runtime: collect stack trace if SIGPROF arrives on non-Go thread
Fixes #15994.
Change-Id: I5aca91ab53985ac7dcb07ce094ec15eb8ec341f8
Reviewed-on: https://go-review.googlesource.com/23891
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index 031e412..8a8f3cc 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -253,7 +253,7 @@
get_tls(CX)
MOVQ g(CX),AX
TESTQ AX, AX
- JZ sigtramp // g == nil
+ JZ sigtrampnog // g == nil
MOVQ g_m(AX), AX
TESTQ AX, AX
JZ sigtramp // g.m == nil
@@ -276,8 +276,8 @@
// Jump to a function in runtime/cgo.
// That function, written in C, will call the user's traceback
// function with proper unwind info, and will then call back here.
- // The first three arguments are already in registers.
- // Set the last three arguments now.
+ // The first three arguments, and the fifth, are already in registers.
+ // Set the two remaining arguments now.
MOVQ runtime·cgoTraceback(SB), CX
MOVQ $runtime·sigtramp(SB), R9
MOVQ _cgo_callers(SB), AX
@@ -286,6 +286,30 @@
sigtramp:
JMP runtime·sigtramp(SB)
+sigtrampnog:
+ // Signal arrived on a non-Go thread. If this is SIGPROF, get a
+ // stack trace.
+ CMPL DI, $27 // 27 == SIGPROF
+ JNZ sigtramp
+
+ // Lock sigprofCallersUse.
+ MOVL $0, AX
+ MOVL $1, CX
+ MOVQ $runtime·sigprofCallersUse(SB), BX
+ LOCK
+ CMPXCHGL CX, 0(BX)
+ JNZ sigtramp // Skip stack trace if already locked.
+
+ // Jump to the traceback function in runtime/cgo.
+ // It will call back to sigprofNonGo, which will ignore the
+ // arguments passed in registers.
+ // First three arguments to traceback function are in registers already.
+ MOVQ runtime·cgoTraceback(SB), CX
+ MOVQ $runtime·sigprofCallers(SB), R8
+ MOVQ $runtime·sigprofNonGo(SB), R9
+ MOVQ _cgo_callers(SB), AX
+ JMP AX
+
// For cgo unwinding to work, this function must look precisely like
// the one in glibc. The glibc source code is:
// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/x86_64/sigaction.c
