195 lines
4.4 KiB
C
195 lines
4.4 KiB
C
/*++
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Copyright (c) 1990-1993 Microsoft Corporation
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Module Name:
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probe.c
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Abstract:
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This module implements the probe for write function.
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Author:
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David N. Cutler (davec) 19-Jan-1990
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Environment:
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Any mode.
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Revision History:
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--*/
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#include "exp.h"
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#if defined(ALLOC_PRAGMA)
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#pragma alloc_text(PAGE, ProbeForWrite)
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#pragma alloc_text(PAGE, ProbeForRead)
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#endif
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VOID
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ProbeForWrite (
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IN PVOID Address,
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IN ULONG Length,
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IN ULONG Alignment
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)
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/*++
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Routine Description:
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This function probes a structure for write accessibility and ensures
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correct alignment of the structure. If the structure is not accessible
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or has incorrect alignment, then an exception is raised.
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Arguments:
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Address - Supplies a pointer to the structure to be probed.
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Length - Supplies the length of the structure.
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Alignment - Supplies the required alignment of the structure expressed
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as the number of bytes in the primitive datatype (e.g., 1 for char,
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2 for short, 4 for long, and 8 for quad).
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Return Value:
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None.
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--*/
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{
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ULONG_PTR EndAddress;
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ULONG_PTR StartAddress;
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// If the structure has zero length, then do not probe the structure for
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// write accessibility or alignment.
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if (Length != 0) {
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// If the structure is not properly aligned, then raise a data
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// misalignment exception.
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ASSERT((Alignment == 1) || (Alignment == 2) ||
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(Alignment == 4) || (Alignment == 8) ||
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(Alignment == 16));
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StartAddress = (ULONG_PTR)Address;
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if ((StartAddress & (Alignment - 1)) == 0) {
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// Compute the ending address of the structure and probe for
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// write accessibility.
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EndAddress = StartAddress + Length - 1;
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if ((StartAddress <= EndAddress) &&
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(EndAddress < MM_USER_PROBE_ADDRESS)) {
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// N.B. Only the contents of the buffer may be probed.
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// Therefore the starting byte is probed for the
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// first page, and then the first byte in the page
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// for each succeeding page.
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EndAddress = (EndAddress & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
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#if defined(_ALPHA_)
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// N.B. The address is truncated to a longword aligned
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// address since Alpha has no load or store byte
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// instructions.
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StartAddress &= ~((ULONG_PTR)sizeof(LONG) - 1);
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do {
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*(volatile LONG *)StartAddress = *(volatile LONG *)StartAddress;
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StartAddress = (StartAddress & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
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} while (StartAddress != EndAddress);
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#else
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do {
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*(volatile CHAR *)StartAddress = *(volatile CHAR *)StartAddress;
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StartAddress = (StartAddress & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
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} while (StartAddress != EndAddress);
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#endif
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return;
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} else {
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ExRaiseAccessViolation();
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}
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} else {
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ExRaiseDatatypeMisalignment();
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}
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}
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return;
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}
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#undef ProbeForRead
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NTKERNELAPI
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VOID
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NTAPI
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ProbeForRead(
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IN CONST VOID *Address,
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IN ULONG Length,
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IN ULONG Alignment
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)
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/*++
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Routine Description:
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This function probes a structure for read accessibility and ensures
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correct alignment of the structure. If the structure is not accessible
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or has incorrect alignment, then an exception is raised.
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Arguments:
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Address - Supplies a pointer to the structure to be probed.
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Length - Supplies the length of the structure.
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Alignment - Supplies the required alignment of the structure expressed
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as the number of bytes in the primitive datatype (e.g., 1 for char,
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2 for short, 4 for long, and 8 for quad).
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Return Value:
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None.
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--*/
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{
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PAGED_CODE();
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ASSERT(((Alignment) == 1) || ((Alignment) == 2) ||
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((Alignment) == 4) || ((Alignment) == 8) ||
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((Alignment) == 16));
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if ((Length) != 0) {
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if (((ULONG_PTR)(Address) & ((Alignment) - 1)) != 0) {
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ExRaiseDatatypeMisalignment();
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} else if ((((ULONG_PTR)(Address) + (Length)) < (ULONG_PTR)(Address)) ||
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(((ULONG_PTR)(Address) + (Length)) > (ULONG_PTR)MM_USER_PROBE_ADDRESS)) {
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ExRaiseAccessViolation();
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}
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}
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}
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