diff --git a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
index b402e35..2208d26 100644
--- a/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/ARM64Ops.go
@@ -498,13 +498,14 @@
 		// auxint = offset into duffzero code to start executing
 		// returns mem
 		// R20 changed as side effect
+		// R16 and R17 may be clobbered by linker trampoline.
 		{
 			name:      "DUFFZERO",
 			aux:       "Int64",
 			argLength: 2,
 			reg: regInfo{
 				inputs:   []regMask{buildReg("R20")},
-				clobbers: buildReg("R20 R30"),
+				clobbers: buildReg("R16 R17 R20 R30"),
 			},
 			faultOnNilArg0: true,
 		},
@@ -537,13 +538,14 @@
 		// auxint = offset into duffcopy code to start executing
 		// returns mem
 		// R20, R21 changed as side effect
+		// R16 and R17 may be clobbered by linker trampoline.
 		{
 			name:      "DUFFCOPY",
 			aux:       "Int64",
 			argLength: 3,
 			reg: regInfo{
 				inputs:   []regMask{buildReg("R21"), buildReg("R20")},
-				clobbers: buildReg("R20 R21 R26 R30"),
+				clobbers: buildReg("R16 R17 R20 R21 R26 R30"),
 			},
 			faultOnNilArg0: true,
 			faultOnNilArg1: true,
@@ -664,7 +666,8 @@
 		// LoweredWB invokes runtime.gcWriteBarrier. arg0=destptr, arg1=srcptr, arg2=mem, aux=runtime.gcWriteBarrier
 		// It saves all GP registers if necessary,
 		// but clobbers R30 (LR) because it's a call.
-		{name: "LoweredWB", argLength: 3, reg: regInfo{inputs: []regMask{buildReg("R2"), buildReg("R3")}, clobbers: (callerSave &^ gpg) | buildReg("R30")}, clobberFlags: true, aux: "Sym", symEffect: "None"},
+		// R16 and R17 may be clobbered by linker trampoline.
+		{name: "LoweredWB", argLength: 3, reg: regInfo{inputs: []regMask{buildReg("R2"), buildReg("R3")}, clobbers: (callerSave &^ gpg) | buildReg("R16 R17 R30")}, clobberFlags: true, aux: "Sym", symEffect: "None"},
 
