Add muldiv/rd_tsc support for arm64 platform.

Signed-off-by: Haibo Xu <haibo.xu@arm.com>
Change-Id: If35459be78e023346a140184401172f8e023c7f9
PiperOrigin-RevId: 231638020

5 files changed, 167 insertions, 1 deletions

diff --git a/pkg/sentry/time/BUILD b/pkg/sentry/time/BUILD
index 5dadb8a2d..1191010e6 100644
--- a/pkg/sentry/time/BUILD
+++ b/pkg/sentry/time/BUILD
@@ -1,6 +1,6 @@
 load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
 
-package(licenses = ["notice"])  # Apache 2.0
+package(licenses = ["notice"])  # Apache 2.0, portions BSD
 
 load("//tools/go_generics:defs.bzl", "go_template_instance")
 
@@ -18,15 +18,18 @@ go_template_instance(
 go_library(
     name = "time",
     srcs = [
+        "arith_arm64.go",
         "calibrated_clock.go",
         "clock_id.go",
         "clocks.go",
         "muldiv_amd64.s",
+        "muldiv_arm64.s",
         "parameters.go",
         "sampler.go",
         "sampler_unsafe.go",
         "seqatomic_parameters.go",
         "tsc_amd64.s",
+        "tsc_arm64.s",
     ],
     importpath = "gvisor.googlesource.com/gvisor/pkg/sentry/time",
     visibility = ["//pkg/sentry:internal"],
diff --git a/pkg/sentry/time/LICENSE b/pkg/sentry/time/LICENSE
new file mode 100644
index 000000000..6a66aea5e
--- /dev/null
+++ b/pkg/sentry/time/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/pkg/sentry/time/arith_arm64.go b/pkg/sentry/time/arith_arm64.go
new file mode 100644
index 000000000..b94740c2a
--- /dev/null
+++ b/pkg/sentry/time/arith_arm64.go
@@ -0,0 +1,70 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file provides a generic Go implementation of uint128 divided by uint64.
+
+// The code is derived from Go's generic math/big.divWW_g
+// (src/math/big/arith.go), but is only used on ARM64.
+
+package time
+
+import "math/bits"
+
+type word uint
+
+const (
+	_W  = bits.UintSize // word size in bits
+	_W2 = _W / 2        // half word size in bits
+	_B2 = 1 << _W2      // half digit base
+	_M2 = _B2 - 1       // half digit mask
+)
+
+// nlz returns the number of leading zeros in x.
+// Wraps bits.LeadingZeros call for convenience.
+func nlz(x word) uint {
+	return uint(bits.LeadingZeros(uint(x)))
+}
+
+// q = (u1<<_W + u0 - r)/y
+// Adapted from Warren, Hacker's Delight, p. 152.
+func divWW(u1, u0, v word) (q, r word) {
+	if u1 >= v {
+		return 1<<_W - 1, 1<<_W - 1
+	}
+
+	s := nlz(v)
+	v <<= s
+
+	vn1 := v >> _W2
+	vn0 := v & _M2
+	un32 := u1<<s | u0>>(_W-s)
+	un10 := u0 << s
+	un1 := un10 >> _W2
+	un0 := un10 & _M2
+	q1 := un32 / vn1
+	rhat := un32 - q1*vn1
+
+	for q1 >= _B2 || q1*vn0 > _B2*rhat+un1 {
+		q1--
+		rhat += vn1
+
+		if rhat >= _B2 {
+			break
+		}
+	}
+
+	un21 := un32*_B2 + un1 - q1*v
+	q0 := un21 / vn1
+	rhat = un21 - q0*vn1
+
+	for q0 >= _B2 || q0*vn0 > _B2*rhat+un0 {
+		q0--
+		rhat += vn1
+		if rhat >= _B2 {
+			break
+		}
+	}
+
+	return q1*_B2 + q0, (un21*_B2 + un0 - q0*v) >> s
+}
diff --git a/pkg/sentry/time/muldiv_arm64.s b/pkg/sentry/time/muldiv_arm64.s
new file mode 100644
index 000000000..5fa82a136
--- /dev/null
+++ b/pkg/sentry/time/muldiv_arm64.s
@@ -0,0 +1,44 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "textflag.h"
+
+// Documentation is available in parameters.go.
+//
+// func muldiv64(value, multiplier, divisor uint64) (uint64, bool)
+TEXT ·muldiv64(SB),NOSPLIT,$40-33
+    MOVD    value+0(FP), R0
+    MOVD    multiplier+8(FP), R1
+    MOVD    divisor+16(FP), R2
+
+    UMULH   R0, R1, R3
+    MUL     R0, R1, R4
+
+    CMP     R2, R3
+    BHS     overflow
+
+    MOVD    R3, 8(RSP)
+    MOVD    R4, 16(RSP)
+    MOVD    R2, 24(RSP)
+    CALL    ·divWW(SB)
+    MOVD    32(RSP), R0
+    MOVD    R0, result+24(FP)
+    MOVD    $1, R0
+    MOVB    R0, ok+32(FP)
+    RET
+
+overflow:
+    MOVD    ZR, result+24(FP)
+    MOVB    ZR, ok+32(FP)
+    RET
diff --git a/pkg/sentry/time/tsc_arm64.s b/pkg/sentry/time/tsc_arm64.s
new file mode 100644
index 000000000..c1c9760ef
--- /dev/null
+++ b/pkg/sentry/time/tsc_arm64.s
@@ -0,0 +1,22 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "textflag.h"
+
+TEXT ·Rdtsc(SB),NOSPLIT,$0-8
+	// Get the virtual counter.
+	ISB	$15
+	WORD	$0xd53be040     //MRS	CNTVCT_EL0, R0
+	MOVD	R0, ret+0(FP)
+	RET