From: Andrey Bokhanko <andreybokhanko@gmail.com>
Date: Fri, 31 Jan 2025 13:59:02 +0000 (+0300)
Subject: runtime: check LSE support on ARM64 at runtime init
X-Git-Tag: go1.25rc1~1003
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=81c66e71d480ae2372b7eea4bcdf600b50fdd5e1;p=gostls13.git

runtime: check LSE support on ARM64 at runtime init

Check presence of LSE support on ARM64 chip if we targeted it at compile
time.

Related to #69124
Updates #60905
Fixes #71411

Change-Id: I65e899a28ff64a390182572c0c353aa5931fc85d
Reviewed-on: https://go-review.googlesource.com/c/go/+/645795
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
---

diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s
index 64a1880589..bf9ab6bcbc 100644
--- a/src/runtime/asm_arm64.s
+++ b/src/runtime/asm_arm64.s
@@ -8,6 +8,28 @@
 #include "funcdata.h"
 #include "textflag.h"
 
+#ifdef GOARM64_LSE
+DATA no_lse_msg<>+0x00(SB)/64, $"This program can only run on ARM64 processors with LSE support.\n"
+GLOBL no_lse_msg<>(SB), RODATA, $64
+#endif
+
+// We know for sure that Linux and FreeBSD allow to read instruction set
+// attribute registers (while some others OSes, like OpenBSD and Darwin,
+// are not). Let's be conservative and allow code reading such registers
+// only when we sure this won't lead to sigill.
+#ifdef GOOS_linux
+#define ISA_REGS_READABLE
+#endif
+#ifdef GOOS_freebsd
+#define ISA_REGS_READABLE
+#endif
+
+#ifdef GOARM64_LSE
+#ifdef ISA_REGS_READABLE
+#define CHECK_GOARM64_LSE
+#endif
+#endif
+
 TEXT runtime·rt0_go(SB),NOSPLIT|TOPFRAME,$0
 	// SP = stack; R0 = argc; R1 = argv
 
@@ -77,6 +99,19 @@ nocgo:
 	BL	runtime·wintls(SB)
 #endif
 
+	// Check that CPU we use for execution supports instructions targeted during compile-time.
+#ifdef CHECK_GOARM64_LSE
+	// Read the ID_AA64ISAR0_EL1 register
+	MRS	ID_AA64ISAR0_EL1, R0
+
+	// Extract the LSE field (bits [23:20])
+	LSR	$20, R0, R0
+	AND	$0xf, R0, R0
+
+	// LSE support is indicated by a non-zero value
+	CBZ	R0, no_lse
+#endif
+
 	MOVW	8(RSP), R0	// copy argc
 	MOVW	R0, -8(RSP)
 	MOVD	16(RSP), R0		// copy argv
@@ -95,6 +130,21 @@ nocgo:
 
 	// start this M
 	BL	runtime·mstart(SB)
+	UNDEF
+
+#ifdef CHECK_GOARM64_LSE
+no_lse:
+	MOVD	$1, R0 // stderr
+	MOVD	R0, 8(RSP)
+	MOVD	$no_lse_msg<>(SB), R1 // message address
+	MOVD	R1, 16(RSP)
+	MOVD	$64, R2 // message length
+	MOVD	R2, 24(RSP)
+	CALL	runtime·write(SB)
+	CALL	runtime·exit(SB)
+	CALL	runtime·abort(SB)
+	RET
+#endif
 
 	// Prevent dead-code elimination of debugCallV2 and debugPinnerV1, which are
 	// intended to be called by debuggers.