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// 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
// handleLoadUint32Fault returns the value stored in DI. Control is transferred
// to it when LoadUint32 below receives SIGSEGV or SIGBUS, with the signal
// number stored in DI.
//
// It must have the same frame configuration as loadUint32 so that it can undo
// any potential call frame set up by the assembler.
TEXT handleLoadUint32Fault(SB), NOSPLIT, $0-16
MOVW R1, sig+12(FP)
RET
// loadUint32 atomically loads *addr and returns it. If a SIGSEGV or SIGBUS
// signal is received, the value returned is unspecified, and sig is the number
// of the signal that was received.
//
// Preconditions: addr must be aligned to a 4-byte boundary.
//
//func loadUint32(ptr unsafe.Pointer) (val uint32, sig int32)
TEXT ·loadUint32(SB), NOSPLIT, $0-16
// 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,
// handleLoadUint32Fault will store a different value in this address.
MOVW $0, sig+12(FP)
MOVD addr+0(FP), R0
LDARW (R0), R1
MOVW R1, val+8(FP)
RET
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