 		// There are three of these functions so that they can have three different register inputs.
 		// When we check 0 <= c <= cap (A), then 0 <= b <= c (B), then 0 <= a <= b (C), we want the
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 8a27c4b..39320c8 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -20738,7 +20738,7 @@
 			inputs: []inputInfo{
 				{0, 1048576}, // R20
 			},
-			clobbers: 537919488, // R20 R30
+			clobbers: 538116096, // R16 R17 R20 R30
 		},
 	},
 	{
@@ -20765,7 +20765,7 @@
 				{0, 2097152}, // R21
 				{1, 1048576}, // R20
 			},
-			clobbers: 607125504, // R20 R21 R26 R30
+			clobbers: 607322112, // R16 R17 R20 R21 R26 R30
 		},
 	},
 	{
@@ -21090,7 +21090,7 @@
 				{0, 4}, // R2
 				{1, 8}, // R3
 			},
-			clobbers: 9223372035244163072, // R30 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
+			clobbers: 9223372035244359680, // R16 R17 R30 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
 		},
 	},
 	{
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index ddbb3b9..3300ea7 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -1286,6 +1286,11 @@
 				Err:           errors.New("import cycle not allowed"),
 				IsImportCycle: true,
 			}
+		} else if !p.Error.IsImportCycle {
+			// If the error is already set, but it does not indicate that
+			// we are in an import cycle, set IsImportCycle so that we don't
+			// end up stuck in a loop down the road.
+			p.Error.IsImportCycle = true
 		}
 		p.Incomplete = true
 	}
diff --git a/src/cmd/go/internal/modcmd/vendor.go b/src/cmd/go/internal/modcmd/vendor.go
index 5a5bb94..d83b3de 100644
--- a/src/cmd/go/internal/modcmd/vendor.go
+++ b/src/cmd/go/internal/modcmd/vendor.go
@@ -10,6 +10,7 @@
 	"io"
 	"io/ioutil"
 	"os"
+	"path"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -192,7 +193,7 @@
 		if modPath == pkg {
 			break
 		}
-		pkg = filepath.Dir(pkg)
+		pkg = path.Dir(pkg)
 		dst = filepath.Dir(dst)
 		src = filepath.Dir(src)
 	}
diff --git a/src/cmd/go/testdata/script/list_err_cycle.txt b/src/cmd/go/testdata/script/list_err_cycle.txt
new file mode 100644
index 0000000..44b82a6
--- /dev/null
+++ b/src/cmd/go/testdata/script/list_err_cycle.txt
@@ -0,0 +1,15 @@
+# Check that we don't get infinite recursion when loading a package with
+# an import cycle and another error. Verifies #25830.
+! go list
+stderr 'found packages a \(a.go\) and b \(b.go\)'
+
+-- go.mod --
+module errcycle
+
+go 1.16
+-- a.go --
+package a
+
+import _ "errcycle"
+-- b.go --
+package b
\ No newline at end of file
diff --git a/src/net/http/httputil/reverseproxy.go b/src/net/http/httputil/reverseproxy.go
index f49cefb..68754cb 100644
--- a/src/net/http/httputil/reverseproxy.go
+++ b/src/net/http/httputil/reverseproxy.go
@@ -234,6 +234,15 @@
 	if req.ContentLength == 0 {
 		outreq.Body = nil // Issue 16036: nil Body for http.Transport retries
 	}
+	if outreq.Body != nil {
+		// Reading from the request body after returning from a handler is not
+		// allowed, and the RoundTrip goroutine that reads the Body can outlive
+		// this handler. This can lead to a crash if the handler panics (see
+		// Issue 46866). Although calling Close doesn't guarantee there isn't
+		// any Read in flight after the handle returns, in practice it's safe to
+		// read after closing it.
+		defer outreq.Body.Close()
+	}
 	if outreq.Header == nil {
 		outreq.Header = make(http.Header) // Issue 33142: historical behavior was to always allocate
 	}
diff --git a/src/net/http/httputil/reverseproxy_test.go b/src/net/http/httputil/reverseproxy_test.go
index 1f2dfb9..aab94da 100644
--- a/src/net/http/httputil/reverseproxy_test.go
+++ b/src/net/http/httputil/reverseproxy_test.go
@@ -1122,6 +1122,45 @@
 	rproxy.ServeHTTP(httptest.NewRecorder(), req)
 }
 
+// Issue #46866: panic without closing incoming request body causes a panic
+func TestReverseProxy_PanicClosesIncomingBody(t *testing.T) {
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		out := "this call was relayed by the reverse proxy"
+		// Coerce a wrong content length to induce io.ErrUnexpectedEOF
+		w.Header().Set("Content-Length", fmt.Sprintf("%d", len(out)*2))
+		fmt.Fprintln(w, out)
+	}))
+	defer backend.Close()
+	backendURL, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	proxyHandler := NewSingleHostReverseProxy(backendURL)
+	proxyHandler.ErrorLog = log.New(ioutil.Discard, "", 0) // quiet for tests
+	frontend := httptest.NewServer(proxyHandler)
+	defer frontend.Close()
+	frontendClient := frontend.Client()
+
+	var wg sync.WaitGroup
+	for i := 0; i < 2; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 10; j++ {
+				const reqLen = 6 * 1024 * 1024
+				req, _ := http.NewRequest("POST", frontend.URL, &io.LimitedReader{R: neverEnding('x'), N: reqLen})
+				req.ContentLength = reqLen
+				resp, _ := frontendClient.Transport.RoundTrip(req)
+				if resp != nil {
+					io.Copy(ioutil.Discard, resp.Body)
+					resp.Body.Close()
+				}
+			}
+		}()
+	}
+	wg.Wait()
+}
+
 func TestSelectFlushInterval(t *testing.T) {
 	tests := []struct {
 		name string
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index faa77e9..83c85ea 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -6290,10 +6290,11 @@
 // Test that a new request which uses the connection of an active request
 // cannot cause it to be canceled as well.
 func TestCancelRequestWhenSharingConnection(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping in short mode")
-	}
+	reqc := make(chan chan struct{}, 2)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, req *Request) {
+		ch := make(chan struct{}, 1)
+		reqc <- ch
+		<-ch
 		w.Header().Add("Content-Length", "0")
 	}))
 	defer ts.Close()
@@ -6305,34 +6306,58 @@
 
