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asm_arm.s
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "go_asm.h"
#include "go_tls.h"
#include "funcdata.h"
#include "textflag.h"
// _rt0_arm is common startup code for most ARM systems when using
// internal linking. This is the entry point for the program from the
// kernel for an ordinary -buildmode=exe program. The stack holds the
// number of arguments and the C-style argv.
TEXT _rt0_arm(SB),NOSPLIT|NOFRAME,$0
MOVW (R13), R0 // argc
MOVW $4(R13), R1 // argv
B runtime·rt0_go(SB)
// main is common startup code for most ARM systems when using
// external linking. The C startup code will call the symbol "main"
// passing argc and argv in the usual C ABI registers R0 and R1.
TEXT main(SB),NOSPLIT|NOFRAME,$0
B runtime·rt0_go(SB)
// _rt0_arm_lib is common startup code for most ARM systems when
// using -buildmode=c-archive or -buildmode=c-shared. The linker will
// arrange to invoke this function as a global constructor (for
// c-archive) or when the shared library is loaded (for c-shared).
// We expect argc and argv to be passed in the usual C ABI registers
// R0 and R1.
TEXT _rt0_arm_lib(SB),NOSPLIT,$104
// Preserve callee-save registers. Raspberry Pi's dlopen(), for example,
// actually cares that R11 is preserved.
MOVW R4, 12(R13)
MOVW R5, 16(R13)
MOVW R6, 20(R13)
MOVW R7, 24(R13)
MOVW R8, 28(R13)
MOVW g, 32(R13)
MOVW R11, 36(R13)
// Skip floating point registers on goarmsoftfp != 0.
MOVB runtime·goarmsoftfp(SB), R11
CMP $0, R11
BNE skipfpsave
MOVD F8, (40+8*0)(R13)
MOVD F9, (40+8*1)(R13)
MOVD F10, (40+8*2)(R13)
MOVD F11, (40+8*3)(R13)
MOVD F12, (40+8*4)(R13)
MOVD F13, (40+8*5)(R13)
MOVD F14, (40+8*6)(R13)
MOVD F15, (40+8*7)(R13)
skipfpsave:
// Save argc/argv.
MOVW R0, _rt0_arm_lib_argc<>(SB)
MOVW R1, _rt0_arm_lib_argv<>(SB)
MOVW $0, g // Initialize g.
// Synchronous initialization.
CALL runtime·libpreinit(SB)
// Create a new thread to do the runtime initialization.
MOVW _cgo_sys_thread_create(SB), R2
CMP $0, R2
BEQ nocgo
MOVW $_rt0_arm_lib_go<>(SB), R0
MOVW $0, R1
BL (R2)
B rr
nocgo:
MOVW $0x800000, R0 // stacksize = 8192KB
MOVW $_rt0_arm_lib_go<>(SB), R1 // fn
MOVW R0, 4(R13)
MOVW R1, 8(R13)
BL runtime·newosproc0(SB)
rr:
// Restore callee-save registers and return.
MOVB runtime·goarmsoftfp(SB), R11
CMP $0, R11
BNE skipfprest
MOVD (40+8*0)(R13), F8
MOVD (40+8*1)(R13), F9
MOVD (40+8*2)(R13), F10
MOVD (40+8*3)(R13), F11
MOVD (40+8*4)(R13), F12
MOVD (40+8*5)(R13), F13
MOVD (40+8*6)(R13), F14
MOVD (40+8*7)(R13), F15
skipfprest:
MOVW 12(R13), R4
MOVW 16(R13), R5
MOVW 20(R13), R6
MOVW 24(R13), R7
MOVW 28(R13), R8
MOVW 32(R13), g
MOVW 36(R13), R11
RET
// _rt0_arm_lib_go initializes the Go runtime.
// This is started in a separate thread by _rt0_arm_lib.
TEXT _rt0_arm_lib_go<>(SB),NOSPLIT,$8
MOVW _rt0_arm_lib_argc<>(SB), R0
MOVW _rt0_arm_lib_argv<>(SB), R1
B runtime·rt0_go(SB)
DATA _rt0_arm_lib_argc<>(SB)/4,$0
GLOBL _rt0_arm_lib_argc<>(SB),NOPTR,$4
DATA _rt0_arm_lib_argv<>(SB)/4,$0
GLOBL _rt0_arm_lib_argv<>(SB),NOPTR,$4
// using NOFRAME means do not save LR on stack.
// argc is in R0, argv is in R1.
