Text file src/runtime/asm_amd64.s

     1  // Copyright 2009 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 "funcdata.h"
     8  #include "textflag.h"
     9  #include "cgo/abi_amd64.h"
    10  
    11  // _rt0_amd64 is common startup code for most amd64 systems when using
    12  // internal linking. This is the entry point for the program from the
    13  // kernel for an ordinary -buildmode=exe program. The stack holds the
    14  // number of arguments and the C-style argv.
    15  TEXT _rt0_amd64(SB),NOSPLIT,$-8
    16  	MOVQ	0(SP), DI	// argc
    17  	LEAQ	8(SP), SI	// argv
    18  	JMP	runtime·rt0_go(SB)
    19  
    20  // main is common startup code for most amd64 systems when using
    21  // external linking. The C startup code will call the symbol "main"
    22  // passing argc and argv in the usual C ABI registers DI and SI.
    23  TEXT main(SB),NOSPLIT,$-8
    24  	JMP	runtime·rt0_go(SB)
    25  
    26  // _rt0_amd64_lib is common startup code for most amd64 systems when
    27  // using -buildmode=c-archive or -buildmode=c-shared. The linker will
    28  // arrange to invoke this function as a global constructor (for
    29  // c-archive) or when the shared library is loaded (for c-shared).
    30  // We expect argc and argv to be passed in the usual C ABI registers
    31  // DI and SI.
    32  TEXT _rt0_amd64_lib(SB),NOSPLIT|NOFRAME,$0
    33  	// Transition from C ABI to Go ABI.
    34  	PUSH_REGS_HOST_TO_ABI0()
    35  
    36  	MOVQ	DI, _rt0_amd64_lib_argc<>(SB)
    37  	MOVQ	SI, _rt0_amd64_lib_argv<>(SB)
    38  
    39  #ifdef GOOS_windows
    40  	// Set up a dummy TLS value on Windows so that the autogenerated
    41  	// ABI wrappers don't crash when trying to load G from TLS before
    42  	// wintls has set up the real TLS slot in rt0_go.
    43  	MOVQ	$zeroTLS<>(SB), DI
    44  	CALL	runtime·settls(SB)
    45  #endif
    46  
    47  	CALL	runtime·libInit(SB)
    48  
    49  	POP_REGS_HOST_TO_ABI0()
    50  	RET
    51  
    52  // rt0_lib_go initializes the Go runtime.
    53  // This is started in a separate thread by _rt0_amd64_lib.
    54  TEXT runtime·rt0_lib_go<ABIInternal>(SB),NOSPLIT,$0
    55  	MOVQ	_rt0_amd64_lib_argc<>(SB), DI
    56  	MOVQ	_rt0_amd64_lib_argv<>(SB), SI
    57  	JMP	runtime·rt0_go(SB)
    58  
    59  DATA _rt0_amd64_lib_argc<>(SB)/8, $0
    60  GLOBL _rt0_amd64_lib_argc<>(SB),NOPTR, $8
    61  DATA _rt0_amd64_lib_argv<>(SB)/8, $0
    62  GLOBL _rt0_amd64_lib_argv<>(SB),NOPTR, $8
    63  
    64  #ifdef GOAMD64_v2
    65  DATA bad_cpu_msg<>+0x00(SB)/84, $"This program can only be run on AMD64 processors with v2 microarchitecture support.\n"
    66  #endif
    67  
    68  #ifdef GOAMD64_v3
    69  DATA bad_cpu_msg<>+0x00(SB)/84, $"This program can only be run on AMD64 processors with v3 microarchitecture support.\n"
    70  #endif
    71  
    72  #ifdef GOAMD64_v4
    73  DATA bad_cpu_msg<>+0x00(SB)/84, $"This program can only be run on AMD64 processors with v4 microarchitecture support.\n"
    74  #endif
    75  
    76  GLOBL bad_cpu_msg<>(SB), RODATA, $84
    77  
    78  // Define a list of AMD64 microarchitecture level features
    79  // https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels
    80  
    81                       // SSE3     SSSE3    CMPXCHNG16 SSE4.1    SSE4.2    POPCNT
    82  #define V2_FEATURES_CX (1 << 0 | 1 << 9 | 1 << 13  | 1 << 19 | 1 << 20 | 1 << 23)
    83                           // LAHF/SAHF
    84  #define V2_EXT_FEATURES_CX (1 << 0)
    85                                        // FMA       MOVBE     OSXSAVE   AVX       F16C
    86  #define V3_FEATURES_CX (V2_FEATURES_CX | 1 << 12 | 1 << 22 | 1 << 27 | 1 << 28 | 1 << 29)
    87                                                // ABM (FOR LZNCT)
    88  #define V3_EXT_FEATURES_CX (V2_EXT_FEATURES_CX | 1 << 5)
    89                           // BMI1     AVX2     BMI2
    90  #define V3_EXT_FEATURES_BX (1 << 3 | 1 << 5 | 1 << 8)
    91                         // XMM      YMM
    92  #define V3_OS_SUPPORT_AX (1 << 1 | 1 << 2)
    93  
    94  #define V4_FEATURES_CX V3_FEATURES_CX
    95  
    96  #define V4_EXT_FEATURES_CX V3_EXT_FEATURES_CX
    97                                                // AVX512F   AVX512DQ  AVX512CD  AVX512BW  AVX512VL
    98  #define V4_EXT_FEATURES_BX (V3_EXT_FEATURES_BX | 1 << 16 | 1 << 17 | 1 << 28 | 1 << 30 | 1 << 31)
    99                                            // OPMASK   ZMM
   100  #define V4_OS_SUPPORT_AX (V3_OS_SUPPORT_AX | 1 << 5 | (1 << 6 | 1 << 7))
   101  
   102  #ifdef GOAMD64_v2
   103  #define NEED_MAX_CPUID 0x80000001
   104  #define NEED_FEATURES_CX V2_FEATURES_CX
   105  #define NEED_EXT_FEATURES_CX V2_EXT_FEATURES_CX
   106  #endif
   107  
   108  #ifdef GOAMD64_v3
   109  #define NEED_MAX_CPUID 0x80000001
   110  #define NEED_FEATURES_CX V3_FEATURES_CX
   111  #define NEED_EXT_FEATURES_CX V3_EXT_FEATURES_CX
   112  #define NEED_EXT_FEATURES_BX V3_EXT_FEATURES_BX
   113  #define NEED_OS_SUPPORT_AX V3_OS_SUPPORT_AX
   114  #endif
   115  
   116  #ifdef GOAMD64_v4
   117  #define NEED_MAX_CPUID 0x80000001
   118  #define NEED_FEATURES_CX V4_FEATURES_CX
   119  #define NEED_EXT_FEATURES_CX V4_EXT_FEATURES_CX
   120  #define NEED_EXT_FEATURES_BX V4_EXT_FEATURES_BX
   121  
   122  // Darwin requires a different approach to check AVX512 support, see CL 285572.
   123  #ifdef GOOS_darwin
   124  #define NEED_OS_SUPPORT_AX V3_OS_SUPPORT_AX
   125  // These values are from:
   126  // https://github.com/apple/darwin-xnu/blob/xnu-4570.1.46/osfmk/i386/cpu_capabilities.h
   127  #define commpage64_base_address         0x00007fffffe00000
   128  #define commpage64_cpu_capabilities64   (commpage64_base_address+0x010)
   129  #define commpage64_version              (commpage64_base_address+0x01E)
   130  #define AVX512F                         0x0000004000000000
   131  #define AVX512CD                        0x0000008000000000
   132  #define AVX512DQ                        0x0000010000000000
   133  #define AVX512BW                        0x0000020000000000
   134  #define AVX512VL                        0x0000100000000000
   135  #define NEED_DARWIN_SUPPORT             (AVX512F | AVX512DQ | AVX512CD | AVX512BW | AVX512VL)
   136  #else
   137  #define NEED_OS_SUPPORT_AX V4_OS_SUPPORT_AX
   138  #endif
   139  
   140  #endif
   141  
   142  TEXT runtime·rt0_go(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
   143  	// copy arguments forward on an even stack
   144  	MOVQ	DI, AX		// argc
   145  	MOVQ	SI, BX		// argv
   146  	SUBQ	$(5*8), SP		// 3args 2auto
   147  	ANDQ	$~15, SP
   148  	MOVQ	AX, 24(SP)
   149  	MOVQ	BX, 32(SP)
   150  
   151  	// This is typically the entry point for Go programs.
   152  	// Call stack unwinding must not proceed past this frame.
   153  	// Set the frame pointer register to 0 so that frame pointer-based unwinders
   154  	// (which don't use debug info for performance reasons)
   155  	// won't attempt to unwind past this function.
   156  	// See go.dev/issue/63630
   157  	MOVQ	$0, BP
   158  
   159  	// create istack out of the given (operating system) stack.
   160  	// _cgo_init may update stackguard.
   161  	MOVQ	$runtime·g0(SB), DI
   162  	LEAQ	(-64*1024)(SP), BX
   163  	MOVQ	BX, g_stackguard0(DI)
   164  	MOVQ	BX, g_stackguard1(DI)
   165  	MOVQ	BX, (g_stack+stack_lo)(DI)
   166  	MOVQ	SP, (g_stack+stack_hi)(DI)
   167  
   168  	// find out information about the processor we're on
   169  	MOVL	$0, AX
   170  	CPUID
   171  	CMPL	AX, $0
   172  	JE	nocpuinfo
   173  
   174  	CMPL	BX, $0x756E6547  // "Genu"
   175  	JNE	notintel
   176  	CMPL	DX, $0x49656E69  // "ineI"
   177  	JNE	notintel
   178  	CMPL	CX, $0x6C65746E  // "ntel"
   179  	JNE	notintel
   180  	MOVB	$1, runtime·isIntel(SB)
   181  
   182  notintel:
   183  	// Load EAX=1 cpuid flags
   184  	MOVL	$1, AX
   185  	CPUID
   186  	MOVL	AX, runtime·processorVersionInfo(SB)
   187  
   188  nocpuinfo:
   189  	// if there is an _cgo_init, call it.
