IBM Novell 10 SP1 EAL4 - Manual (Page 229)

passed as system-call parameters. For the sake of efficiency, and satisfying the access control requirement,
the SLES kernel performs validation in a two-step process, as follows:
1. Verifies that the linear address (virtual address for System p and System z) passed as a parameter does not
fall within the range of interval addresses reserved for the kernel. That is, that the linear address is lower than
PAGE_OFFSET.
2. Because bad addresses lower than PAGE_OFFSET cause a page fault, the kernel consults the exception
table and verifies that the address of the instruction that triggered the exception is NOT included in the table.
Exception tables are automatically generated by the C compiler when building the kernel image. They
contain addresses of instructions that access the process address space.
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