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mirror of https://github.com/golang/go synced 2024-11-22 03:24:41 -07:00

runtime: allow cgo callbacks on non-Go threads

Fixes #4435.

R=golang-dev, iant, alex.brainman, minux.ma, dvyukov
CC=golang-dev
https://golang.org/cl/7304104
This commit is contained in:
Russ Cox 2013-02-20 17:48:23 -05:00
parent 43da336b15
commit 6c976393ae
20 changed files with 566 additions and 36 deletions

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@ -35,5 +35,6 @@ func Test4029(t *testing.T) { test4029(t) }
func TestBoolAlign(t *testing.T) { testBoolAlign(t) }
func Test3729(t *testing.T) { test3729(t) }
func Test3775(t *testing.T) { test3775(t) }
func TestCthread(t *testing.T) { testCthread(t) }
func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }

44
misc/cgo/test/cthread.go Normal file
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@ -0,0 +1,44 @@
// Copyright 2013 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.
package cgotest
// extern void doAdd(int, int);
import "C"
import (
"runtime"
"sync"
"testing"
)
var sum struct {
sync.Mutex
i int
}
//export Add
func Add(x int) {
defer func() {
recover()
}()
sum.Lock()
sum.i += x
sum.Unlock()
var p *int
*p = 2
}
func testCthread(t *testing.T) {
if runtime.GOARCH == "arm" {
t.Skip("testCthread disabled on arm")
}
C.doAdd(10, 6)
want := 10 * (10 - 1) / 2 * 6
if sum.i != want {
t.Fatalf("sum=%d, want %d", sum.i, want)
}
}

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@ -0,0 +1,34 @@
// Copyright 2013 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.
// +build darwin freebsd linux netbsd openbsd
#include <pthread.h>
#include "_cgo_export.h"
static void*
addThread(void *p)
{
int i, max;
max = *(int*)p;
for(i=0; i<max; i++)
Add(i);
return 0;
}
void
doAdd(int max, int nthread)
{
enum { MaxThread = 20 };
int i;
pthread_t thread_id[MaxThread];
if(nthread > MaxThread)
nthread = MaxThread;
for(i=0; i<nthread; i++)
pthread_create(&thread_id[i], 0, addThread, &max);
for(i=0; i<nthread; i++)
pthread_join(thread_id[i], 0);
}

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@ -0,0 +1,37 @@
// Copyright 2013 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.
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <process.h>
#include "_cgo_export.h"
__stdcall
static unsigned int
addThread(void *p)
{
int i, max;
max = *(int*)p;
for(i=0; i<max; i++)
Add(i);
return 0;
}
void
doAdd(int max, int nthread)
{
enum { MaxThread = 20 };
int i;
uintptr_t thread_id[MaxThread];
if(nthread > MaxThread)
nthread = MaxThread;
for(i=0; i<nthread; i++)
thread_id[i] = _beginthreadex(0, 0, addThread, &max, 0, 0);
for(i=0; i<nthread; i++) {
WaitForSingleObject((HANDLE)thread_id[i], INFINITE);
CloseHandle((HANDLE)thread_id[i]);
}
}