   190  	MOVQ	_cgo_init(SB), AX
   191  	TESTQ	AX, AX
   192  	JZ	needtls
   193  	// arg 1: g0, already in DI
   194  	MOVQ	$setg_gcc<>(SB), SI // arg 2: setg_gcc
   195  	MOVQ	$0, DX	// arg 3, 4: not used when using platform's TLS
   196  	MOVQ	$0, CX
   197  #ifdef GOOS_android
   198  	MOVQ	$runtime·tls_g(SB), DX 	// arg 3: &tls_g
   199  	// arg 4: TLS base, stored in slot 0 (Android's TLS_SLOT_SELF).
   200  	// Compensate for tls_g (+16).
   201  	MOVQ	-16(TLS), CX
   202  #endif
   203  #ifdef GOOS_windows
   204  	MOVQ	$runtime·tls_g(SB), DX 	// arg 3: &tls_g
   205  	// Adjust for the Win64 calling convention.
   206  	MOVQ	CX, R9 // arg 4
   207  	MOVQ	DX, R8 // arg 3
   208  	MOVQ	SI, DX // arg 2
   209  	MOVQ	DI, CX // arg 1
   210  #endif
   211  	CALL	AX
   212  
   213  	// update stackguard after _cgo_init
   214  	MOVQ	$runtime·g0(SB), CX
   215  	MOVQ	(g_stack+stack_lo)(CX), AX
   216  	ADDQ	$const_stackGuard, AX
   217  	MOVQ	AX, g_stackguard0(CX)
   218  	MOVQ	AX, g_stackguard1(CX)
   219  
   220  #ifndef GOOS_windows
   221  	JMP ok
   222  #endif
   223  needtls:
   224  #ifdef GOOS_plan9
   225  	// skip TLS setup on Plan 9
   226  	JMP ok
   227  #endif
   228  #ifdef GOOS_solaris
   229  	// skip TLS setup on Solaris
   230  	JMP ok
   231  #endif
   232  #ifdef GOOS_illumos
   233  	// skip TLS setup on illumos
   234  	JMP ok
   235  #endif
   236  #ifdef GOOS_darwin
   237  	// skip TLS setup on Darwin
   238  	JMP ok
   239  #endif
   240  #ifdef GOOS_openbsd
   241  	// skip TLS setup on OpenBSD
   242  	JMP ok
   243  #endif
   244  
   245  #ifdef GOOS_windows
   246  	CALL	runtime·wintls(SB)
   247  #endif
   248  
   249  	LEAQ	runtime·m0+m_tls(SB), DI
   250  	CALL	runtime·settls(SB)
   251  
   252  	// store through it, to make sure it works
   253  	get_tls(BX)
   254  	MOVQ	$0x123, g(BX)
   255  	MOVQ	runtime·m0+m_tls(SB), AX
   256  	CMPQ	AX, $0x123
   257  	JEQ 2(PC)
   258  	CALL	runtime·abort(SB)
   259  ok:
   260  	// set the per-goroutine and per-mach "registers"
   261  	get_tls(BX)
   262  	LEAQ	runtime·g0(SB), CX
   263  	MOVQ	CX, g(BX)
   264  	LEAQ	runtime·m0(SB), AX
   265  
   266  	// save m->g0 = g0
   267  	MOVQ	CX, m_g0(AX)
   268  	// save m0 to g0->m
   269  	MOVQ	AX, g_m(CX)
   270  
   271  	CLD				// convention is D is always left cleared
   272  
   273  	// Check GOAMD64 requirements
   274  	// We need to do this after setting up TLS, so that
   275  	// we can report an error if there is a failure. See issue 49586.
   276  #ifdef NEED_FEATURES_CX
   277  	MOVL	$0, AX
   278  	CPUID
   279  	CMPL	AX, $0
   280  	JE	bad_cpu
   281  	MOVL	$1, AX
   282  	CPUID
   283  	ANDL	$NEED_FEATURES_CX, CX
   284  	CMPL	CX, $NEED_FEATURES_CX
   285  	JNE	bad_cpu
   286  #endif
   287  
   288  #ifdef NEED_MAX_CPUID
   289  	MOVL	$0x80000000, AX
   290  	CPUID
   291  	CMPL	AX, $NEED_MAX_CPUID
   292  	JL	bad_cpu
   293  #endif
   294  
   295  #ifdef NEED_EXT_FEATURES_BX
   296  	MOVL	$7, AX
   297  	MOVL	$0, CX
   298  	CPUID
   299  	ANDL	$NEED_EXT_FEATURES_BX, BX
   300  	CMPL	BX, $NEED_EXT_FEATURES_BX
   301  	JNE	bad_cpu
   302  #endif
   303  
   304  #ifdef NEED_EXT_FEATURES_CX
   305  	MOVL	$0x80000001, AX
   306  	CPUID
   307  	ANDL	$NEED_EXT_FEATURES_CX, CX
   308  	CMPL	CX, $NEED_EXT_FEATURES_CX
   309  	JNE	bad_cpu
   310  #endif
   311  
   312  #ifdef NEED_OS_SUPPORT_AX
   313  	XORL    CX, CX
   314  	XGETBV
   315  	ANDL	$NEED_OS_SUPPORT_AX, AX
   316  	CMPL	AX, $NEED_OS_SUPPORT_AX
   317  	JNE	bad_cpu
   318  #endif
   319  
   320  #ifdef NEED_DARWIN_SUPPORT
   321  	MOVQ	$commpage64_version, BX
   322  	CMPW	(BX), $13  // cpu_capabilities64 undefined in versions < 13
   323  	JL	bad_cpu
   324  	MOVQ	$commpage64_cpu_capabilities64, BX
   325  	MOVQ	(BX), BX
   326  	MOVQ	$NEED_DARWIN_SUPPORT, CX
   327  	ANDQ	CX, BX
   328  	CMPQ	BX, CX
   329  	JNE	bad_cpu
   330  #endif
   331  
   332  	CALL	runtime·check(SB)
   333  
   334  	MOVL	24(SP), AX		// copy argc
   335  	MOVL	AX, 0(SP)
   336  	MOVQ	32(SP), AX		// copy argv
   337  	MOVQ	AX, 8(SP)
   338  	CALL	runtime·args(SB)
   339  	CALL	runtime·osinit(SB)
   340  	CALL	runtime·schedinit(SB)
   341  
   342  	// create a new goroutine to start program
   343  	MOVQ	$runtime·mainPC(SB), AX		// entry
   344  	PUSHQ	AX
   345  	CALL	runtime·newproc(SB)
   346  	POPQ	AX
   347  
   348  	// start this M
   349  	CALL	runtime·mstart(SB)
   350  
   351  	CALL	runtime·abort(SB)	// mstart should never return
   352  	RET
   353  
   354  bad_cpu: // show that the program requires a certain microarchitecture level.
   355  	MOVQ	$2, 0(SP)
   356  	MOVQ	$bad_cpu_msg<>(SB), AX
   357  	MOVQ	AX, 8(SP)
   358  	MOVQ	$84, 16(SP)
   359  	CALL	runtime·write(SB)
   360  	MOVQ	$1, 0(SP)
   361  	CALL	runtime·exit(SB)
   362  	CALL	runtime·abort(SB)
   363  	RET
   364  
   365  	// Prevent dead-code elimination of debugCallV2 and debugPinnerV1, which are
   366  	// intended to be called by debuggers.
   367  	MOVQ	$runtime·debugPinnerV1<ABIInternal>(SB), AX
   368  	MOVQ	$runtime·debugCallV2<ABIInternal>(SB), AX
   369  	RET
   370  
   371  // mainPC is a function value for runtime.main, to be passed to newproc.
   372  // The reference to runtime.main is made via ABIInternal, since the
   373  // actual function (not the ABI0 wrapper) is needed by newproc.
   374  DATA	runtime·mainPC+0(SB)/8,$runtime·main<ABIInternal>(SB)
   375  GLOBL	runtime·mainPC(SB),RODATA,$8
   376  
   377  TEXT runtime·breakpoint(SB),NOSPLIT,$0-0
   378  	BYTE	$0xcc
   379  	RET
   380  
   381  TEXT runtime·asminit(SB),NOSPLIT,$0-0
   382  	// No per-thread init.
   383  	RET
   384  
   385  TEXT runtime·mstart(SB),NOSPLIT|TOPFRAME|NOFRAME,$0
   386  	// This is the root frame of new Go-created OS threads.
   387  	// Call stack unwinding must not proceed past this frame.
   388  	// Set the frame pointer register to 0 so that frame pointer-based unwinders
   389  	// (which don't use debug info for performance reasons)
   390  	// won't attempt to unwind past this function.
   391  	// See go.dev/issue/63630
   392  	MOVD	$0, BP
   393  	CALL	runtime·mstart0(SB)
   394  	RET // not reached
   395  
   396  /*
   397   *  go-routine
   398   */
   399  
   400  // func gogo(buf *gobuf)
   401  // restore state from Gobuf; longjmp
   402  TEXT runtime·gogo(SB), NOSPLIT, $0-8
   403  	MOVQ	buf+0(FP), BX		// gobuf
   404  	MOVQ	gobuf_g(BX), DX
   405  	MOVQ	0(DX), CX		// make sure g != nil
   406  	JMP	gogo<>(SB)
   407  
   408  TEXT gogo<>(SB), NOSPLIT, $0
   409  	get_tls(CX)
   410  	MOVQ	DX, g(CX)
   411  	MOVQ	DX, R14		// set the g register
   412  	MOVQ	gobuf_sp(BX), SP	// restore SP
   413  	MOVQ	gobuf_ctxt(BX), DX
   414  	MOVQ	gobuf_bp(BX), BP
   415  	MOVQ	$0, gobuf_sp(BX)	// clear to help garbage collector
   416  	MOVQ	$0, gobuf_ctxt(BX)
   417  	MOVQ	$0, gobuf_bp(BX)
   418  	MOVQ	gobuf_pc(BX), BX
   419  	JMP	BX
   420  
   421  // func mcall(fn func(*g))
   422  // Switch to m->g0's stack, call fn(g).
   423  // Fn must never return. It should gogo(&g->sched)
   424  // to keep running g.
   425  TEXT runtime·mcall<ABIInternal>(SB), NOSPLIT, $0-8
   426  #ifdef GOEXPERIMENT_runtimesecret
   427  	CMPL	g_secret(R14), $0
   428  	JEQ	nosecret
   429  	CALL	·secretEraseRegistersMcall(SB)
   430  nosecret:
   431  #endif
   432  
   433  	MOVQ	AX, DX	// DX = fn
   434  
   435  	// Save state in g->sched. The caller's SP and PC are restored by gogo to
   436  	// resume execution in the caller's frame (implicit return). The caller's BP
   437  	// is also restored to support frame pointer unwinding.