TEXT runtime·rt0_go(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
MOVW $0xcafebabe, R12
// copy arguments forward on an even stack
// use R13 instead of SP to avoid linker rewriting the offsets
SUB $64, R13 // plenty of scratch
AND $~7, R13
MOVW R0, 60(R13) // save argc, argv away
MOVW R1, 64(R13)
// set up g register
// g is R10
MOVW $runtime·g0(SB), g
MOVW $runtime·m0(SB), R8
// save m->g0 = g0
MOVW g, m_g0(R8)
// save g->m = m0
MOVW R8, g_m(g)
// create istack out of the OS stack
// (1MB of system stack is available on iOS and Android)
MOVW $(-64*1024+104)(R13), R0
MOVW R0, g_stackguard0(g)
MOVW R0, g_stackguard1(g)
MOVW R0, (g_stack+stack_lo)(g)
MOVW R13, (g_stack+stack_hi)(g)
BL runtime·emptyfunc(SB) // fault if stack check is wrong
#ifdef GOOS_openbsd
// Save g to TLS so that it is available from signal trampoline.
BL runtime·save_g(SB)
#endif
BL runtime·_initcgo(SB) // will clobber R0-R3
// update stackguard after _cgo_init
MOVW (g_stack+stack_lo)(g), R0
ADD $const_stackGuard, R0
MOVW R0, g_stackguard0(g)
MOVW R0, g_stackguard1(g)
BL runtime·check(SB)
// saved argc, argv
MOVW 60(R13), R0
MOVW R0, 4(R13)
MOVW 64(R13), R1
MOVW R1, 8(R13)
BL runtime·args(SB)
BL runtime·checkgoarm(SB)
BL runtime·osinit(SB)
BL runtime·schedinit(SB)
// create a new goroutine to start program
SUB $8, R13
MOVW $runtime·mainPC(SB), R0
MOVW R0, 4(R13) // arg 1: fn
MOVW $0, R0
MOVW R0, 0(R13) // dummy LR
BL runtime·newproc(SB)
ADD $8, R13 // pop args and LR
// start this M
BL runtime·mstart(SB)
MOVW $1234, R0
MOVW $1000, R1
MOVW R0, (R1) // fail hard
DATA runtime·mainPC+0(SB)/4,$runtime·main(SB)
GLOBL runtime·mainPC(SB),RODATA,$4
TEXT runtime·breakpoint(SB),NOSPLIT,$0-0
// gdb won't skip this breakpoint instruction automatically,
// so you must manually "set $pc+=4" to skip it and continue.
#ifdef GOOS_plan9
WORD $0xD1200070 // undefined instruction used as armv5 breakpoint in Plan 9
#else
WORD $0xe7f001f0 // undefined instruction that gdb understands is a software breakpoint
#endif
RET
TEXT runtime·asminit(SB),NOSPLIT,$0-0
// disable runfast (flush-to-zero) mode of vfp if runtime.goarmsoftfp == 0
MOVB runtime·goarmsoftfp(SB), R11
CMP $0, R11
BNE 4(PC)
WORD $0xeef1ba10 // vmrs r11, fpscr
BIC $(1<<24), R11
WORD $0xeee1ba10 // vmsr fpscr, r11
RET
TEXT runtime·mstart(SB),NOSPLIT|TOPFRAME,$0
BL runtime·mstart0(SB)
RET // not reached
/*
* go-routine
*/
// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB),NOSPLIT|NOFRAME,$0-4
MOVW buf+0(FP), R1
MOVW gobuf_g(R1), R0
MOVW 0(R0), R2 // make sure g != nil
B gogo<>(SB)
TEXT gogo<>(SB),NOSPLIT|NOFRAME,$0
BL setg<>(SB)
MOVW gobuf_sp(R1), R13 // restore SP==R13
MOVW gobuf_lr(R1), LR
MOVW gobuf_ret(R1), R0
MOVW gobuf_ctxt(R1), R7
MOVW $0, R11
MOVW R11, gobuf_sp(R1) // clear to help garbage collector
MOVW R11, gobuf_ret(R1)
MOVW R11, gobuf_lr(R1)
MOVW R11, gobuf_ctxt(R1)
MOVW gobuf_pc(R1), R11
CMP R11, R11 // set condition codes for == test, needed by stack split
B (R11)
// func mcall(fn func(*g))
// Switch to m->g0's stack, call fn(g).
// Fn must never return. It should gogo(&g->sched)
// to keep running g.
TEXT runtime·mcall(SB),NOSPLIT|NOFRAME,$0-4
// Save caller state in g->sched.
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW LR, (g_sched+gobuf_pc)(g)
MOVW $0, R11
MOVW R11, (g_sched+gobuf_lr)(g)
// Switch to m->g0 & its stack, call fn.
