From 511cd9b8af10de9cad86be38a22e5eb2e5d4cd8d Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Tue, 12 Jul 2022 16:35:26 -0400 Subject: [PATCH] runtime: switch gp when jumping stacks during traceback Currently, when traceback jumps from the system stack to a user stack (e.g., during profiling tracebacks), it leaves gp pointing at the g0. This is currently harmless since it's only used during profiling, so the code paths in gentraceback that care about gp aren't used, but it's really confusing and would certainly break if _TraceJumpStack were ever used in a context other than profiling. Fix this by updating gp to point to the user g when we switch stacks. For #54466. Change-Id: I1541e004667a52e37671803ce45c91d8c5308830 Reviewed-on: https://go-review.googlesource.com/c/go/+/424257 Reviewed-by: Michael Pratt Reviewed-by: Cherry Mui Auto-Submit: Austin Clements TryBot-Result: Gopher Robot Run-TryBot: Austin Clements --- src/runtime/traceback.go | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go index ed64343470..8ecddc8935 100644 --- a/src/runtime/traceback.go +++ b/src/runtime/traceback.go @@ -167,20 +167,22 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in // This keeps morestack() from showing up in the backtrace, // but that makes some sense since it'll never be returned // to. - frame.pc = gp.m.curg.sched.pc + gp = gp.m.curg + frame.pc = gp.sched.pc frame.fn = findfunc(frame.pc) f = frame.fn flag = f.flag - frame.lr = gp.m.curg.sched.lr - frame.sp = gp.m.curg.sched.sp - stack = gp.m.curg.stack - cgoCtxt = gp.m.curg.cgoCtxt + frame.lr = gp.sched.lr + frame.sp = gp.sched.sp + stack = gp.stack + cgoCtxt = gp.cgoCtxt case funcID_systemstack: // systemstack returns normally, so just follow the // stack transition. - frame.sp = gp.m.curg.sched.sp - stack = gp.m.curg.stack - cgoCtxt = gp.m.curg.cgoCtxt + gp = gp.m.curg + frame.sp = gp.sched.sp + stack = gp.stack + cgoCtxt = gp.cgoCtxt flag &^= funcFlag_SPWRITE } } -- 2.50.0