enable kvm/testutil to support arm64

enable kvm/testutil to support arm64

The Arm64 user-mode execution stat consists of:
1, X0- X30
2, PC, SP, PSTATE
3, TPIDR_EL0, used for TLS
4, V0-V31: 32 128-bit registers for floating point and simd
5, FPSR

Currently, we first try to achieve goals 1 and 2.

This patch provids basic test utils for goals 1 & 2

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

5 files changed, 155 insertions, 3 deletions

diff --git a/pkg/sentry/platform/kvm/testutil/BUILD b/pkg/sentry/platform/kvm/testutil/BUILD
index 77a449a8b..b0e45f159 100644
--- a/pkg/sentry/platform/kvm/testutil/BUILD
+++ b/pkg/sentry/platform/kvm/testutil/BUILD
@@ -9,6 +9,8 @@ go_library(
         "testutil.go",
         "testutil_amd64.go",
         "testutil_amd64.s",
+        "testutil_arm64.go",
+        "testutil_arm64.s",
     ],
     importpath = "gvisor.dev/gvisor/pkg/sentry/platform/kvm/testutil",
     visibility = ["//pkg/sentry/platform/kvm:__pkg__"],
diff --git a/pkg/sentry/platform/kvm/testutil/testutil.go b/pkg/sentry/platform/kvm/testutil/testutil.go
index 6cf2359a3..5c1efa0fd 100644
--- a/pkg/sentry/platform/kvm/testutil/testutil.go
+++ b/pkg/sentry/platform/kvm/testutil/testutil.go
@@ -41,9 +41,6 @@ func TwiddleRegsFault()
 // TwiddleRegsSyscall twiddles registers then executes a syscall.
 func TwiddleRegsSyscall()
 
-// TwiddleSegments reads segments into known registers.
-func TwiddleSegments()
-
 // FloatingPointWorks is a floating point test.
 //
 // It returns true or false.
diff --git a/pkg/sentry/platform/kvm/testutil/testutil_amd64.go b/pkg/sentry/platform/kvm/testutil/testutil_amd64.go
index 203d71528..4c108abbf 100644
--- a/pkg/sentry/platform/kvm/testutil/testutil_amd64.go
+++ b/pkg/sentry/platform/kvm/testutil/testutil_amd64.go
@@ -21,6 +21,9 @@ import (
 	"syscall"
 )
 
+// TwiddleSegments reads segments into known registers.
+func TwiddleSegments()
+
 // SetTestTarget sets the rip appropriately.
 func SetTestTarget(regs *syscall.PtraceRegs, fn func()) {
 	regs.Rip = uint64(reflect.ValueOf(fn).Pointer())
diff --git a/pkg/sentry/platform/kvm/testutil/testutil_arm64.go b/pkg/sentry/platform/kvm/testutil/testutil_arm64.go
new file mode 100644
index 000000000..40b2e4acc
--- /dev/null
+++ b/pkg/sentry/platform/kvm/testutil/testutil_arm64.go
@@ -0,0 +1,59 @@
+// Copyright 2019 The gVisor Authors.
+//
+// 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.
+
+// +build arm64
+
+package testutil
+
+import (
+	"fmt"
+	"reflect"
+	"syscall"
+)
+
+// SetTestTarget sets the rip appropriately.
+func SetTestTarget(regs *syscall.PtraceRegs, fn func()) {
+	regs.Pc = uint64(reflect.ValueOf(fn).Pointer())
+}
+
+// SetTouchTarget sets rax appropriately.
+func SetTouchTarget(regs *syscall.PtraceRegs, target *uintptr) {
+	if target != nil {
+		regs.Regs[8] = uint64(reflect.ValueOf(target).Pointer())
+	} else {
+		regs.Regs[8] = 0
+	}
+}
+
+// RewindSyscall rewinds a syscall RIP.
+func RewindSyscall(regs *syscall.PtraceRegs) {
+	regs.Pc -= 4
+}
+
+// SetTestRegs initializes registers to known values.
+func SetTestRegs(regs *syscall.PtraceRegs) {
+	for i := 0; i <= 30; i++ {
+		regs.Regs[i] = uint64(i) + 1
+	}
+}
+
+// CheckTestRegs checks that registers were twiddled per TwiddleRegs.
+func CheckTestRegs(regs *syscall.PtraceRegs, full bool) (err error) {
+	for i := 0; i <= 30; i++ {
+		if need := ^uint64(i + 1); regs.Regs[i] != need {
+			err = addRegisterMismatch(err, fmt.Sprintf("R%d", i), regs.Regs[i], need)
+		}
+	}
+	return
+}
diff --git a/pkg/sentry/platform/kvm/testutil/testutil_arm64.s b/pkg/sentry/platform/kvm/testutil/testutil_arm64.s
new file mode 100644
index 000000000..2cd28b2d2
--- /dev/null
+++ b/pkg/sentry/platform/kvm/testutil/testutil_arm64.s
@@ -0,0 +1,91 @@
+// Copyright 2019 The gVisor Authors.
+//
+// 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.
+
+// +build arm64
+
+// test_util_arm64.s provides ARM64 test functions.
+
+#include "funcdata.h"
+#include "textflag.h"
+
+#define SYS_GETPID 172
+
+// This function simulates the getpid syscall.
+TEXT ·Getpid(SB),NOSPLIT,$0
+	NO_LOCAL_POINTERS
+	MOVD $SYS_GETPID, R8
+	SVC
+	RET
+
+TEXT ·Touch(SB),NOSPLIT,$0
+start:
+	MOVD 0(R8), R1
+	MOVD $SYS_GETPID, R8   // getpid
+	SVC
+	B start
+
+TEXT ·HaltLoop(SB),NOSPLIT,$0
+start:
+	HLT
+	B start
+
+// This function simulates a loop of syscall.
+TEXT ·SyscallLoop(SB),NOSPLIT,$0
+start:
+	SVC
+	B start
+
+TEXT ·SpinLoop(SB),NOSPLIT,$0
+start:
+	B start
+
+// MVN: bitwise logical NOT
+// This case simulates an application that modified R0-R30.
+#define TWIDDLE_REGS() \
+        MVN R0, R0; \
+        MVN R1, R1; \
+        MVN R2, R2; \
+        MVN R3, R3; \
+        MVN R4, R4; \
+        MVN R5, R5; \
+        MVN R6, R6; \
+        MVN R7, R7; \
+        MVN R8, R8; \
+        MVN R9, R9; \
+        MVN R10, R10; \
+        MVN R11, R11; \
+        MVN R12, R12; \
+        MVN R13, R13; \
+        MVN R14, R14; \
+        MVN R15, R15; \
+        MVN R16, R16; \
+        MVN R17, R17; \
+        MVN R18_PLATFORM, R18_PLATFORM; \
+        MVN R19, R19; \
+        MVN R20, R20; \
+        MVN R21, R21; \
+        MVN R22, R22; \
+        MVN R23, R23; \
+        MVN R24, R24; \
+        MVN R25, R25; \
+        MVN R26, R26; \
+        MVN R27, R27; \
+        MVN g, g; \
+        MVN R29, R29; \
+        MVN R30, R30;
+
+TEXT ·TwiddleRegsSyscall(SB),NOSPLIT,$0
+	TWIDDLE_REGS()
+	SVC
+	RET // never reached