MOVW g, R1
MOVW g_m(g), R8
MOVW m_g0(R8), R0
BL setg<>(SB)
CMP g, R1
B.NE 2(PC)
B runtime·badmcall(SB)
MOVW fn+0(FP), R0
MOVW (g_sched+gobuf_sp)(g), R13
SUB $8, R13
MOVW R1, 4(R13)
MOVW R0, R7
MOVW 0(R0), R0
BL (R0)
B runtime·badmcall2(SB)
RET
// systemstack_switch is a dummy routine that systemstack leaves at the bottom
// of the G stack. We need to distinguish the routine that
// lives at the bottom of the G stack from the one that lives
// at the top of the system stack because the one at the top of
// the system stack terminates the stack walk (see topofstack()).
TEXT runtime·systemstack_switch(SB),NOSPLIT,$0-0
MOVW $0, R0
BL (R0) // clobber lr to ensure push {lr} is kept
RET
// func systemstack(fn func())
TEXT runtime·systemstack(SB),NOSPLIT,$0-4
MOVW fn+0(FP), R0 // R0 = fn
MOVW g_m(g), R1 // R1 = m
MOVW m_gsignal(R1), R2 // R2 = gsignal
CMP g, R2
B.EQ noswitch
MOVW m_g0(R1), R2 // R2 = g0
CMP g, R2
B.EQ noswitch
MOVW m_curg(R1), R3
CMP g, R3
B.EQ switch
// Bad: g is not gsignal, not g0, not curg. What is it?
// Hide call from linker nosplit analysis.
MOVW $runtime·badsystemstack(SB), R0
BL (R0)
B runtime·abort(SB)
switch:
// save our state in g->sched. Pretend to
// be systemstack_switch if the G stack is scanned.
BL gosave_systemstack_switch<>(SB)
// switch to g0
MOVW R0, R5
MOVW R2, R0
BL setg<>(SB)
MOVW R5, R0
MOVW (g_sched+gobuf_sp)(R2), R13
// call target function
MOVW R0, R7
MOVW 0(R0), R0
BL (R0)
// switch back to g
MOVW g_m(g), R1
MOVW m_curg(R1), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R13
MOVW $0, R3
MOVW R3, (g_sched+gobuf_sp)(g)
RET
noswitch:
// Using a tail call here cleans up tracebacks since we won't stop
// at an intermediate systemstack.
MOVW R0, R7
MOVW 0(R0), R0
MOVW.P 4(R13), R14 // restore LR
B (R0)
/*
* support for morestack
*/
// Called during function prolog when more stack is needed.
// R3 prolog's LR
// using NOFRAME means do not save LR on stack.
//
// The traceback routines see morestack on a g0 as being
// the top of a stack (for example, morestack calling newstack
// calling the scheduler calling newm calling gc), so we must
// record an argument size. For that purpose, it has no arguments.
TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
// Cannot grow scheduler stack (m->g0).
MOVW g_m(g), R8
MOVW m_g0(R8), R4
CMP g, R4
BNE 3(PC)
BL runtime·badmorestackg0(SB)
B runtime·abort(SB)
// Cannot grow signal stack (m->gsignal).
MOVW m_gsignal(R8), R4
CMP g, R4
BNE 3(PC)
BL runtime·badmorestackgsignal(SB)
B runtime·abort(SB)
// Called from f.
// Set g->sched to context in f.
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW LR, (g_sched+gobuf_pc)(g)
MOVW R3, (g_sched+gobuf_lr)(g)
MOVW R7, (g_sched+gobuf_ctxt)(g)
// Called from f.
// Set m->morebuf to f's caller.
MOVW R3, (m_morebuf+gobuf_pc)(R8) // f's caller's PC
MOVW R13, (m_morebuf+gobuf_sp)(R8) // f's caller's SP
MOVW g, (m_morebuf+gobuf_g)(R8)
// Call newstack on m->g0's stack.
MOVW m_g0(R8), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R13
MOVW $0, R0
MOVW.W R0, -4(R13) // create a call frame on g0 (saved LR)
BL runtime·newstack(SB)
// Not reached, but make sure the return PC from the call to newstack
// is still in this function, and not the beginning of the next.
RET
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R3), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVW R13, R13
MOVW $0, R7
B runtime·morestack(SB)
// reflectcall: call a function with the given argument list
// func call(stackArgsType *_type, f *FuncVal, stackArgs *byte, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs).
// we don't have variable-sized frames, so we use a small number
// of constant-sized-frame functions to encode a few bits of size in the pc.
