func TestUnsignedInt(t *testing.T) { testUnsignedInt(t) }
func TestZeroArgCallback(t *testing.T) { testZeroArgCallback(t) }
-func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }
-func BenchmarkGoString(b *testing.B) { benchGoString(b) }
-func BenchmarkCGoCallback(b *testing.B) { benchCallback(b) }
-func BenchmarkCGoInCThread(b *testing.B) { benchCGoInCthread(b) }
+func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }
+func BenchmarkGoString(b *testing.B) { benchGoString(b) }
+func BenchmarkCGoCallback(b *testing.B) { benchCallback(b) }
for(i=0; i<nthread; i++)
pthread_join(thread_id[i], 0);
}
-
-static void*
-goDummyCallbackThread(void* p)
-{
- int i, max;
-
- max = *(int*)p;
- for(i=0; i<max; i++)
- goDummy();
- return NULL;
-}
-
-int
-callGoInCThread(int max)
-{
- pthread_t thread;
-
- if (pthread_create(&thread, NULL, goDummyCallbackThread, (void*)(&max)) != 0)
- return -1;
- if (pthread_join(thread, NULL) != 0)
- return -1;
-
- return max;
-}
CloseHandle((HANDLE)thread_id[i]);
}
}
-
-__stdcall
-static unsigned int
-goDummyCallbackThread(void* p)
-{
- int i, max;
-
- max = *(int*)p;
- for(i=0; i<max; i++)
- goDummy();
- return 0;
-}
-
-int
-callGoInCThread(int max)
-{
- uintptr_t thread_id;
- thread_id = _beginthreadex(0, 0, goDummyCallbackThread, &max, 0, 0);
- WaitForSingleObject((HANDLE)thread_id, INFINITE);
- CloseHandle((HANDLE)thread_id);
- return max;
-}
/*
// threads
extern void doAdd(int, int);
-extern int callGoInCThread(int);
// issue 1328
void IntoC(void);
*p = 2
}
-//export goDummy
-func goDummy() {
-}
-
func testCthread(t *testing.T) {
if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && runtime.GOARCH == "arm64" {
t.Skip("the iOS exec wrapper is unable to properly handle the panic from Add")
}
}
-// Benchmark measuring overhead from C to Go in a C thread.
-// Create a new C thread and invoke Go function repeatedly in the new C thread.
-func benchCGoInCthread(b *testing.B) {
- n := C.callGoInCThread(C.int(b.N))
- if int(n) != b.N {
- b.Fatal("unmatch loop times")
- }
-}
-
// issue 1328
//export BackIntoGo
t.Error(err)
}
}
-
-// Issue 59294. Test calling Go function from C after using some
-// stack space.
-func TestDeepStack(t *testing.T) {
- t.Parallel()
-
- if !testWork {
- defer func() {
- os.Remove("testp9" + exeSuffix)
- os.Remove("libgo9.a")
- os.Remove("libgo9.h")
- }()
- }
-
- cmd := exec.Command("go", "build", "-buildmode=c-archive", "-o", "libgo9.a", "./libgo9")
- out, err := cmd.CombinedOutput()
- t.Logf("%v\n%s", cmd.Args, out)
- if err != nil {
- t.Fatal(err)
- }
- checkLineComments(t, "libgo9.h")
- checkArchive(t, "libgo9.a")
-
- // build with -O0 so the C compiler won't optimize out the large stack frame
- ccArgs := append(cc, "-O0", "-o", "testp9"+exeSuffix, "main9.c", "libgo9.a")
- out, err = exec.Command(ccArgs[0], ccArgs[1:]...).CombinedOutput()
- t.Logf("%v\n%s", ccArgs, out)
- if err != nil {
- t.Fatal(err)
- }
-
- argv := cmdToRun("./testp9")
- cmd = exec.Command(argv[0], argv[1:]...)
- sb := new(strings.Builder)
- cmd.Stdout = sb
- cmd.Stderr = sb
- if err := cmd.Start(); err != nil {
- t.Fatal(err)
- }
-
- timer := time.AfterFunc(time.Minute,
- func() {
- t.Error("test program timed out")
- cmd.Process.Kill()
- },
- )
- defer timer.Stop()
-
- err = cmd.Wait()
- t.Logf("%v\n%s", cmd.Args, sb)
- if err != nil {
- t.Error(err)
- }
-}
+++ /dev/null
-// Copyright 2023 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 main
-
-import "runtime"
-
-import "C"
-
-func main() {}
-
-//export GoF
-func GoF() { runtime.GC() }
+++ /dev/null
-// Copyright 2023 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 "libgo9.h"
-
-void use(int *x) { (*x)++; }
-
-void callGoFWithDeepStack() {
- int x[10000];
-
- use(&x[0]);
- use(&x[9999]);
-
- GoF();
-
- use(&x[0]);
- use(&x[9999]);
-}
-
-int main() {
- GoF(); // call GoF without using much stack
- callGoFWithDeepStack(); // call GoF with a deep stack
-}
+++ /dev/null
-// Copyright 2023 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 main
-
-// This program failed when run under the C/C++ ThreadSanitizer.
