Information Technology & Cybersecurity

In this post I will keep on adding the best references for the stuffs related to Linux Kernel like powerful tools and utilities, memory related stuffs, vulnerabilities & hacks, process, kernel internals etc. 1. How to translate the virtual into physical address through /proc/pid/pagemap http://fivelinesofcode.blogspot.com/2014/03/how-to-translate-virtual-to-physical.html This I tried, but I am not sure if the physical address that has been read from the pagemap is proven. I was getting a 64-Bit long address. 2. Understanding how insmod works http://gomathikumar1006.blogspot.com/2013/09/linux-kernel-module-internals-of-insmod.html

In this write up, we will focus mainly on the ARMv8-A exceptions, the role of ARM Trusted Firmware (that provides Secure Monitor functionality) and how the World Switch happens between Secure and Normal. If we look on the the architectural diagram of ARM Trustzone w.r.t ARMv8-A, the Execution Level is divided into four levels namely: EL0 (Secure & Non-Secure) - User Application EL1 (Secure & Non-Secure) - Kernel EL2 - Hypervisor for running different OS's simuntaneously EL3 - Security Monitor Now, whenever a normal world User Application calls for some Secure Operation, the calls goes via IOCTL call to the Linux Driver, which ultimately calls the smc instruction. To understand what the smc instruction, we have to look on the Exceptions in ARMv8 ARMv8 Exceptions In ARMv8 the exceptions are divided into two categories: Synchronous & Asynchronous.  An exception is described as synchronous if it is generated as a result of execution or attempted executi...

The scope of this documentation is to understand the Memory Management Unit for ARMv8 Based processor. Memory management Unit converts the virtual Address (in CPU's logical space) into Physical Address. For an example let us suppose in the following program: int variable; printf("Addrss of variable = 0x%x\n", &variable); The address could be anything (Let's assume  0x40000200 ). Now 0x40000200 may or may not the actual memory address in the Physical Memory (RAM). It could be anything thing (lets assume  0xA0000200 ). Thus the CPU produce the logical address 0x40000200 which is converted into the physical address 0xA0000200 by the Memory Management Unit. Now the question remains Why we require an Address Translation, or in other word in the above program why we don't operate on actual physical memory 0xA0000200? Let us suppose a program that requires a huge amount of contagious memory in the RAM. Now our external memory would have that much memory requ...