// Caution: ugly multiline assembly macros in your future!
#define DISPATCH(NAME,MAXSIZE) \
CMP $MAXSIZE, R0; \
B.HI 3(PC); \
MOVW $NAME(SB), R1; \
B (R1)
TEXT ·reflectcall(SB),NOSPLIT|NOFRAME,$0-28
MOVW frameSize+20(FP), R0
DISPATCH(runtime·call16, 16)
DISPATCH(runtime·call32, 32)
DISPATCH(runtime·call64, 64)
DISPATCH(runtime·call128, 128)
DISPATCH(runtime·call256, 256)
DISPATCH(runtime·call512, 512)
DISPATCH(runtime·call1024, 1024)
DISPATCH(runtime·call2048, 2048)
DISPATCH(runtime·call4096, 4096)
DISPATCH(runtime·call8192, 8192)
DISPATCH(runtime·call16384, 16384)
DISPATCH(runtime·call32768, 32768)
DISPATCH(runtime·call65536, 65536)
DISPATCH(runtime·call131072, 131072)
DISPATCH(runtime·call262144, 262144)
DISPATCH(runtime·call524288, 524288)
DISPATCH(runtime·call1048576, 1048576)
DISPATCH(runtime·call2097152, 2097152)
DISPATCH(runtime·call4194304, 4194304)
DISPATCH(runtime·call8388608, 8388608)
DISPATCH(runtime·call16777216, 16777216)
DISPATCH(runtime·call33554432, 33554432)
DISPATCH(runtime·call67108864, 67108864)
DISPATCH(runtime·call134217728, 134217728)
DISPATCH(runtime·call268435456, 268435456)
DISPATCH(runtime·call536870912, 536870912)
DISPATCH(runtime·call1073741824, 1073741824)
MOVW $runtime·badreflectcall(SB), R1
B (R1)
#define CALLFN(NAME,MAXSIZE) \
TEXT NAME(SB), WRAPPER, $MAXSIZE-28; \
NO_LOCAL_POINTERS; \
/* copy arguments to stack */ \
MOVW stackArgs+8(FP), R0; \
MOVW stackArgsSize+12(FP), R2; \
ADD $4, R13, R1; \
CMP $0, R2; \
B.EQ 5(PC); \
MOVBU.P 1(R0), R5; \
MOVBU.P R5, 1(R1); \
SUB $1, R2, R2; \
B -5(PC); \
/* call function */ \
MOVW f+4(FP), R7; \
MOVW (R7), R0; \
PCDATA $PCDATA_StackMapIndex, $0; \
BL (R0); \
/* copy return values back */ \
MOVW stackArgsType+0(FP), R4; \
MOVW stackArgs+8(FP), R0; \
MOVW stackArgsSize+12(FP), R2; \
MOVW stackArgsRetOffset+16(FP), R3; \
ADD $4, R13, R1; \
ADD R3, R1; \
ADD R3, R0; \
SUB R3, R2; \
BL callRet<>(SB); \
RET
// callRet copies return values back at the end of call*. This is a
// separate function so it can allocate stack space for the arguments
// to reflectcallmove. It does not follow the Go ABI; it expects its
// arguments in registers.
TEXT callRet<>(SB), NOSPLIT, $20-0
MOVW R4, 4(R13)
MOVW R0, 8(R13)
MOVW R1, 12(R13)
MOVW R2, 16(R13)
MOVW $0, R7
MOVW R7, 20(R13)
BL runtime·reflectcallmove(SB)
RET
CALLFN(·call16, 16)
CALLFN(·call32, 32)
CALLFN(·call64, 64)
CALLFN(·call128, 128)
CALLFN(·call256, 256)
CALLFN(·call512, 512)
CALLFN(·call1024, 1024)
CALLFN(·call2048, 2048)
CALLFN(·call4096, 4096)
CALLFN(·call8192, 8192)
CALLFN(·call16384, 16384)
CALLFN(·call32768, 32768)
CALLFN(·call65536, 65536)
CALLFN(·call131072, 131072)
CALLFN(·call262144, 262144)
CALLFN(·call524288, 524288)
CALLFN(·call1048576, 1048576)
CALLFN(·call2097152, 2097152)
CALLFN(·call4194304, 4194304)
CALLFN(·call8388608, 8388608)
CALLFN(·call16777216, 16777216)
CALLFN(·call33554432, 33554432)
CALLFN(·call67108864, 67108864)
CALLFN(·call134217728, 134217728)
CALLFN(·call268435456, 268435456)
CALLFN(·call536870912, 536870912)
CALLFN(·call1073741824, 1073741824)
// Save state of caller into g->sched,
// but using fake PC from systemstack_switch.
