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runtime: find g in Windows profiler using SP

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The architecture-specific interpretation of m->tls[0]
is unnecessary and fragile. Delete it.

This CL is part of a stack adding windows/arm64
support (#36439), intended to land in the Go 1.17 cycle.
This CL is, however, not windows/arm64-specific.
It is cleanup meant to make the port (and future ports) easier.

Change-Id: I927345e52fa2f1741d4914478a29d1fb8acb0dc3
Reviewed-on: https://go-review.googlesource.com/c/go/+/288806
Trust: Russ Cox <rsc@golang.org>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Russ Cox 2021-01-27 11:06:04 -05:00
parent a54f7fc0fd
commit ece954d8b8
2 changed files with 11 additions and 45 deletions
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22
src/runtime/os_windows.go
View File

@ -1132,21 +1132,21 @@ func profilem(mp *m, thread uintptr) {
c.contextflags = _CONTEXT_CONTROL
stdcall2(_GetThreadContext, thread, uintptr(unsafe.Pointer(c)))
gp := gFromTLS(mp)
gp := gFromSP(mp, c.sp())
sigprof(c.ip(), c.sp(), c.lr(), gp, mp)
}
func gFromTLS(mp *m) *g {
switch GOARCH {
case "arm":
tls := &mp.tls[0]
return **((***g)(unsafe.Pointer(tls)))
case "386", "amd64":
tls := &mp.tls[0]
return *((**g)(unsafe.Pointer(tls)))
func gFromSP(mp *m, sp uintptr) *g {
if gp := mp.g0; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
return gp
}
if gp := mp.gsignal; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
return gp
}
if gp := mp.curg; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
return gp
}
throw("unsupported architecture")
return nil
}
@ -1295,7 +1295,7 @@ func preemptM(mp *m) {
unlock(&suspendLock)
// Does it want a preemption and is it safe to preempt?
gp := gFromTLS(mp)
gp := gFromSP(mp, c.sp())
if wantAsyncPreempt(gp) {
if ok, newpc := isAsyncSafePoint(gp, c.ip(), c.sp(), c.lr()); ok {
// Inject call to asyncPreempt

34
src/runtime/sys_windows_arm.s
View File

@ -350,9 +350,6 @@ TEXT runtime·tstart_stdcall(SB),NOSPLIT|NOFRAME,$0
MOVW R0, g_m(g)
BL runtime·save_g(SB)
// do per-thread TLS initialization
BL init_thread_tls<>(SB)
// Layout new m scheduler stack on os stack.
MOVW R13, R0
MOVW R0, g_stack+stack_hi(g)
@ -581,39 +578,8 @@ TEXT runtime·_initcgo(SB),NOSPLIT|NOFRAME,$0
MOVW $runtime·tls_g(SB), R1
MOVW R0, (R1)
BL init_thread_tls<>(SB)
MOVW R4, R13
MOVM.IA.W (R13), [R4, R15] // pop {r4, pc}
// void init_thread_tls()
//
// Does per-thread TLS initialization. Saves a pointer to the TLS slot
// holding G, in the current m.
//
// g->m->tls[0] = &_TEB->TlsSlots[tls_g]
//
// The purpose of this is to enable the profiling handler to get the
// current g associated with the thread. We cannot use m->curg because curg
// only holds the current user g. If the thread is executing system code or
// external code, m->curg will be NULL. The thread's TLS slot always holds
// the current g, so save a reference to this location so the profiling
// handler can get the real g from the thread's m.
//
// Clobbers R0-R3
TEXT init_thread_tls<>(SB),NOSPLIT|NOFRAME,$0
// compute &_TEB->TlsSlots[tls_g]
MRC 15, 0, R0, C13, C0, 2
ADD $0xe10, R0
MOVW $runtime·tls_g(SB), R1
MOVW (R1), R1
MOVW R1<<2, R1
ADD R1, R0
// save in g->m->tls[0]
MOVW g_m(g), R1
MOVW R0, m_tls(R1)
RET
// Holds the TLS Slot, which was allocated by TlsAlloc()
GLOBL runtime·tls_g+0(SB), NOPTR, $4