   438  	MOVQ	SP, BX	// hide (SP) reads from vet
   439  	MOVQ	8(BX), BX	// caller's PC
   440  	MOVQ	BX, (g_sched+gobuf_pc)(R14)
   441  	LEAQ	fn+0(FP), BX	// caller's SP
   442  	MOVQ	BX, (g_sched+gobuf_sp)(R14)
   443  	// Get the caller's frame pointer by dereferencing BP. Storing BP as it is
   444  	// can cause a frame pointer cycle, see CL 476235.
   445  	MOVQ	(BP), BX // caller's BP
   446  	MOVQ	BX, (g_sched+gobuf_bp)(R14)
   447  
   448  	// switch to m->g0 & its stack, call fn
   449  	MOVQ	g_m(R14), BX
   450  	MOVQ	m_g0(BX), SI	// SI = g.m.g0
   451  	CMPQ	SI, R14	// if g == m->g0 call badmcall
   452  	JNE	goodm
   453  	JMP	runtime·badmcall(SB)
   454  goodm:
   455  	MOVQ	R14, AX		// AX (and arg 0) = g
   456  	MOVQ	SI, R14		// g = g.m.g0
   457  	get_tls(CX)		// Set G in TLS
   458  	MOVQ	R14, g(CX)
   459  	MOVQ	(g_sched+gobuf_sp)(R14), SP	// sp = g0.sched.sp
   460  	MOVQ	$0, BP	// clear frame pointer, as caller may execute on another M
   461  	PUSHQ	AX	// open up space for fn's arg spill slot
   462  	MOVQ	0(DX), R12
   463  	CALL	R12		// fn(g)
   464  	// The Windows native stack unwinder incorrectly classifies the next instruction
   465  	// as part of the function epilogue, producing a wrong call stack.
   466  	// Add a NOP to work around this issue. See go.dev/issue/67007.
   467  	BYTE	$0x90
   468  	POPQ	AX
   469  	JMP	runtime·badmcall2(SB)
   470  	RET
   471  
   472  // systemstack_switch is a dummy routine that systemstack leaves at the bottom
   473  // of the G stack. We need to distinguish the routine that
   474  // lives at the bottom of the G stack from the one that lives
   475  // at the top of the system stack because the one at the top of
   476  // the system stack terminates the stack walk (see topofstack()).
   477  // The frame layout needs to match systemstack
   478  // so that it can pretend to be systemstack_switch.
   479  TEXT runtime·systemstack_switch(SB), NOSPLIT, $0-0
   480  	// Align for consistency with offset used in gosave_systemstack_switch
   481  	PCALIGN	$8
   482  	UNDEF
   483  	// Make sure this function is not leaf,
   484  	// so the frame is saved.
   485  	CALL	runtime·abort(SB)
   486  	RET
   487  
   488  // func systemstack(fn func())
   489  TEXT runtime·systemstack(SB), NOSPLIT, $0-8
   490  #ifdef GOEXPERIMENT_runtimesecret
   491  	// If in secret mode, erase registers on transition
   492  	// from G stack to M stack,
   493  	get_tls(CX)
   494  	MOVQ	g(CX), AX
   495  	CMPL	g_secret(AX), $0
   496  	JEQ	nosecret
   497  	CALL	·secretEraseRegisters(SB)
   498  nosecret:
   499  #endif
   500  
   501  	MOVQ	fn+0(FP), DI	// DI = fn
   502  	get_tls(CX)
   503  	MOVQ	g(CX), AX	// AX = g
   504  	MOVQ	g_m(AX), BX	// BX = m
   505  
   506  	CMPQ	AX, m_gsignal(BX)
   507  	JEQ	noswitch
   508  
   509  	MOVQ	m_g0(BX), DX	// DX = g0
   510  	CMPQ	AX, DX
   511  	JEQ	noswitch
   512  
   513  	CMPQ	AX, m_curg(BX)
   514  	JNE	bad
   515  
   516  	// Switch stacks.
   517  	// The original frame pointer is stored in BP,
   518  	// which is useful for stack unwinding.
   519  	// Save our state in g->sched. Pretend to
   520  	// be systemstack_switch if the G stack is scanned.
   521  	CALL	gosave_systemstack_switch<>(SB)
   522  
   523  	// switch to g0
   524  	MOVQ	DX, g(CX)
   525  	MOVQ	DX, R14 // set the g register
   526  	MOVQ	(g_sched+gobuf_sp)(DX), SP
   527  
   528  	// call target function
   529  	MOVQ	DI, DX
   530  	MOVQ	0(DI), DI
   531  	CALL	DI
   532  
   533  	// switch back to g
   534  	get_tls(CX)
   535  	MOVQ	g(CX), AX
   536  	MOVQ	g_m(AX), BX
   537  	MOVQ	m_curg(BX), AX
   538  	MOVQ	AX, g(CX)
   539  	MOVQ	(g_sched+gobuf_sp)(AX), SP
   540  	MOVQ	(g_sched+gobuf_bp)(AX), BP
   541  	MOVQ	$0, (g_sched+gobuf_sp)(AX)
   542  	MOVQ	$0, (g_sched+gobuf_bp)(AX)
   543  	RET
   544  
   545  noswitch:
   546  	// already on m stack; tail call the function
   547  	// Using a tail call here cleans up tracebacks since we won't stop
   548  	// at an intermediate systemstack.
   549  	MOVQ	DI, DX
   550  	MOVQ	0(DI), DI
   551  	// The function epilogue is not called on a tail call.
   552  	// Pop BP from the stack to simulate it.
   553  	POPQ	BP
   554  	JMP	DI
   555  
   556  bad:
   557  	// Bad: g is not gsignal, not g0, not curg. What is it?
   558  	MOVQ	$runtime·badsystemstack(SB), AX
   559  	CALL	AX
   560  	INT	$3
   561  
   562  // func switchToCrashStack0(fn func())
   563  TEXT runtime·switchToCrashStack0<ABIInternal>(SB), NOSPLIT, $0-8
   564  	MOVQ	g_m(R14), BX // curm
   565  
   566  	// set g to gcrash
   567  	LEAQ	runtime·gcrash(SB), R14 // g = &gcrash
   568  	MOVQ	BX, g_m(R14)            // g.m = curm
   569  	MOVQ	R14, m_g0(BX)           // curm.g0 = g
   570  	get_tls(CX)
   571  	MOVQ	R14, g(CX)
   572  
   573  	// switch to crashstack
   574  	MOVQ	(g_stack+stack_hi)(R14), BX
   575  	SUBQ	$(4*8), BX
   576  	MOVQ	BX, SP
   577  
   578  	// call target function
   579  	MOVQ	AX, DX
   580  	MOVQ	0(AX), AX
   581  	CALL	AX
   582  
   583  	// should never return
   584  	CALL	runtime·abort(SB)
   585  	UNDEF
   586  
   587  /*
   588   * support for morestack
   589   */
   590  
   591  // Called during function prolog when more stack is needed.
   592  //
   593  // The traceback routines see morestack on a g0 as being
   594  // the top of a stack (for example, morestack calling newstack
   595  // calling the scheduler calling newm calling gc), so we must
   596  // record an argument size. For that purpose, it has no arguments.
   597  TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
   598  	// Cannot grow scheduler stack (m->g0).
   599  	get_tls(CX)
   600  	MOVQ	g(CX), DI     // DI = g
   601  	MOVQ	g_m(DI), BX   // BX = m
   602  
   603  	// Set g->sched to context in f.
   604  	MOVQ	0(SP), AX // f's PC
   605  	MOVQ	AX, (g_sched+gobuf_pc)(DI)
   606  	LEAQ	8(SP), AX // f's SP
   607  	MOVQ	AX, (g_sched+gobuf_sp)(DI)
   608  	MOVQ	BP, (g_sched+gobuf_bp)(DI)
   609  	MOVQ	DX, (g_sched+gobuf_ctxt)(DI)
   610  
   611  	MOVQ	m_g0(BX), SI  // SI = m.g0
   612  	CMPQ	DI, SI
   613  	JNE	3(PC)
   614  	CALL	runtime·badmorestackg0(SB)
   615  	CALL	runtime·abort(SB)
   616  
   617  	// Cannot grow signal stack (m->gsignal).
   618  	MOVQ	m_gsignal(BX), SI
   619  	CMPQ	DI, SI
   620  	JNE	3(PC)
   621  	CALL	runtime·badmorestackgsignal(SB)
   622  	CALL	runtime·abort(SB)
   623  
   624  	// Called from f.
   625  	// Set m->morebuf to f's caller.
   626  	NOP	SP	// tell vet SP changed - stop checking offsets
   627  	MOVQ	8(SP), AX	// f's caller's PC
   628  	MOVQ	AX, (m_morebuf+gobuf_pc)(BX)
   629  	LEAQ	16(SP), AX	// f's caller's SP
   630  	MOVQ	AX, (m_morebuf+gobuf_sp)(BX)
   631  	MOVQ	DI, (m_morebuf+gobuf_g)(BX)
   632  
   633  	// If in secret mode, erase registers on transition
   634  	// from G stack to M stack,
   635  #ifdef GOEXPERIMENT_runtimesecret
   636  	CMPL	g_secret(DI), $0
   637  	JEQ	nosecret
   638  	CALL	·secretEraseRegisters(SB)
   639  	get_tls(CX)
   640  	MOVQ	g(CX), DI     // DI = g
   641  	MOVQ	g_m(DI), BX   // BX = m
   642  nosecret:
   643  #endif
   644  
   645  	// Call newstack on m->g0's stack.
   646  	MOVQ	m_g0(BX), BX
   647  	MOVQ	BX, g(CX)
   648  	MOVQ	(g_sched+gobuf_sp)(BX), SP
   649  	MOVQ	$0, BP			// clear frame pointer, as caller may execute on another M
   650  	CALL	runtime·newstack(SB)
   651  	CALL	runtime·abort(SB)	// crash if newstack returns
   652  	RET
   653  
   654  // morestack but not preserving ctxt.
   655  TEXT runtime·morestack_noctxt(SB),NOSPLIT,$0
   656  	MOVL	$0, DX
   657  	JMP	runtime·morestack(SB)
   658  
   659  // spillArgs stores return values from registers to a *internal/abi.RegArgs in R12.
