From: Keith Randall <khr@google.com>
Date: Mon, 16 Sep 2019 21:38:12 +0000 (-0700)
Subject: runtime: allow the Go runtime to return multiple stack frames for a single PC
X-Git-Tag: go1.14beta1~1015
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=a14efb1be3a59dffbf4dd9121191d6d656049564;p=gostls13.git

runtime: allow the Go runtime to return multiple stack frames for a single PC

Upgrade the thread sanitizer to handle mid-stack inlining correctly.
We can now return multiple stack frames for each pc that the thread sanitizer
gives us to symbolize.

To fix #33309, we still need to modify the tsan library with its portion
of this fix, rebuild the .syso files on all supported archs, and check
them into runtime/race.

Update #33309

Change-Id: I340013631ffc8428043ab7efe3a41b6bf5638eaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/195781
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
---

diff --git a/src/runtime/race.go b/src/runtime/race.go
index c41e1ba222..d2fc6a3c47 100644
--- a/src/runtime/race.go
+++ b/src/runtime/race.go
@@ -155,15 +155,51 @@ func racecallback(cmd uintptr, ctx unsafe.Pointer) {
 	}
 }
 
+// raceSymbolizeCode reads ctx.pc and populates the rest of *ctx with
+// information about the code at that pc.
+//
+// The race detector has already subtracted 1 from pcs, so they point to the last
+// byte of call instructions (including calls to runtime.racewrite and friends).
+//
+// If the incoming pc is part of an inlined function, *ctx is populated
+// with information about the inlined function, and on return ctx.pc is set
+// to a pc in the logically containing function. (The race detector should call this
+// function again with that pc.)
+//
+// If the incoming pc is not part of an inlined function, the return pc is unchanged.
 func raceSymbolizeCode(ctx *symbolizeCodeContext) {
-	f := findfunc(ctx.pc)._Func()
+	pc := ctx.pc
+	fi := findfunc(pc)
+	f := fi._Func()
 	if f != nil {
-		file, line := f.FileLine(ctx.pc)
+		file, line := f.FileLine(pc)
 		if line != 0 {
-			ctx.fn = cfuncname(f.funcInfo())
+			if inldata := funcdata(fi, _FUNCDATA_InlTree); inldata != nil {
+				inltree := (*[1 << 20]inlinedCall)(inldata)
+				for {
+					ix := pcdatavalue(fi, _PCDATA_InlTreeIndex, pc, nil)
+					if ix >= 0 {
+						if inltree[ix].funcID == funcID_wrapper {
+							// ignore wrappers
+							// Back up to an instruction in the "caller".
+							pc = f.Entry() + uintptr(inltree[ix].parentPc)
+							continue
+						}
+						ctx.pc = f.Entry() + uintptr(inltree[ix].parentPc) // "caller" pc
+						ctx.fn = cfuncnameFromNameoff(fi, inltree[ix].func_)
+						ctx.line = uintptr(line)
+						ctx.file = &bytes(file)[0] // assume NUL-terminated
+						ctx.off = pc - f.Entry()
+						ctx.res = 1
+						return
+					}
+					break
+				}
+			}
+			ctx.fn = cfuncname(fi)
 			ctx.line = uintptr(line)
 			ctx.file = &bytes(file)[0] // assume NUL-terminated
-			ctx.off = ctx.pc - f.Entry()
+			ctx.off = pc - f.Entry()
 			ctx.res = 1
 			return
 		}
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index c2f32e0e5d..367e06003a 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -735,13 +735,15 @@ func funcname(f funcInfo) string {
 	return gostringnocopy(cfuncname(f))
 }
 
-func funcnameFromNameoff(f funcInfo, nameoff int32) string {
-	datap := f.datap
+func cfuncnameFromNameoff(f funcInfo, nameoff int32) *byte {
 	if !f.valid() {
-		return ""
+		return nil
 	}
-	cstr := &datap.pclntable[nameoff]
-	return gostringnocopy(cstr)
+	return &f.datap.pclntable[nameoff]
+}
+
+func funcnameFromNameoff(f funcInfo, nameoff int32) string {
+	return gostringnocopy(cfuncnameFromNameoff(f, nameoff))
 }
 
 func funcfile(f funcInfo, fileno int32) string {