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Diffstat (limited to 'pkg/sentry/platform/safecopy/safecopy.go')
-rw-r--r-- | pkg/sentry/platform/safecopy/safecopy.go | 144 |
1 files changed, 0 insertions, 144 deletions
diff --git a/pkg/sentry/platform/safecopy/safecopy.go b/pkg/sentry/platform/safecopy/safecopy.go deleted file mode 100644 index 2fb7e5809..000000000 --- a/pkg/sentry/platform/safecopy/safecopy.go +++ /dev/null @@ -1,144 +0,0 @@ -// 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. - -// Package safecopy provides an efficient implementation of functions to access -// memory that may result in SIGSEGV or SIGBUS being sent to the accessor. -package safecopy - -import ( - "fmt" - "reflect" - "runtime" - "syscall" - - "gvisor.dev/gvisor/pkg/syserror" -) - -// SegvError is returned when a safecopy function receives SIGSEGV. -type SegvError struct { - // Addr is the address at which the SIGSEGV occurred. - Addr uintptr -} - -// Error implements error.Error. -func (e SegvError) Error() string { - return fmt.Sprintf("SIGSEGV at %#x", e.Addr) -} - -// BusError is returned when a safecopy function receives SIGBUS. -type BusError struct { - // Addr is the address at which the SIGBUS occurred. - Addr uintptr -} - -// Error implements error.Error. -func (e BusError) Error() string { - return fmt.Sprintf("SIGBUS at %#x", e.Addr) -} - -// AlignmentError is returned when a safecopy function is passed an address -// that does not meet alignment requirements. -type AlignmentError struct { - // Addr is the invalid address. - Addr uintptr - - // Alignment is the required alignment. - Alignment uintptr -} - -// Error implements error.Error. -func (e AlignmentError) Error() string { - return fmt.Sprintf("address %#x is not aligned to a %d-byte boundary", e.Addr, e.Alignment) -} - -var ( - // The begin and end addresses below are for the functions that are - // checked by the signal handler. - memcpyBegin uintptr - memcpyEnd uintptr - memclrBegin uintptr - memclrEnd uintptr - swapUint32Begin uintptr - swapUint32End uintptr - swapUint64Begin uintptr - swapUint64End uintptr - compareAndSwapUint32Begin uintptr - compareAndSwapUint32End uintptr - loadUint32Begin uintptr - loadUint32End uintptr - - // savedSigSegVHandler is a pointer to the SIGSEGV handler that was - // configured before we replaced it with our own. We still call into it - // when we get a SIGSEGV that is not interesting to us. - savedSigSegVHandler uintptr - - // same a above, but for SIGBUS signals. - savedSigBusHandler uintptr -) - -// signalHandler is our replacement signal handler for SIGSEGV and SIGBUS -// signals. -func signalHandler() - -// FindEndAddress returns the end address (one byte beyond the last) of the -// function that contains the specified address (begin). -func FindEndAddress(begin uintptr) uintptr { - f := runtime.FuncForPC(begin) - if f != nil { - for p := begin; ; p++ { - g := runtime.FuncForPC(p) - if f != g { - return p - } - } - } - return begin -} - -// initializeAddresses initializes the addresses used by the signal handler. -func initializeAddresses() { - // The following functions are written in assembly language, so they won't - // be inlined by the existing compiler/linker. Tests will fail if this - // assumption is violated. - memcpyBegin = reflect.ValueOf(memcpy).Pointer() - memcpyEnd = FindEndAddress(memcpyBegin) - memclrBegin = reflect.ValueOf(memclr).Pointer() - memclrEnd = FindEndAddress(memclrBegin) - swapUint32Begin = reflect.ValueOf(swapUint32).Pointer() - swapUint32End = FindEndAddress(swapUint32Begin) - swapUint64Begin = reflect.ValueOf(swapUint64).Pointer() - swapUint64End = FindEndAddress(swapUint64Begin) - compareAndSwapUint32Begin = reflect.ValueOf(compareAndSwapUint32).Pointer() - compareAndSwapUint32End = FindEndAddress(compareAndSwapUint32Begin) - loadUint32Begin = reflect.ValueOf(loadUint32).Pointer() - loadUint32End = FindEndAddress(loadUint32Begin) -} - -func init() { - initializeAddresses() - if err := ReplaceSignalHandler(syscall.SIGSEGV, reflect.ValueOf(signalHandler).Pointer(), &savedSigSegVHandler); err != nil { - panic(fmt.Sprintf("Unable to set handler for SIGSEGV: %v", err)) - } - if err := ReplaceSignalHandler(syscall.SIGBUS, reflect.ValueOf(signalHandler).Pointer(), &savedSigBusHandler); err != nil { - panic(fmt.Sprintf("Unable to set handler for SIGBUS: %v", err)) - } - syserror.AddErrorUnwrapper(func(e error) (syscall.Errno, bool) { - switch e.(type) { - case SegvError, BusError, AlignmentError: - return syscall.EFAULT, true - default: - return 0, false - } - }) -} |