From: Guoqi Chen <chenguoqi@loongson.cn>
Date: Tue, 28 Mar 2023 21:10:45 +0000 (+0800)
Subject: runtime: save/fetch g register during VDSO on linux/loong64
X-Git-Tag: go1.21rc1~570
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=42023d6f529239680773eab5343eedf641e78bb3;p=gostls13.git

runtime: save/fetch g register during VDSO on linux/loong64

Like arm64, ppc64 and risv64, on loong64, the G register may be temporarily
broken during a VDSO call. If a signal is received during a VDSO call, an
invalid G may be obtained.

See #34391.

Change-Id: Iaffa8cce4f0ef8ef74225c355ec3c20ed238025f
Reviewed-on: https://go-review.googlesource.com/c/go/+/426355
Reviewed-by: WANG Xuerui <git@xen0n.name>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: WANG Xuerui <git@xen0n.name>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go
index 5f733a90da..8a745ecda0 100644
--- a/src/runtime/signal_unix.go
+++ b/src/runtime/signal_unix.go
@@ -397,7 +397,7 @@ func preemptM(mp *m) {
 //go:nosplit
 func sigFetchG(c *sigctxt) *g {
 	switch GOARCH {
-	case "arm", "arm64", "ppc64", "ppc64le", "riscv64", "s390x":
+	case "arm", "arm64", "loong64", "ppc64", "ppc64le", "riscv64", "s390x":
 		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_loong64.s b/src/runtime/sys_linux_loong64.s
index 486a9b1570..12e5455345 100644
--- a/src/runtime/sys_linux_loong64.s
+++ b/src/runtime/sys_linux_loong64.s
@@ -11,7 +11,9 @@
 #include "textflag.h"
 #include "cgo/abi_loong64.h"
 
-#define AT_FDCWD -100
+#define AT_FDCWD	-100
+#define CLOCK_REALTIME	0
+#define CLOCK_MONOTONIC	1
 
 #define SYS_exit		93
 #define SYS_read		63
@@ -233,7 +235,7 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
 	RET
 
 // func walltime() (sec int64, nsec int32)
-TEXT runtime·walltime(SB),NOSPLIT,$16-12
+TEXT runtime·walltime(SB),NOSPLIT,$24-12
 	MOVV	R3, R23	// R23 is unchanged by C code
 	MOVV	R3, R25
 
@@ -263,12 +265,29 @@ noswitch:
 	AND	$~15, R25	// Align for C code
 	MOVV	R25, R3
 
-	MOVW	$0, R4 // CLOCK_REALTIME=0
+	MOVW	$CLOCK_REALTIME, R4
 	MOVV	$0(R3), R5
 
 	MOVV	runtime·vdsoClockgettimeSym(SB), R20
 	BEQ	R20, fallback
 
+	// Store g on gsignal's stack, see sys_linux_arm64.s for detail
+	MOVBU	runtime·iscgo(SB), R25
+	BNE	R25, nosaveg
+
+	MOVV	m_gsignal(R24), R25	// g.m.gsignal
+	BEQ	R25, nosaveg
+	BEQ	g, R25, nosaveg
+
+	MOVV	(g_stack+stack_lo)(R25), R25	// g.m.gsignal.stack.lo
+	MOVV	g, (R25)
+
+	JAL	(R20)
+
+	MOVV	R0, (R25)
+	JMP	finish
+
+nosaveg:
 	JAL	(R20)
 
 finish:
@@ -326,12 +345,29 @@ noswitch:
 	AND	$~15, R25	// Align for C code
 	MOVV	R25, R3
 
-	MOVW	$1, R4 // CLOCK_MONOTONIC=1
+	MOVW	$CLOCK_MONOTONIC, R4
 	MOVV	$0(R3), R5
 
 	MOVV	runtime·vdsoClockgettimeSym(SB), R20
 	BEQ	R20, fallback
 
+	// Store g on gsignal's stack, see sys_linux_arm64.s for detail
+	MOVBU	runtime·iscgo(SB), R25
+	BNE	R25, nosaveg
+
+	MOVV	m_gsignal(R24), R25	// g.m.gsignal
+	BEQ	R25, nosaveg
+	BEQ	g, R25, nosaveg
+
+	MOVV	(g_stack+stack_lo)(R25), R25	// g.m.gsignal.stack.lo
+	MOVV	g, (R25)
+
+	JAL	(R20)
+
+	MOVV	R0, (R25)
+	JMP	finish
+
+nosaveg:
 	JAL	(R20)
 
 finish: