $16, RSP // skip over saved frame pointer below RSP
109 BL (R1)
110 ADD $16, RSP
111
112 // handle in R0 already
113 MOVD $runtime·badsignalmsg(SB), R1 // lpBuffer
114 MOVD $runtime·badsignallen(SB), R2 // lpNumberOfBytesToWrite
115 MOVD (R2), R2
116 MOVD R13, R3 // lpNumberOfBytesWritten
117 MOVD $0, R4 // lpOverlapped
118 MOVD runtime·_WriteFile(SB), R12
119 SUB $16, RSP // skip over saved frame pointer below RSP
120 BL (R12)
121
122 // Does not return.
123 B runtime·abort(SB)
124
125 RET
126
127 TEXT runtime·getlasterror(SB),NOSPLIT|NOFRAME,$0
128 MOVD TEB_error(R18_PLATFORM), R0
129 MOVD R0, ret+0(FP)
130 RET
131
132 // Called by Windows as a Vectored Exception Handler (VEH).
133 // First argument is pointer to struct containing
134 // exception record and context pointers.
135 // Handler function is stored in R1
136 // Return 0 for 'not handled', -1 for handled.
137 // int32_t sigtramp(
138 // PEXCEPTION_POINTERS ExceptionInfo,
139 // func *GoExceptionHandler);
140 TEXT sigtramp<>(SB),NOSPLIT|NOFRAME,$0
141 // Save R0, R1 (args) as well as LR, R27, R28 (callee-save).
142 MOVD R0, R5
143 MOVD R1, R6
144 MOVD LR, R7
145 MOVD R27, R16 // saved R27 (callee-save)
146 MOVD g, R17 // saved R28 (callee-save from Windows, not really g)
147
148 BL runtime·load_g(SB) // smashes R0, R27, R28 (g)
149 CMP $0, g // is there a current g?
150 BNE 2(PC)
151 BL runtime·badsignal2(SB)
152
153 // Do we need to switch to the g0 stack?
154 MOVD g, R3 // R3 = oldg (for sigtramp_g0)
155 MOVD g_m(g), R2 // R2 = m
156 MOVD m_g0(R2), R2 // R2 = g0
157 CMP g, R2 // if curg == g0
158 BNE switch
159
160 // No: on g0 stack already, tail call to sigtramp_g0.
161 // Restore all the callee-saves so sigtramp_g0 can return to our caller.
162 // We also pass R2 = g0, R3 = oldg, both set above.
163 MOVD R5, R0
164 MOVD R6, R1
165 MOVD R7, LR
166 MOVD R16, R27 // restore R27
167 MOVD R17, g // restore R28
168 B sigtramp_g0<>(SB)
169
170 switch:
171 // switch to g0 stack (but do not update g - that's sigtramp_g0's job)
172 MOVD RSP, R8
173 MOVD (g_sched+gobuf_sp)(R2), R4 // R4 = g->gobuf.sp
174 SUB $(6*8), R4 // alloc space for saves - 2 words below SP for frame pointer, 3 for us to use, 1 for alignment
175 MOVD R4, RSP // switch to g0 stack
176
177 MOVD $0, (0*8)(RSP) // fake saved LR
178 MOVD R7, (1*8)(RSP) // saved LR
179 MOVD R8, (2*8)(RSP) // saved SP
180
181 MOVD R5, R0 // original args
182 MOVD R6, R1 // original args
183 MOVD R16, R27
184 MOVD R17, g // R28
185 BL sigtramp_g0<>(SB)
186
187 // switch back to original stack; g already updated
188 MOVD (1*8)(RSP), R7 // saved LR
189 MOVD (2*8)(RSP), R8 // saved SP
190 MOVD R7, LR
191 MOVD R8, RSP
192 RET
193
194 // sigtramp_g0 is running on the g0 stack, with R2 = g0, R3 = oldg.
195 // But g itself is not set - that's R28, a callee-save register,
196 // and it still holds the value from the Windows DLL caller.
197 TEXT sigtramp_g0<>(SB),NOSPLIT,$128
198 NO_LOCAL_POINTERS
199
200 // Push C callee-save registers R19-R28. LR, FP already saved.
201 // These registers will occupy the upper 10 words of the frame.