-//
-// cgocallback on a new thread calls into runtime.needm -> _cgo_getstackbound
-// to update gp.stack.lo with the stack bounds. If the G itself is passed to
-// _cgo_getstackbound, then writes to the same G can be seen on multiple
-// threads (when the G is reused after thread exit). This would trigger TSAN.
-
-/*
-#include <pthread.h>
-
-void go_callback();
-
-static void *thr(void *arg) {
- go_callback();
- return 0;
-}
-
-static void foo() {
- pthread_t th;
- pthread_attr_t attr;
- pthread_attr_init(&attr);
- pthread_attr_setstacksize(&attr, 256 << 10);
- pthread_create(&th, &attr, thr, 0);
- pthread_join(th, 0);
-}
-*/
-import "C"
-
-import (
- "time"
-)
-
-//export go_callback
-func go_callback() {
-}
-
-func main() {
- for i := 0; i < 2; i++ {
- go func() {
- for {
- C.foo()
- }
- }()
- }
-
- time.Sleep(1000*time.Millisecond)
-}
{src: "tsan11.go", needsRuntime: true},
{src: "tsan12.go", needsRuntime: true},
{src: "tsan13.go", needsRuntime: true},
- {src: "tsan14.go", needsRuntime: true},
}
for _, tc := range cases {
tc := tc
TEXT ·cgocallback(SB),NOSPLIT,$12-12 // Frame size must match commented places below
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.
- MOVL fn+0(FP), AX
- CMPL AX, $0
- JNE loadg
- // Restore the g from frame.
- get_tls(CX)
- MOVL frame+4(FP), BX
- MOVL BX, g(CX)
- JMP dropm
-
-loadg:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
MOVL BP, savedm-4(SP) // saved copy of oldm
JMP havem
needm:
- MOVL $runtime·needAndBindM(SB), AX
+ MOVL $runtime·needm(SB), AX
CALL AX
- MOVL $0, savedm-4(SP)
+ MOVL $0, savedm-4(SP) // dropm on return
get_tls(CX)
MOVL g(CX), BP
MOVL g_m(BP), BP
MOVL 0(SP), AX
MOVL AX, (g_sched+gobuf_sp)(SI)
- // 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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVL savedm-4(SP), DX
CMPL DX, $0
- JNE droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVL _cgo_pthread_key_created(SB), DX
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- CMPL DX, $0
- JEQ dropm
- CMPL (DX), $0
- JNE droppedm
-
-dropm:
+ JNE 3(PC)
MOVL $runtime·dropm(SB), AX
CALL AX
-droppedm:
// Done!
RET
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOVQ fn+0(FP), AX
- CMPQ AX, $0
- JNE loadg
- // Restore the g from frame.
- get_tls(CX)
- MOVQ frame+8(FP), BX
- MOVQ BX, g(CX)
- JMP dropm
-
-loadg:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g is nil, Go did not create the current thread.
// Call needm to obtain one m 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
// a bad value in there, in case needm tries to use it.
XORPS X15, X15
XORQ R14, R14
- MOVQ $runtime·need
AndBindM<ABIInternal>(SB), AX
+ MOVQ $runtime·need
m<ABIInternal>(SB), AX
CALL AX
- MOVQ $0, savedm-8(SP)
+ MOVQ $0, savedm-8(SP) // dropm on return
get_tls(CX)
MOVQ g(CX), BX
MOVQ g_m(BX), BX
MOVQ 0(SP), AX
MOVQ AX, (g_sched+gobuf_sp)(SI)
- // 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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVQ savedm-8(SP), BX
CMPQ BX, $0
JNE done
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVQ _cgo_pthread_key_created(SB), AX
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- CMPQ AX, $0
- JEQ dropm
- CMPQ (AX), $0
- JNE done
-
-dropm:
MOVQ $runtime·dropm(SB), AX
CALL AX
#ifdef GOOS_windows
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)
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.
+ // If g 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
needm:
MOVW g, savedm-4(SP) // g is zero, so is m.
- MOVW $runtime·needAndBindM(SB), R0
+ MOVW $runtime·needm(SB), R0
BL (R0)
// Set m->g0->sched.sp = SP, so that if a panic happens
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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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-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:
+ B.NE 3(PC)
MOVW $runtime·dropm(SB), R0
BL (R0)
-done:
// Done!
RET
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOVD fn+0(FP), R1
- CBNZ R1, loadg
- // Restore the g from frame.
- MOVD frame+8(FP), g
- B dropm
-
-loadg:
// Load g from thread-local storage.
BL runtime·load_g(SB)
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOVD g, savedm-8(SP) // g is zero, so is m.