   660  TEXT ·spillArgs(SB),NOSPLIT,$0-0
   661  	MOVQ AX, 0(R12)
   662  	MOVQ BX, 8(R12)
   663  	MOVQ CX, 16(R12)
   664  	MOVQ DI, 24(R12)
   665  	MOVQ SI, 32(R12)
   666  	MOVQ R8, 40(R12)
   667  	MOVQ R9, 48(R12)
   668  	MOVQ R10, 56(R12)
   669  	MOVQ R11, 64(R12)
   670  	MOVQ X0, 72(R12)
   671  	MOVQ X1, 80(R12)
   672  	MOVQ X2, 88(R12)
   673  	MOVQ X3, 96(R12)
   674  	MOVQ X4, 104(R12)
   675  	MOVQ X5, 112(R12)
   676  	MOVQ X6, 120(R12)
   677  	MOVQ X7, 128(R12)
   678  	MOVQ X8, 136(R12)
   679  	MOVQ X9, 144(R12)
   680  	MOVQ X10, 152(R12)
   681  	MOVQ X11, 160(R12)
   682  	MOVQ X12, 168(R12)
   683  	MOVQ X13, 176(R12)
   684  	MOVQ X14, 184(R12)
   685  	RET
   686  
   687  // unspillArgs loads args into registers from a *internal/abi.RegArgs in R12.
   688  TEXT ·unspillArgs(SB),NOSPLIT,$0-0
   689  	MOVQ 0(R12), AX
   690  	MOVQ 8(R12), BX
   691  	MOVQ 16(R12), CX
   692  	MOVQ 24(R12), DI
   693  	MOVQ 32(R12), SI
   694  	MOVQ 40(R12), R8
   695  	MOVQ 48(R12), R9
   696  	MOVQ 56(R12), R10
   697  	MOVQ 64(R12), R11
   698  	MOVQ 72(R12), X0
   699  	MOVQ 80(R12), X1
   700  	MOVQ 88(R12), X2
   701  	MOVQ 96(R12), X3
   702  	MOVQ 104(R12), X4
   703  	MOVQ 112(R12), X5
   704  	MOVQ 120(R12), X6
   705  	MOVQ 128(R12), X7
   706  	MOVQ 136(R12), X8
   707  	MOVQ 144(R12), X9
   708  	MOVQ 152(R12), X10
   709  	MOVQ 160(R12), X11
   710  	MOVQ 168(R12), X12
   711  	MOVQ 176(R12), X13
   712  	MOVQ 184(R12), X14
   713  	RET
   714  
   715  // reflectcall: call a function with the given argument list
   716  // func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
   717  // we don't have variable-sized frames, so we use a small number
   718  // of constant-sized-frame functions to encode a few bits of size in the pc.
   719  // Caution: ugly multiline assembly macros in your future!
   720  
   721  #define DISPATCH(NAME,MAXSIZE)		\
   722  	CMPQ	CX, $MAXSIZE;		\
   723  	JA	3(PC);			\
   724  	MOVQ	$NAME(SB), AX;		\
   725  	JMP	AX
   726  // Note: can't just "JMP NAME(SB)" - bad inlining results.
   727  
   728  TEXT ·reflectcall(SB), NOSPLIT, $0-48
   729  	MOVLQZX frameSize+32(FP), CX
   730  	DISPATCH(runtime·call16, 16)
   731  	DISPATCH(runtime·call32, 32)
   732  	DISPATCH(runtime·call64, 64)
   733  	DISPATCH(runtime·call128, 128)
   734  	DISPATCH(runtime·call256, 256)
   735  	DISPATCH(runtime·call512, 512)
   736  	DISPATCH(runtime·call1024, 1024)
   737  	DISPATCH(runtime·call2048, 2048)
   738  	DISPATCH(runtime·call4096, 4096)
   739  	DISPATCH(runtime·call8192, 8192)
   740  	DISPATCH(runtime·call16384, 16384)
   741  	DISPATCH(runtime·call32768, 32768)
   742  	DISPATCH(runtime·call65536, 65536)
   743  	DISPATCH(runtime·call131072, 131072)
   744  	DISPATCH(runtime·call262144, 262144)
   745  	DISPATCH(runtime·call524288, 524288)
   746  	DISPATCH(runtime·call1048576, 1048576)
   747  	DISPATCH(runtime·call2097152, 2097152)
   748  	DISPATCH(runtime·call4194304, 4194304)
   749  	DISPATCH(runtime·call8388608, 8388608)
   750  	DISPATCH(runtime·call16777216, 16777216)
   751  	DISPATCH(runtime·call33554432, 33554432)
   752  	DISPATCH(runtime·call67108864, 67108864)
   753  	DISPATCH(runtime·call134217728, 134217728)
   754  	DISPATCH(runtime·call268435456, 268435456)
   755  	DISPATCH(runtime·call536870912, 536870912)
   756  	DISPATCH(runtime·call1073741824, 1073741824)
   757  	MOVQ	$runtime·badreflectcall(SB), AX
   758  	JMP	AX
   759  
   760  #define CALLFN(NAME,MAXSIZE)			\
   761  TEXT NAME(SB), WRAPPER, $MAXSIZE-48;		\
   762  	NO_LOCAL_POINTERS;			\
   763  	/* copy arguments to stack */		\
   764  	MOVQ	stackArgs+16(FP), SI;		\
   765  	MOVLQZX stackArgsSize+24(FP), CX;		\
   766  	MOVQ	SP, DI;				\
   767  	REP;MOVSB;				\
   768  	/* set up argument registers */		\
   769  	MOVQ    regArgs+40(FP), R12;		\
   770  	CALL    ·unspillArgs(SB);		\
   771  	/* call function */			\
   772  	MOVQ	f+8(FP), DX;			\
   773  	PCDATA  $PCDATA_StackMapIndex, $0;	\
   774  	MOVQ	(DX), R12;			\
   775  	CALL	R12;				\
   776  	/* copy register return values back */		\
   777  	MOVQ    regArgs+40(FP), R12;		\
   778  	CALL    ·spillArgs(SB);		\
   779  	MOVLQZX	stackArgsSize+24(FP), CX;		\
   780  	MOVLQZX	stackRetOffset+28(FP), BX;		\
   781  	MOVQ	stackArgs+16(FP), DI;		\
   782  	MOVQ	stackArgsType+0(FP), DX;		\
   783  	MOVQ	SP, SI;				\
   784  	ADDQ	BX, DI;				\
   785  	ADDQ	BX, SI;				\
   786  	SUBQ	BX, CX;				\
   787  	CALL	callRet<>(SB);			\
   788  	RET
   789  
   790  // callRet copies return values back at the end of call*. This is a
   791  // separate function so it can allocate stack space for the arguments
   792  // to reflectcallmove. It does not follow the Go ABI; it expects its
   793  // arguments in registers.
   794  TEXT callRet<>(SB), NOSPLIT, $40-0
   795  	NO_LOCAL_POINTERS
   796  	MOVQ	DX, 0(SP)
   797  	MOVQ	DI, 8(SP)
   798  	MOVQ	SI, 16(SP)
   799  	MOVQ	CX, 24(SP)
   800  	MOVQ	R12, 32(SP)
   801  	CALL	runtime·reflectcallmove(SB)
   802  	RET
   803  
   804  CALLFN(·call16, 16)
   805  CALLFN(·call32, 32)
   806  CALLFN(·call64, 64)
   807  CALLFN(·call128, 128)
   808  CALLFN(·call256, 256)
   809  CALLFN(·call512, 512)
   810  CALLFN(·call1024, 1024)
   811  CALLFN(·call2048, 2048)
   812  CALLFN(·call4096, 4096)
   813  CALLFN(·call8192, 8192)
   814  CALLFN(·call16384, 16384)
   815  CALLFN(·call32768, 32768)
   816  CALLFN(·call65536, 65536)
   817  CALLFN(·call131072, 131072)
   818  CALLFN(·call262144, 262144)
   819  CALLFN(·call524288, 524288)
   820  CALLFN(·call1048576, 1048576)
   821  CALLFN(·call2097152, 2097152)
   822  CALLFN(·call4194304, 4194304)
   823  CALLFN(·call8388608, 8388608)
   824  CALLFN(·call16777216, 16777216)
   825  CALLFN(·call33554432, 33554432)
   826  CALLFN(·call67108864, 67108864)
   827  CALLFN(·call134217728, 134217728)
   828  CALLFN(·call268435456, 268435456)
   829  CALLFN(·call536870912, 536870912)
   830  CALLFN(·call1073741824, 1073741824)
   831  
   832  TEXT runtime·procyieldAsm(SB),NOSPLIT,$0-0
   833  	MOVL	cycles+0(FP), AX
   834  	TESTL	AX, AX
   835  	JZ	done
   836  again:
   837  	PAUSE
   838  	SUBL	$1, AX
   839  	JNZ	again
   840  done:
   841  	RET
   842  
   843  
   844  TEXT ·publicationBarrier<ABIInternal>(SB),NOSPLIT,$0-0
   845  	// Stores are already ordered on x86, so this is just a
   846  	// compile barrier.
   847  	RET
   848  
   849  // Save state of caller into g->sched,
   850  // but using fake PC from systemstack_switch.
   851  // Must only be called from functions with frame pointer
   852  // and without locals ($0) or else unwinding from
   853  // systemstack_switch is incorrect.
   854  // Smashes R9.
   855  TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
   856  	// Take systemstack_switch PC and add 8 bytes to skip
   857  	// the prologue. Keep 8 bytes offset consistent with
   858  	// PCALIGN $8 in systemstack_swtich, pointing start of
   859  	// UNDEF instruction beyond prologue.
   860  	MOVQ	$runtime·systemstack_switch+8(SB), R9
   861  	MOVQ	R9, (g_sched+gobuf_pc)(R14)
   862  	LEAQ	8(SP), R9
   863  	MOVQ	R9, (g_sched+gobuf_sp)(R14)
   864  	MOVQ	BP, (g_sched+gobuf_bp)(R14)
   865  	// Assert ctxt is zero. See func save.
   866  	MOVQ	(g_sched+gobuf_ctxt)(R14), R9
   867  	TESTQ	R9, R9
   868  	JZ	2(PC)
   869  	CALL	runtime·abort(SB)
   870  	RET
   871  
   872  // func asmcgocall_no_g(fn, arg unsafe.Pointer)
   873  // Call fn(arg) aligned appropriately for the gcc ABI.
