Fast system call method
A method of a fast system call is provided. First, a logical operation to compute a kernel service routine is used. Then the logical operation result is compared with ciphertext from a key register. At least one input for the logical operation is from the relevant information of the required kernel service routine. For example, the start address of the kernel service routine or the content of the start address of the kernel service routine, or combinations thereof. If the logical operation result equals to the ciphertext of the key register, a switch from a user mode to a kernel mode to read the kernel service routine is allowed. Otherwise, the central processing system executes a corresponding exceptional handler routine. Then the operating system terminates the mode switch request and reports an error to the operating system.
1. A fast system call method, comprising:
designating a ciphertext in a kernel service routine by a kernel, the ciphertext controlling an entry point to the kernel service routine;
requesting access to the kernel service routine by a user mode program;
computing the kernel service routine using a logical operation to generate a logical operation result;
comparing the logical operation result with the ciphertext; and
directly accessing the kernel service routine through the entry point if the logical operation result is equal to the ciphertext;
wherein the logical operation computes relevant information of the kernel service routine to generate the logical operation result;
wherein the logical operation is an AND operation, an OR operation, a NOT operation, an AND-NOT operation, an exclusive OR operation, a NOT exclusive OR operation, or a Data Encryption Standard, and
executing a corresponding exceptional handler routine if the logical operation result is not equal to the ciphertext.
2. The fast system call method of claim 1 , wherein a data segment and a code segment of the kernel service routine are stored in the same page.
3. A fast system call apparatus, comprising:
a kernel for designating a ciphertext in a kernel service routine, the ciphertext controlling an entry point to the kernel service routine;
a user mode program for requesting access to the kernel service routine; means for computing the kernel service routine using a logical operation to generate a logical operation result;
means for comparing the logical operation result with the ciphertext; and
means for directly accessing the kernel service routine through the entry point if the logical operation result is equal to the ciphertext,
wherein the logical operation computes relevant information of the kernel service routine to generate the logical operation result,
wherein the logical operation is an AND operation, an OR operation, a NOT operation, an AND-NOT operation, an exclusive OR operation, a NOT exclusive OR operation, or a Data Encryption Standard, and
means for executing a corresponding exceptional handler routine if the logical operation result is not equal to the ciphertext.
4. The fast system call apparatus of claim 3 , wherein a data segment and a code segment of the kernel service routine are stored in the same page.