// Must only be called from functions with no locals ($0)
// or else unwinding from systemstack_switch is incorrect.
// Smashes R11.
TEXT gosave_systemstack_switch<>(SB),NOSPLIT|NOFRAME,$0
MOVW $runtime·systemstack_switch(SB), R11
ADD $4, R11 // get past push {lr}
MOVW R11, (g_sched+gobuf_pc)(g)
MOVW R13, (g_sched+gobuf_sp)(g)
MOVW $0, R11
MOVW R11, (g_sched+gobuf_lr)(g)
MOVW R11, (g_sched+gobuf_ret)(g)
// Assert ctxt is zero. See func save.
MOVW (g_sched+gobuf_ctxt)(g), R11
TST R11, R11
B.EQ 2(PC)
BL runtime·abort(SB)
RET
// func asmcgocall_no_g(fn, arg unsafe.Pointer)
// Call fn(arg) aligned appropriately for the gcc ABI.
// Called on a system stack, and there may be no g yet (during needm).
TEXT ·asmcgocall_no_g(SB),NOSPLIT,$0-8
MOVW fn+0(FP), R1
MOVW arg+4(FP), R0
MOVW R13, R2
SUB $32, R13
BIC $0x7, R13 // alignment for gcc ABI
MOVW R2, 8(R13)
BL (R1)
MOVW 8(R13), R2
MOVW R2, R13
RET
// func asmcgocall(fn, arg unsafe.Pointer) int32
// Call fn(arg) on the scheduler stack,
// aligned appropriately for the gcc ABI.
// See cgocall.go for more details.
TEXT ·asmcgocall(SB),NOSPLIT,$0-12
MOVW fn+0(FP), R1
MOVW arg+4(FP), R0
MOVW R13, R2
CMP $0, g
BEQ nosave
MOVW g, R4
// Figure out if we need to switch to m->g0 stack.
// We get called to create new OS threads too, and those
// come in on the m->g0 stack already. Or we might already
// be on the m->gsignal stack.
MOVW g_m(g), R8
MOVW m_gsignal(R8), R3
CMP R3, g
BEQ nosave
MOVW m_g0(R8), R3
CMP R3, g
BEQ nosave
BL gosave_systemstack_switch<>(SB)
MOVW R0, R5
MOVW R3, R0
BL setg<>(SB)
MOVW R5, R0
MOVW (g_sched+gobuf_sp)(g), R13
// Now on a scheduling stack (a pthread-created stack).
SUB $24, R13
BIC $0x7, R13 // alignment for gcc ABI
MOVW R4, 20(R13) // save old g
MOVW (g_stack+stack_hi)(R4), R4
SUB R2, R4
MOVW R4, 16(R13) // save depth in stack (can't just save SP, as stack might be copied during a callback)
BL (R1)
// Restore registers, g, stack pointer.
MOVW R0, R5
MOVW 20(R13), R0
BL setg<>(SB)
MOVW (g_stack+stack_hi)(g), R1
MOVW 16(R13), R2
SUB R2, R1
MOVW R5, R0
MOVW R1, R13
MOVW R0, ret+8(FP)
RET
nosave:
// Running on a system stack, perhaps even without a g.
// Having no g can happen during thread creation or thread teardown
// (see needm/dropm on Solaris, for example).
// This code is like the above sequence but without saving/restoring g
// and without worrying about the stack moving out from under us
// (because we're on a system stack, not a goroutine stack).
// The above code could be used directly if already on a system stack,
// but then the only path through this code would be a rare case on Solaris.
// Using this code for all "already on system stack" calls exercises it more,
// which should help keep it correct.
SUB $24, R13
BIC $0x7, R13 // alignment for gcc ABI
// save null g in case someone looks during debugging.
MOVW $0, R4
MOVW R4, 20(R13)
MOVW R2, 16(R13) // Save old stack pointer.
BL (R1)
// Restore stack pointer.
MOVW 16(R13), R2
MOVW R2, R13
MOVW R0, ret+8(FP)
RET
// cgocallback(fn, frame unsafe.Pointer, ctxt uintptr)
// See cgocall.go for more details.
TEXT ·cgocallback(SB),NOSPLIT,$12-12
NO_LOCAL_POINTERS
// Skip cgocallbackg, just dropm when fn is nil, and frame is the saved g.
// It is used to dropm while thread is exiting.
MOVW fn+0(FP), R1
CMP $0, R1
B.NE loadg
// Restore the g from frame.