   874  // Called on a system stack, and there may be no g yet (during needm).
   875  TEXT ·asmcgocall_no_g(SB),NOSPLIT,$32-16
   876  	MOVQ	fn+0(FP), AX
   877  	MOVQ	arg+8(FP), BX
   878  	MOVQ	SP, DX
   879  	ANDQ	$~15, SP	// alignment
   880  	MOVQ	DX, 8(SP)
   881  	MOVQ	BX, DI		// DI = first argument in AMD64 ABI
   882  	MOVQ	BX, CX		// CX = first argument in Win64
   883  	CALL	AX
   884  	MOVQ	8(SP), DX
   885  	MOVQ	DX, SP
   886  	RET
   887  
   888  // asmcgocall_landingpad calls AX with BX as argument.
   889  // Must be called on the system stack.
   890  TEXT ·asmcgocall_landingpad(SB),NOSPLIT,$0-0
   891  #ifdef GOOS_windows
   892  	// Make sure we have enough room for 4 stack-backed fast-call
   893  	// registers as per Windows amd64 calling convention.
   894  	ADJSP	$32
   895  	// On Windows, asmcgocall_landingpad acts as landing pad for exceptions
   896  	// thrown in the cgo call. Exceptions that reach this function will be
   897  	// handled by runtime.sehtramp thanks to the SEH metadata added
   898  	// by the compiler.
   899  	// Note that runtime.sehtramp can't be attached directly to asmcgocall
   900  	// because its initial stack pointer can be outside the system stack bounds,
   901  	// and Windows stops the stack unwinding without calling the exception handler
   902  	// when it reaches that point.
   903  	MOVQ	BX, CX		// CX = first argument in Win64
   904  	CALL	AX
   905  	// The exception handler is not called if the next instruction is part of
   906  	// the epilogue, which includes the RET instruction, so we need to add a NOP here.
   907  	BYTE	$0x90
   908  	ADJSP	$-32
   909  	RET
   910  #endif
   911  	// Tail call AX on non-Windows, as the extra stack frame is not needed.
   912  	MOVQ	BX, DI		// DI = first argument in AMD64 ABI
   913  	JMP	AX
   914  
   915  // func asmcgocall(fn, arg unsafe.Pointer) int32
   916  // Call fn(arg) on the scheduler stack,
   917  // aligned appropriately for the gcc ABI.
   918  // See cgocall.go for more details.
   919  TEXT ·asmcgocall(SB),NOSPLIT,$0-20
   920  	// Figure out if we need to switch to m->g0 stack.
   921  	// We get called to create new OS threads too, and those
   922  	// come in on the m->g0 stack already. Or we might already
   923  	// be on the m->gsignal stack.
   924  	get_tls(CX)
   925  	MOVQ	g(CX), DI
   926  	CMPQ	DI, $0
   927  	JEQ	nosave
   928  	MOVQ	g_m(DI), R8
   929  	MOVQ	m_gsignal(R8), SI
   930  	CMPQ	DI, SI
   931  	JEQ	nosave
   932  	MOVQ	m_g0(R8), SI
   933  	CMPQ	DI, SI
   934  	JEQ	nosave
   935  
   936  	// Running on a user G
   937  	// Figure out if we're running secret code and clear the registers
   938  	// so that the C code we're about to call doesn't spill confidential
   939  	// information into memory
   940  #ifdef GOEXPERIMENT_runtimesecret
   941  	CMPL	g_secret(DI), $0
   942  	JEQ	nosecret
   943  	CALL	·secretEraseRegisters(SB)
   944  
   945  	get_tls(CX)
   946  	MOVQ    g(CX), DI
   947  	MOVQ    g_m(DI), R8
   948  	MOVQ    m_g0(R8), SI
   949  
   950  nosecret:
   951  #endif
   952  	MOVQ	fn+0(FP), AX
   953  	MOVQ	arg+8(FP), BX
   954  	MOVQ	SP, DX
   955  
   956  	// Switch to system stack.
   957  	// The original frame pointer is stored in BP,
   958  	// which is useful for stack unwinding.
   959  	CALL	gosave_systemstack_switch<>(SB)
   960  	MOVQ	SI, g(CX)
   961  	MOVQ	(g_sched+gobuf_sp)(SI), SP
   962  
   963  	// Now on a scheduling stack (a pthread-created stack).
   964  	SUBQ	$16, SP
   965  	ANDQ	$~15, SP	// alignment for gcc ABI
   966  	MOVQ	DI, 8(SP)	// save g
   967  	MOVQ	(g_stack+stack_hi)(DI), DI
   968  	SUBQ	DX, DI
   969  	MOVQ	DI, 0(SP)	// save depth in stack (can't just save SP, as stack might be copied during a callback)
   970  	CALL	runtime·asmcgocall_landingpad(SB)
   971  
   972  	// Restore registers, g, stack pointer.
   973  	get_tls(CX)
   974  	MOVQ	8(SP), DI
   975  	MOVQ	(g_stack+stack_hi)(DI), SI
   976  	SUBQ	0(SP), SI
   977  	MOVQ	DI, g(CX)
   978  	MOVQ	SI, SP
   979  
   980  	MOVL	AX, ret+16(FP)
   981  	RET
   982  
   983  nosave:
   984  	// Running on a system stack, perhaps even without a g.
   985  	// Having no g can happen during thread creation or thread teardown
   986  	// (see needm/dropm on Solaris, for example).
   987  	// This code is like the above sequence but without saving/restoring g
   988  	// and without worrying about the stack moving out from under us
   989  	// (because we're on a system stack, not a goroutine stack).
   990  	MOVQ	fn+0(FP), AX
   991  	MOVQ	arg+8(FP), BX
   992  	MOVQ	SP, DX
   993  
   994  	SUBQ	$16, SP
   995  	ANDQ	$~15, SP
   996  	MOVQ	$0, 8(SP)		// where above code stores g, in case someone looks during debugging
   997  	MOVQ	DX, 0(SP)	// save original stack pointer
   998  	CALL	runtime·asmcgocall_landingpad(SB)
   999  	MOVQ	0(SP), SI	// restore original stack pointer
  1000  	MOVQ	SI, SP
  1001  	MOVL	AX, ret+16(FP)
  1002  	RET
  1003  
  1004  #ifdef GOOS_windows
  1005  // Dummy TLS that's used on Windows so that we don't crash trying
  1006  // to restore the G register in needm. needm and its callees are
  1007  // very careful never to actually use the G, the TLS just can't be
  1008  // unset since we're in Go code.
  1009  GLOBL zeroTLS<>(SB),RODATA,$const_tlsSize
  1010  #endif
  1011  
  1012  // func cgocallback(fn, frame unsafe.Pointer, ctxt uintptr)
  1013  // See cgocall.go for more details.
  1014  TEXT ·cgocallback(SB),NOSPLIT,$24-24
  1015  	NO_LOCAL_POINTERS
  1016  
  1017  	// Skip cgocallbackg, just dropm when fn is nil, and frame is the saved g.
  1018  	// It is used to dropm while thread is exiting.
  1019  	MOVQ	fn+0(FP), AX
  1020  	CMPQ	AX, $0
  1021  	JNE	loadg
  1022  	// Restore the g from frame.
  1023  	get_tls(CX)
  1024  	MOVQ	frame+8(FP), BX
  1025  	MOVQ	BX, g(CX)
  1026  	JMP	dropm
  1027  
  1028  loadg:
  1029  	// If g is nil, Go did not create the current thread,
  1030  	// or if this thread never called into Go on pthread platforms.
  1031  	// Call needm to obtain one m for temporary use.
  1032  	// In this case, we're running on the thread stack, so there's
  1033  	// lots of space, but the linker doesn't know. Hide the call from
  1034  	// the linker analysis by using an indirect call through AX.
  1035  	get_tls(CX)
  1036  #ifdef GOOS_windows
  1037  	MOVL	$0, BX
  1038  	CMPQ	CX, $0
  1039  	JEQ	2(PC)
  1040  #endif
  1041  	MOVQ	g(CX), BX
  1042  	CMPQ	BX, $0
  1043  	JEQ	needm
  1044  	MOVQ	g_m(BX), BX
  1045  	MOVQ	BX, savedm-8(SP)	// saved copy of oldm
  1046  	JMP	havem
  1047  needm:
  1048  #ifdef GOOS_windows
  1049  	// Set up a dummy TLS value. needm is careful not to use it,
  1050  	// but it needs to be there to prevent autogenerated code from
  1051  	// crashing when it loads from it.
  1052  	// We don't need to clear it or anything later because needm
  1053  	// will set up TLS properly.
  1054  	MOVQ	$zeroTLS<>(SB), DI
  1055  	CALL	runtime·settls(SB)
  1056  #endif
  1057  	// On some platforms (Windows) we cannot call needm through
  1058  	// an ABI wrapper because there's no TLS set up, and the ABI
  1059  	// wrapper will try to restore the G register (R14) from TLS.
  1060  	// Clear X15 because Go expects it and we're not calling
  1061  	// through a wrapper, but otherwise avoid setting the G
  1062  	// register in the wrapper and call needm directly. It
  1063  	// takes no arguments and doesn't return any values so
  1064  	// there's no need to handle that. Clear R14 so that there's
  1065  	// a bad value in there, in case needm tries to use it.
  1066  	XORPS	X15, X15
  1067  	XORQ    R14, R14
  1068  	MOVQ	$runtime·needAndBindM<ABIInternal>(SB), AX
  1069  	CALL	AX
  1070  	MOVQ	$0, savedm-8(SP)
  1071  	get_tls(CX)
  1072  	MOVQ	g(CX), BX
  1073  	MOVQ	g_m(BX), BX
  1074  
  1075  	// Set m->sched.sp = SP, so that if a panic happens
  1076  	// during the function we are about to execute, it will
  1077  	// have a valid SP to run on the g0 stack.
  1078  	// The next few lines (after the havem label)
  1079  	// will save this SP onto the stack and then write
  1080  	// the same SP back to m->sched.sp. That seems redundant,
  1081  	// but if an unrecovered panic happens, unwindm will
  1082  	// restore the g->sched.sp from the stack location
  1083  	// and then systemstack will try to use it. If we don't set it here,
  1084  	// that restored SP will be uninitialized (typically 0) and
  1085  	// will not be usable.
