add usr-tls test cases for Arm64

Signed-off-by: Bin Lu <bin.lu@arm.com>

pkg/sentry/platform/kvm/testutil/testutil_arm64.go

@@ -56,5 +56,9 @@ func CheckTestRegs(regs *arch.Registers, full bool) (err error) {
 			err = addRegisterMismatch(err, fmt.Sprintf("R%d", i), regs.Regs[i], need)
 		}
 	}
+	// Check tls.
+	if need := ^uint64(11); regs.TPIDR_EL0 != need {
+		err = addRegisterMismatch(err, "tpdir_el0", regs.TPIDR_EL0, need)
+	}
 	return
 }

pkg/sentry/platform/kvm/testutil/testutil_arm64.s

@@ -52,6 +52,8 @@ start:
 
 TEXT ·FloatingPointWorks(SB),NOSPLIT,$0-8
 	NO_LOCAL_POINTERS
+	// gc will touch fpsimd, so we should test it.
+	// such as in <runtime.deductSweepCredit>.
 	FMOVD $(9.9), F0
 	MOVD $SYS_GETPID, R8 // getpid
 	SVC
@@ -102,11 +104,15 @@ isNaN:
 
 TEXT ·TwiddleRegsSyscall(SB),NOSPLIT,$0
 	TWIDDLE_REGS()
+	MSR R10, TPIDR_EL0
+	// Trapped in el0_svc.
 	SVC
 	RET // never reached
 
 TEXT ·TwiddleRegsFault(SB),NOSPLIT,$0
-        TWIDDLE_REGS()
-        // Branch to Register branches unconditionally to an address in <Rn>.
-        JMP (R4) // <=> br x4, must fault
-        RET // never reached
+	TWIDDLE_REGS()
+	MSR R10, TPIDR_EL0
+	// Trapped in el0_ia.
+	// Branch to Register branches unconditionally to an address in <Rn>.
+	JMP (R6) // <=> br x6, must fault
+	RET // never reached