MOVW frame+4(FP), g
B dropm
loadg:
// Load m and g from thread-local storage.
#ifdef GOOS_openbsd
BL runtime·load_g(SB)
#else
MOVB runtime·iscgo(SB), R0
CMP $0, R0
BL.NE runtime·load_g(SB)
#endif
// If g is nil, Go did not create the current thread,
// or if this thread never called into Go on pthread platforms.
// Call needm to obtain one for temporary use.
// In this case, we're running on the thread stack, so there's
// lots of space, but the linker doesn't know. Hide the call from
// the linker analysis by using an indirect call.
CMP $0, g
B.EQ needm
MOVW g_m(g), R8
MOVW R8, savedm-4(SP)
B havem
needm:
MOVW g, savedm-4(SP) // g is zero, so is m.
MOVW $runtime·needAndBindM(SB), R0
BL (R0)
// Set m->g0->sched.sp = SP, so that if a panic happens
// during the function we are about to execute, it will
// have a valid SP to run on the g0 stack.
// The next few lines (after the havem label)
// will save this SP onto the stack and then write
// the same SP back to m->sched.sp. That seems redundant,
// but if an unrecovered panic happens, unwindm will
// restore the g->sched.sp from the stack location
// and then systemstack will try to use it. If we don't set it here,
// that restored SP will be uninitialized (typically 0) and
// will not be usable.
MOVW g_m(g), R8
MOVW m_g0(R8), R3
MOVW R13, (g_sched+gobuf_sp)(R3)
havem:
// Now there's a valid m, and we're running on its m->g0.
// Save current m->g0->sched.sp on stack and then set it to SP.
// Save current sp in m->g0->sched.sp in preparation for
// switch back to m->curg stack.
// NOTE: unwindm knows that the saved g->sched.sp is at 4(R13) aka savedsp-12(SP).
MOVW m_g0(R8), R3
MOVW (g_sched+gobuf_sp)(R3), R4
MOVW R4, savedsp-12(SP) // must match frame size
MOVW R13, (g_sched+gobuf_sp)(R3)
// Switch to m->curg stack and call runtime.cgocallbackg.
// Because we are taking over the execution of m->curg
// but *not* resuming what had been running, we need to
// save that information (m->curg->sched) so we can restore it.
// We can restore m->curg->sched.sp easily, because calling
// runtime.cgocallbackg leaves SP unchanged upon return.
// To save m->curg->sched.pc, we push it onto the curg stack and
// open a frame the same size as cgocallback's g0 frame.
// Once we switch to the curg stack, the pushed PC will appear
// to be the return PC of cgocallback, so that the traceback
// will seamlessly trace back into the earlier calls.
MOVW m_curg(R8), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R4 // prepare stack as R4
MOVW (g_sched+gobuf_pc)(g), R5
MOVW R5, -(12+4)(R4) // "saved LR"; must match frame size
// Gather our arguments into registers.
MOVW fn+0(FP), R1
MOVW frame+4(FP), R2
MOVW ctxt+8(FP), R3
MOVW $-(12+4)(R4), R13 // switch stack; must match frame size
MOVW R1, 4(R13)
MOVW R2, 8(R13)
MOVW R3, 12(R13)
BL runtime·cgocallbackg(SB)
// Restore g->sched (== m->curg->sched) from saved values.
MOVW 0(R13), R5
MOVW R5, (g_sched+gobuf_pc)(g)
MOVW $(12+4)(R13), R4 // must match frame size
MOVW R4, (g_sched+gobuf_sp)(g)
// Switch back to m->g0's stack and restore m->g0->sched.sp.
// (Unlike m->curg, the g0 goroutine never uses sched.pc,
// so we do not have to restore it.)
MOVW g_m(g), R8
MOVW m_g0(R8), R0
BL setg<>(SB)
MOVW (g_sched+gobuf_sp)(g), R13
MOVW savedsp-12(SP), R4 // must match frame size
MOVW R4, (g_sched+gobuf_sp)(g)
// If the m on entry was nil, we called needm above to borrow an m,
// 1. for the duration of the call on non-pthread platforms,
// 2. or the duration of the C thread alive on pthread platforms.
// If the m on entry wasn't nil,
// 1. the thread might be a Go thread,
// 2. or it wasn't the first call from a C thread on pthread platforms,
// since then we skip dropm to reuse the m in the first call.
MOVW savedm-4(SP), R6
CMP $0, R6
B.NE done
// Skip dropm to reuse it in the next call, when a pthread key has been created.
