mirror of
https://github.com/golang/go
synced 2024-11-22 16:25:07 -07:00
runtime: eliminate externalthreadhandler
This function is no longer used. Eliminating this actually fixes several problems: - It made assumptions about what registers memclrNoHeapPointers would preserve. Besides being an abstraction violation and lurking maintenance issue, this actively became a problem for regabi because the call to memclrNoHeapPointers now happens through an ABI wrapper, which is generated by the compiler and hence we can't easily control what registers it clobbers. - The amd64 implementation (at least), does not interact with the host ABI correctly. Notably, it doesn't save many of the registers that are callee-save in the host ABI but caller-save in the Go ABI. - It interacts strangely with the NOSPLIT checker because it allocates an entire M and G on its stack. It worked around this on arm64, and happened to do things the NOSPLIT checker couldn't track on 386 and amd64, and happened to be *4 bytes* below the limit on arm (so any addition to the m or g structs would cause a NOSPLIT failure). See CL 309031 for a more complete explanation. Fixes #45530. Updates #40724. Change-Id: Ic70d4d7e1c17f1d796575b3377b8529449e93576 Reviewed-on: https://go-review.googlesource.com/c/go/+/309634 Trust: Austin Clements <austin@google.com> Run-TryBot: Austin Clements <austin@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
This commit is contained in:
Austin Clements
parent
e69f02265c
commit
c19759aa48
@ -29,7 +29,6 @@ const (
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FuncID_asyncPreempt
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FuncID_cgocallback
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FuncID_debugCallV1
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FuncID_externalthreadhandler
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FuncID_gcBgMarkWorker
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FuncID_goexit
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FuncID_gogo
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@ -50,28 +49,27 @@ const (
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)
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var funcIDs = map[string]FuncID{
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"abort": FuncID_abort,
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"asmcgocall": FuncID_asmcgocall,
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"asyncPreempt": FuncID_asyncPreempt,
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"cgocallback": FuncID_cgocallback,
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"debugCallV1": FuncID_debugCallV1,
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"externalthreadhandler": FuncID_externalthreadhandler,
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"gcBgMarkWorker": FuncID_gcBgMarkWorker,
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"go": FuncID_rt0_go,
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"goexit": FuncID_goexit,
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"gogo": FuncID_gogo,
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"gopanic": FuncID_gopanic,
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"handleAsyncEvent": FuncID_handleAsyncEvent,
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"jmpdefer": FuncID_jmpdefer,
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"main": FuncID_runtime_main,
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"mcall": FuncID_mcall,
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"morestack": FuncID_morestack,
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"mstart": FuncID_mstart,
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"panicwrap": FuncID_panicwrap,
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"runfinq": FuncID_runfinq,
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"sigpanic": FuncID_sigpanic,
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"switch": FuncID_systemstack_switch,
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"systemstack": FuncID_systemstack,
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"abort": FuncID_abort,
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"asmcgocall": FuncID_asmcgocall,
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"asyncPreempt": FuncID_asyncPreempt,
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"cgocallback": FuncID_cgocallback,
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"debugCallV1": FuncID_debugCallV1,
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"gcBgMarkWorker": FuncID_gcBgMarkWorker,
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"go": FuncID_rt0_go,
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"goexit": FuncID_goexit,
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"gogo": FuncID_gogo,
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"gopanic": FuncID_gopanic,
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"handleAsyncEvent": FuncID_handleAsyncEvent,
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"jmpdefer": FuncID_jmpdefer,
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"main": FuncID_runtime_main,
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"mcall": FuncID_mcall,
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"morestack": FuncID_morestack,
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"mstart": FuncID_mstart,
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"panicwrap": FuncID_panicwrap,
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"runfinq": FuncID_runfinq,
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"sigpanic": FuncID_sigpanic,
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"switch": FuncID_systemstack_switch,
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"systemstack": FuncID_systemstack,
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// Don't show in call stack but otherwise not special.
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"deferreturn": FuncID_wrapper,
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@ -947,9 +947,7 @@ func (f *peFile) writeOptionalHeader(ctxt *Link) {
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// calls that may need more stack than we think.
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//
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// The default stack reserve size directly affects only the main
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// thread and threads that enter in externalthreadhandler.
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// For this, it must be greater than the stack size assumed by
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// externalthreadhandler.
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// thread.
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//
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// For other threads, the runtime explicitly asks the kernel
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// to use the default stack size so that all stacks are
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@ -7,8 +7,6 @@
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#include "go_asm.h"
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#include "textflag.h"
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// NOTE: Windows externalthreadhandler expects memclr to preserve DX.
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// See memclrNoHeapPointers Go doc for important implementation constraints.
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// func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
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@ -7,8 +7,6 @@
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#include "go_asm.h"
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#include "textflag.h"
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// NOTE: Windows externalthreadhandler expects memclr to preserve DX.
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// See memclrNoHeapPointers Go doc for important implementation constraints.