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@ -476,21 +476,33 @@ TEXT runtime·asmcgocall(SB),7,$0
// cgocallback(void (*fn)(void*), void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT runtime·cgocallback(SB),7,$12
MOVL fn+0(FP), AX
MOVL frame+4(FP), BX
MOVL framesize+8(FP), DX
// Save current m->g0->sched.sp on stack and then set it to SP.
// If m is nil, Go did not create the current thread.
// 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 through AX.
get_tls(CX)
#ifdef GOOS_windows
CMPL CX, $0
JNE 3(PC)
PUSHL $0
JMP needm
#endif
MOVL m(CX), BP
PUSHL BP
CMPL BP, $0
JNE havem
needm:
MOVL $runtime·needm(SB), AX
CALL AX
get_tls(CX)
MOVL m(CX), BP
// If m is nil, it is almost certainly because we have been called
// on a thread that Go did not create. We're going to crash as
// soon as we try to use m; instead, try to print a nice error and exit.
CMPL BP, $0
JNE 2(PC)
CALL runtime·badcallback(SB)
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.
MOVL m_g0(BP), SI
PUSHL (g_sched+gobuf_sp)(SI)
MOVL SP, (g_sched+gobuf_sp)(SI)
@ -509,6 +521,10 @@ TEXT runtime·cgocallback(SB),7,$12
// a frame size of 12, the same amount that we use below),
// so that the traceback will seamlessly trace back into
// the earlier calls.
MOVL fn+0(FP), AX
MOVL frame+4(FP), BX
MOVL framesize+8(FP), DX
MOVL m_curg(BP), SI
MOVL SI, g(CX)
MOVL (g_sched+gobuf_sp)(SI), DI // prepare stack as DI
@ -546,10 +562,38 @@ TEXT runtime·cgocallback(SB),7,$12
MOVL SI, g(CX)
MOVL (g_sched+gobuf_sp)(SI), SP
POPL (g_sched+gobuf_sp)(SI)
// If the m on entry was nil, we called needm above to borrow an m
// for the duration of the call. Since the call is over, return it with dropm.
POPL BP
CMPL BP, $0
JNE 3(PC)
MOVL $runtime·dropm(SB), AX
CALL AX
// Done!
RET
// void setmg(M*, G*); set m and g. for use by needm.
TEXT runtime·setmg(SB), 7, $0
#ifdef GOOS_windows
MOVL mm+0(FP), AX
CMPL AX, $0
JNE settls
MOVL $0, 0x14(FS)
RET
settls:
LEAL m_tls(AX), AX
MOVL AX, 0x14(FS)
#endif
MOVL mm+0(FP), AX
get_tls(CX)
MOVL mm+0(FP), AX
MOVL AX, m(CX)
MOVL gg+4(FP), BX
MOVL BX, g(CX)
RET
// check that SP is in range [g->stackbase, g->stackguard)
TEXT runtime·stackcheck(SB), 7, $0
get_tls(CX)

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@ -509,21 +509,33 @@ TEXT runtime·asmcgocall(SB),7,$0
// cgocallback(void (*fn)(void*), void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT runtime·cgocallback(SB),7,$24
MOVQ fn+0(FP), AX
MOVQ frame+8(FP), BX
MOVQ framesize+16(FP), DX
// Save current m->g0->sched.sp on stack and then set it to SP.
// If m is nil, Go did not create the current thread.
// 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 through AX.
get_tls(CX)
#ifdef GOOS_windows
CMPQ CX, $0
JNE 3(PC)
PUSHQ $0
JMP needm
#endif
MOVQ m(CX), BP
PUSHQ BP
CMPQ BP, $0
JNE havem
needm:
MOVQ $runtime·needm(SB), AX
CALL AX
get_tls(CX)
MOVQ m(CX), BP
// If m is nil, it is almost certainly because we have been called
// on a thread that Go did not create. We're going to crash as
// soon as we try to use m; instead, try to print a nice error and exit.
CMPQ BP, $0
JNE 2(PC)
CALL runtime·badcallback(SB)
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.
MOVQ m_g0(BP), SI
PUSHQ (g_sched+gobuf_sp)(SI)
MOVQ SP, (g_sched+gobuf_sp)(SI)
@ -542,6 +554,10 @@ TEXT runtime·cgocallback(SB),7,$24
// a frame size of 24, the same amount that we use below),
// so that the traceback will seamlessly trace back into
// the earlier calls.
MOVQ fn+0(FP), AX
MOVQ frame+8(FP), BX
MOVQ framesize+16(FP), DX
MOVQ m_curg(BP), SI
MOVQ SI, g(CX)
MOVQ (g_sched+gobuf_sp)(SI), DI // prepare stack as DI
@ -579,10 +595,37 @@ TEXT runtime·cgocallback(SB),7,$24
MOVQ SI, g(CX)
MOVQ (g_sched+gobuf_sp)(SI), SP
POPQ (g_sched+gobuf_sp)(SI)
// If the m on entry was nil, we called needm above to borrow an m
// for the duration of the call. Since the call is over, return it with dropm.
POPQ BP
CMPQ BP, $0
JNE 3(PC)
MOVQ $runtime·dropm(SB), AX
CALL AX
// Done!
RET
// void setmg(M*, G*); set m and g. for use by needm.
TEXT runtime·setmg(SB), 7, $0
MOVQ mm+0(FP), AX
#ifdef GOOS_windows
CMPQ AX, $0
JNE settls
MOVQ $0, 0x28(GS)
RET
settls:
LEAQ m_tls(AX), AX
MOVQ AX, 0x28(GS)
#endif
get_tls(CX)
MOVQ mm+0(FP), AX
MOVQ AX, m(CX)
MOVQ gg+8(FP), BX
MOVQ BX, g(CX)
RET
// check that SP is in range [g->stackbase, g->stackguard)
TEXT runtime·stackcheck(SB), 7, $0
get_tls(CX)

