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The MMU detects the page fault, but the operating system's kernel handles the exception by making the required page accessible in the physical memory or denying an illegal memory access. Valid page faults are common and necessary to increase the amount of memory available to programs in any operating system that uses virtual memory , such as ...
After recompiling a kernel binary image from source code, a kernel panic while booting the resulting kernel is a common problem if the kernel was not correctly configured, compiled or installed. [8] Add-on hardware or malfunctioning RAM could also be sources of fatal kernel errors during start up, due to incompatibility with the OS or a missing ...
One set of page tables includes both kernel-space and user-space addresses same as before, but it is only used when the system is running in kernel mode. The second set of page tables for use in user mode contains a copy of user-space and a minimal set of kernel-space mappings that provides the information needed to enter or exit system calls ...
Address space layout randomization (ASLR) is a computer security technique involved in preventing exploitation of memory corruption vulnerabilities. [1] In order to prevent an attacker from reliably redirecting code execution to, for example, a particular exploited function in memory, ASLR randomly arranges the address space positions of key data areas of a process, including the base of the ...
W – word […] G – paragraph […] xR – inpage […] P – page […] A – absolute […] the x in the inpage alignment code can be any other alignment code. […] a segment can have the inpage attribute, meaning it must reside within a 256 byte page and can have the word attribute, meaning it must reside on an even numbered byte.
After a system has experienced an oops, some internal resources may no longer be operational. Thus, even if the system appears to work correctly, undesirable side effects may have resulted from the active task being killed. A kernel oops often leads to a kernel panic when the system attempts to use resources that have been lost. Some kernels ...
Dereferencing any of these variables could cause a segmentation fault: dereferencing the null pointer generally will cause a segfault, while reading from the wild pointer may instead result in random data but no segfault, and reading from the dangling pointer may result in valid data for a while, and then random data as it is overwritten.
This allows for the kernel to use a different stack than the user program, and also have this stack be unique for each user program. A new feature introduced in the AMD64 extensions is called the Interrupt Stack Table (IST), which also resides in the TSS and contains logical (segment+offset) stack pointers.