diff options
| -rwxr-xr-x | pkg/safecopy/safecopy_unsafe.go | 98 |
1 files changed, 62 insertions, 36 deletions
diff --git a/pkg/safecopy/safecopy_unsafe.go b/pkg/safecopy/safecopy_unsafe.go index eef028e68..41dd567f3 100755 --- a/pkg/safecopy/safecopy_unsafe.go +++ b/pkg/safecopy/safecopy_unsafe.go @@ -16,6 +16,7 @@ package safecopy import ( "fmt" + "runtime" "syscall" "unsafe" ) @@ -35,7 +36,7 @@ const maxRegisterSize = 16 // successfully copied. // //go:noescape -func memcpy(dst, src unsafe.Pointer, n uintptr) (fault unsafe.Pointer, sig int32) +func memcpy(dst, src uintptr, n uintptr) (fault uintptr, sig int32) // memclr sets the n bytes following ptr to zeroes. If a SIGSEGV or SIGBUS // signal is received during the write, it returns the address that caused the @@ -47,7 +48,7 @@ func memcpy(dst, src unsafe.Pointer, n uintptr) (fault unsafe.Pointer, sig int32 // successfully written. // //go:noescape -func memclr(ptr unsafe.Pointer, n uintptr) (fault unsafe.Pointer, sig int32) +func memclr(ptr uintptr, n uintptr) (fault uintptr, sig int32) // swapUint32 atomically stores new into *ptr and returns (the previous *ptr // value, 0). If a SIGSEGV or SIGBUS signal is received during the swap, the @@ -90,29 +91,35 @@ func loadUint32(ptr unsafe.Pointer) (val uint32, sig int32) // CopyIn copies len(dst) bytes from src to dst. It returns the number of bytes // copied and an error if SIGSEGV or SIGBUS is received while reading from src. func CopyIn(dst []byte, src unsafe.Pointer) (int, error) { + n, err := copyIn(dst, uintptr(src)) + runtime.KeepAlive(src) + return n, err +} + +// copyIn is the underlying definition for CopyIn. +func copyIn(dst []byte, src uintptr) (int, error) { toCopy := uintptr(len(dst)) if len(dst) == 0 { return 0, nil } - fault, sig := memcpy(unsafe.Pointer(&dst[0]), src, toCopy) + fault, sig := memcpy(uintptr(unsafe.Pointer(&dst[0])), src, toCopy) if sig == 0 { return len(dst), nil } - faultN, srcN := uintptr(fault), uintptr(src) - if faultN < srcN || faultN >= srcN+toCopy { - panic(fmt.Sprintf("CopyIn raised signal %d at %#x, which is outside source [%#x, %#x)", sig, faultN, srcN, srcN+toCopy)) + if fault < src || fault >= src+toCopy { + panic(fmt.Sprintf("CopyIn raised signal %d at %#x, which is outside source [%#x, %#x)", sig, fault, src, src+toCopy)) } // memcpy might have ended the copy up to maxRegisterSize bytes before // fault, if an instruction caused a memory access that straddled two // pages, and the second one faulted. Try to copy up to the fault. var done int - if faultN-srcN > maxRegisterSize { - done = int(faultN - srcN - maxRegisterSize) + if fault-src > maxRegisterSize { + done = int(fault - src - maxRegisterSize) } - n, err := CopyIn(dst[done:int(faultN-srcN)], unsafe.Pointer(srcN+uintptr(done))) + n, err := copyIn(dst[done:int(fault-src)], src+uintptr(done)) done += n if err != nil { return done, err @@ -124,29 +131,35 @@ func CopyIn(dst []byte, src unsafe.Pointer) (int, error) { // bytes done and an error if SIGSEGV or SIGBUS is received while writing to // dst. func CopyOut(dst unsafe.Pointer, src []byte) (int, error) { + n, err := copyOut(uintptr(dst), src) + runtime.KeepAlive(dst) + return n, err +} + +// copyOut is the