- MOVD $runtime·needAndBindM(SB), R0
+ MOVD $runtime·needm(SB), R0
BL (R0)
// Set m->g0->sched.sp = SP, so that if a panic happens
MOVD savedsp-16(SP), R4
MOVD 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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVD savedm-8(SP), R6
CBNZ R6, droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVD _cgo_pthread_key_created(SB), R6
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- CBZ R6, dropm
- MOVD (R6), R6
- CBNZ R6, droppedm
-
-dropm:
MOVD $runtime·dropm(SB), R0
BL (R0)
droppedm:
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOVV fn+0(FP), R5
- BNE R5, loadg
- // Restore the g from frame.
- MOVV frame+8(FP), g
- JMP dropm
-
-loadg:
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R19
BEQ R19, nocgo
JAL runtime·load_g(SB)
nocgo:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOVV g, savedm-8(SP) // g is zero, so is m.
- MOVV $runtime·needAndBindM(SB), R4
+ MOVV $runtime·needm(SB), R4
JAL (R4)
// Set m->sched.sp = SP, so that if a panic happens
MOVV savedsp-24(SP), R13 // must match frame size
MOVV R13, (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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVV savedm-8(SP), R12
BNE R12, droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVV _cgo_pthread_key_created(SB), R12
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- BEQ R12, dropm
- MOVV (R12), R12
- BNE R12, droppedm
-
-dropm:
MOVV $runtime·dropm(SB), R4
JAL (R4)
droppedm:
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOVV fn+0(FP), R5
- BNE R5, loadg
- // Restore the g from frame.
- MOVV frame+8(FP), g
- JMP dropm
-
-loadg:
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R1
BEQ R1, nocgo
JAL runtime·load_g(SB)
nocgo:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOVV g, savedm-8(SP) // g is zero, so is m.
- MOVV $runtime·needAndBindM(SB), R4
+ MOVV $runtime·needm(SB), R4
JAL (R4)
// Set m->sched.sp = SP, so that if a panic happens
MOVV savedsp-24(SP), R2 // must match frame size
MOVV R2, (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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVV savedm-8(SP), R3
BNE R3, droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVV _cgo_pthread_key_created(SB), R3
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- BEQ R3, dropm
- MOVV (R3), R3
- BNE R3, droppedm
-
-dropm:
MOVV $runtime·dropm(SB), R4
JAL (R4)
droppedm:
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), R5
- BNE R5, loadg
- // Restore the g from frame.
- MOVW frame+4(FP), g
- JMP dropm
-
-loadg:
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R1
BEQ R1, nocgo
JAL runtime·load_g(SB)
nocgo:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOVW g, savedm-4(SP) // g is zero, so is m.
- MOVW $runtime·needAndBindM(SB), R4
+ MOVW $runtime·needm(SB), R4
JAL (R4)
// Set m->sched.sp = SP, so that if a panic happens
MOVW savedsp-12(SP), R2 // must match frame size
MOVW R2, (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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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-4(SP), R3
BNE R3, droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVW _cgo_pthread_key_created(SB), R3
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- BEQ R3, dropm
- MOVW (R3), R3
- BNE R3, droppedm
-
-dropm:
MOVW $runtime·dropm(SB), R4
JAL (R4)
droppedm:
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOVD fn+0(FP), R5
- CMP R5, $0
- BNE loadg
- // Restore the g from frame.
- MOVD frame+8(FP), g
- BR dropm
-
-loadg:
// Load m and g from thread-local storage.
MOVBZ runtime·iscgo(SB), R3
CMP R3, $0
BL runtime·load_g(SB)
nocgo:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOVD g, savedm-8(SP) // g is zero, so is m.
- MOVD $runtime·needAndBindM(SB), R12
+ MOVD $runtime·needm(SB), R12
MOVD R12, CTR
BL (CTR)
MOVD savedsp-24(SP), R4 // must match frame size
MOVD 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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVD savedm-8(SP), R6
CMP R6, $0
BNE droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVD _cgo_pthread_key_created(SB), R6
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- CMP R6, $0
- BEQ dropm
- MOVD (R6), R6
- CMP R6, $0
- BNE droppedm
-
-dropm:
MOVD $runtime·dropm(SB), R12
MOVD R12, CTR
BL (CTR)
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOV fn+0(FP), X7
- BNE ZERO, X7, loadg
- // Restore the g from frame.
- MOV frame+8(FP), g
- JMP dropm
-
-loadg:
// Load m and g from thread-local storage.
MOVBU runtime·iscgo(SB), X5
BEQ ZERO, X5, nocgo
CALL runtime·load_g(SB)
nocgo:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOV g, savedm-8(SP) // g is zero, so is m.
