[dev.boringcrypto.go1.15] all: merge go1.15.6 into dev.boringcrypto.go1.15

Change-Id: I0c17db50b6cab4b59d26e8e247870c0d709665b5

15 files changed, 272 insertions, 34 deletions

diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index ee9ccfb41c6..f7eb92dc8b6 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -1429,11 +1429,11 @@
 (NOTQ (MOVQconst [c])) -> (MOVQconst [^c])
 (NOTL (MOVLconst [c])) -> (MOVLconst [^c])
 (BTSQconst [c] (MOVQconst [d])) -> (MOVQconst [d|(1<<uint32(c))])
-(BTSLconst [c] (MOVLconst [d])) -> (MOVLconst [d|(1<<uint32(c))])
+(BTSLconst [c] (MOVLconst [d])) => (MOVLconst [d|(1<<uint32(c))])
 (BTRQconst [c] (MOVQconst [d])) -> (MOVQconst [d&^(1<<uint32(c))])
-(BTRLconst [c] (MOVLconst [d])) -> (MOVLconst [d&^(1<<uint32(c))])
+(BTRLconst [c] (MOVLconst [d])) => (MOVLconst [d&^(1<<uint32(c))])
 (BTCQconst [c] (MOVQconst [d])) -> (MOVQconst [d^(1<<uint32(c))])
-(BTCLconst [c] (MOVLconst [d])) -> (MOVLconst [d^(1<<uint32(c))])
+(BTCLconst [c] (MOVLconst [d])) => (MOVLconst [d^(1<<uint32(c))])
 
