runtime: print a message on bad morestack
If morestack runs on the g0 or gsignal stack, it currently performs
some abort operation that typically produces a signal (e.g., it does
an INT $3 on x86). This is useful if you're running in a debugger, but
if you're not, the runtime tries to trap this signal, which is likely
to send the program into a deeper spiral of collapse and lead to very
confusing diagnostic output.
Help out people trying to debug without a debugger by making morestack
print an informative message before blowing up.
Change-Id: I2814c64509b137bfe20a00091d8551d18c2c4749
Reviewed-on: https://go-review.googlesource.com/31133
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/runtime/asm_s390x.s b/src/runtime/asm_s390x.s
index 70e3b5e..9ed4d91 100644
--- a/src/runtime/asm_s390x.s
+++ b/src/runtime/asm_s390x.s
@@ -279,13 +279,15 @@
// Cannot grow scheduler stack (m->g0).
MOVD g_m(g), R7
MOVD m_g0(R7), R8
- CMPBNE g, R8, 2(PC)
+ CMPBNE g, R8, 3(PC)
+ BL runtime·badmorestackg0(SB)
BL runtime·abort(SB)
// Cannot grow signal stack (m->gsignal).
MOVD m_gsignal(R7), R8
CMP g, R8
- BNE 2(PC)
+ BNE 3(PC)
+ BL runtime·badmorestackgsignal(SB)
BL runtime·abort(SB)
// Called from f.