MOVW _cgo_pthread_key_created(SB), R6
// It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
CMP $0, R6
B.EQ dropm
MOVW (R6), R6
CMP $0, R6
B.NE done
dropm:
MOVW $runtime·dropm(SB), R0
BL (R0)
done:
// Done!
RET
// void setg(G*); set g. for use by needm.
TEXT runtime·setg(SB),NOSPLIT|NOFRAME,$0-4
MOVW gg+0(FP), R0
B setg<>(SB)
TEXT setg<>(SB),NOSPLIT|NOFRAME,$0-0
MOVW R0, g
// Save g to thread-local storage.
#ifdef GOOS_windows
B runtime·save_g(SB)
#else
#ifdef GOOS_openbsd
B runtime·save_g(SB)
#else
MOVB runtime·iscgo(SB), R0
CMP $0, R0
B.EQ 2(PC)
B runtime·save_g(SB)
MOVW g, R0
RET
#endif
#endif
TEXT runtime·emptyfunc(SB),0,$0-0
RET
TEXT runtime·abort(SB),NOSPLIT|NOFRAME,$0-0
MOVW $0, R0
MOVW (R0), R1
// armPublicationBarrier is a native store/store barrier for ARMv7+.
// On earlier ARM revisions, armPublicationBarrier is a no-op.
// This will not work on SMP ARMv6 machines, if any are in use.
// To implement publicationBarrier in sys_$GOOS_arm.s using the native
// instructions, use:
//
// TEXT ·publicationBarrier(SB),NOSPLIT|NOFRAME,$0-0
// B runtime·armPublicationBarrier(SB)
//
TEXT runtime·armPublicationBarrier(SB),NOSPLIT|NOFRAME,$0-0
MOVB runtime·goarm(SB), R11
CMP $7, R11
BLT 2(PC)
DMB MB_ST
RET
// AES hashing not implemented for ARM
TEXT runtime·memhash(SB),NOSPLIT|NOFRAME,$0-16
JMP runtime·memhashFallback(SB)
TEXT runtime·strhash(SB),NOSPLIT|NOFRAME,$0-12
JMP runtime·strhashFallback(SB)
TEXT runtime·memhash32(SB),NOSPLIT|NOFRAME,$0-12
JMP runtime·memhash32Fallback(SB)
TEXT runtime·memhash64(SB),NOSPLIT|NOFRAME,$0-12
JMP runtime·memhash64Fallback(SB)
TEXT runtime·return0(SB),NOSPLIT,$0
MOVW $0, R0
RET
TEXT runtime·procyield(SB),NOSPLIT|NOFRAME,$0
MOVW cycles+0(FP), R1
MOVW $0, R0
yieldloop:
WORD $0xe320f001 // YIELD (NOP pre-ARMv6K)
CMP R0, R1
B.NE 2(PC)
RET
SUB $1, R1
B yieldloop
// Called from cgo wrappers, this function returns g->m->curg.stack.hi.
// Must obey the gcc calling convention.
TEXT _cgo_topofstack(SB),NOSPLIT,$8
// R11 and g register are clobbered by load_g. They are
// callee-save in the gcc calling convention, so save them here.
MOVW R11, saveR11-4(SP)
MOVW g, saveG-8(SP)
BL runtime·load_g(SB)
MOVW g_m(g), R0
MOVW m_curg(R0), R0
MOVW (g_stack+stack_hi)(R0), R0
MOVW saveG-8(SP), g
MOVW saveR11-4(SP), R11
RET
// The top-most function running on a goroutine
// returns to goexit+PCQuantum.
TEXT runtime·goexit(SB),NOSPLIT|NOFRAME|TOPFRAME,$0-0
MOVW R0, R0 // NOP
BL runtime·goexit1(SB) // does not return
// traceback from goexit1 must hit code range of goexit
MOVW R0, R0 // NOP
// x -> x/1000000, x%1000000, called from Go with args, results on stack.
TEXT runtime·usplit(SB),NOSPLIT,$0-12
MOVW x+0(FP), R0
CALL runtime·usplitR0(SB)
MOVW R0, q+4(FP)
MOVW R1, r+8(FP)
RET
// R0, R1 = R0/1000000, R0%1000000
TEXT runtime·usplitR0(SB),NOSPLIT,$0
// magic multiply to avoid software divide without available m.
// see output of go tool compile -S for x/1000000.
MOVW R0, R3
MOVW $1125899907, R1
MULLU R1, R0, (R0, R1)
MOVW R0>>18, R0
MOVW $1000000, R1
MULU R0, R1
SUB R1, R3, R1
RET
// This is called from .init_array and follows the platform, not Go, ABI.
TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0
MOVW R9, saver9-4(SP) // The access to global variables below implicitly uses R9, which is callee-save
MOVW R11, saver11-8(SP) // Likewise, R11 is the temp register, but callee-save in C ABI
MOVW runtime·lastmoduledatap(SB), R1
MOVW R0, moduledata_next(R1)
MOVW R0, runtime·lastmoduledatap(SB)
MOVW saver11-8(SP), R11
MOVW saver9-4(SP), R9
RET
TEXT ·checkASM(SB),NOSPLIT,$0-1
MOVW $1, R3
MOVB R3, ret+0(FP)
RET
// gcWriteBarrier informs the GC about heap pointer writes.
//
// gcWriteBarrier does NOT follow the Go ABI. It accepts the
// number of bytes of buffer needed in R8, and returns a pointer
// to the buffer space in R8.
// It clobbers condition codes.
// It does not clobber any other general-purpose registers,
// but may clobber others (e.g., floating point registers).
// The act of CALLing gcWriteBarrier will clobber R14 (LR).
TEXT gcWriteBarrier<>(SB),NOSPLIT|NOFRAME,$0
// Save the registers clobbered by the fast path.
MOVM.DB.W [R0,R1], (R13)
retry:
MOVW g_m(g), R0
MOVW m_p(R0), R0
MOVW (p_wbBuf+wbBuf_next)(R0), R1
MOVW (p_wbBuf+wbBuf_end)(R0), R11
// Increment wbBuf.next position.
ADD R8, R1
// Is the buffer full?
CMP R11, R1
BHI flush
// Commit to the larger buffer.
MOVW R1, (p_wbBuf+wbBuf_next)(R0)
// Make return value (the original next position)
SUB R8, R1, R8
// Restore registers.
MOVM.IA.W (R13), [R0,R1]
RET
flush:
// Save all general purpose registers since these could be
// clobbered by wbBufFlush and were not saved by the caller.
//
// R0 and R1 were saved at entry.
// R10 is g, so preserved.
// R11 is linker temp, so no need to save.
// R13 is stack pointer.
// R15 is PC.
MOVM.DB.W [R2-R9,R12], (R13)
// Save R14 (LR) because the fast path above doesn't save it,
// but needs it to RET.
MOVM.DB.W [R14], (R13)
CALL runtime·wbBufFlush(SB)
MOVM.IA.W (R13), [R14]
MOVM.IA.W (R13), [R2-R9,R12]
JMP retry
TEXT runtime·gcWriteBarrier1<ABIInternal>(SB),NOSPLIT,$0
MOVW $4, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier2<ABIInternal>(SB),NOSPLIT,$0
MOVW $8, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier3<ABIInternal>(SB),NOSPLIT,$0
MOVW $12, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier4<ABIInternal>(SB),NOSPLIT,$0
MOVW $16, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier5<ABIInternal>(SB),NOSPLIT,$0
MOVW $20, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier6<ABIInternal>(SB),NOSPLIT,$0
MOVW $24, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier7<ABIInternal>(SB),NOSPLIT,$0
MOVW $28, R8
JMP gcWriteBarrier<>(SB)
TEXT runtime·gcWriteBarrier8<ABIInternal>(SB),NOSPLIT,$0
MOVW $32, R8
JMP gcWriteBarrier<>(SB)
// Note: these functions use a special calling convention to save generated code space.
// Arguments are passed in registers, but the space for those arguments are allocated
// in the caller's stack frame. These stubs write the args into that stack space and
// then tail call to the corresponding runtime handler.
// The tail call makes these stubs disappear in backtraces.
TEXT runtime·panicIndex(SB),NOSPLIT,$0-8
MOVW R0, x+0(FP)
MOVW R1, y+4(FP)
JMP runtime·goPanicIndex(SB)
TEXT runtime·panicIndexU(SB),NOSPLIT,$0-8
MOVW R0, x+0(FP)
MOVW R1, y+4(FP)
JMP runtime·goPanicIndexU(SB)
TEXT runtime·panicSliceAlen(SB),NOSPLIT,$0-8
MOVW R1, x+0(FP)
MOVW R2, y+4(FP)
JMP runtime·goPanicSliceAlen(SB)
TEXT runtime·panicSliceAlenU(SB),NOSPLIT,$0-8
MOVW R1, x+0(FP)
MOVW R2, y+4(FP)
JMP runtime·goPanicSliceAlenU(SB)
TEXT runtime·panicSliceAcap(SB),NOSPLIT,$0-8
MOVW R1, x+0(FP)
MOVW R2, y+4(FP)
JMP runtime·goPanicSliceAcap(SB)