 	var wg sync.WaitGroup
 
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-
-	for i := 0; i < 10; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
-			for ctx.Err() == nil {
-				reqctx, reqcancel := context.WithCancel(ctx)
-				go reqcancel()
-				req, _ := NewRequestWithContext(reqctx, "GET", ts.URL, nil)
-				res, err := client.Do(req)
-				if err == nil {
-					res.Body.Close()
-				}
-			}
-		}()
-	}
-
-	for ctx.Err() == nil {
-		req, _ := NewRequest("GET", ts.URL, nil)
-		if res, err := client.Do(req); err != nil {
-			t.Errorf("unexpected: %p %v", req, err)
-			break
-		} else {
+	wg.Add(1)
+	putidlec := make(chan chan struct{})
+	go func() {
+		defer wg.Done()
+		ctx := httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
+			PutIdleConn: func(error) {
+				// Signal that the idle conn has been returned to the pool,
+				// and wait for the order to proceed.
+				ch := make(chan struct{})
+				putidlec <- ch
+				<-ch
+			},
+		})
+		req, _ := NewRequestWithContext(ctx, "GET", ts.URL, nil)
+		res, err := client.Do(req)
+		if err == nil {
 			res.Body.Close()
 		}
-	}
+		if err != nil {
+			t.Errorf("request 1: got err %v, want nil", err)
+		}
+	}()
 
