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Diffstat (limited to 'pkg/safecopy/atomic_amd64.s')
| -rwxr-xr-x | pkg/safecopy/atomic_amd64.s | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/pkg/safecopy/atomic_amd64.s b/pkg/safecopy/atomic_amd64.s new file mode 100755 index 000000000..a0cd78f33 --- /dev/null +++ b/pkg/safecopy/atomic_amd64.s @@ -0,0 +1,136 @@ +// Copyright 2018 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. + +#include "textflag.h" + +// handleSwapUint32Fault returns the value stored in DI. Control is transferred +// to it when swapUint32 below receives SIGSEGV or SIGBUS, with the signal +// number stored in DI. +// +// 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 + MOVL DI, sig+20(FP) + RET + +// swapUint32 atomically stores new into *addr and returns (the previous *addr +// value, 0). If a SIGSEGV or SIGBUS signal is received during the swap, the +// value of old is unspecified, and sig is the number of the signal that was +// received. +// +// Preconditions: addr must be aligned to a 4-byte boundary. +// +//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. + MOVL $0, sig+20(FP) + + MOVQ addr+0(FP), DI + MOVL new+8(FP), AX + XCHGL AX, 0(DI) + MOVL AX, old+16(FP) + RET + +// handleSwapUint64Fault returns the value stored in DI. Control is transferred +// to it when swapUint64 below receives SIGSEGV or SIGBUS, with the signal +// number stored in DI. +// +// 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 + MOVL DI, sig+24(FP) + RET + +// swapUint64 atomically stores new into *addr and returns (the previous *addr +// value, 0). If a SIGSEGV or SIGBUS signal is received during the swap, the +// value of old is unspecified, and sig is the number of the signal that was +// received. +// +// Preconditions: addr must be aligned to a 8-byte boundary. +// +//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. + MOVL $0, sig+24(FP) + + MOVQ addr+0(FP), DI + MOVQ new+8(FP), AX + XCHGQ AX, 0(DI) + MOVQ AX, old+16(FP) + RET + +// handleCompareAndSwapUint32Fault returns the value stored in DI. Control is +// transferred to it when swapUint64 below receives SIGSEGV or SIGBUS, with the +// signal number stored in DI. +// +// 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 + MOVL DI, sig+20(FP) + RET + +// compareAndSwapUint32 is like sync/atomic.CompareAndSwapUint32, but returns +// (the value previously stored at addr, 0). If a SIGSEGV or SIGBUS signal is +// received during the operation, the value of prev is unspecified, and sig is +// the number of the signal that was received. +// +// Preconditions: addr must be aligned to a 4-byte boundary. +// +//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. + MOVL $0, sig+20(FP) + + MOVQ addr+0(FP), DI + MOVL old+8(FP), AX + MOVL new+12(FP), DX + LOCK + CMPXCHGL DX, 0(DI) + MOVL AX, 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 + MOVL DI, 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. + MOVL $0, sig+12(FP) + + MOVQ addr+0(FP), AX + MOVL (AX), BX + MOVL BX, val+8(FP) + RET |