 // If c or d doesn't fit into 32 bits, then we can't construct ORQconst,
 // but we can still constant-fold.
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index 72ed1eb62c8..e59fa208c1e 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -3526,13 +3526,13 @@ func rewriteValueAMD64_OpAMD64BTCLconst(v *Value) bool {
 	// match: (BTCLconst [c] (MOVLconst [d]))
 	// result: (MOVLconst [d^(1<<uint32(c))])
 	for {
-		c := v.AuxInt
+		c := auxIntToInt8(v.AuxInt)
 		if v_0.Op != OpAMD64MOVLconst {
 			break
 		}
-		d := v_0.AuxInt
+		d := auxIntToInt32(v_0.AuxInt)
 		v.reset(OpAMD64MOVLconst)
-		v.AuxInt = d ^ (1 << uint32(c))
+		v.AuxInt = int32ToAuxInt(d ^ (1 << uint32(c)))
 		return true
 	}
 	return false
@@ -4010,13 +4010,13 @@ func rewriteValueAMD64_OpAMD64BTRLconst(v *Value) bool {
 	// match: (BTRLconst [c] (MOVLconst [d]))
 	// result: (MOVLconst [d&^(1<<uint32(c))])
 	for {
-		c := v.AuxInt
+		c := auxIntToInt8(v.AuxInt)
 		if v_0.Op != OpAMD64MOVLconst {
 			break
 		}
-		d := v_0.AuxInt
+		d := auxIntToInt32(v_0.AuxInt)
 		v.reset(OpAMD64MOVLconst)
-		v.AuxInt = d &^ (1 << uint32(c))
+		v.AuxInt = int32ToAuxInt(d &^ (1 << uint32(c)))
 		return true
 	}
 	return false
@@ -4356,13 +4356,13 @@ func rewriteValueAMD64_OpAMD64BTSLconst(v *Value) bool {
 	// match: (BTSLconst [c] (MOVLconst [d]))
 	// result: (MOVLconst [d|(1<<uint32(c))])
 	for {
-		c := v.AuxInt
+		c := auxIntToInt8(v.AuxInt)
 		if v_0.Op != OpAMD64MOVLconst {
 			break
 		}
-		d := v_0.AuxInt
+		d := auxIntToInt32(v_0.AuxInt)
 		v.reset(OpAMD64MOVLconst)
-		v.AuxInt = d | (1 << uint32(c))
+		v.AuxInt = int32ToAuxInt(d | (1 << uint32(c)))
 		return true
 	}
 	return false
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 13d4c8cbb45..dc0c4fc3444 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -2766,6 +2766,21 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 				idx = bytes.Index(src, []byte(cgoLdflag))
 			}
 		}
+
+		// We expect to find the contents of cgoLDFLAGS in flags.
+		if len(cgoLDFLAGS) > 0 {
+		outer:
+			for i := range flags {
+				for j, f := range cgoLDFLAGS {
+					if f != flags[i+j] {
+						continue outer
+					}
+				}
+				flags = append(flags[:i], flags[i+len(cgoLDFLAGS):]...)
+				break
+			}
+		}
+
 		if err := checkLinkerFlags("LDFLAGS", "go:cgo_ldflag", flags); err != nil {
 			return nil, nil, err
 		}
diff --git a/src/cmd/go/testdata/script/ldflag.txt b/src/cmd/go/testdata/script/ldflag.txt
new file mode 100644
index 00000000000..6ceb33bb70e
--- /dev/null
+++ b/src/cmd/go/testdata/script/ldflag.txt
@@ -0,0 +1,44 @@
+# Issue #42565
+
+[!cgo] skip
+
+# We can't build package bad, which uses #cgo LDFLAGS.
+cd bad
+! go build
+stderr no-such-warning
+
+# We can build package ok with the same flags in CGO_LDFLAGS.
+env CGO_LDFLAGS=-Wno-such-warning -Wno-unknown-warning-option
+cd ../ok
+go build
+
+# Build a main program that actually uses LDFLAGS.
+cd ..
+go build -ldflags=-v
+
+# Because we passed -v the Go linker should print the external linker
+# command which should include the flag we passed in CGO_LDFLAGS.
+stderr no-such-warning
+
+-- go.mod --
+module ldflag
+
+-- bad/bad.go --
+package bad
+
+// #cgo LDFLAGS: -Wno-such-warning -Wno-unknown-warning
+import "C"
+
+func F() {}
+-- ok/ok.go --
+package ok
+
+import "C"
+
+func F() {}
+-- main.go --
+package main
+
+import _ "ldflag/ok"
+
+func main() {}
diff --git a/src/cmd/internal/obj/dwarf.go b/src/cmd/internal/obj/dwarf.go
index cd1d5b86878..8a12849d772 100644
--- a/src/cmd/internal/obj/dwarf.go
+++ b/src/cmd/internal/obj/dwarf.go
@@ -106,7 +106,8 @@ func (ctxt *Link) generateDebugLinesSymbol(s, lines *LSym) {
 	// GDB will assign a line number of zero the last row in the line
 	// table, which we don't want.
 	lastlen := uint64(s.Size - (lastpc - s.Func.Text.Pc))
-	putpclcdelta(ctxt, dctxt, lines, lastlen, 0)
+	dctxt.AddUint8(lines, dwarf.DW_LNS_advance_pc)
+	dwarf.Uleb128put(dctxt, lines, int64(lastlen))
 	dctxt.AddUint8(lines, 0) // start extended opcode
 	dwarf.Uleb128put(dctxt, lines, 1)
 	dctxt.AddUint8(lines, dwarf.DW_LNE_end_sequence)
diff --git a/src/cmd/link/internal/ld/outbuf.go b/src/cmd/link/internal/ld/outbuf.go
index 09162ae90f5..7bc89540c69 100644
--- a/src/cmd/link/internal/ld/outbuf.go
+++ b/src/cmd/link/internal/ld/outbuf.go
@@ -187,7 +187,9 @@ func (out *OutBuf) writeLoc(lenToWrite int64) (int64, []byte) {
 		// See if our heap would grow to be too large, and if so, copy it to the end
 		// of the mmapped area.
 		if heapLen > maxOutBufHeapLen && out.copyHeap() {
-			heapPos, heapLen, lenNeeded = 0, 0, lenToWrite
+			heapPos -= heapLen
+			lenNeeded = heapPos + lenToWrite
+			heapLen = 0
 		}
 		out.heap = append(out.heap, make([]byte, lenNeeded-heapLen)...)
 	}
diff --git a/src/internal/poll/copy_file_range_linux.go b/src/internal/poll/copy_file_range_linux.go
index 09de299ff71..fc34aef4cba 100644
--- a/src/internal/poll/copy_file_range_linux.go
+++ b/src/internal/poll/copy_file_range_linux.go
@@ -10,15 +10,61 @@ import (
 	"syscall"
 )
 