  1086  	MOVQ	m_g0(BX), SI
  1087  	MOVQ	SP, (g_sched+gobuf_sp)(SI)
  1088  
  1089  havem:
  1090  	// Now there's a valid m, and we're running on its m->g0.
  1091  	// Save current m->g0->sched.sp on stack and then set it to SP.
  1092  	// Save current sp in m->g0->sched.sp in preparation for
  1093  	// switch back to m->curg stack.
  1094  	// NOTE: unwindm knows that the saved g->sched.sp is at 0(SP).
  1095  	MOVQ	m_g0(BX), SI
  1096  	MOVQ	(g_sched+gobuf_sp)(SI), AX
  1097  	MOVQ	AX, 0(SP)
  1098  	MOVQ	SP, (g_sched+gobuf_sp)(SI)
  1099  
  1100  	// Switch to m->curg stack and call runtime.cgocallbackg.
  1101  	// Because we are taking over the execution of m->curg
  1102  	// but *not* resuming what had been running, we need to
  1103  	// save that information (m->curg->sched) so we can restore it.
  1104  	// We can restore m->curg->sched.sp easily, because calling
  1105  	// runtime.cgocallbackg leaves SP unchanged upon return.
  1106  	// To save m->curg->sched.pc, we push it onto the curg stack and
  1107  	// open a frame the same size as cgocallback's g0 frame.
  1108  	// Once we switch to the curg stack, the pushed PC will appear
  1109  	// to be the return PC of cgocallback, so that the traceback
  1110  	// will seamlessly trace back into the earlier calls.
  1111  	MOVQ	m_curg(BX), SI
  1112  	MOVQ	SI, g(CX)
  1113  	MOVQ	SI, R14 // set the g register, as required by ABIInternal.
  1114  	XORPS	X15, X15 // clear X15, as required by ABIInternal.
  1115  	MOVQ	(g_sched+gobuf_sp)(SI), DI  // prepare stack as DI
  1116  	MOVQ	(g_sched+gobuf_pc)(SI), BX
  1117  	MOVQ	BX, -8(DI)  // "push" return PC on the g stack
  1118  	// Gather our arguments into registers.
  1119  	MOVQ	fn+0(FP), AX
  1120  	MOVQ	frame+8(FP), BX
  1121  	MOVQ	ctxt+16(FP), CX
  1122  	// Compute the size of the frame, including the return PC and
  1123  	// saved frame pointer
  1124  	LEAQ	fn+0(FP), R8
  1125  	SUBQ	SP, R8   // R8 is our actual frame size
  1126  	SUBQ	R8, DI   // Allocate the same frame size on the g stack
  1127  	MOVQ	DI, SP
  1128  
  1129  	MOVQ	$runtime·cgocallbackg<ABIInternal>(SB), DX
  1130  	CALL	DX	// indirect call to bypass nosplit check. We're on a different stack now.
  1131  
  1132  	// Compute the size of the frame again. FP and SP have
  1133  	// completely different values here than they did above,
  1134  	// but only their difference matters.
  1135  	LEAQ	fn+0(FP), AX
  1136  	SUBQ	SP, AX
  1137  
  1138  	// Restore g->sched (== m->curg->sched) from saved values.
  1139  	get_tls(CX)
  1140  	MOVQ	g(CX), SI
  1141  	MOVQ	SP, DI
  1142  	ADDQ	AX, DI
  1143  	MOVQ	-8(DI), BX
  1144  	MOVQ	BX, (g_sched+gobuf_pc)(SI)
  1145  	MOVQ	DI, (g_sched+gobuf_sp)(SI)
  1146  
  1147  	// Switch back to m->g0's stack and restore m->g0->sched.sp.
  1148  	// (Unlike m->curg, the g0 goroutine never uses sched.pc,
  1149  	// so we do not have to restore it.)
  1150  	MOVQ	g(CX), BX
  1151  	MOVQ	g_m(BX), BX
  1152  	MOVQ	m_g0(BX), SI
  1153  	MOVQ	SI, g(CX)
  1154  	MOVQ	(g_sched+gobuf_sp)(SI), SP
  1155  	MOVQ	0(SP), AX
  1156  	MOVQ	AX, (g_sched+gobuf_sp)(SI)
  1157  
  1158  	// If the m on entry was nil, we called needm above to borrow an m,
  1159  	// 1. for the duration of the call on non-pthread platforms,
  1160  	// 2. or the duration of the C thread alive on pthread platforms.
  1161  	// If the m on entry wasn't nil,
  1162  	// 1. the thread might be a Go thread,
  1163  	// 2. or it wasn't the first call from a C thread on pthread platforms,
  1164  	//    since then we skip dropm to reuse the m in the first call.
  1165  	MOVQ	savedm-8(SP), BX
  1166  	CMPQ	BX, $0
  1167  	JNE	done
  1168  
  1169  	// Skip dropm to reuse it in the next call, when a pthread key has been created.
  1170  	MOVQ	_cgo_pthread_key_created(SB), AX
  1171  	// It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
  1172  	CMPQ	AX, $0
  1173  	JEQ	dropm
  1174  	CMPQ	(AX), $0
  1175  	JNE	done
  1176  
  1177  dropm:
  1178  	MOVQ	$runtime·dropm(SB), AX
  1179  	CALL	AX
  1180  #ifdef GOOS_windows
  1181  	// We need to clear the TLS pointer in case the next
  1182  	// thread that comes into Go tries to reuse that space
  1183  	// but uses the same M.
  1184  	XORQ	DI, DI
  1185  	CALL	runtime·settls(SB)
  1186  #endif
  1187  done:
  1188  
  1189  	// Done!
  1190  	RET
  1191  
  1192  // func setg(gg *g)
  1193  // set g. for use by needm.
  1194  TEXT runtime·setg(SB), NOSPLIT, $0-8
  1195  	MOVQ	gg+0(FP), BX
  1196  	get_tls(CX)
  1197  	MOVQ	BX, g(CX)
  1198  	RET
  1199  
  1200  // void setg_gcc(G*); set g called from gcc.
  1201  TEXT setg_gcc<>(SB),NOSPLIT,$0
  1202  	get_tls(AX)
  1203  	MOVQ	DI, g(AX)
  1204  	MOVQ	DI, R14 // set the g register
  1205  	RET
  1206  
  1207  TEXT runtime·abort(SB),NOSPLIT,$0-0
  1208  	INT	$3
  1209  loop:
  1210  	JMP	loop
  1211  
  1212  // check that SP is in range [g->stack.lo, g->stack.hi)
  1213  TEXT runtime·stackcheck(SB), NOSPLIT|NOFRAME, $0-0
  1214  	get_tls(CX)
  1215  	MOVQ	g(CX), AX
  1216  	CMPQ	(g_stack+stack_hi)(AX), SP
  1217  	JHI	2(PC)
  1218  	CALL	runtime·abort(SB)
  1219  	CMPQ	SP, (g_stack+stack_lo)(AX)
  1220  	JHI	2(PC)
  1221  	CALL	runtime·abort(SB)
  1222  	RET
  1223  
  1224  // func cputicks() int64
  1225  TEXT runtime·cputicks(SB),NOSPLIT,$0-0
  1226  	CMPB	internal∕cpu·X86+const_offsetX86HasRDTSCP(SB), $1
  1227  	JNE	fences
  1228  	// Instruction stream serializing RDTSCP is supported.
  1229  	// RDTSCP is supported by Intel Nehalem (2008) and
  1230  	// AMD K8 Rev. F (2006) and newer.
  1231  	RDTSCP
  1232  done:
  1233  	SHLQ	$32, DX
  1234  	ADDQ	DX, AX
  1235  	MOVQ	AX, ret+0(FP)
  1236  	RET
  1237  fences:
  1238  	// MFENCE is instruction stream serializing and flushes the
  1239  	// store buffers on AMD. The serialization semantics of LFENCE on AMD
  1240  	// are dependent on MSR C001_1029 and CPU generation.
  1241  	// LFENCE on Intel does wait for all previous instructions to have executed.
  1242  	// Intel recommends MFENCE;LFENCE in its manuals before RDTSC to have all
  1243  	// previous instructions executed and all previous loads and stores to globally visible.
  1244  	// Using MFENCE;LFENCE here aligns the serializing properties without
  1245  	// runtime detection of CPU manufacturer.
  1246  	MFENCE
  1247  	LFENCE
  1248  	RDTSC
  1249  	JMP done
  1250  
  1251  // Called from cgo wrappers, this function returns g->m->curg.stack.hi.
  1252  // Must obey the gcc calling convention.
  1253  TEXT _cgo_topofstack(SB),NOSPLIT,$0
  1254  	get_tls(CX)
  1255  	MOVQ	g(CX), AX
  1256  	MOVQ	g_m(AX), AX
  1257  	MOVQ	m_curg(AX), AX
  1258  	MOVQ	(g_stack+stack_hi)(AX), AX
  1259  	RET
  1260  
  1261  // The top-most function running on a goroutine
  1262  // returns to goexit+PCQuantum.
  1263  TEXT runtime·goexit(SB),NOSPLIT|TOPFRAME|NOFRAME,$0-0
  1264  	BYTE	$0x90	// NOP
  1265  	CALL	runtime·goexit1(SB)	// does not return
  1266  	// traceback from goexit1 must hit code range of goexit
  1267  	BYTE	$0x90	// NOP
  1268  
  1269  // This is called from .init_array and follows the platform, not Go, ABI.
  1270  TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0
  1271  	PUSHQ	R15 // The access to global variables below implicitly uses R15, which is callee-save
  1272  	MOVQ	runtime·lastmoduledatap(SB), AX
  1273  	MOVQ	DI, moduledata_next(AX)
  1274  	MOVQ	DI, runtime·lastmoduledatap(SB)
  1275  	POPQ	R15
  1276  	RET
  1277  
  1278  // Initialize special registers then jump to sigpanic.
  1279  // This function is injected from the signal handler for panicking
  1280  // signals. It is quite painful to set X15 in the signal context,
  1281  // so we do it here.
  1282  TEXT ·sigpanic0(SB),NOSPLIT,$0-0
  1283  	get_tls(R14)
  1284  	MOVQ	g(R14), R14
  1285  	XORPS	X15, X15
  1286  	JMP	·sigpanic<ABIInternal>(SB)
  1287  
  1288  // gcWriteBarrier informs the GC about heap pointer writes.