- MOV $runtime·needAndBindM(SB), X6
+ MOV $runtime·needm(SB), X6
JALR RA, X6
// Set m->sched.sp = SP, so that if a panic happens
MOV savedsp-24(SP), X6 // must match frame size
MOV X6, (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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOV savedm-8(SP), X5
BNE ZERO, X5, droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOV _cgo_pthread_key_created(SB), X5
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- BEQ ZERO, X5, dropm
- MOV (X5), X5
- BNE ZERO, X5, droppedm
-
-dropm:
MOV $runtime·dropm(SB), X6
JALR RA, X6
droppedm:
TEXT ·cgocallback(SB),NOSPLIT,$24-24
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.
- MOVD fn+0(FP), R1
- CMPBNE R1, $0, loadg
- // Restore the g from frame.
- MOVD frame+8(FP), g
- BR dropm
-
-loadg:
// Load m and g from thread-local storage.
MOVB runtime·iscgo(SB), R3
CMPBEQ R3, $0, nocgo
BL runtime·load_g(SB)
nocgo:
- // If g is nil, Go did not create the current thread,
- // or if this thread never called into Go on pthread platforms.
+ // If g 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
needm:
MOVD g, savedm-8(SP) // g is zero, so is m.
- MOVD $runtime·needAndBindM(SB), R3
+ MOVD $runtime·needm(SB), R3
BL (R3)
// Set m->sched.sp = SP, so that if a panic happens
MOVD savedsp-24(SP), R4 // must match frame size
MOVD 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's wasn't the first call from a C thread on pthread platforms,
- // since the we skip dropm to resue the m in the first call.
+ // 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.
MOVD savedm-8(SP), R6
CMPBNE R6, $0, droppedm
-
- // Skip dropm to reuse it in the next call, when a pthread key has been created.
- MOVD _cgo_pthread_key_created(SB), R6
- // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
- CMPBEQ R6, $0, dropm
- MOVD (R6), R6
- CMPBNE R6, $0, droppedm
-
-dropm:
MOVD $runtime·dropm(SB), R3
BL (R3)
droppedm:
//go:linkname _cgo_callers _cgo_callers
//go:linkname _cgo_set_context_function _cgo_set_context_function
//go:linkname _cgo_yield _cgo_yield
-//go:linkname _cgo_pthread_key_created _cgo_pthread_key_created
-//go:linkname _cgo_bindm _cgo_bindm
-//go:linkname _cgo_getstackbound _cgo_getstackbound
var (
_cgo_init unsafe.Pointer
_cgo_callers unsafe.Pointer
_cgo_set_context_function unsafe.Pointer
_cgo_yield unsafe.Pointer
- _cgo_pthread_key_created unsafe.Pointer
- _cgo_bindm unsafe.Pointer
- _cgo_getstackbound unsafe.Pointer
)
// iscgo is set to true by the runtime/cgo package
var iscgo bool
-// set_crosscall2 is set by the runtime/cgo package
-var set_crosscall2 func()
-
// cgoHasExtraM is set on startup when an extra M is created for cgo.
// The extra M must be created before any C/C++ code calls cgocallback.
var cgoHasExtraM bool
#include "textflag.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVL _crosscall2_ptr(SB), AX
- MOVL $crosscall2(SB), BX
- MOVL BX, (AX)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
#include "abi_amd64.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVQ _crosscall2_ptr(SB), AX
- MOVQ $crosscall2(SB), BX
- MOVQ BX, (AX)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVW _crosscall2_ptr(SB), R1
- MOVW $crosscall2(SB), R2
- MOVW R2, (R1)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
#include "abi_arm64.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVD _crosscall2_ptr(SB), R1
- MOVD $crosscall2(SB), R2
- MOVD R2, (R1)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
#include "abi_loong64.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVV _crosscall2_ptr(SB), R5
- MOVV $crosscall2(SB), R6
- MOVV R6, (R5)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVV _crosscall2_ptr(SB), R5
- MOVV $crosscall2(SB), R6
- MOVV R6, (R5)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVW _crosscall2_ptr(SB), R5
- MOVW $crosscall2(SB), R6
- MOVW R6, (R5)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "asm_ppc64x.h"
#include "abi_ppc64x.h"
-#ifdef GO_PPC64X_HAS_FUNCDESC
-// crosscall2 is marked with go:cgo_export_static. On AIX, this creates and exports
-// the symbol name and descriptor as the AIX linker expects, but does not work if
-// referenced from within Go. Create and use an aliased descriptor of crosscall2
-// to workaround this.
-DEFINE_PPC64X_FUNCDESC(_crosscall2<>, crosscall2)
-#define CROSSCALL2_FPTR $_crosscall2<>(SB)
-#else
-#define CROSSCALL2_FPTR $crosscall2(SB)
-#endif
-
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVD _crosscall2_ptr(SB), R5
- MOVD CROSSCALL2_FPTR, R6
- MOVD R6, (R5)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#ifdef GO_PPC64X_HAS_FUNCDESC
// Load the real entry address from the first slot of the function descriptor.