202 SAVE_R19_TO_R28(8*7)
203
204 MOVD 0(R0), R5 // R5 = ExceptionPointers->ExceptionRecord
205 MOVD 8(R0), R6 // R6 = ExceptionPointers->ContextRecord
206 MOVD R6, context-(11*8)(SP)
207
208 MOVD R2, g // g0
209 BL runtime·save_g(SB) // smashes R0
210
211 MOVD R5, (1*8)(RSP) // arg0 (ExceptionRecord)
212 MOVD R6, (2*8)(RSP) // arg1 (ContextRecord)
213 MOVD R3, (3*8)(RSP) // arg2 (original g)
214 MOVD R3, oldg-(12*8)(SP)
215 BL (R1)
216 MOVD oldg-(12*8)(SP), g
217 BL runtime·save_g(SB) // smashes R0
218 MOVW (4*8)(RSP), R0 // return value (0 or -1)
219
220 // if return value is CONTINUE_SEARCH, do not set up control
221 // flow guard workaround
222 CMP $0, R0
223 BEQ return
224
225 // Check if we need to set up the control flow guard workaround.
226 // On Windows, the stack pointer in the context must lie within
227 // system stack limits when we resume from exception.
228 // Store the resume SP and PC in alternate registers
229 // and return to sigresume on the g0 stack.
230 // sigresume makes no use of the stack at all,
231 // loading SP from R0 and jumping to R1.
232 // Note that smashing R0 and R1 is only safe because we know sigpanic
233 // will not actually return to the original frame, so the registers
234 // are effectively dead. But this does mean we can't use the
235 // same mechanism for async preemption.
236 MOVD context-(11*8)(SP), R6
237 MOVD context_pc(R6), R2 // load PC from context record
238 MOVD $sigresume<>(SB), R1
239
240 CMP R1, R2
241 BEQ return // do not clobber saved SP/PC
242
243 // Save resume SP and PC into R0, R1.
244 MOVD context_xsp(R6), R2
245 MOVD R2, (context_x+0*8)(R6)
246 MOVD context_pc(R6), R2
247 MOVD R2, (context_x+1*8)(R6)
248
249 // Set up context record to return to sigresume on g0 stack
250 MOVD RSP, R2
251 MOVD R2, context_xsp(R6)
252 MOVD $sigresume<>(SB), R2
253 MOVD R2, context_pc(R6)
254
255 return:
256 RESTORE_R19_TO_R28(8*7) // smashes g
257 RET
258
259 // Trampoline to resume execution from exception handler.
260 // This is part of the control flow guard workaround.
261 // It switches stacks and jumps to the continuation address.
262 // R0 and R1 are set above at the end of sigtramp<>
263 // in the context that starts executing at sigresume<>.
264 TEXT sigresume<>(SB),NOSPLIT|NOFRAME,$0
265 // Important: do not smash LR,
266 // which is set to a live value when handling
267 // a signal by pushing a call to sigpanic onto the stack.
268 MOVD R0, RSP
269 B (R1)
270
271 TEXT runtime·exceptiontramp(SB),NOSPLIT|NOFRAME,$0
272 MOVD $runtime·exceptionhandler(SB), R1
273 B sigtramp<>(SB)
274
275 TEXT runtime·firstcontinuetramp(SB),NOSPLIT|NOFRAME,$0
276 MOVD $runtime·firstcontinuehandler(SB), R1
277 B sigtramp<>(SB)
278
279 TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
280 MOVD $runtime·lastcontinuehandler(SB), R1
281 B sigtramp<>(SB)
282
283 GLOBL runtime·cbctxts(SB), NOPTR, $4
284
285 TEXT runtime·callbackasm1(SB),NOSPLIT,$208-0
286 NO_LOCAL_POINTERS
287
288 // On entry, the trampoline in zcallback_windows_arm64.s left
289 // the callback index in R12 (which is volatile in the C ABI).
290
291 // Save callback register arguments R0-R7.
292 // We do this at the top of the frame so they're contiguous with stack arguments.
293 // The 7*8 setting up R14 looks like a bug but is not: the eighth word
294 // is the space the assembler reserved for our caller's frame pointer,
295 // but we are not called from Go so that space is ours to use,
296 // and we must to be contiguous with the stack arguments.
297 MOVD $arg0-(7*8)(SP), R14
298 STP (R0, R1), (0*8)(R14)
299 STP (R2, R3), (2*8)(R14)
300 STP (R4, R5), (4*8)(R14)
301 STP (R6, R7), (6*8)(R14)
302
303 // Push C callee-save registers R19-R28.
304 // LR, FP already saved.
305 SAVE_R19_TO_R28(8*9)
306
307 // Create a struct callbackArgs on our stack.