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@ -290,11 +290,31 @@ TEXT runtime·asmcgocall(SB),7,$0
// cgocallback(void (*fn)(void*), void *frame, uintptr framesize)
// See cgocall.c for more details.
TEXT runtime·cgocallback(SB),7,$16
// Load m and g from thread-local storage.
MOVW cgo_load_gm(SB), R0
CMP $0, R0
BL.NE (R0)
// If m is nil, Go did not create the current thread.
// 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.
MOVW m, savedm-16(SP)
CMP $0, m
B.NE havem
MOVW $runtime·needm(SB), R0
BL (R0)
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.
MOVW fn+0(FP), R0
MOVW frame+4(FP), R1
MOVW framesize+8(FP), R2
// Save current m->g0->sched.sp on stack and then set it to SP.
MOVW m_g0(m), R3
MOVW (g_sched+gobuf_sp)(R3), R4
MOVW.W R4, -4(R13)
@ -314,6 +334,8 @@ TEXT runtime·cgocallback(SB),7,$16
// a frame size of 16, the same amount that we use below),
// so that the traceback will seamlessly trace back into
// the earlier calls.
// Save current m->g0->sched.sp on stack and then set it to SP.
MOVW m_curg(m), g
MOVW (g_sched+gobuf_sp)(g), R4 // prepare stack as R4
@ -350,9 +372,29 @@ TEXT runtime·cgocallback(SB),7,$16
ADD $4, R13
MOVW R6, (g_sched+gobuf_sp)(g)
// If the m on entry was nil, we called needm above to borrow an m
// for the duration of the call. Since the call is over, return it with dropm.
MOVW savedm-16(SP), R6
CMP $0, R6
B.NE 3(PC)
MOVW $runtime·dropm(SB), R0
BL (R0)
// Done!
RET
// void setmg(M*, G*); set m and g. for use by needm.
TEXT runtime·setmg(SB), 7, $-4
MOVW mm+0(FP), m
MOVW gg+4(FP), g
// Save m and g to thread-local storage.
MOVW cgo_save_gm(SB), R0
CMP $0, R0
BL.NE (R0)
RET
TEXT runtime·getcallerpc(SB),7,$-4
MOVW 0(SP), R0
RET

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@ -216,6 +216,11 @@ runtime·cgocallbackg(void (*fn)(void), void *arg, uintptr argsize)
runtime·exitsyscall(); // coming out of cgo call
if(m->needextram) {
m->needextram = 0;
runtime·newextram();
}
// Add entry to defer stack in case of panic.
d.fn = (byte*)unwindm;
d.siz = 0;

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@ -29,6 +29,7 @@ byte *runtime·compilecallback(Eface fn, bool cleanstack);
void *runtime·callbackasm(void);
void runtime·install_exception_handler(void);
void runtime·remove_exception_handler(void);
// TODO(brainman): should not need those
#define NSIG 65

