[dev.regabi] runtime: initialize special registers before sigpanic

In case that we are panicking in ABI0 context or external code,
special registers are not initialized. Initialized them in
injected code before calling sigpanic.

TODO: Windows, Plan 9.

Change-Id: I0919b80e7cc55463f3dd94f1f63cba305717270a
Reviewed-on: https://go-review.googlesource.com/c/go/+/289710
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

diff --git a/src/runtime/asm.s b/src/runtime/asm.s
index 27d8df9e063ecf8404e5da9ffa15b88c5f4fffbc..72c744925d89aec9d1cc33a6eacf55f826866fcf 100644 (file)
--- a/src/runtime/asm.s
+++ b/src/runtime/asm.s
@@ -11,3 +11,8 @@
 DATA runtime·no_pointers_stackmap+0x00(SB)/4, $2
 DATA runtime·no_pointers_stackmap+0x04(SB)/4, $0
 GLOBL runtime·no_pointers_stackmap(SB),RODATA, $8
+
+#ifndef GOARCH_amd64
+TEXT ·sigpanic0<ABIInternal>(SB),NOSPLIT,$0-0
+       JMP     ·sigpanic<ABIInternal>(SB)
+#endif

diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 9f15990b137cdda53ffbc6d8ff4bf13c74c4527d..83c08a52f742cf60a7336e62f639d91003afd3a3 100644 (file)
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -1364,6 +1364,18 @@ TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0
        POPQ    R15
        RET
 
+// Initialize special registers then jump to sigpanic.
+// This function is injected from the signal handler for panicking
+// signals. It is quite painful to set X15 in the signal context,
+// so we do it here.
+TEXT ·sigpanic0<ABIInternal>(SB),NOSPLIT,$0-0
+#ifdef GOEXPERIMENT_REGABI
+       get_tls(R14)
+       MOVQ    g(R14), R14
+       XORPS   X15, X15
+#endif
+       JMP     ·sigpanic<ABIInternal>(SB)
+
 // gcWriteBarrier performs a heap pointer write and informs the GC.
 //
 // gcWriteBarrier does NOT follow the Go ABI. It takes two arguments:

diff --git a/src/runtime/signal_amd64.go b/src/runtime/signal_amd64.go
index 6ab1f758c2293542396062811536109be2964ccb..3eeb5e044ff0ff1c5cae3d43ca064dda5b37dde1 100644 (file)
--- a/src/runtime/signal_amd64.go
+++ b/src/runtime/signal_amd64.go
@@ -65,11 +65,14 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) {
        pc := uintptr(c.rip())
        sp := uintptr(c.rsp())
 
+       // In case we are panicking from external code, we need to initialize
+       // Go special registers. We inject sigpanic0 (instead of sigpanic),
+       // which takes care of that.
        if shouldPushSigpanic(gp, pc, *(*uintptr)(unsafe.Pointer(sp))) {
-               c.pushCall(funcPC(sigpanic), pc)
+               c.pushCall(funcPC(sigpanic0), pc)
        } else {
                // Not safe to push the call. Just clobber the frame.
-               c.set_rip(uint64(funcPC(sigpanic)))
+               c.set_rip(uint64(funcPC(sigpanic0)))
        }
 }
 

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 36bbc8991ac0f00799d02ca9bfe76fa94d43f93d..3d1e0c0bb4dd702ae3f0a1e91bb40ffc4f7b2225 100644 (file)
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -356,3 +356,7 @@ func duffcopy()
 
 // Called from linker-generated .initarray; declared for go vet; do NOT call from Go.
 func addmoduledata()
+
+// Injected by the signal handler for panicking signals. On many platforms it just
+// jumps to sigpanic.
+func sigpanic0()