underlying definition for CopyOut. +func copyOut(dst uintptr, src []byte) (int, error) { toCopy := uintptr(len(src)) if toCopy == 0 { return 0, nil } - fault, sig := memcpy(dst, unsafe.Pointer(&src[0]), toCopy) + fault, sig := memcpy(dst, uintptr(unsafe.Pointer(&src[0])), toCopy) if sig == 0 { return len(src), nil } - faultN, dstN := uintptr(fault), uintptr(dst) - if faultN < dstN || faultN >= dstN+toCopy { - panic(fmt.Sprintf("CopyOut raised signal %d at %#x, which is outside destination [%#x, %#x)", sig, faultN, dstN, dstN+toCopy)) + if fault < dst || fault >= dst+toCopy { + panic(fmt.Sprintf("CopyOut raised signal %d at %#x, which is outside destination [%#x, %#x)", sig, fault, dst, dst+toCopy)) } // memcpy might have ended the copy up to maxRegisterSize bytes before // fault, if an instruction caused a memory access that straddled two // pages, and the second one faulted. Try to copy up to the fault. var done int - if faultN-dstN > maxRegisterSize { - done = int(faultN - dstN - maxRegisterSize) + if fault-dst > maxRegisterSize { + done = int(fault - dst - maxRegisterSize) } - n, err := CopyOut(unsafe.Pointer(dstN+uintptr(done)), src[done:int(faultN-dstN)]) + n, err := copyOut(dst+uintptr(done), src[done:int(fault-dst)]) done += n if err != nil { return done, err @@ -161,6 +174,14 @@ func CopyOut(dst unsafe.Pointer, src []byte) (int, error) { // Data is copied in order; if [src, src+toCopy) and [dst, dst+toCopy) overlap, // the resulting contents of dst are unspecified. func Copy(dst, src unsafe.Pointer, toCopy uintptr) (uintptr, error) { + n, err := copyN(uintptr(dst), uintptr(src), toCopy) + runtime.KeepAlive(dst) + runtime.KeepAlive(src) + return n, err +} + +// copyN is the underlying definition for Copy. +func copyN(dst, src uintptr, toCopy uintptr) (uintptr, error) { if toCopy == 0 { return 0, nil } @@ -171,17 +192,16 @@ func Copy(dst, src unsafe.Pointer, toCopy uintptr) (uintptr, error) { } // Did the fault occur while reading from src or writing to dst? - faultN, srcN, dstN := uintptr(fault), uintptr(src), uintptr(dst) faultAfterSrc := ^uintptr(0) - if faultN >= srcN { - faultAfterSrc = faultN - srcN + if fault >= src { + faultAfterSrc = fault - src } faultAfterDst := ^uintptr(0) - if faultN >= dstN { - faultAfterDst = faultN - dstN + if fault >= dst { + faultAfterDst = fault - dst } if faultAfterSrc >= toCopy && faultAfterDst >= toCopy { - panic(fmt.Sprintf("Copy raised signal %d at %#x, which is outside source [%#x, %#x) and destination [%#x, %#x)", sig, faultN, srcN, srcN+toCopy, dstN, dstN+toCopy)) + panic(fmt.Sprintf("Copy raised signal %d at %#x, which is outside source [%#x, %#x) and destination [%#x, %#x)", sig, fault, src, src+toCopy, dst, dst+toCopy)) } faultedAfter := faultAfterSrc if faultedAfter > faultAfterDst { @@ -195,7 +215,7 @@ func Copy(dst, src unsafe.Pointer, toCopy uintptr) (uintptr, error) { if faultedAfter > maxRegisterSize { done = faultedAfter - maxRegisterSize } - n, err := Copy(unsafe.Pointer(dstN+done), unsafe.Pointer(srcN+done), faultedAfter-done) + n, err := copyN(dst+done, src+done, faultedAfter-done) done += n if err != nil { return done, err @@ -206,6 +226,13 @@ func Copy(dst, src unsafe.Pointer, toCopy