Change the read/write permissions of an address.

Change the read and write permissions of an address-General Linux technology-Linux programming and kernel information. For more information, see the following. Unsigned int ChangeProtection (const unsigned int ulAddr, const unsigned int ulLength, const unsigned int ulMode)
{
Int iRtn;
Unsigned int ulLastPageEnd;
Unsigned int ulFirstPageStart;

/* Find the start address of the page to which the adress belongs */
UlFirstPageStart = ulAddr-(ulAddr %4096 );

UlLastPageEnd = ulAddr + ulLength;
UlLastPageEnd + = 4096-(ulLastPageEnd % 4096 );

IRtn = mprotect (void *) ulFirstPageStart, ulLastPageEnd-ulFirstPageStart, ulMode );
// IRtn = mprotect (void *) ulFirstPageStart, 4096, ulMode );
If (0! = IRtn)
{
Printf ("\ r \ nCall mprotect fail! \ N ");
Return FALSE;
}

Return TRUE;
}

Use the above code to modify the read and write permissions of a space with the length of ulLength starting from the memory space ulAddr. Is there a problem?