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@ -25,6 +25,7 @@ int32 runtime·gcwaiting;
G* runtime·allg;
G* runtime·lastg;
M* runtime·allm;
M* runtime·extram;
int8* runtime·goos;
int32 runtime·ncpu;
@ -792,8 +793,11 @@ runtime·mstart(void)
// Install signal handlers; after minit so that minit can
// prepare the thread to be able to handle the signals.
if(m == &runtime·m0)
if(m == &runtime·m0) {
runtime·initsig();
if(runtime·iscgo)
runtime·newextram();
}
schedule(nil);
@ -838,9 +842,9 @@ matchmg(void)
}
}
// Create a new m. It will start off with a call to runtime·mstart.
// Allocate a new m unassociated with any thread.
M*
runtime·newm(void)
runtime·allocm(void)
{
M *mp;
static Type *mtype; // The Go type M
@ -854,23 +858,228 @@ runtime·newm(void)
mp = runtime·cnew(mtype);
mcommoninit(mp);
if(runtime·iscgo || Windows)
mp->g0 = runtime·malg(-1);
else
mp->g0 = runtime·malg(8192);
return mp;
}
static M* lockextra(bool nilokay);
static void unlockextra(M*);
// needm is called when a cgo callback happens on a
// thread without an m (a thread not created by Go).
// In this case, needm is expected to find an m to use
// and return with m, g initialized correctly.
// Since m and g are not set now (likely nil, but see below)
// needm is limited in what routines it can call. In particular
// it can only call nosplit functions (textflag 7) and cannot
// do any scheduling that requires an m.
//
// In order to avoid needing heavy lifting here, we adopt
// the following strategy: there is a stack of available m's
// that can be stolen. Using compare-and-swap
// to pop from the stack has ABA races, so we simulate
// a lock by doing an exchange (via casp) to steal the stack
// head and replace the top pointer with MLOCKED (1).
// This serves as a simple spin lock that we can use even
// without an m. The thread that locks the stack in this way
// unlocks the stack by storing a valid stack head pointer.
//
// In order to make sure that there is always an m structure
// available to be stolen, we maintain the invariant that there
// is always one more than needed. At the beginning of the
// program (if cgo is in use) the list is seeded with a single m.
// If needm finds that it has taken the last m off the list, its job
// is - once it has installed its own m so that it can do things like
// allocate memory - to create a spare m and put it on the list.
//
// Each of these extra m's also has a g0 and a curg that are
// pressed into service as the scheduling stack and current
// goroutine for the duration of the cgo callback.
//
// When the callback is done with the m, it calls dropm to
// put the m back on the list.
#pragma textflag 7
void
runtime·needm(byte x)
{
M *mp;
// Lock extra list, take head, unlock popped list.
// nilokay=false is safe here because of the invariant above,
// that the extra list always contains or will soon contain
// at least one m.
mp = lockextra(false);
// Set needextram when we've just emptied the list,
// so that the eventual call into cgocallbackg will
// allocate a new m for the extra list. We delay the
// allocation until then so that it can be done
// after exitsyscall makes sure it is okay to be
// running at all (that is, there's no garbage collection
// running right now).
mp->needextram = mp->schedlink == nil;
unlockextra(mp->schedlink);
// Install m and g (= m->g0) and set the stack bounds
// to match the current stack. We don't actually know
// how big the stack is, like we don't know how big any
// scheduling stack is, but we assume there's at least 32 kB,
// which is more than enough for us.
runtime·setmg(mp, mp->g0);
g->stackbase = (uintptr)(&x + 1024);
g->stackguard = (uintptr)(&x - 32*1024);
// On windows/386, we need to put an SEH frame (two words)
// somewhere on the current stack. We are called
// from needm, and we know there is some available
// space one word into the argument frame. Use that.
m->seh = (SEH*)((uintptr*)&x + 1);
// Initialize this thread to use the m.
runtime·asminit();
runtime·minit();
}
// newextram allocates an m and puts it on the extra list.
// It is called with a working local m, so that it can do things
// like call schedlock and allocate.
void
runtime·newextram(void)
{
M *mp, *mnext;
G *gp;
// Scheduler protects allocation of new m's and g's.
// Create extra goroutine locked to extra m.
// The goroutine is the context in which the cgo callback will run.
// The sched.pc will never be returned to, but setting it to
// runtime.goexit makes clear to the traceback routines where
// the goroutine stack ends.
schedlock();
mp = runtime·allocm();
gp = runtime·malg(4096);
gp->sched.pc = (void*)runtime·goexit;
gp->sched.sp = gp->stackbase;
gp->sched.g = gp;
gp->status = Gsyscall;
mp->curg = gp;
mp->locked = LockInternal;
mp->lockedg = gp;
gp->lockedm = mp;
schedunlock();
// Add m to the extra list.
mnext = lockextra(true);
mp->schedlink = mnext;
unlockextra(mp);
}
// dropm is called when a cgo callback has called needm but is now
// done with the callback and returning back into the non-Go thread.
// It puts the current m back onto the extra list.
//
// The main expense here is the call to signalstack to release the
// m's signal stack, and then the call to needm on the next callback
// from this thread. It is tempting to try to save the m for next time,
// which would eliminate both these costs, but there might not be
// a next time: the current thread (which Go does not control) might exit.
// If we saved the m for that thread, there would be an m leak each time
// such a thread exited. Instead, we acquire and release an m on each
// call. These should typically not be scheduling operations, just a few
// atomics, so the cost should be small.
//
// TODO(rsc): An alternative would be to allocate a dummy pthread per-thread
// variable using pthread_key_create. Unlike the pthread keys we already use
// on OS X, this dummy key would never be read by Go code. It would exist
// only so that we could register at thread-exit-time destructor.
// That destructor would put the m back onto the extra list.
// This is purely a performance optimization. The current version,
// in which dropm happens on each cgo call, is still correct too.
// We may have to keep the current version on systems with cgo
// but without pthreads, like Windows.
void
runtime·dropm(void)
{
M *mp, *mnext;
// Undo whatever initialization minit did during needm.
runtime·unminit();
// Clear m and g, and return m to the extra list.
// After the call to setmg we can only call nosplit functions.
mp = m;
runtime·setmg(nil, nil);
mnext = lockextra(true);
mp->schedlink = mnext;
unlockextra(mp);
}
#define MLOCKED ((M*)1)
// lockextra locks the extra list and returns the list head.
// The caller must unlock the list by storing a new list head
// to runtime.extram. If nilokay is true, then lockextra will
// return a nil list head if that's what it finds. If nilokay is false,
// lockextra will keep waiting until the list head is no longer nil.
#pragma textflag 7
static M*
lockextra(bool nilokay)
{
M *mp;
void (*yield)(void);
for(;;) {
mp = runtime·atomicloadp(&runtime·extram);
if(mp == MLOCKED) {
yield = runtime·osyield;
yield();
continue;
}
if(mp == nil && !nilokay) {
runtime·usleep(1);
continue;
}
if(!runtime·casp(&runtime·extram, mp, MLOCKED)) {
yield = runtime·osyield;
yield();
continue;
}
break;
}
return mp;
}
#pragma textflag 7
static void
unlockextra(M *mp)
{
runtime·atomicstorep(&runtime·extram, mp);
}
// Create a new m. It will start off with a call to runtime·mstart.
M*
runtime·newm(void)
{
M *mp;
mp = runtime·allocm();
if(runtime·iscgo) {
CgoThreadStart ts;
if(libcgo_thread_start == nil)
runtime·throw("libcgo_thread_start missing");
// pthread_create will make us a stack.
mp->g0 = runtime·malg(-1);
ts.m = mp;
ts.g = mp->g0;
ts.fn = runtime·mstart;
runtime·asmcgocall(libcgo_thread_start, &ts);
} else {
if(Windows)
// windows will layout sched stack on os stack
mp->g0 = runtime·malg(-1);
else
mp->g0 = runtime·malg(8192);
runtime·newosproc(mp, mp->g0, (byte*)mp->g0->stackbase, runtime·mstart);
}

