From: Roland Shoemaker <roland@golang.org>
Date: Wed, 10 Jul 2024 22:02:34 +0000 (-0500)
Subject: cmd/internal/obj/arm64: support MSR DIT
X-Git-Tag: go1.24rc1~1406
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=b5c2b1ec13f324743613bb33cbe6c664974db48e;p=gostls13.git

cmd/internal/obj/arm64: support MSR DIT

Set the right instruction bits in asmout in order
to allow using MSR with DIT and an immediate
value. This allows us to avoid using an
intermediary register when we want to set DIT
(unsetting DIT already worked with the zero
register).

Ref: https://developer.arm.com/documentation/ddi0602/2024-06/Base-Instructions/MSR--immediate---Move-immediate-value-to-special-register-?lang=en
Change-Id: Id049a0b4e0feb534cea992553228f9b5e12ddcea
Reviewed-on: https://go-review.googlesource.com/c/go/+/597595
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---

diff --git a/src/cmd/asm/internal/asm/testdata/arm64.s b/src/cmd/asm/internal/asm/testdata/arm64.s
index f12cdaf921..14a1c9141d 100644
--- a/src/cmd/asm/internal/asm/testdata/arm64.s
+++ b/src/cmd/asm/internal/asm/testdata/arm64.s
@@ -1777,6 +1777,7 @@ next:
 	MSR	R17, ZCR_EL1                       // 111218d5
 	SYS	$32768, R1                         // 018008d5
 	SYS	$32768                             // 1f8008d5
+	MSR	$1, DIT                            // 5f4103d5
 
 // TLBI instruction
 	TLBI	VMALLE1IS                          // 1f8308d5
diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index c6601cb49e..178c83c0bc 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -4229,6 +4229,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		// PSTATEfield can be special registers and special operands.
 		if p.To.Type == obj.TYPE_REG && p.To.Reg == REG_SPSel {
 			v = 0<<16 | 4<<12 | 5<<5
+		} else if p.To.Type == obj.TYPE_REG && p.To.Reg == REG_DIT {
+			// op1 = 011 (3) op2 = 010 (2)
+			v = 3<<16 | 2<<5
 		} else if p.To.Type == obj.TYPE_SPECIAL {
 			opd := SpecialOperand(p.To.Offset)
 			for _, pf := range pstatefield {