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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 23 Nov 2021 20:04:24 +0100
Subject: [PATCH] [release-branch.go1.17] runtime: support non-cooperative
preemption on windows/arm
This adds support for injecting asynchronous preemption calls on
windows/arm. This code follows sigctxt.pushCall for POSIX OSes
on arm, except we subtract 1 from IP, just as in CL 273727.
Updates #10958.
Updates #24543.
Updates #49759.
Change-Id: Id0c2aed28662f50631b8c8cede3b4e6f088dafea
Reviewed-on: https://go-review.googlesource.com/c/go/+/366734
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Patrik Nyblom <pnyb@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---
src/runtime/os_windows.go | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index f0935264ac..faeb6ce552 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -1303,7 +1303,7 @@ func setThreadCPUProfiler(hz int32) {
atomic.Store((*uint32)(unsafe.Pointer(&getg().m.profilehz)), uint32(hz))
}
-const preemptMSupported = GOARCH == "386" || GOARCH == "amd64"
+const preemptMSupported = GOARCH != "arm64"
// suspendLock protects simultaneous SuspendThread operations from
// suspending each other.
@@ -1396,8 +1396,20 @@ func preemptM(mp *m) {
*(*uintptr)(unsafe.Pointer(sp)) = newpc
c.set_sp(sp)
c.set_ip(targetPC)
- }
+ case "arm":
+ // Push LR. The injected call is responsible
+ // for restoring LR. gentraceback is aware of
+ // this extra slot. See sigctxt.pushCall in
+ // signal_arm.go, which is similar except we
+ // subtract 1 from IP here.
+ sp := c.sp()
+ sp -= sys.PtrSize
+ c.set_sp(sp)
+ *(*uint32)(unsafe.Pointer(sp)) = uint32(c.lr())
+ c.set_lr(newpc - 1)
+ c.set_ip(targetPC)
+ }
stdcall2(_SetThreadContext, thread, uintptr(unsafe.Pointer(c)))
}
}
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