  1289  //
  1290  // gcWriteBarrier returns space in a write barrier buffer which
  1291  // should be filled in by the caller.
  1292  // gcWriteBarrier does NOT follow the Go ABI. It accepts the
  1293  // number of bytes of buffer needed in R11, and returns a pointer
  1294  // to the buffer space in R11.
  1295  // It clobbers FLAGS. It does not clobber any general-purpose registers,
  1296  // but may clobber others (e.g., SSE registers).
  1297  // Typical use would be, when doing *(CX+88) = AX
  1298  //     CMPL    $0, runtime.writeBarrier(SB)
  1299  //     JEQ     dowrite
  1300  //     CALL    runtime.gcBatchBarrier2(SB)
  1301  //     MOVQ    AX, (R11)
  1302  //     MOVQ    88(CX), DX
  1303  //     MOVQ    DX, 8(R11)
  1304  // dowrite:
  1305  //     MOVQ    AX, 88(CX)
  1306  TEXT gcWriteBarrier<>(SB),NOSPLIT,$112
  1307  	// Save the registers clobbered by the fast path. This is slightly
  1308  	// faster than having the caller spill these.
  1309  	MOVQ	R12, 96(SP)
  1310  	MOVQ	R13, 104(SP)
  1311  retry:
  1312  	// TODO: Consider passing g.m.p in as an argument so they can be shared
  1313  	// across a sequence of write barriers.
  1314  	MOVQ	g_m(R14), R13
  1315  	MOVQ	m_p(R13), R13
  1316  	// Get current buffer write position.
  1317  	MOVQ	(p_wbBuf+wbBuf_next)(R13), R12	// original next position
  1318  	ADDQ	R11, R12			// new next position
  1319  	// Is the buffer full?
  1320  	CMPQ	R12, (p_wbBuf+wbBuf_end)(R13)
  1321  	JA	flush
  1322  	// Commit to the larger buffer.
  1323  	MOVQ	R12, (p_wbBuf+wbBuf_next)(R13)
  1324  	// Make return value (the original next position)
  1325  	SUBQ	R11, R12
  1326  	MOVQ	R12, R11
  1327  	// Restore registers.
  1328  	MOVQ	96(SP), R12
  1329  	MOVQ	104(SP), R13
  1330  	RET
  1331  
  1332  flush:
  1333  	// Save all general purpose registers since these could be
  1334  	// clobbered by wbBufFlush and were not saved by the caller.
  1335  	// It is possible for wbBufFlush to clobber other registers
  1336  	// (e.g., SSE registers), but the compiler takes care of saving
  1337  	// those in the caller if necessary. This strikes a balance
  1338  	// with registers that are likely to be used.
  1339  	//
  1340  	// We don't have type information for these, but all code under
  1341  	// here is NOSPLIT, so nothing will observe these.
  1342  	//
  1343  	// TODO: We could strike a different balance; e.g., saving X0
  1344  	// and not saving GP registers that are less likely to be used.
  1345  	MOVQ	DI, 0(SP)
  1346  	MOVQ	AX, 8(SP)
  1347  	MOVQ	BX, 16(SP)
  1348  	MOVQ	CX, 24(SP)
  1349  	MOVQ	DX, 32(SP)
  1350  	// DI already saved
  1351  	MOVQ	SI, 40(SP)
  1352  	MOVQ	BP, 48(SP)
  1353  	MOVQ	R8, 56(SP)
  1354  	MOVQ	R9, 64(SP)
  1355  	MOVQ	R10, 72(SP)
  1356  	MOVQ	R11, 80(SP)
  1357  	// R12 already saved
  1358  	// R13 already saved
  1359  	// R14 is g
  1360  	MOVQ	R15, 88(SP)
  1361  
  1362  	CALL	runtime·wbBufFlush(SB)
  1363  
  1364  	MOVQ	0(SP), DI
  1365  	MOVQ	8(SP), AX
  1366  	MOVQ	16(SP), BX
  1367  	MOVQ	24(SP), CX
  1368  	MOVQ	32(SP), DX
  1369  	MOVQ	40(SP), SI
  1370  	MOVQ	48(SP), BP
  1371  	MOVQ	56(SP), R8
  1372  	MOVQ	64(SP), R9
  1373  	MOVQ	72(SP), R10
  1374  	MOVQ	80(SP), R11
  1375  	MOVQ	88(SP), R15
  1376  	JMP	retry
  1377  
  1378  TEXT runtime·gcWriteBarrier1<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1379  	MOVL   $8, R11
  1380  	JMP     gcWriteBarrier<>(SB)
  1381  TEXT runtime·gcWriteBarrier2<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1382  	MOVL   $16, R11
  1383  	JMP     gcWriteBarrier<>(SB)
  1384  TEXT runtime·gcWriteBarrier3<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1385  	MOVL   $24, R11
  1386  	JMP     gcWriteBarrier<>(SB)
  1387  TEXT runtime·gcWriteBarrier4<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1388  	MOVL   $32, R11
  1389  	JMP     gcWriteBarrier<>(SB)
  1390  TEXT runtime·gcWriteBarrier5<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1391  	MOVL   $40, R11
  1392  	JMP     gcWriteBarrier<>(SB)
  1393  TEXT runtime·gcWriteBarrier6<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1394  	MOVL   $48, R11
  1395  	JMP     gcWriteBarrier<>(SB)
  1396  TEXT runtime·gcWriteBarrier7<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1397  	MOVL   $56, R11
  1398  	JMP     gcWriteBarrier<>(SB)
  1399  TEXT runtime·gcWriteBarrier8<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1400  	MOVL   $64, R11
  1401  	JMP     gcWriteBarrier<>(SB)
  1402  
  1403  DATA	debugCallFrameTooLarge<>+0x00(SB)/20, $"call frame too large"
  1404  GLOBL	debugCallFrameTooLarge<>(SB), RODATA, $20	// Size duplicated below
  1405  
  1406  // debugCallV2 is the entry point for debugger-injected function
  1407  // calls on running goroutines. It informs the runtime that a
  1408  // debug call has been injected and creates a call frame for the
  1409  // debugger to fill in.
  1410  //
  1411  // To inject a function call, a debugger should:
  1412  // 1. Check that the goroutine is in state _Grunning and that
  1413  //    there are at least 256 bytes free on the stack.
  1414  // 2. Push the current PC on the stack (updating SP).
  1415  // 3. Write the desired argument frame size at SP-16 (using the SP
  1416  //    after step 2).
  1417  // 4. Save all machine registers (including flags and XMM registers)
  1418  //    so they can be restored later by the debugger.
  1419  // 5. Set the PC to debugCallV2 and resume execution.
  1420  //
  1421  // If the goroutine is in state _Grunnable, then it's not generally
  1422  // safe to inject a call because it may return out via other runtime
  1423  // operations. Instead, the debugger should unwind the stack to find
  1424  // the return to non-runtime code, add a temporary breakpoint there,
  1425  // and inject the call once that breakpoint is hit.
  1426  //
  1427  // If the goroutine is in any other state, it's not safe to inject a call.
  1428  //
  1429  // This function communicates back to the debugger by setting R12 and
  1430  // invoking INT3 to raise a breakpoint signal. See the comments in the
  1431  // implementation for the protocol the debugger is expected to
  1432  // follow. InjectDebugCall in the runtime tests demonstrates this protocol.
  1433  //
  1434  // The debugger must ensure that any pointers passed to the function
  1435  // obey escape analysis requirements. Specifically, it must not pass
  1436  // a stack pointer to an escaping argument. debugCallV2 cannot check
  1437  // this invariant.
  1438  //
  1439  // This is ABIInternal because Go code injects its PC directly into new
  1440  // goroutine stacks.
  1441  TEXT runtime·debugCallV2<ABIInternal>(SB),NOSPLIT,$152-0
  1442  	// Save all registers that may contain pointers so they can be
  1443  	// conservatively scanned.
  1444  	//
  1445  	// We can't do anything that might clobber any of these
  1446  	// registers before this.
  1447  	MOVQ	R15, r15-(14*8+8)(SP)
  1448  	MOVQ	R14, r14-(13*8+8)(SP)
  1449  	MOVQ	R13, r13-(12*8+8)(SP)
  1450  	MOVQ	R12, r12-(11*8+8)(SP)
  1451  	MOVQ	R11, r11-(10*8+8)(SP)
  1452  	MOVQ	R10, r10-(9*8+8)(SP)
  1453  	MOVQ	R9, r9-(8*8+8)(SP)
  1454  	MOVQ	R8, r8-(7*8+8)(SP)
  1455  	MOVQ	DI, di-(6*8+8)(SP)
  1456  	MOVQ	SI, si-(5*8+8)(SP)
  1457  	MOVQ	BP, bp-(4*8+8)(SP)
  1458  	MOVQ	BX, bx-(3*8+8)(SP)
  1459  	MOVQ	DX, dx-(2*8+8)(SP)
  1460  	// Save the frame size before we clobber it. Either of the last
  1461  	// saves could clobber this depending on whether there's a saved BP.
  1462  	MOVQ	frameSize-24(FP), DX	// aka -16(RSP) before prologue
  1463  	MOVQ	CX, cx-(1*8+8)(SP)
  1464  	MOVQ	AX, ax-(0*8+8)(SP)
  1465  
  1466  	// Save the argument frame size.
  1467  	MOVQ	DX, frameSize-128(SP)
  1468  
  1469  	// Perform a safe-point check.
  1470  	MOVQ	retpc-8(FP), AX	// Caller's PC
  1471  	MOVQ	AX, 0(SP)
  1472  	CALL	runtime·debugCallCheck(SB)
  1473  	MOVQ	8(SP), AX
  1474  	TESTQ	AX, AX
  1475  	JZ	good
  1476  	// The safety check failed. Put the reason string at the top
  1477  	// of the stack.
  1478  	MOVQ	AX, 0(SP)
  1479  	MOVQ	16(SP), AX
  1480  	MOVQ	AX, 8(SP)
  1481  	// Set R12 to 8 and invoke INT3. The debugger should get the
  1482  	// reason a call can't be injected from the top of the stack
  1483  	// and resume execution.
  1484  	MOVQ	$8, R12
  1485  	BYTE	$0xcc
  1486  	JMP	restore
  1487  
  1488  good:
  1489  	// Registers are saved and it's safe to make a call.
  1490  	// Open up a call frame, moving the stack if necessary.