-var copyFileRangeSupported int32 = 1 // accessed atomically
+var copyFileRangeSupported int32 = -1 // accessed atomically
 
 const maxCopyFileRangeRound = 1 << 30
 
+func kernelVersion() (major int, minor int) {
+	var uname syscall.Utsname
+	if err := syscall.Uname(&uname); err != nil {
+		return
+	}
+
+	rl := uname.Release
+	var values [2]int
+	vi := 0
+	value := 0
+	for _, c := range rl {
+		if '0' <= c && c <= '9' {
+			value = (value * 10) + int(c-'0')
+		} else {
+			// Note that we're assuming N.N.N here.  If we see anything else we are likely to
+			// mis-parse it.
+			values[vi] = value
+			vi++
+			if vi >= len(values) {
+				break
+			}
+			value = 0
+		}
+	}
+	switch vi {
+	case 0:
+		return 0, 0
+	case 1:
+		return values[0], 0
+	case 2:
+		return values[0], values[1]
+	}
+	return
+}
+
 // CopyFileRange copies at most remain bytes of data from src to dst, using
 // the copy_file_range system call. dst and src must refer to regular files.
 func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err error) {
-	if atomic.LoadInt32(&copyFileRangeSupported) == 0 {
+	if supported := atomic.LoadInt32(&copyFileRangeSupported); supported == 0 {
 		return 0, false, nil
+	} else if supported == -1 {
+		major, minor := kernelVersion()
+		if major > 5 || (major == 5 && minor >= 3) {
+			atomic.StoreInt32(&copyFileRangeSupported, 1)
+		} else {
+			// copy_file_range(2) is broken in various ways on kernels older than 5.3,
+			// see issue #42400 and
+			// https://man7.org/linux/man-pages/man2/copy_file_range.2.html#VERSIONS
+			atomic.StoreInt32(&copyFileRangeSupported, 0)
+			return 0, false, nil
+		}
 	}
 	for remain > 0 {
 		max := remain
@@ -41,7 +87,7 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
 			// use copy_file_range(2) again.
 			atomic.StoreInt32(&copyFileRangeSupported, 0)
 			return 0, false, nil
-		case syscall.EXDEV, syscall.EINVAL, syscall.EOPNOTSUPP, syscall.EPERM:
+		case syscall.EXDEV, syscall.EINVAL, syscall.EIO, syscall.EOPNOTSUPP, syscall.EPERM:
 			// Prior to Linux 5.3, it was not possible to
 			// copy_file_range across file systems. Similarly to
 			// the ENOSYS case above, if we see EXDEV, we have
@@ -53,6 +99,9 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
 			// file. This is another case where no data has been
 			// transfered, so we consider it unhandled.
 			//
+			// If src and dst are on CIFS, we can see EIO.
+			// See issue #42334.
+			//
 			// If the file is on NFS, we can see EOPNOTSUPP.
 			// See issue #40731.
 			//
diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index 4872189f16b..57c3639f710 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -600,3 +600,16 @@ func TestEINTR(t *testing.T) {
 		t.Fatalf("want %s, got %s\n", want, output)
 	}
 }
+
+// Issue #42207.
+func TestNeedmDeadlock(t *testing.T) {
+	switch runtime.GOOS {
+	case "plan9", "windows":
+		t.Skipf("no signals on %s", runtime.GOOS)
+	}
+	output := runTestProg(t, "testprogcgo", "NeedmDeadlock")
+	want := "OK\n"
+	if output != want {
+		t.Fatalf("want %s, got %s\n", want, output)
+	}
+}
diff --git a/src/runtime/os_js.go b/src/runtime/os_js.go
index ff0ee3aa6be..94983b358d4 100644
--- a/src/runtime/os_js.go
+++ b/src/runtime/os_js.go
@@ -59,7 +59,7 @@ func mpreinit(mp *m) {
 }
 
