[release-branch.go1.14] all: merge master into release-branch.go1.14

1cd724acb6 doc/go1.14: highlight the addition of hash/maphash package
a0cf2c872f doc/go1.14: remove TODO comment for CL 200439
a9ea91d571 cmd/link, runtime: skip holes in func table
88e564edb1 doc/go1.14: add missing period at sentence end
6917529cc6 testing: remove obsolete comment in testing.(*T) docs

Change-Id: Ifb581c251474e9445d65a4f34dd4dcbc469fdd79

4 files changed, 47 insertions, 24 deletions

diff --git a/doc/go1.14.html b/doc/go1.14.html
index d5ad07754a..f83b365704 100644
--- a/doc/go1.14.html
+++ b/doc/go1.14.html
@@ -343,8 +343,6 @@ appropriately.)
   visible changes.
 </p>
 
-<!-- TODO: Maybe CL 200439? -->
-
 <h2 id="compiler">Compiler</h2>
 
 <p><!-- CL 162237 -->
@@ -378,7 +376,7 @@ appropriately.)
 <p><!-- CL 204338 -->
   The compiler can now emit machine-readable logs of key optimizations
   using the <code>-json</code> flag, including inlining, escape
-  analysis, bounds-check elimination, and nil-check elimination
+  analysis, bounds-check elimination, and nil-check elimination.
 </p>
 
 <p><!-- CL 196959 -->
@@ -407,8 +405,22 @@ appropriately.)
 
 <h2 id="library">Core library</h2>
 
+<h3 id="hash/maphash">New byte sequence hashing package</h3>
+
+<p> <!-- golang.org/issue/28322, CL 186877 -->
+  Go 1.14 includes a new package,
+  <a href="/pkg/hash/maphash/"><code>hash/maphash</code></a>,
+  which provides hash functions on byte sequences.
+  These hash functions are intended to be used to implement hash tables or
+  other data structures that need to map arbitrary strings or byte
+  sequences to a uniform distribution on unsigned 64-bit integers.
+</p>
 <p>
-  All of the changes to the standard library are minor.
+  The hash functions are collision-resistant but not cryptographically secure.
+</p>
+<p>
+  The hash value of a given byte sequence is consistent within a
+  single process, but will be different in different processes.
 </p>
 
 <h3 id="minor_library_changes">Minor changes to the library</h3>
@@ -605,24 +617,6 @@ appropriately.)
   </dd>
 </dl><!-- go/doc -->
 
-<dl id="hash/maphash"><dt><a href="/pkg/hash/maphash/">hash/maphash</a></dt>
-  <dd>
-    <p><!-- CL 186877 -->
-      This new package provides hash functions on byte sequences.
-      These hash functions are intended to be used to implement hash tables or
-      other data structures that need to map arbitrary strings or byte
-      sequences to a uniform distribution of integers.
-    </p>
-    <p>
-      The hash functions are collision-resistant but not cryptographically secure.
-    </p>
-    <p>
-      The hash value of a given byte sequence is consistent within a
-      single process, but will be different in different processes.
-    </p>
-  </dd>
-</dl><!-- hash/maphash -->
-
 <dl id="io/ioutil"><dt><a href="/pkg/io/ioutil/">io/ioutil</a></dt>
   <dd>
     <p><!-- CL 198488 -->
diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go
index db44c0292e..3e8135c959 100644
--- a/src/cmd/link/internal/ld/pcln.go
+++ b/src/cmd/link/internal/ld/pcln.go
@@ -138,6 +138,7 @@ func (ctxt *Link) pclntab() {
 
 	// Gather some basic stats and info.
 	var nfunc int32
+	prevSect := ctxt.Textp[0].Sect
 	for _, s := range ctxt.Textp {
 		if !emitPcln(ctxt, s) {
 			continue
@@ -146,6 +147,14 @@ func (ctxt *Link) pclntab() {
 		if pclntabFirstFunc == nil {
 			pclntabFirstFunc = s
 		}
+		if s.Sect != prevSect {
+			// With multiple text sections, the external linker may insert functions
+			// between the sections, which are not known by Go. This leaves holes in
+			// the PC range covered by the func table. We need to generate an entry
+			// to mark the hole.
+			nfunc++
+			prevSect = s.Sect
+		}
 	}
 
 	pclntabNfunc = nfunc
@@ -181,10 +190,23 @@ func (ctxt *Link) pclntab() {
 	}
 
 	nfunc = 0 // repurpose nfunc as a running index
+	prevFunc := ctxt.Textp[0]
 	for _, s := range ctxt.Textp {
 		if !emitPcln(ctxt, s) {
 			continue
 		}
+
+		if s.Sect != prevFunc.Sect {
+			// With multiple text sections, there may be a hole here in the address
+			// space (see the comment above). We use an invalid funcoff value to
+			// mark the hole.
+			// See also runtime/symtab.go:findfunc
+			ftab.SetAddrPlus(ctxt.Arch, 8+int64(ctxt.Arch.PtrSize)+int64(nfunc)*2*int64(ctxt.Arch.PtrSize), prevFunc, prevFunc.Size)
+			ftab.SetUint(ctxt.Arch, 8+int64(ctxt.Arch.PtrSize)+int64(nfunc)*2*int64(ctxt.Arch.PtrSize)+int64(ctxt.Arch.PtrSize), ^uint64(0))
+			nfunc++
+		}
+		prevFunc = s
+
 		pcln := s.FuncInfo
 		if pcln == nil {
 			pcln = &pclntabZpcln
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index ddcf231929..a6e08d7214 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -614,7 +614,15 @@ func findfunc(pc uintptr) funcInfo {
 			idx++
 		}
 	}
-	return funcInfo{(*_func)(unsafe.Pointer(&datap.pclntable[datap.ftab[idx].funcoff])), datap}
+	funcoff := datap.ftab[idx].funcoff
+	if funcoff == ^uintptr(0) {
+		// With multiple text sections, there may be functions inserted by the external
+		// linker that are not known by Go. This means there may be holes in the PC
+		// range covered by the func table. The invalid funcoff value indicates a hole.
+		// See also cmd/link/internal/ld/pcln.go:pclntab
+		return funcInfo{}
+	}
+	return funcInfo{(*_func)(unsafe.Pointer(&datap.pclntable[funcoff])), datap}
 }
 
 type pcvalueCache struct {
diff --git a/src/testing/testing.go b/src/testing/testing.go
index 030feb7112..8a0c7b3021 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -571,7 +571,6 @@ var _ TB = (*T)(nil)
 var _ TB = (*B)(nil)
 
 // T is a type passed to Test functions to manage test state and support formatted test logs.
-// Logs are accumulated during execution and dumped to standard output when done.
 //
 // A test ends when its Test function returns or calls any of the methods
 // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods, as well as