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// func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
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@ -386,7 +386,6 @@ const (
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)
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// in sys_windows_386.s and sys_windows_amd64.s:
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func externalthreadhandler()
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func getlasterror() uint32
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// When loading DLLs, we prefer to use LoadLibraryEx with
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@ -317,7 +317,6 @@ const (
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funcID_asyncPreempt
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funcID_cgocallback
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funcID_debugCallV1
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funcID_externalthreadhandler
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funcID_gcBgMarkWorker
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funcID_goexit
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funcID_gogo
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@ -156,57 +156,6 @@ TEXT runtime·lastcontinuetramp<ABIInternal>(SB),NOSPLIT,$0-0
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MOVL $runtime·lastcontinuehandler(SB), AX
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JMP sigtramp<>(SB)
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TEXT runtime·externalthreadhandler<ABIInternal>(SB),NOSPLIT|TOPFRAME,$0
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PUSHL BP
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MOVL SP, BP
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PUSHL BX
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PUSHL SI
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PUSHL DI
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PUSHL 0x14(FS)
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MOVL SP, DX
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// setup dummy m, g
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SUBL $m__size, SP // space for M
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MOVL SP, 0(SP)
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MOVL $m__size, 4(SP)
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CALL runtime·memclrNoHeapPointers(SB) // smashes AX,BX,CX
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LEAL m_tls(SP), CX
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MOVL CX, 0x14(FS)
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MOVL SP, BX
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SUBL $g__size, SP // space for G
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MOVL SP, g(CX)
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MOVL SP, m_g0(BX)
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MOVL SP, 0(SP)
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MOVL $g__size, 4(SP)
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CALL runtime·memclrNoHeapPointers(SB) // smashes AX,BX,CX
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LEAL g__size(SP), BX
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MOVL BX, g_m(SP)
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LEAL -32768(SP), CX // must be less than SizeOfStackReserve set by linker
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MOVL CX, (g_stack+stack_lo)(SP)
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ADDL $const__StackGuard, CX
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MOVL CX, g_stackguard0(SP)
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MOVL CX, g_stackguard1(SP)
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MOVL DX, (g_stack+stack_hi)(SP)
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PUSHL AX // room for return value
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PUSHL 16(BP) // arg for handler
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CALL 8(BP)
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POPL CX
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POPL AX // pass return value to Windows in AX
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get_tls(CX)
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MOVL g(CX), CX
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MOVL (g_stack+stack_hi)(CX), SP
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POPL 0x14(FS)
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POPL DI
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POPL SI
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POPL BX
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POPL BP
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RET
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GLOBL runtime·cbctxts(SB), NOPTR, $4
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TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT,$0
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@ -202,57 +202,6 @@ TEXT runtime·lastcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0-0
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MOVQ $runtime·lastcontinuehandler(SB), AX
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JMP sigtramp<>(SB)
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TEXT runtime·externalthreadhandler<ABIInternal>(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
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PUSHQ BP
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MOVQ SP, BP
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PUSHQ BX
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PUSHQ SI
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PUSHQ DI
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PUSHQ 0x28(GS)
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MOVQ SP, DX
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// setup dummy m, g
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SUBQ $m__size, SP // space for M
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MOVQ SP, 0(SP)
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MOVQ $m__size, 8(SP)
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CALL runtime·memclrNoHeapPointers(SB) // smashes AX,BX,CX, maybe BP
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LEAQ m_tls(SP), CX
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MOVQ CX, 0x28(GS)
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MOVQ SP, BX
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SUBQ $g__size, SP // space for G
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MOVQ SP, g(CX)
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MOVQ SP, m_g0(BX)
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MOVQ SP, 0(SP)
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MOVQ $g__size, 8(SP)
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CALL runtime·memclrNoHeapPointers(SB) // smashes AX,BX,CX, maybe BP
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LEAQ g__size(SP), BX
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MOVQ BX, g_m(SP)
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LEAQ -32768(SP), CX // must be less than SizeOfStackReserve set by linker
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MOVQ CX, (g_stack+stack_lo)(SP)
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ADDQ $const__StackGuard, CX
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MOVQ CX, g_stackguard0(SP)
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MOVQ CX, g_stackguard1(SP)
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MOVQ DX, (g_stack+stack_hi)(SP)
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PUSHQ AX // room for return value
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PUSHQ 32(BP) // arg for handler
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CALL 16(BP)
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POPQ CX
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POPQ AX // pass return value to Windows in AX
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get_tls(CX)
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MOVQ g(CX), CX
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MOVQ (g_stack+stack_hi)(CX), SP
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POPQ 0x28(GS)
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POPQ DI
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POPQ SI
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POPQ BX
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POPQ BP
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RET
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GLOBL runtime·cbctxts(SB), NOPTR, $8
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TEXT runtime·callbackasm1(SB),NOSPLIT,$0
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@ -233,73 +233,6 @@ TEXT runtime·lastcontinuetramp<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
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MOVW $runtime·lastcontinuehandler(SB), R1
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B sigtramp<>(SB)
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// int32 externalthreadhandler(uint32 arg, int (*func)(uint32))