- // The first argument fn might be null, that means dropm in pthread key destructor.
- CMP R3, $0
- BEQ nil_fn
MOVD 8(R3), R2
MOVD (R3), R3
-nil_fn:
#endif
MOVD R3, FIXED_FRAME+0(R1) // fn unsafe.Pointer
MOVD R4, FIXED_FRAME+8(R1) // a unsafe.Pointer
#include "textflag.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOV _crosscall2_ptr(SB), X7
- MOV $crosscall2(SB), X8
- MOV X8, (X7)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- MOVD _crosscall2_ptr(SB), R1
- MOVD $crosscall2(SB), R2
- MOVD R2, (R1)
- RET
-
// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
#include "textflag.h"
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
- UNDEF
-
TEXT crosscall2(SB), NOSPLIT, $0
UNDEF
var x_cgo_sys_thread_create byte
var _cgo_sys_thread_create = &x_cgo_sys_thread_create
-// Indicates whether a dummy thread key has been created or not.
-//
-// When calling go exported function from C, we register a destructor
-// callback, for a dummy thread key, by using pthread_key_create.
-
-//go:cgo_import_static x_cgo_pthread_key_created
-//go:linkname x_cgo_pthread_key_created x_cgo_pthread_key_created
-//go:linkname _cgo_pthread_key_created _cgo_pthread_key_created
-var x_cgo_pthread_key_created byte
-var _cgo_pthread_key_created = &x_cgo_pthread_key_created
-
-// Export crosscall2 to a c function pointer variable.
-// Used to dropm in pthread key destructor, while C thread is exiting.
-
-//go:cgo_import_static x_crosscall2_ptr
-//go:linkname x_crosscall2_ptr x_crosscall2_ptr
-//go:linkname _crosscall2_ptr _crosscall2_ptr
-var x_crosscall2_ptr byte
-var _crosscall2_ptr = &x_crosscall2_ptr
-
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's for the runtime package to call at init time.
-func set_crosscall2()
-
-//go:linkname _set_crosscall2 runtime.set_crosscall2
-var _set_crosscall2 = set_crosscall2
-
-// Store the g into the thread-specific value.
-// So that pthread_key_destructor will dropm when the thread is exiting.
-
-//go:cgo_import_static x_cgo_bindm
-//go:linkname x_cgo_bindm x_cgo_bindm
-//go:linkname _cgo_bindm _cgo_bindm
-var x_cgo_bindm byte
-var _cgo_bindm = &x_cgo_bindm
-
// Notifies that the runtime has been initialized.
//
// We currently block at every CGO entry point (via _cgo_wait_runtime_init_done)
//go:cgo_export_static _cgo_topofstack
//go:cgo_export_dynamic _cgo_topofstack
-
-// x_cgo_getstackbound gets the thread's C stack size and
-// set the G's stack bound based on the stack size.
-
-//go:cgo_import_static x_cgo_getstackbound
-//go:linkname x_cgo_getstackbound x_cgo_getstackbound
-//go:linkname _cgo_getstackbound _cgo_getstackbound
-var x_cgo_getstackbound byte
-var _cgo_getstackbound = &x_cgo_getstackbound
static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
static int runtime_init_done;
-// pthread_g is a pthread specific key, for storing the g that binded to the C thread.
-// The registered pthread_key_destructor will dropm, when the pthread-specified value g is not NULL,
-// while a C thread is exiting.
-static pthread_key_t pthread_g;
-static void pthread_key_destructor(void* g);
-uintptr_t x_cgo_pthread_key_created;
-void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
-
// The context function, used when tracing back C calls into Go.
static void (*cgo_context_function)(struct context_arg*);
pthread_cond_wait(&runtime_init_cond, &runtime_init_mu);
}
- // The key and x_cgo_pthread_key_created are for the whole program,
- // whereas the specific and destructor is per thread.
- if (x_cgo_pthread_key_created == 0 && pthread_key_create(&pthread_g, pthread_key_destructor) == 0) {
- x_cgo_pthread_key_created = 1;
- }
-
// TODO(iant): For the case of a new C thread calling into Go, such
// as when using -buildmode=c-archive, we know that Go runtime
// initialization is complete but we do not know that all Go init
return 0;
}
-// Store the g into a thread-specific value associated with the pthread key pthread_g.
-// And pthread_key_destructor will dropm when the thread is exiting.
-void x_cgo_bindm(void* g) {
- // We assume this will always succeed, otherwise, there might be extra M leaking,
- // when a C thread exits after a cgo call.
- // We only invoke this function once per thread in runtime.needAndBindM,
- // and the next calls just reuse the bound m.
