From: Sebastian Nickolls <sebastian.nickolls@arm.com>
Date: Tue, 13 Aug 2024 10:47:40 +0000 (+0100)
Subject: cmd/internal/obj/arm64: Emit UDF instruction for undefined Prog nodes
X-Git-Tag: go1.24rc1~1201
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=3e3ce20df87b2de86fbcbbad863b07b1a133e879;p=gostls13.git

cmd/internal/obj/arm64: Emit UDF instruction for undefined Prog nodes

UDF provides a stronger guarantee for generating the Undefined
Instruction exception than the current value being emitted.

Change-Id: I234cd70ce04f21311959c1061ae24992438105f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/605155
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index 178c83c0bc..bd2bd037ba 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -5338,10 +5338,10 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 	// This is supposed to be something that stops execution.
 	// It's not supposed to be reached, ever, but if it is, we'd
 	// like to be able to tell how we got there. Assemble as
-	// 0xbea71700 which is guaranteed to raise undefined instruction
+	// UDF which is guaranteed to raise the undefined instruction
 	// exception.
 	case 90:
-		o1 = 0xbea71700
+		o1 = 0x0
 
 	case 91: /* prfm imm(Rn), <prfop | $imm5> */
 		imm := uint32(p.From.Offset)