Add safecopy support for arm64 platform.

Signed-off-by: Haibo Xu <haibo.xu@arm.com>
Change-Id: I565214581eeb44045169da7f44d45a489082ac3a
PiperOrigin-RevId: 224938170

1 files changed, 98 insertions, 0 deletions

diff --git a/pkg/sentry/platform/safecopy/atomic_arm64.s b/pkg/sentry/platform/safecopy/atomic_arm64.s
new file mode 100644
index 000000000..554a5c1e1
--- /dev/null
+++ b/pkg/sentry/platform/safecopy/atomic_arm64.s
@@ -0,0 +1,98 @@
+// Copyright 2014 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.
+
+#include "textflag.h"
+
+// handleSwapUint32Fault returns the value stored in R1. Control is transferred
+// to it when swapUint32 below receives SIGSEGV or SIGBUS, with the signal
+// number stored in R1.
+//
+// It must have the same frame configuration as swapUint32 so that it can undo
+// any potential call frame set up by the assembler.
+TEXT handleSwapUint32Fault(SB), NOSPLIT, $0-24
+	MOVW R1, sig+20(FP)
+	RET
+
+// See the corresponding doc in safecopy_unsafe.go
+//
+// The code is derived from Go source runtime/internal/atomic.Xchg.
+//
+//func swapUint32(ptr unsafe.Pointer, new uint32) (old uint32, sig int32)
+TEXT ·swapUint32(SB), NOSPLIT, $0-24
+	// Store 0 as the returned signal number. If we run to completion,
+	// this is the value the caller will see; if a signal is received,
+	// handleSwapUint32Fault will store a different value in this address.
+	MOVW $0, sig+20(FP)
+again:
+	MOVD addr+0(FP), R0
+	MOVW new+8(FP), R1
+	LDAXRW (R0), R2
+	STLXRW R1, (R0), R3
+	CBNZ R3, again
+	MOVW R2, old+16(FP)
+	RET
+
+// handleSwapUint64Fault returns the value stored in R1. Control is transferred
+// to it when swapUint64 below receives SIGSEGV or SIGBUS, with the signal
+// number stored in R1.
+//
+// It must have the same frame configuration as swapUint64 so that it can undo
+// any potential call frame set up by the assembler.
+TEXT handleSwapUint64Fault(SB), NOSPLIT, $0-28
+	MOVW R1, sig+24(FP)
+	RET
+
+// See the corresponding doc in safecopy_unsafe.go
+//
+// The code is derived from Go source runtime/internal/atomic.Xchg64.
+//
+//func swapUint64(ptr unsafe.Pointer, new uint64) (old uint64, sig int32)
+TEXT ·swapUint64(SB), NOSPLIT, $0-28
+	// Store 0 as the returned signal number. If we run to completion,
+	// this is the value the caller will see; if a signal is received,
+	// handleSwapUint64Fault will store a different value in this address.
+	MOVW $0, sig+24(FP)
+again:
+	MOVD addr+0(FP), R0
+	MOVD new+8(FP), R1
+	LDAXR (R0), R2
+	STLXR R1, (R0), R3
+	CBNZ R3, again
+	MOVD R2, old+16(FP)
+	RET
+
+// handleCompareAndSwapUint32Fault returns the value stored in R1. Control is
+// transferred to it when compareAndSwapUint32 below receives SIGSEGV or SIGBUS,
+// with the signal number stored in R1.
+//
+// It must have the same frame configuration as compareAndSwapUint32 so that it
+// can undo any potential call frame set up by the assembler.
+TEXT handleCompareAndSwapUint32Fault(SB), NOSPLIT, $0-24
+	MOVW R1, sig+20(FP)
+	RET
+
+// See the corresponding doc in safecopy_unsafe.go
+//
+// The code is derived from Go source runtime/internal/atomic.Cas.
+//
+//func compareAndSwapUint32(ptr unsafe.Pointer, old, new uint32) (prev uint32, sig int32)
+TEXT ·compareAndSwapUint32(SB), NOSPLIT, $0-24
+	// Store 0 as the returned signal number. If we run to completion, this is
+	// the value the caller will see; if a signal is received,
+	// handleCompareAndSwapUint32Fault will store a different value in this
+	// address.
+	MOVW $0, sig+20(FP)
+
+	MOVD addr+0(FP), R0
+	MOVW old+8(FP), R1
+	MOVW new+12(FP), R2
+again:
+	LDAXRW (R0), R3
+	CMPW R1, R3
+	BNE done
+	STLXRW R2, (R0), R4
+	CBNZ R4, again
+done:
+	MOVW R3, prev+16(FP)
+	RET