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// stack layout:
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// +----------------+
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// | callee-save |
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// | registers |
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// +----------------+
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// | m |
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// +----------------+
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// 20| g |
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// +----------------+
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// 16| func ptr (r1) |
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// +----------------+
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// 12| argument (r0) |
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//---+----------------+
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// 8 | param1 | (also return value for called Go function)
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// +----------------+
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// 4 | param0 |
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// +----------------+
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// 0 | slot for LR |
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// +----------------+
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//
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TEXT runtime·externalthreadhandler<ABIInternal>(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
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MOVM.DB.W [R4-R11, R14], (R13) // push {r4-r11, lr}
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SUB $(m__size + g__size + 20), R13 // space for locals
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MOVW R14, 0(R13) // push LR again for anything unwinding the stack
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MOVW R0, 12(R13)
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MOVW R1, 16(R13)
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// zero out m and g structures
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ADD $20, R13, R0 // compute pointer to g
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MOVW R0, 4(R13)
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MOVW $(m__size + g__size), R0
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MOVW R0, 8(R13)
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BL runtime·memclrNoHeapPointers(SB)
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// initialize m and g structures
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ADD $20, R13, R2 // R2 = g
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ADD $(20 + g__size), R13, R3 // R3 = m
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MOVW R2, m_g0(R3) // m->g0 = g
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MOVW R3, g_m(R2) // g->m = m
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MOVW R2, m_curg(R3) // m->curg = g
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MOVW R2, g
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BL runtime·save_g(SB)
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// set up stackguard stuff
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MOVW R13, R0
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MOVW R0, g_stack+stack_hi(g)
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SUB $(32*1024), R0
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MOVW R0, (g_stack+stack_lo)(g)
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MOVW R0, g_stackguard0(g)
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MOVW R0, g_stackguard1(g)
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// move argument into position and call function
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MOVW 12(R13), R0
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MOVW R0, 4(R13)
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MOVW 16(R13), R1
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BL (R1)
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// clear g
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MOVW $0, g
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BL runtime·save_g(SB)
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MOVW 8(R13), R0 // load return value
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ADD $(m__size + g__size + 20), R13 // free locals
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MOVM.IA.W (R13), [R4-R11, R15] // pop {r4-r11, pc}
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GLOBL runtime·cbctxts(SB), NOPTR, $4
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TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT|NOFRAME,$0
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@ -299,66 +299,6 @@ TEXT runtime·lastcontinuetramp(SB),NOSPLIT|NOFRAME,$0
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MOVD $runtime·lastcontinuehandler<ABIInternal>(SB), R1
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B sigtramp<>(SB)
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// externalthreadhander called with R0 = uint32 arg, R1 = Go function f.
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// Need to call f(arg), which returns a uint32, and return it in R0.
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TEXT runtime·externalthreadhandler<ABIInternal>(SB),NOSPLIT|TOPFRAME,$96-0
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NO_LOCAL_POINTERS
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// Push C callee-save registers R19-R28. LR, FP already saved.
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SAVE_R19_TO_R28(-10*8)
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// Allocate space for args, saved R0+R1, g, and m structures.
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// Hide from nosplit check.
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#define extra ((64+g__size+m__size+15)&~15)
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SUB $extra, RSP, R2 // hide from nosplit overflow check
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MOVD R2, RSP
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// Save R0 and R1 (our args).
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MOVD R0, 32(RSP)
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MOVD R1, 40(RSP)
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// Zero out m and g structures.
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MOVD $64(RSP), R0
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MOVD R0, 8(RSP)
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MOVD $(m__size + g__size), R0
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MOVD R0, 16(RSP)
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MOVD $0, 0(RSP) // not-saved LR
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BL runtime·memclrNoHeapPointers(SB)
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// Initialize m and g structures.
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MOVD $64(RSP), g
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MOVD $g__size(g), R3 // m
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MOVD R3, g_m(g) // g->m = m
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MOVD g, m_g0(R3) // m->g0 = g
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MOVD g, m_curg(R3) // m->curg = g
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MOVD RSP, R0
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MOVD R0, g_stack+stack_hi(g)
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SUB $(32*1024), R0
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MOVD R0, (g_stack+stack_lo)(g)
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MOVD R0, g_stackguard0(g)
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MOVD R0, g_stackguard1(g)
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BL runtime·save_g(SB)
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// Call function.
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MOVD 32(RSP), R0
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MOVD 40(RSP), R1
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MOVW R0, 8(RSP)
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BL (R1)
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// Clear g.
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MOVD $0, g
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BL runtime·save_g(SB)
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// Load return value (save_g would have smashed)
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MOVW (2*8)(RSP), R0
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ADD $extra, RSP, R2
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MOVD R2, RSP
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#undef extra
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RESTORE_R19_TO_R28(-10*8)
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RET
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GLOBL runtime·cbctxts(SB), NOPTR, $4
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TEXT runtime·callbackasm1<ABIInternal>(SB),NOSPLIT,$208-0
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