- pthread_setspecific(pthread_g, g);
-}
-
void
x_cgo_notify_runtime_init_done(void* dummy __attribute__ ((unused))) {
pthread_mutex_lock(&runtime_init_mu);
}
return EAGAIN;
}
-
-static void
-pthread_key_destructor(void* g) {
- if (x_crosscall2_ptr != NULL) {
- // fn == NULL means dropm.
- // We restore g by using the stored g, before dropm in runtime.cgocallback,
- // since the g stored in the TLS by Go might be cleared in some platforms,
- // before this destructor invoked.
- x_crosscall2_ptr(NULL, g, 0, 0);
- }
-}
static HANDLE runtime_init_wait;
static int runtime_init_done;
-uintptr_t x_cgo_pthread_key_created;
-void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
-
// Pre-initialize the runtime synchronization objects
void
_cgo_preinit_init() {
return 0;
}
-// Should not be used since x_cgo_pthread_key_created will always be zero.
-void x_cgo_bindm(void* dummy) {
- fprintf(stderr, "unexpected cgo_bindm on Windows\n");
- abort();
-}
-
void
x_cgo_notify_runtime_init_done(void* dummy) {
_cgo_maybe_run_preinit();
+++ /dev/null
-// Copyright 2023 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 <pthread.h>
-#include "libcgo.h"
-
-void
-x_cgo_getstackbound(uintptr *low)
-{
- void* addr;
- size_t size;
- pthread_t p;
-
- p = pthread_self();
- addr = pthread_get_stackaddr_np(p); // high address (!)
- size = pthread_get_stacksize_np(p);
- *low = (uintptr)addr - size;
-}
+++ /dev/null
-// Copyright 2023 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.
-
-//go:build unix && !darwin
-
-#ifndef _GNU_SOURCE // pthread_getattr_np
-#define _GNU_SOURCE
-#endif
-
-#include <pthread.h>
-#include "libcgo.h"
-
-void
-x_cgo_getstackbound(uintptr *low)
-{
- pthread_attr_t attr;
- void *addr;
- size_t size;
-
-#if defined(__GLIBC__) || (defined(__sun) && !defined(__illumos__))
- // pthread_getattr_np is a GNU extension supported in glibc.
- // Solaris is not glibc but does support pthread_getattr_np
- // (and the fallback doesn't work...). Illumos does not.
- pthread_getattr_np(pthread_self(), &attr); // GNU extension
- pthread_attr_getstack(&attr, &addr, &size); // low address
-#elif defined(__illumos__)
- pthread_attr_init(&attr);
- pthread_attr_get_np(pthread_self(), &attr);
- pthread_attr_getstack(&attr, &addr, &size); // low address
-#else
- pthread_attr_init(&attr);
- pthread_attr_getstacksize(&attr, &size);
- addr = __builtin_frame_address(0) + 4096 - size;
-#endif
- pthread_attr_destroy(&attr);
-
- *low = (uintptr)addr;
-}
+++ /dev/null
-// Copyright 2023 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 "libcgo.h"
-
-void x_cgo_getstackbound(uintptr *low) {} // no-op for now
*/
extern void (*_cgo_sys_thread_create)(void* (*func)(void*), void* arg);
-/*
- * Indicates whether a dummy pthread per-thread variable is allocated.
- */
-extern uintptr_t *_cgo_pthread_key_created;
-
/*
* Creates the new operating system thread (OS, arch dependent).
*/
savedpc := gp.syscallpc
exitsyscall() // coming out of cgo call
gp.m.incgo = false
- if gp.m.isextra {
- gp.m.isExtraInC = false
- }
osPreemptExtExit(gp.m)
// This is enforced by checking incgo in the schedule function.
gp.m.incgo = true
- if gp.m.isextra {
- gp.m.isExtraInC = true
- }
if gp.m != checkm {
throw("m changed unexpectedly in cgocallbackg")
t.Errorf("expected %q, but got:\n%s", want, got)
}
}
-
-func TestEnsureBindM(t *testing.T) {
- t.Parallel()
- switch runtime.GOOS {
- case "windows", "plan9":
- t.Skipf("skipping bindm test on %s", runtime.GOOS)
- }
- got := runTestProg(t, "testprogcgo", "EnsureBindM")
- want := "OK\n"
- if got != want {
- t.Errorf("expected %q, got %v", want, got)
- }
-}
main_init_done = make(chan bool)
if iscgo {
- if _cgo_pthread_key_created == nil {
- throw("_cgo_pthread_key_created missing")
- }
-
if _cgo_thread_start == nil {
throw("_cgo_thread_start missing")
}
if _cgo_notify_runtime_init_done == nil {
throw("_cgo_notify_runtime_init_done missing")
}
-
- // Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
- if set_crosscall2 == nil {
- throw("set_crosscall2 missing")
- }
- set_crosscall2()
-
// Start the template thread in case we enter Go from
// a C-created thread and need to create a new thread.
startTemplateThread()
// pressed into service as the scheduling stack and current
// goroutine for the duration of the cgo callback.
