runtime: add async preemption support on MIPS and MIPS64

This CL adds support of call injection and async preemption on
MIPS and MIPS64.

Like ARM64, we need to clobber one register (REGTMP) for
returning from the injected call. Previous CLs have marked code
sequences that use REGTMP async-nonpreemtible.

It seems on MIPS/MIPS64, a CALL instruction is not "atomic" (!).
If a signal is delivered right at the CALL instruction, we may
see an updated LR with a not-yet-updated PC. In some cases this
may lead to failed stack unwinding. Don't preempt in this case.

Change-Id: I99437b2d05869ded5c0c8cb55265dbfc933aedab
Reviewed-on: https://go-review.googlesource.com/c/go/+/203720
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 133 insertions, 2 deletions

diff --git a/src/runtime/preempt_mips64x.s b/src/runtime/preempt_mips64x.s
index 713c074abf..8048a87cd3 100644
--- a/src/runtime/preempt_mips64x.s
+++ b/src/runtime/preempt_mips64x.s
@@ -6,5 +6,136 @@
 #include "textflag.h"
 
 TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0
-	// Not implemented yet
-	JMP ·abort(SB)
+	MOVV R31, -488(R29)
+	SUBV $488, R29
+	MOVV R1, 8(R29)
+	MOVV R2, 16(R29)
+	MOVV R3, 24(R29)
+	MOVV R4, 32(R29)
+	MOVV R5, 40(R29)
+	MOVV R6, 48(R29)
+	MOVV R7, 56(R29)
+	MOVV R8, 64(R29)
+	MOVV R9, 72(R29)
+	MOVV R10, 80(R29)
+	MOVV R11, 88(R29)
+	MOVV R12, 96(R29)
+	MOVV R13, 104(R29)
+	MOVV R14, 112(R29)
+	MOVV R15, 120(R29)
+	MOVV R16, 128(R29)
+	MOVV R17, 136(R29)
+	MOVV R18, 144(R29)
+	MOVV R19, 152(R29)
+	MOVV R20, 160(R29)
+	MOVV R21, 168(R29)
+	MOVV R22, 176(R29)
+	MOVV R24, 184(R29)
+	MOVV R25, 192(R29)
+	MOVV RSB, 200(R29)
+	MOVV HI, R1
+	MOVV R1, 208(R29)
+	MOVV LO, R1
+	MOVV R1, 216(R29)
+	MOVV FCR31, R1
+	MOVV R1, 224(R29)
+	MOVD F0, 232(R29)
+	MOVD F1, 240(R29)
+	MOVD F2, 248(R29)
+	MOVD F3, 256(R29)
+	MOVD F4, 264(R29)
+	MOVD F5, 272(R29)
+	MOVD F6, 280(R29)
+	MOVD F7, 288(R29)
+	MOVD F8, 296(R29)
+	MOVD F9, 304(R29)
+	MOVD F10, 312(R29)
+	MOVD F11, 320(R29)
+	MOVD F12, 328(R29)
+	MOVD F13, 336(R29)
+	MOVD F14, 344(R29)
+	MOVD F15, 352(R29)
+	MOVD F16, 360(R29)
+	MOVD F17, 368(R29)
+	MOVD F18, 376(R29)
+	MOVD F19, 384(R29)
+	MOVD F20, 392(R29)
+	MOVD F21, 400(R29)
+	MOVD F22, 408(R29)
+	MOVD F23, 416(R29)
+	MOVD F24, 424(R29)
+	MOVD F25, 432(R29)
+	MOVD F26, 440(R29)
+	MOVD F27, 448(R29)
+	MOVD F28, 456(R29)
+	MOVD F29, 464(R29)
+	MOVD F30, 472(R29)
+	MOVD F31, 480(R29)
+	CALL ·asyncPreempt2(SB)
+	MOVD 480(R29), F31
+	MOVD 472(R29), F30
+	MOVD 464(R29), F29
+	MOVD 456(R29), F28
+	MOVD 448(R29), F27
+	MOVD 440(R29), F26
+	MOVD 432(R29), F25
+	MOVD 424(R29), F24
+	MOVD 416(R29), F23
+	MOVD 408(R29), F22
+	MOVD 400(R29), F21
+	MOVD 392(R29), F20
+	MOVD 384(R29), F19
+	MOVD 376(R29), F18
+	MOVD 368(R29), F17
+	MOVD 360(R29), F16
+	MOVD 352(R29), F15
+	MOVD 344(R29), F14
+	MOVD 336(R29), F13
+	MOVD 328(R29), F12
+	MOVD 320(R29), F11
+	MOVD 312(R29), F10
+	MOVD 304(R29), F9
+	MOVD 296(R29), F8
+	MOVD 288(R29), F7
+	MOVD 280(R29), F6
+	MOVD 272(R29), F5
+	MOVD 264(R29), F4
+	MOVD 256(R29), F3
+	MOVD 248(R29), F2
+	MOVD 240(R29), F1
+	MOVD 232(R29), F0
+	MOVV 224(R29), R1
+	MOVV R1, FCR31
+	MOVV 216(R29), R1
+	MOVV R1, LO
+	MOVV 208(R29), R1
+	MOVV R1, HI
+	MOVV 200(R29), RSB
+	MOVV 192(R29), R25
+	MOVV 184(R29), R24
+	MOVV 176(R29), R22
+	MOVV 168(R29), R21
+	MOVV 160(R29), R20
+	MOVV 152(R29), R19
+	MOVV 144(R29), R18
+	MOVV 136(R29), R17
+	MOVV 128(R29), R16
+	MOVV 120(R29), R15
+	MOVV 112(R29), R14
+	MOVV 104(R29), R13
+	MOVV 96(R29), R12
+	MOVV 88(R29), R11
+	MOVV 80(R29), R10
+	MOVV 72(R29), R9
+	MOVV 64(R29), R8
+	MOVV 56(R29), R7
+	MOVV 48(R29), R6
+	MOVV 40(R29), R5
+	MOVV 32(R29), R4
+	MOVV 24(R29), R3
+	MOVV 16(R29), R2
+	MOVV 8(R29), R1
+	MOVV 488(R29), R31
+	MOVV (R29), R23
+	ADDV $496, R29
+	JMP (R23)