From: Keith Randall <khr@golang.org>
Date: Mon, 27 Feb 2023 16:53:34 +0000 (-0800)
Subject: cmd/asm: preserve 3rd arg when GOT-rewriting assembly instructions
X-Git-Tag: go1.21rc1~1451
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=1e0c32cccbe73be45414967612800be76d933870;p=gostls13.git

cmd/asm: preserve 3rd arg when GOT-rewriting assembly instructions

Fixes #58735

Change-Id: I7cc1c34ed8454553328d44b2ea72e4c0255b6ec1
Reviewed-on: https://go-review.googlesource.com/c/go/+/471675
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/cmd/asm/internal/asm/testdata/amd64dynlinkerror.s b/src/cmd/asm/internal/asm/testdata/amd64dynlinkerror.s
index 1eee1a17db..e110ee8118 100644
--- a/src/cmd/asm/internal/asm/testdata/amd64dynlinkerror.s
+++ b/src/cmd/asm/internal/asm/testdata/amd64dynlinkerror.s
@@ -66,3 +66,9 @@ two:
 one:
 	MOVL $0, R15
 	JMP two
+
+// Ensure 3-arg instructions get GOT-rewritten without errors.
+// See issue 58735.
+TEXT ·a13(SB), 0, $0-0
+	MULXQ runtime·writeBarrier(SB), AX, CX
+	RET
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index 5c7fb5c763..21126adfda 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -497,6 +497,9 @@ func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
 	p2.As = p.As
 	p2.From = p.From
 	p2.To = p.To
+	if from3 := p.GetFrom3(); from3 != nil {
+		p2.SetFrom3(*from3)
+	}
 	if p.From.Name == obj.NAME_EXTERN {
 		p2.From.Reg = reg
 		p2.From.Name = obj.NAME_NONE