  1491  	//
  1492  	// Once the frame is allocated, this will set R12 to 0 and
  1493  	// invoke INT3. The debugger should write the argument
  1494  	// frame for the call at SP, set up argument registers, push
  1495  	// the trapping PC on the stack, set the PC to the function to
  1496  	// call, set RDX to point to the closure (if a closure call),
  1497  	// and resume execution.
  1498  	//
  1499  	// If the function returns, this will set R12 to 1 and invoke
  1500  	// INT3. The debugger can then inspect any return value saved
  1501  	// on the stack at SP and in registers and resume execution again.
  1502  	//
  1503  	// If the function panics, this will set R12 to 2 and invoke INT3.
  1504  	// The interface{} value of the panic will be at SP. The debugger
  1505  	// can inspect the panic value and resume execution again.
  1506  #define DEBUG_CALL_DISPATCH(NAME,MAXSIZE)	\
  1507  	CMPQ	AX, $MAXSIZE;			\
  1508  	JA	5(PC);				\
  1509  	MOVQ	$NAME(SB), AX;			\
  1510  	MOVQ	AX, 0(SP);			\
  1511  	CALL	runtime·debugCallWrap(SB);	\
  1512  	JMP	restore
  1513  
  1514  	MOVQ	frameSize-128(SP), AX
  1515  	DEBUG_CALL_DISPATCH(debugCall32<>, 32)
  1516  	DEBUG_CALL_DISPATCH(debugCall64<>, 64)
  1517  	DEBUG_CALL_DISPATCH(debugCall128<>, 128)
  1518  	DEBUG_CALL_DISPATCH(debugCall256<>, 256)
  1519  	DEBUG_CALL_DISPATCH(debugCall512<>, 512)
  1520  	DEBUG_CALL_DISPATCH(debugCall1024<>, 1024)
  1521  	DEBUG_CALL_DISPATCH(debugCall2048<>, 2048)
  1522  	DEBUG_CALL_DISPATCH(debugCall4096<>, 4096)
  1523  	DEBUG_CALL_DISPATCH(debugCall8192<>, 8192)
  1524  	DEBUG_CALL_DISPATCH(debugCall16384<>, 16384)
  1525  	DEBUG_CALL_DISPATCH(debugCall32768<>, 32768)
  1526  	DEBUG_CALL_DISPATCH(debugCall65536<>, 65536)
  1527  	// The frame size is too large. Report the error.
  1528  	MOVQ	$debugCallFrameTooLarge<>(SB), AX
  1529  	MOVQ	AX, 0(SP)
  1530  	MOVQ	$20, 8(SP) // length of debugCallFrameTooLarge string
  1531  	MOVQ	$8, R12
  1532  	BYTE	$0xcc
  1533  	JMP	restore
  1534  
  1535  restore:
  1536  	// Calls and failures resume here.
  1537  	//
  1538  	// Set R12 to 16 and invoke INT3. The debugger should restore
  1539  	// all registers except RIP and RSP and resume execution.
  1540  	MOVQ	$16, R12
  1541  	BYTE	$0xcc
  1542  	// We must not modify flags after this point.
  1543  
  1544  	// Restore pointer-containing registers, which may have been
  1545  	// modified from the debugger's copy by stack copying.
  1546  	MOVQ	ax-(0*8+8)(SP), AX
  1547  	MOVQ	cx-(1*8+8)(SP), CX
  1548  	MOVQ	dx-(2*8+8)(SP), DX
  1549  	MOVQ	bx-(3*8+8)(SP), BX
  1550  	MOVQ	bp-(4*8+8)(SP), BP
  1551  	MOVQ	si-(5*8+8)(SP), SI
  1552  	MOVQ	di-(6*8+8)(SP), DI
  1553  	MOVQ	r8-(7*8+8)(SP), R8
  1554  	MOVQ	r9-(8*8+8)(SP), R9
  1555  	MOVQ	r10-(9*8+8)(SP), R10
  1556  	MOVQ	r11-(10*8+8)(SP), R11
  1557  	MOVQ	r12-(11*8+8)(SP), R12
  1558  	MOVQ	r13-(12*8+8)(SP), R13
  1559  	MOVQ	r14-(13*8+8)(SP), R14
  1560  	MOVQ	r15-(14*8+8)(SP), R15
  1561  
  1562  	RET
  1563  
  1564  // runtime.debugCallCheck assumes that functions defined with the
  1565  // DEBUG_CALL_FN macro are safe points to inject calls.
  1566  #define DEBUG_CALL_FN(NAME,MAXSIZE)		\
  1567  TEXT NAME(SB),WRAPPER,$MAXSIZE-0;		\
  1568  	NO_LOCAL_POINTERS;			\
  1569  	MOVQ	$0, R12;				\
  1570  	BYTE	$0xcc;				\
  1571  	MOVQ	$1, R12;				\
  1572  	BYTE	$0xcc;				\
  1573  	RET
  1574  DEBUG_CALL_FN(debugCall32<>, 32)
  1575  DEBUG_CALL_FN(debugCall64<>, 64)
  1576  DEBUG_CALL_FN(debugCall128<>, 128)
  1577  DEBUG_CALL_FN(debugCall256<>, 256)
  1578  DEBUG_CALL_FN(debugCall512<>, 512)
  1579  DEBUG_CALL_FN(debugCall1024<>, 1024)
  1580  DEBUG_CALL_FN(debugCall2048<>, 2048)
  1581  DEBUG_CALL_FN(debugCall4096<>, 4096)
  1582  DEBUG_CALL_FN(debugCall8192<>, 8192)
  1583  DEBUG_CALL_FN(debugCall16384<>, 16384)
  1584  DEBUG_CALL_FN(debugCall32768<>, 32768)
  1585  DEBUG_CALL_FN(debugCall65536<>, 65536)
  1586  
  1587  // func debugCallPanicked(val interface{})
  1588  TEXT runtime·debugCallPanicked(SB),NOSPLIT,$16-16
  1589  	// Copy the panic value to the top of stack.
  1590  	MOVQ	val_type+0(FP), AX
  1591  	MOVQ	AX, 0(SP)
  1592  	MOVQ	val_data+8(FP), AX
  1593  	MOVQ	AX, 8(SP)
  1594  	MOVQ	$2, R12
  1595  	BYTE	$0xcc
  1596  	RET
  1597  
  1598  TEXT runtime·panicBounds<ABIInternal>(SB),NOSPLIT,$144-0
  1599  	NO_LOCAL_POINTERS
  1600  	// Save all 14 int registers that could have an index in them.
  1601  	// They may be pointers, but if they are they are dead.
  1602  	MOVQ	AX, 16(SP)
  1603  	MOVQ	CX, 24(SP)
  1604  	MOVQ	DX, 32(SP)
  1605  	MOVQ	BX, 40(SP)
  1606  	// skip SP @ 48(SP)
  1607  	MOVQ	BP, 56(SP)
  1608  	MOVQ	SI, 64(SP)
  1609  	MOVQ	DI, 72(SP)
  1610  	MOVQ	R8, 80(SP)
  1611  	MOVQ	R9, 88(SP)
  1612  	MOVQ	R10, 96(SP)
  1613  	MOVQ	R11, 104(SP)
  1614  	MOVQ	R12, 112(SP)
  1615  	MOVQ	R13, 120(SP)
  1616  	// skip R14 @ 128(SP) (aka G)
  1617  	MOVQ	R15, 136(SP)
  1618  
  1619  	MOVQ	SP, AX		// hide SP read from vet
  1620  	MOVQ	152(AX), AX	// PC immediately after call to panicBounds
  1621  	LEAQ	16(SP), BX
  1622  	CALL	runtime·panicBounds64<ABIInternal>(SB)
  1623  	RET
  1624  
  1625  #ifdef GOOS_android
  1626  // Use the free TLS_SLOT_APP slot #2 on Android Q.
  1627  // Earlier androids are set up in gcc_android.c.
  1628  DATA runtime·tls_g+0(SB)/8, $16
  1629  GLOBL runtime·tls_g+0(SB), NOPTR, $8
  1630  #endif
  1631  #ifdef GOOS_windows
  1632  GLOBL runtime·tls_g+0(SB), NOPTR, $8
  1633  #endif
  1634  
  1635  // The compiler and assembler's -spectre=ret mode rewrites
  1636  // all indirect CALL AX / JMP AX instructions to be
  1637  // CALL retpolineAX / JMP retpolineAX.
  1638  // See https://support.google.com/faqs/answer/7625886.
  1639  #define RETPOLINE(reg) \
  1640  	/*   CALL setup */     BYTE $0xE8; BYTE $(2+2); BYTE $0; BYTE $0; BYTE $0;	\
  1641  	/* nospec: */									\
  1642  	/*   PAUSE */           BYTE $0xF3; BYTE $0x90;					\
  1643  	/*   JMP nospec */      BYTE $0xEB; BYTE $-(2+2);				\
  1644  	/* setup: */									\
  1645  	/*   MOVQ AX, 0(SP) */  BYTE $0x48|((reg&8)>>1); BYTE $0x89;			\
  1646  	                        BYTE $0x04|((reg&7)<<3); BYTE $0x24;			\
  1647  	/*   RET */             BYTE $0xC3
  1648  
  1649  TEXT runtime·retpolineAX(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(0)
  1650  TEXT runtime·retpolineCX(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(1)
  1651  TEXT runtime·retpolineDX(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(2)
  1652  TEXT runtime·retpolineBX(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(3)
  1653  /* SP is 4, can't happen / magic encodings */
  1654  TEXT runtime·retpolineBP(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(5)
  1655  TEXT runtime·retpolineSI(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(6)
  1656  TEXT runtime·retpolineDI(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(7)
  1657  TEXT runtime·retpolineR8(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(8)
  1658  TEXT runtime·retpolineR9(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(9)
  1659  TEXT runtime·retpolineR10(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(10)
  1660  TEXT runtime·retpolineR11(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(11)
  1661  TEXT runtime·retpolineR12(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(12)
  1662  TEXT runtime·retpolineR13(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(13)
  1663  TEXT runtime·retpolineR14(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(14)
  1664  TEXT runtime·retpolineR15(SB),NOSPLIT|NOFRAME,$0; RETPOLINE(15)
  1665  
  1666  TEXT ·getfp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
  1667  	MOVQ BP, AX
  1668  	RET
  1669  

View as plain text