 //go:nosplit
-func msigsave(mp *m) {
+func sigsave(p *sigset) {
 }
 
 //go:nosplit
diff --git a/src/runtime/os_plan9.go b/src/runtime/os_plan9.go
index 9e187d22205..8f5380d3d90 100644
--- a/src/runtime/os_plan9.go
+++ b/src/runtime/os_plan9.go
@@ -167,7 +167,7 @@ func mpreinit(mp *m) {
 	mp.errstr = (*byte)(mallocgc(_ERRMAX, nil, true))
 }
 
-func msigsave(mp *m) {
+func sigsave(p *sigset) {
 }
 
 func msigrestore(sigmask sigset) {
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 769197db46e..81d9ccf8f08 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -830,7 +830,7 @@ func mpreinit(mp *m) {
 }
 
 //go:nosplit
-func msigsave(mp *m) {
+func sigsave(p *sigset) {
 }
 
 //go:nosplit
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 2f1272d310b..7fa19d867b4 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -569,7 +569,7 @@ func schedinit() {
 	typelinksinit() // uses maps, activeModules
 	itabsinit()     // uses activeModules
 
-	msigsave(_g_.m)
+	sigsave(&_g_.m.sigmask)
 	initSigmask = _g_.m.sigmask
 
 	goargs()
@@ -1536,6 +1536,18 @@ func needm(x byte) {
 		exit(1)
 	}
 
+	// Save and block signals before getting an M.
+	// The signal handler may call needm itself,
+	// and we must avoid a deadlock. Also, once g is installed,
+	// any incoming signals will try to execute,
+	// but we won't have the sigaltstack settings and other data
+	// set up appropriately until the end of minit, which will
+	// unblock the signals. This is the same dance as when
+	// starting a new m to run Go code via newosproc.
+	var sigmask sigset
+	sigsave(&sigmask)
+	sigblock()
+
 	// Lock extra list, take head, unlock popped list.
 	// nilokay=false is safe here because of the invariant above,
 	// that the extra list always contains or will soon contain
@@ -1553,14 +1565,8 @@ func needm(x byte) {
 	extraMCount--
 	unlockextra(mp.schedlink.ptr())
 
-	// Save and block signals before installing g.
-	// Once g is installed, any incoming signals will try to execute,
-	// but we won't have the sigaltstack settings and other data
-	// set up appropriately until the end of minit, which will
-	// unblock the signals. This is the same dance as when
-	// starting a new m to run Go code via newosproc.
-	msigsave(mp)
-	sigblock()
+	// Store the original signal mask for use by minit.
+	mp.sigmask = sigmask
 
 	// Install g (= m->g0) and set the stack bounds
 	// to match the current stack. We don't actually know
@@ -3417,7 +3423,7 @@ func beforefork() {
 	// a signal handler before exec if a signal is sent to the process
 	// group. See issue #18600.
 	gp.m.locks++
-	msigsave(gp.m)
+	sigsave(&gp.m.sigmask)
 	sigblock()
 
 	// This function is called before fork in syscall package.
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 80fd2d66049..003c7b0bc81 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -1032,15 +1032,15 @@ func sigfwdgo(sig uint32, info *siginfo, ctx unsafe.Pointer) bool {
 	return true
 }
 