+	// Wait for the first request to receive a response and return the
+	// connection to the idle pool.
+	r1c := <-reqc
+	close(r1c)
+	idlec := <-putidlec
+
+	wg.Add(1)
+	cancelctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		defer wg.Done()
+		req, _ := NewRequestWithContext(cancelctx, "GET", ts.URL, nil)
+		res, err := client.Do(req)
+		if err == nil {
+			res.Body.Close()
+		}
+		if !errors.Is(err, context.Canceled) {
+			t.Errorf("request 2: got err %v, want Canceled", err)
+		}
+	}()
+
+	// Wait for the second request to arrive at the server, and then cancel
+	// the request context.
+	r2c := <-reqc
 	cancel()
+
+	// Give the cancelation a moment to take effect, and then unblock the first request.
+	time.Sleep(1 * time.Millisecond)
+	close(idlec)
+
+	close(r2c)
 	wg.Wait()
 }
diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s
index 6b3d1e7..141ed76 100644
--- a/src/runtime/asm_arm64.s
+++ b/src/runtime/asm_arm64.s
@@ -1161,10 +1161,10 @@
 // It does not clobber any general-purpose registers,
 // but may clobber others (e.g., floating point registers)
 // The act of CALLing gcWriteBarrier will clobber R30 (LR).
-TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$216
+TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$200
 	// Save the registers clobbered by the fast path.
-	MOVD	R0, 200(RSP)
-	MOVD	R1, 208(RSP)
+	MOVD	R0, 184(RSP)
+	MOVD	R1, 192(RSP)
 	MOVD	g_m(g), R0
 	MOVD	m_p(R0), R0
 	MOVD	(p_wbBuf+wbBuf_next)(R0), R1
@@ -1180,8 +1180,8 @@
 	// Is the buffer full? (flags set in CMP above)
 	BEQ	flush
 ret:
-	MOVD	200(RSP), R0
-	MOVD	208(RSP), R1
+	MOVD	184(RSP), R0
+	MOVD	192(RSP), R1
 	// Do the write.
 	MOVD	R3, (R2)
 	RET
@@ -1205,17 +1205,16 @@
 	MOVD	R13, 96(RSP)
 	MOVD	R14, 104(RSP)
 	MOVD	R15, 112(RSP)
-	MOVD	R16, 120(RSP)
-	MOVD	R17, 128(RSP)
+	// R16, R17 may be clobbered by linker trampoline
 	// R18 is unused.
-	MOVD	R19, 136(RSP)
-	MOVD	R20, 144(RSP)
-	MOVD	R21, 152(RSP)
-	MOVD	R22, 160(RSP)
-	MOVD	R23, 168(RSP)
-	MOVD	R24, 176(RSP)
-	MOVD	R25, 184(RSP)
-	MOVD	R26, 192(RSP)
+	MOVD	R19, 120(RSP)
+	MOVD	R20, 128(RSP)
+	MOVD	R21, 136(RSP)
+	MOVD	R22, 144(RSP)
+	MOVD	R23, 152(RSP)
+	MOVD	R24, 160(RSP)
+	MOVD	R25, 168(RSP)
+	MOVD	R26, 176(RSP)
 	// R27 is temp register.
 	// R28 is g.
 	// R29 is frame pointer (unused).
@@ -1239,16 +1238,14 @@
 	MOVD	96(RSP), R13
 	MOVD	104(RSP), R14
 	MOVD	112(RSP), R15
-	MOVD	120(RSP), R16
-	MOVD	128(RSP), R17
-	MOVD	136(RSP), R19
-	MOVD	144(RSP), R20
-	MOVD	152(RSP), R21
-	MOVD	160(RSP), R22
-	MOVD	168(RSP), R23
-	MOVD	176(RSP), R24
-	MOVD	184(RSP), R25
-	MOVD	192(RSP), R26
+	MOVD	120(RSP), R19
+	MOVD	128(RSP), R20
+	MOVD	136(RSP), R21
+	MOVD	144(RSP), R22
+	MOVD	152(RSP), R23
+	MOVD	160(RSP), R24
+	MOVD	168(RSP), R25
+	MOVD	176(RSP), R26
 	JMP	ret
 
 // Note: these functions use a special calling convention to save generated code space.
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 003c7b0..8e1eb9e 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -393,7 +393,7 @@
 //go:nosplit
 func sigFetchG(c *sigctxt) *g {
 	switch GOARCH {
-	case "arm", "arm64":
+	case "arm", "arm64", "ppc64", "ppc64le":
 		if !iscgo && inVDSOPage(c.sigpc()) {
 			// When using cgo, we save the g on TLS and load it from there
 			// in sigtramp. Just use that.
diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index fd69ee7..7be8c4c 100644
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -215,15 +215,45 @@
 	MOVD	(g_sched+gobuf_sp)(R7), R1	// Set SP to g0 stack
 
 noswitch:
-	SUB	$16, R1			// Space for results
-	RLDICR	$0, R1, $59, R1		// Align for C code
+	SUB	$16, R1                 // Space for results
+	RLDICR	$0, R1, $59, R1         // Align for C code
 	MOVD	R12, CTR
 	MOVD	R1, R4
-	BL	(CTR)			// Call from VDSO
-	MOVD	$0, R0			// Restore R0
-	MOVD	0(R1), R3		// sec
-	MOVD	8(R1), R5		// nsec
-	MOVD	R15, R1			// Restore SP
+
+	// Store g on gsignal's stack, so if we receive a signal
+	// during VDSO code we can find the g.
+	// If we don't have a signal stack, we won't receive signal,
+	// so don't bother saving g.
+	// When using cgo, we already saved g on TLS, also don't save
+	// g here.
+	// Also don't save g if we are already on the signal stack.
+	// We won't get a nested signal.
+	MOVBZ	runtime·iscgo(SB), R22
+	CMP	R22, $0
+	BNE	nosaveg
+	MOVD	m_gsignal(R21), R22	// g.m.gsignal
+	CMP	R22, $0
+	BEQ	nosaveg
+
+	CMP	g, R22
+	BEQ	nosaveg
+	MOVD	(g_stack+stack_lo)(R22), R22 // g.m.gsignal.stack.lo
+	MOVD	g, (R22)
+
+	BL	(CTR)	// Call from VDSO
+
+	MOVD	$0, (R22)	// clear g slot, R22 is unchanged by C code
+
+	JMP	finish
+
+nosaveg:
+	BL	(CTR)	// Call from VDSO
+
+finish:
+	MOVD	$0, R0		// Restore R0
+	MOVD	0(R1), R3	// sec
+	MOVD	8(R1), R5	// nsec
+	MOVD	R15, R1		// Restore SP
 