308 MOVD $cbargs-(18*8+callbackArgs__size)(SP), R13
309 MOVD R12, callbackArgs_index(R13) // callback index
310 MOVD R14, R0
311 MOVD R0, callbackArgs_args(R13) // address of args vector
312 MOVD $0, R0
313 MOVD R0, callbackArgs_result(R13) // result
314
315 // Call cgocallback, which will call callbackWrap(frame).
316 MOVD $·callbackWrap<ABIInternal>(SB), R0 // PC of function to call, cgocallback takes an ABIInternal entry-point
317 MOVD R13, R1 // frame (&callbackArgs{...})
318 MOVD $0, R2 // context
319 STP (R0, R1), (1*8)(RSP)
320 MOVD R2, (3*8)(RSP)
321 BL runtime·cgocallback(SB)
322
323 // Get callback result.
324 MOVD $cbargs-(18*8+callbackArgs__size)(SP), R13
325 MOVD callbackArgs_result(R13), R0
326
327 RESTORE_R19_TO_R28(8*9)
328
329 RET
330
331 // uint32 tstart_stdcall(M *newm);
332 TEXT runtime·tstart_stdcall(SB),NOSPLIT,$96-0
333 SAVE_R19_TO_R28(8*3)
334
335 MOVD m_g0(R0), g
336 MOVD R0, g_m(g)
337 BL runtime·save_g(SB)
338
339 // Set up stack guards for OS stack.
340 MOVD RSP, R0
341 MOVD R0, g_stack+stack_hi(g)
342 SUB $(64*1024), R0
343 MOVD R0, (g_stack+stack_lo)(g)
344 MOVD R0, g_stackguard0(g)
345 MOVD R0, g_stackguard1(g)
346
347 BL runtime·emptyfunc(SB) // fault if stack check is wrong
348 BL runtime·mstart(SB)
349
350 RESTORE_R19_TO_R28(8*3)
351
352 // Exit the thread.
353 MOVD $0, R0
354 RET
355
356 // Runs on OS stack.
357 // duration (in -100ns units) is in dt+0(FP).
358 // g may be nil.
359 TEXT runtime·usleep2(SB),NOSPLIT,$32-4
360 MOVW dt+0(FP), R0
361 MOVD $16(RSP), R2 // R2 = pTime
362 MOVD R0, 0(R2) // *pTime = -dt
363 MOVD $-1, R0 // R0 = handle
364 MOVD $0, R1 // R1 = FALSE (alertable)
365 MOVD runtime·_NtWaitForSingleObject(SB), R3
366 SUB $16, RSP // skip over saved frame pointer below RSP
367 BL (R3)
368 ADD $16, RSP
369 RET
370
371 // Runs on OS stack.
372 // duration (in -100ns units) is in dt+0(FP).
373 // g is valid.
374 // TODO: needs to be implemented properly.
375 TEXT runtime·usleep2HighRes(SB),NOSPLIT,$0-4
376 B runtime·abort(SB)
377
378 // Runs on OS stack.
379 TEXT runtime·switchtothread(SB),NOSPLIT,$16-0
380 MOVD runtime·_SwitchToThread(SB), R0
381 SUB $16, RSP // skip over saved frame pointer below RSP
382 BL (R0)
383 ADD $16, RSP
384 RET
385
386 TEXT runtime·nanotime1(SB),NOSPLIT|NOFRAME,$0-8
387 MOVB runtime·useQPCTime(SB), R0
388 CMP $0, R0
389 BNE useQPC
390 MOVD $_INTERRUPT_TIME, R3
391 MOVD time_lo(R3), R0
392 MOVD $100, R1
393 MUL R1, R0
394 MOVD R0, ret+0(FP)
395 RET
396 useQPC:
397 B runtime·nanotimeQPC(SB) // tail call
398
399 // This is called from rt0_go, which runs on the system stack
400 // using the initial stack allocated by the OS.
401 // It calls back into standard C using the BL below.
402 TEXT runtime·wintls(SB),NOSPLIT,$0
403 // Allocate a TLS slot to hold g across calls to external code
404 MOVD runtime·_TlsAlloc(SB), R0
405 SUB $16, RSP // skip over saved frame pointer below RSP
406 BL (R0)
407 ADD $16, RSP
408
409 // Assert that slot is less than 64 so we can use _TEB->TlsSlots
410 CMP $64, R0
411 BLT ok
412 MOVD $runtime·abort(SB), R1
413 BL (R1)
414 ok:
415
416 // Save offset from R18 into tls_g.
417 LSL $3, R0
418 ADD $TEB_TlsSlots, R0
419 MOVD R0, runtime·tls_g(SB)
420 RET
421
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