//
-// It calls dropm to put the m back on the list,
-// 1. when the callback is done with the m in non-pthread platforms,
-// 2. or when the C thread exiting on pthread platforms.
-//
-// The signal argument indicates whether we're called from a signal
-// handler.
+// When the callback is done with the m, it calls dropm to
+// put the m back on the list.
//
//go:nosplit
-func needm(signal bool) {
+func needm() {
if (iscgo || GOOS == "windows") && !cgoHasExtraM {
// Can happen if C/C++ code calls Go from a global ctor.
// Can also happen on Windows if a global ctor uses a
osSetupTLS(mp)
// Install g (= m->g0) and set the stack bounds
- // to match the current stack. If we don't actually know
+ // 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.
- // If we can get a more accurate stack bound from pthread,
- // use that.
+ // scheduling stack is, but we assume there's at least 32 kB,
+ // which is more than enough for us.
setg(mp.g0)
gp := getg()
gp.stack.hi = getcallersp() + 1024
gp.stack.lo = getcallersp() - 32*1024
- if !signal && _cgo_getstackbound != nil {
- // Don't adjust if called from the signal handler.
- // We are on the signal stack, not the pthread stack.
- // (We could get the stack bounds from sigaltstack, but
- // we're getting out of the signal handler very soon
- // anyway. Not worth it.)
- var low uintptr
- asmcgocall(_cgo_getstackbound, unsafe.Pointer(&low))
- // getstackbound is an unsupported no-op on Windows.
- if low != 0 {
- gp.stack.lo = low
- // TODO: Also get gp.stack.hi from getstackbound.
- }
- }
gp.stackguard0 = gp.stack.lo + stackGuard
- // Should mark we are already in Go now.
- // Otherwise, we may call needm again when we get a signal, before cgocallbackg1,
- // which means the extram list may be empty, that will cause a deadlock.
- mp.isExtraInC = false
-
// Initialize this thread to use the m.
asminit()
minit()
sched.ngsys.Add(-1)
}
-// Acquire an extra m and bind it to the C thread when a pthread key has been created.
-//
-//go:nosplit
-func needAndBindM() {
- needm(false)
-
- if _cgo_pthread_key_created != nil && *(*uintptr)(_cgo_pthread_key_created) != 0 {
- cgoBindM()
- }
-}
-
// newextram allocates m's and puts them on the extra list.
// It is called with a working local m, so that it can do things
// like call schedlock and allocate.
gp.m = mp
mp.curg = gp
mp.isextra = true
- // mark we are in C by default.
- mp.isExtraInC = true
mp.lockedInt++
mp.lockedg.set(gp)
gp.lockedm.set(mp)
unlockextra(mp)
}
-// dropm puts the current m back onto the extra list.
-//
-// 1. On systems without pthreads, like Windows
// 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
// call. These should typically not be scheduling operations, just a few
// atomics, so the cost should be small.
//
-// 2. On systems with pthreads
-// dropm is called while a non-Go thread is exiting.
-// We allocate a pthread per-thread variable using pthread_key_create,
-// to register a thread-exit-time destructor.
-// And store the g into a thread-specific value associated with the pthread key,
-// when first return back to C.
-// So that the destructor would invoke dropm while the non-Go thread is exiting.
-// This is much faster since it avoids expensive signal-related syscalls.
-//
-// NOTE: this always runs without a P, so, nowritebarrierrec required.
-//
-//go:nowritebarrierrec
+// 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.
func dropm() {
// Clear m and g, and return m to the extra list.
// After the call to setg we can only call nosplit functions
msigrestore(sigmask)
}
-// bindm store the g0 of the current m into a thread-specific value.
-//
-// We allocate a pthread per-thread variable using pthread_key_create,
-// to register a thread-exit-time destructor.
-// We are here setting the thread-specific value of the pthread key, to enable the destructor.
-// So that the pthread_key_destructor would dropm while the C thread is exiting.
-//
-// And the saved g will be used in pthread_key_destructor,
-// since the g stored in the TLS by Go might be cleared in some platforms,
-// before the destructor invoked, so, we restore g by the stored g, before dropm.
-//
-// We store g0 instead of m, to make the assembly code simpler,
-// since we need to restore g0 in runtime.cgocallback.
-//
-// On systems without pthreads, like Windows, bindm shouldn't be used.
-//
-// NOTE: this always runs without a P, so, nowritebarrierrec required.