 	// Restore vdsoPC, vdsoSP
 	// We don't worry about being signaled between the two stores.
@@ -235,7 +265,7 @@
 	MOVD	32(R1), R6
 	MOVD	R6, m_vdsoPC(R21)
 
-finish:
+return:
 	MOVD	R3, sec+0(FP)
 	MOVW	R5, nsec+8(FP)
 	RET
@@ -246,7 +276,7 @@
 	SYSCALL $SYS_clock_gettime
 	MOVD	32(R1), R3
 	MOVD	40(R1), R5
-	JMP	finish
+	JMP	return
 
 TEXT runtime·nanotime1(SB),NOSPLIT,$16-8
 	MOVD	$1, R3		// CLOCK_MONOTONIC
@@ -282,7 +312,37 @@
 	RLDICR	$0, R1, $59, R1		// Align for C code
 	MOVD	R12, CTR
 	MOVD	R1, R4
-	BL	(CTR)			// Call from VDSO
+
+	// Store g on gsignal's stack, so if we receive a signal
+	// during VDSO code we can find the g.
+	// If we don't have a signal stack, we won't receive signal,
+	// so don't bother saving g.
+	// When using cgo, we already saved g on TLS, also don't save
+	// g here.
+	// Also don't save g if we are already on the signal stack.
+	// We won't get a nested signal.
+	MOVBZ	runtime·iscgo(SB), R22
+	CMP	R22, $0
+	BNE	nosaveg
+	MOVD	m_gsignal(R21), R22	// g.m.gsignal
+	CMP	R22, $0
+	BEQ	nosaveg
+
+	CMP	g, R22
+	BEQ	nosaveg
+	MOVD	(g_stack+stack_lo)(R22), R22 // g.m.gsignal.stack.lo
+	MOVD	g, (R22)
+
+	BL	(CTR)	// Call from VDSO
+
+	MOVD	$0, (R22)	// clear g slot, R22 is unchanged by C code
+
+	JMP	finish
+
+nosaveg:
+	BL	(CTR)	// Call from VDSO
+
+finish:
 	MOVD	$0, R0			// Restore R0
 	MOVD	0(R1), R3		// sec
 	MOVD	8(R1), R5		// nsec
@@ -298,7 +358,7 @@
 	MOVD	32(R1), R6
 	MOVD	R6, m_vdsoPC(R21)
 
-finish:
+return:
 	// sec is in R3, nsec in R5
 	// return nsec in R3
 	MOVD	$1000000000, R4
@@ -313,7 +373,7 @@
 	SYSCALL $SYS_clock_gettime
 	MOVD	32(R1), R3
 	MOVD	40(R1), R5
-	JMP	finish
+	JMP	return
 
 TEXT runtime·rtsigprocmask(SB),NOSPLIT|NOFRAME,$0-28
 	MOVW	how+0(FP), R3
@@ -366,7 +426,7 @@
 	// this might be called in external code context,
 	// where g is not set.
 	MOVBZ	runtime·iscgo(SB), R6
-	CMP 	R6, $0
+	CMP	R6, $0
 	BEQ	2(PC)
 	BL	runtime·load_g(SB)