runtime: use MRS instruction to read system registers on freebsd/arm64

Support for these was added in CL 189577

Change-Id: Iaf2a774b141995cbbdfb3888aea67ae9c7f928b1
Reviewed-on: https://go-review.googlesource.com/c/go/+/210677
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/runtime/sys_freebsd_arm64.s b/src/runtime/sys_freebsd_arm64.s
index e0ef2f679de4a697d0886d2334e8ccdcf022263c..78cd9f15ee38338821caa1a96d93fe0755496006 100644 (file)
--- a/src/runtime/sys_freebsd_arm64.s
+++ b/src/runtime/sys_freebsd_arm64.s
@@ -506,38 +506,33 @@ TEXT runtime·getCntxct(SB),NOSPLIT,$0
        CMP     $0, R0
        BEQ     3(PC)
 
-       // get CNTPCT (Physical Count Register) into x0
-       // mrs x0, cntpct_el0 = d53be020
-       WORD    $0xd53be020 // SIGILL
+       // get CNTPCT (Physical Count Register) into R0
+       MRS     CNTPCT_EL0, R0 // SIGILL
        B       2(PC)
 
-       // get CNTVCT (Virtual Count Register) into x0
-       // mrs x0, cntvct_el0 = d53be040
-       WORD    $0xd53be040
+       // get CNTVCT (Virtual Count Register) into R0
+       MRS     CNTVCT_EL0, R0
 
        MOVW    R0, ret+8(FP)
        RET
 
 // func getisar0() uint64
 TEXT runtime·getisar0(SB),NOSPLIT,$0
-       // get Instruction Set Attributes 0 into x0
-       // mrs x0, ID_AA64ISAR0_EL1 = d5380600
-       WORD    $0xd5380600
+       // get Instruction Set Attributes 0 into R0
+       MRS     ID_AA64ISAR0_EL1, R0
        MOVD    R0, ret+0(FP)
        RET
 
 // func getisar1() uint64
 TEXT runtime·getisar1(SB),NOSPLIT,$0
-       // get Instruction Set Attributes 1 into x0
-       // mrs x0, ID_AA64ISAR1_EL1 = d5380620
-       WORD    $0xd5380620
+       // get Instruction Set Attributes 1 into R0
+       MRS     ID_AA64ISAR1_EL1, R0
        MOVD    R0, ret+0(FP)
        RET
 
 // func getpfr0() uint64
 TEXT runtime·getpfr0(SB),NOSPLIT,$0
-       // get Processor Feature Register 0 into x0
-       // mrs x0, ID_AA64PFR0_EL1 = d5380400
-       WORD    $0xd5380400
+       // get Processor Feature Register 0 into R0
+       MRS     ID_AA64PFR0_EL1, R0
        MOVD    R0, ret+0(FP)
        RET