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@ -289,6 +289,7 @@ struct M
uint32 waitsemalock;
GCStats gcstats;
bool racecall;
bool needextram;
void* racepc;
uint32 moreframesize_minalloc;
@ -657,10 +658,11 @@ void runtime·ready(G*);
byte* runtime·getenv(int8*);
int32 runtime·atoi(byte*);
void runtime·newosproc(M *mp, G *gp, void *stk, void (*fn)(void));
void runtime·signalstack(byte*, int32);
G* runtime·malg(int32);
void runtime·asminit(void);
void runtime·minit(void);
void runtime·unminit(void);
void runtime·signalstack(byte*, int32);
Func* runtime·findfunc(uintptr);
int32 runtime·funcline(Func*, uintptr);
void* runtime·stackalloc(uint32);
@ -683,6 +685,8 @@ int32 runtime·gcount(void);
void runtime·mcall(void(*)(G*));
uint32 runtime·fastrand1(void);
void runtime·setmg(M*, G*);
void runtime·newextram(void);
void runtime·exit(int32);
void runtime·breakpoint(void);
void runtime·gosched(void);

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@ -303,3 +303,15 @@ TEXT runtime·install_exception_handler(SB),7,$0
MOVL DX, 0(FS)
RET
// void remove_exception_handler()
TEXT runtime·remove_exception_handler(SB),7,$0
get_tls(CX)
MOVL m(CX), CX // m
// Remove SEH frame
MOVL m_seh(CX), DX
MOVL seh_prev(DX), AX
MOVL AX, 0(FS)
RET

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@ -343,3 +343,6 @@ TEXT runtime·settls(SB),7,$0
TEXT runtime·install_exception_handler(SB),7,$0
CALL runtime·setstacklimits(SB)
RET
TEXT runtime·remove_exception_handler(SB),7,$0
RET

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@ -121,6 +121,13 @@ runtime·minit(void)
runtime·setprof(m->profilehz > 0);
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·signalstack(nil, 0);
}
// Mach IPC, to get at semaphores
// Definitions are in /usr/include/mach on a Mac.

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@ -130,6 +130,13 @@ runtime·minit(void)
runtime·sigprocmask(&sigset_none, nil);
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·signalstack(nil, 0);
}
void
runtime·sigpanic(void)
{

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@ -181,6 +181,13 @@ runtime·minit(void)
runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof(Sigset));
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·signalstack(nil, 0);
}
void
runtime·sigpanic(void)
{

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@ -199,6 +199,13 @@ runtime·minit(void)
runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·signalstack(nil, 0);
}
void
runtime·sigpanic(void)
{

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@ -176,6 +176,13 @@ runtime·minit(void)
runtime·sigprocmask(SIG_SETMASK, sigset_none);
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·signalstack(nil, 0);
}
void
runtime·sigpanic(void)
{

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@ -23,6 +23,13 @@ runtime·minit(void)
runtime·setfpmasks();
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
}
static int32
getproccount(void)
{
@ -82,6 +89,7 @@ runtime·initsig(void)
{
}
#pragma textflag 7
void
runtime·osyield(void)
{

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@ -135,6 +135,7 @@ runtime·write(int32 fd, void *buf, int32 n)
return written;
}
#pragma textflag 7
void
runtime·osyield(void)
{
@ -211,6 +212,13 @@ runtime·minit(void)
runtime·install_exception_handler();
}
// Called from dropm to undo the effect of an minit.
void
runtime·unminit(void)
{
runtime·remove_exception_handler();
}
int64
runtime·nanotime(void)
{