uintptr) (uintptr, error) { // ZeroOut writes toZero zero bytes to dst. It returns the number of bytes // written and an error if SIGSEGV or SIGBUS is received while writing to dst. func ZeroOut(dst unsafe.Pointer, toZero uintptr) (uintptr, error) { + n, err := zeroOut(uintptr(dst), toZero) + runtime.KeepAlive(dst) + return n, err +} + +// zeroOut is the underlying definition for ZeroOut. +func zeroOut(dst uintptr, toZero uintptr) (uintptr, error) { if toZero == 0 { return 0, nil } @@ -215,19 +242,18 @@ func ZeroOut(dst unsafe.Pointer, toZero uintptr) (uintptr, error) { return toZero, nil } - faultN, dstN := uintptr(fault), uintptr(dst) - if faultN < dstN || faultN >= dstN+toZero { - panic(fmt.Sprintf("ZeroOut raised signal %d at %#x, which is outside destination [%#x, %#x)", sig, faultN, dstN, dstN+toZero)) + if fault < dst || fault >= dst+toZero { + panic(fmt.Sprintf("ZeroOut raised signal %d at %#x, which is outside destination [%#x, %#x)", sig, fault, dst, dst+toZero)) } // memclr might have ended the write up to maxRegisterSize bytes before // fault, if an instruction caused a memory access that straddled two // pages, and the second one faulted. Try to write up to the fault. var done uintptr - if faultN-dstN > maxRegisterSize { - done = faultN - dstN - maxRegisterSize + if fault-dst > maxRegisterSize { + done = fault - dst - maxRegisterSize } - n, err := ZeroOut(unsafe.Pointer(dstN+done), faultN-dstN-done) + n, err := zeroOut(dst+done, fault-dst-done) done += n if err != nil { return done, err @@ -243,7 +269,7 @@ func SwapUint32(ptr unsafe.Pointer, new uint32) (uint32, error) { return 0, AlignmentError{addr, 4} } old, sig := swapUint32(ptr, new) - return old, errorFromFaultSignal(ptr, sig) + return old, errorFromFaultSignal(uintptr(ptr), sig) } // SwapUint64 is equivalent to sync/atomic.SwapUint64, except that it returns @@ -254,7 +280,7 @@ func SwapUint64(ptr unsafe.Pointer, new uint64) (uint64, error) { return 0, AlignmentError{addr, 8} } old, sig := swapUint64(ptr, new) - return old, errorFromFaultSignal(ptr, sig) + return old, errorFromFaultSignal(uintptr(ptr), sig) } // CompareAndSwapUint32 is equivalent to atomicbitops.CompareAndSwapUint32, @@ -265,7 +291,7 @@ func CompareAndSwapUint32(ptr unsafe.Pointer, old, new uint32) (uint32, error) { return 0, AlignmentError{addr, 4} } prev, sig := compareAndSwapUint32(ptr, old, new) - return prev, errorFromFaultSignal(ptr, sig) + return prev, errorFromFaultSignal(uintptr(ptr), sig) } // LoadUint32 is like sync/atomic.LoadUint32, but operates with user memory. It @@ -277,17 +303,17 @@ func LoadUint32(ptr unsafe.Pointer) (uint32, error) { return 0, AlignmentError{addr, 4} } val, sig := loadUint32(ptr) - return val, errorFromFaultSignal(ptr, sig) + return val, errorFromFaultSignal(uintptr(ptr), sig) } -func errorFromFaultSignal(addr unsafe.Pointer, sig int32) error { +func errorFromFaultSignal(addr uintptr, sig int32) error { switch sig { case 0: return nil case int32(syscall.SIGSEGV): - return SegvError{uintptr(addr)} + return SegvError{addr} case int32(syscall.SIGBUS): - return BusError{uintptr(addr)} + return BusError{addr} default: panic(fmt.Sprintf("safecopy got unexpected signal %d at address %#x", sig, addr)) } |