-//
-//go:nosplit
-//go:nowritebarrierrec
-func cgoBindM() {
- if GOOS == "windows" || GOOS == "plan9" {
- fatal("bindm in unexpected GOOS")
- }
- g := getg()
- if g.m.g0 != g {
- fatal("the current g is not g0")
- }
- if _cgo_bindm != nil {
- asmcgocall(_cgo_bindm, unsafe.Pointer(g))
- }
-}
-
// A helper function for EnsureDropM.
func getm() uintptr {
return uintptr(unsafe.Pointer(getg().m))
printlock int8
incgo bool // m is executing a cgo call
isextra bool // m is an extra m
- isExtraInC bool // m is an extra m that is not executing Go code
freeWait atomic.Uint32 // Whether it is safe to free g0 and delete m (one of freeMRef, freeMStack, freeMWait)
fastrand uint64
needextram bool
c := &sigctxt{info, ctx}
gp := sigFetchG(c)
setg(gp)
- if gp == nil || (gp.m != nil && gp.m.isExtraInC) {
+ if gp == nil {
if sig == _SIGPROF {
// Some platforms (Linux) have per-thread timers, which we use in
// combination with the process-wide timer. Avoid double-counting.
return
}
c.fixsigcode(sig)
- // Set g to nil here and badsignal will use g0 by needm.
- // TODO: reuse the current m here by using the gsignal and adjustSignalStack,
- // since the current g maybe a normal goroutine and actually running on the signal stack,
- // it may hit stack split that is not expected here.
- if gp != nil {
- setg(nil)
- }
badsignal(uintptr(sig), c)
- // Restore g
- if gp != nil {
- setg(gp)
- }
return
}
// sp is not within gsignal stack, g0 stack, or sigaltstack. Bad.
setg(nil)
- needm(true)
+ needm()
if st.ss_flags&_SS_DISABLE != 0 {
noSignalStack(sig)
} else {
exit(2)
*(*uintptr)(unsafe.Pointer(uintptr(123))) = 2
}
- needm(true)
+ needm()
if !sigsend(uint32(sig)) {
// A foreign thread received the signal sig, and the
// Go code does not want to handle it.
// (1) we weren't in VDSO page,
// (2) we were in a goroutine (i.e., m.curg != nil), and
// (3) we weren't in CGO.
- // (4) we weren't in dropped extra m.
gp := sigFetchG(c)
- if gp != nil && gp.m != nil && gp.m.curg != nil && !gp.m.isExtraInC && !gp.m.incgo {
+ if gp != nil && gp.m != nil && gp.m.curg != nil && !gp.m.incgo {
return false
}
// cgocallback is not called from Go, only from crosscall2.
// This in turn calls cgocallbackg, which is where we'll find
// pointer-declared arguments.
-//
-// When fn is nil (frame is saved g), call dropm instead,
-// this is used when the C thread is exiting.
func cgocallback(fn, frame, ctxt uintptr)
func gogo(buf *gobuf)
+++ /dev/null
-// Copyright 2023 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.
-
-//go:build !plan9 && !windows
-
-#include <stdint.h>
-#include <pthread.h>
-#include <unistd.h>
-#include "_cgo_export.h"
-
-#define CTHREADS 2
-#define CHECKCALLS 100
-
-static void* checkBindMThread(void* thread) {
- int i;
- for (i = 0; i < CHECKCALLS; i++) {
- GoCheckBindM((uintptr_t)thread);
- usleep(1);
- }
- return NULL;
-}
-
-void CheckBindM() {
- int i;
- pthread_t s[CTHREADS];
-
- for (i = 0; i < CTHREADS; i++) {
- pthread_create(&s[i], NULL, checkBindMThread, &s[i]);
- }
- for (i = 0; i < CTHREADS; i++) {
- pthread_join(s[i], NULL);
- }
-}
+++ /dev/null
-// Copyright 2023 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.
-
-//go:build !plan9 && !windows
-
-// Test that callbacks from C to Go in the same C-thread always get the same m.
-// Make sure the extra M bind to the C-thread.
-
-package main
-
-/*
-extern void CheckBindM();
-*/
-import "C"
-
-import (
- "fmt"
- "os"
- "runtime"
- "sync"
- "sync/atomic"
-)
-
-var (
- mutex = sync.Mutex{}
- cThreadToM = map[uintptr]uintptr{}
- started = atomic.Uint32{}
-)
-
-// same as CTHREADS in C, make sure all the C threads are actually started.
-const cThreadNum = 2
-
-func init() {
- register("EnsureBindM", EnsureBindM)
-}
-
-//export GoCheckBindM
-func GoCheckBindM(thread uintptr) {
- // Wait all threads start
- if started.Load() != cThreadNum {
- // Only once for each thread, since it will wait all threads start.
- started.Add(1)
- for started.Load() < cThreadNum {
- runtime.Gosched()
- }
- }
- m := runtime_getm_for_test()
- mutex.Lock()
- defer mutex.Unlock()
- if savedM, ok := cThreadToM[thread]; ok && savedM != m {
- fmt.Printf("m == %x want %x\n", m, savedM)
- os.Exit(1)
- }
- cThreadToM[thread] = m
-}
-
-func EnsureBindM() {
- C.CheckBindM()
- fmt.Println("OK")
-}