-// msigsave saves the current thread's signal mask into mp.sigmask.
+// sigsave saves the current thread's signal mask into *p.
 // This is used to preserve the non-Go signal mask when a non-Go
 // thread calls a Go function.
 // This is nosplit and nowritebarrierrec because it is called by needm
 // which may be called on a non-Go thread with no g available.
 //go:nosplit
 //go:nowritebarrierrec
-func msigsave(mp *m) {
-	sigprocmask(_SIG_SETMASK, nil, &mp.sigmask)
+func sigsave(p *sigset) {
+	sigprocmask(_SIG_SETMASK, nil, p)
 }
 
 // msigrestore sets the current thread's signal mask to sigmask.
@@ -1112,7 +1112,7 @@ func minitSignalStack() {
 // thread's signal mask. When this is called all signals have been
 // blocked for the thread.  This starts with m.sigmask, which was set
 // either from initSigmask for a newly created thread or by calling
-// msigsave if this is a non-Go thread calling a Go function. It
+// sigsave if this is a non-Go thread calling a Go function. It
 // removes all essential signals from the mask, thus causing those
 // signals to not be blocked. Then it sets the thread's signal mask.
 // After this is called the thread can receive signals.
diff --git a/src/runtime/testdata/testprogcgo/needmdeadlock.go b/src/runtime/testdata/testprogcgo/needmdeadlock.go
new file mode 100644
index 00000000000..5a9c359006d
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/needmdeadlock.go
@@ -0,0 +1,95 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9,!windows
+
+package main
+
+// This is for issue #42207.
+// During a call to needm we could get a SIGCHLD signal
+// which would itself call needm, causing a deadlock.
+
+/*
+#include <signal.h>
+#include <pthread.h>
+#include <sched.h>
+#include <unistd.h>
+
+extern void GoNeedM();
+
+#define SIGNALERS 10
+
+static void* needmSignalThread(void* p) {
+	pthread_t* pt = (pthread_t*)(p);
+	int i;
+
+	for (i = 0; i < 100; i++) {
+		if (pthread_kill(*pt, SIGCHLD) < 0) {
+			return NULL;
+		}
+		usleep(1);
+	}
+	return NULL;
+}
+
+// We don't need many calls, as the deadlock is only likely
+// to occur the first couple of times that needm is called.
+// After that there will likely be an extra M available.
+#define CALLS 10
+
+static void* needmCallbackThread(void* p) {
+	int i;
+
+	for (i = 0; i < SIGNALERS; i++) {
+		sched_yield(); // Help the signal threads get started.
+	}
+	for (i = 0; i < CALLS; i++) {
+		GoNeedM();
+	}
+	return NULL;
+}
+
+static void runNeedmSignalThread() {
+	int i;
+	pthread_t caller;
+	pthread_t s[SIGNALERS];
+
+	pthread_create(&caller, NULL, needmCallbackThread, NULL);
+	for (i = 0; i < SIGNALERS; i++) {
+		pthread_create(&s[i], NULL, needmSignalThread, &caller);
+	}
+	for (i = 0; i < SIGNALERS; i++) {
+		pthread_join(s[i], NULL);
+	}
+	pthread_join(caller, NULL);
+}
+*/
+import "C"
+
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+func init() {
+	register("NeedmDeadlock", NeedmDeadlock)
+}
+
+//export GoNeedM
+func GoNeedM() {
+}
+
+func NeedmDeadlock() {
+	// The failure symptom is that the program hangs because of a
+	// deadlock in needm, so set an alarm.
+	go func() {
+		time.Sleep(5 * time.Second)
+		fmt.Println("Hung for 5 seconds")
+		os.Exit(1)
+	}()
+
+	C.runNeedmSignalThread()
+	fmt.Println("OK")
+}
diff --git a/test/fixedbugs/issue42753.go b/test/fixedbugs/issue42753.go
new file mode 100644
index 00000000000..a998d1d3b3d
--- /dev/null
+++ b/test/fixedbugs/issue42753.go
@@ -0,0 +1,13 @@
+// compile -d=ssa/check/on
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func f() uint32 {
+	s := "\x01"
+	x := -int32(s[0])
+	return uint32(x) & 0x7fffffff
+}