|
VDSO
vDSO (virtual dynamic shared object) is a kernel mechanism for exporting a carefully selected set of kernel space routines to user space applications so that applications can call these kernel space routines in-process, without incurring the performance penalty of a mode switch from user mode to kernel mode that is inherent when calling these same kernel space routines by means of the system call interface. vDSO uses standard mechanisms for linking and loading i.e. standard Executable and Linkable Format (ELF) format. vDSO is a memory area allocated in user space which exposes some kernel functionalities. vDSO is dynamically allocated, offers improved safety through address space layout randomization, and supports more than four system calls. Some C standard libraries, like glibc, may provide vDSO links so that if the kernel does not have vDSO support, a traditional syscall is made. vDSO helps to reduce the calling overhead on simple kernel routines, and it also can work as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigreturn-oriented Programming
Sigreturn-oriented programming (SROP) is a computer security exploit technique that allows an attacker to execute code in presence of security measures such as non-executable memory and code signing. It was presented for the first time at the 35th IEEE Symposium on Security and Privacy in 2014 where it won the ''best student paper award''. This technique employs the same basic assumptions behind the return-oriented programming (ROP) technique: an attacker controlling the call stack, for example through a stack buffer overflow, is able to influence the control flow of the program through simple instruction sequences called ''gadgets''. The attack works by pushing a forged ''sigcontext'' structure on the call stack, overwriting the original return address with the location of a gadget that allows the attacker to call the ''sigreturn'' system call. Often just a single gadget is needed to successfully put this attack into effect. This gadget may reside at a fixed location, making this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel Mode
In computer science, hierarchical protection domains, often called protection rings, are mechanisms to protect data and functionality from faults (by improving fault tolerance) and malicious behavior (by providing computer security). Computer operating systems provide different levels of access to resources. A protection ring is one of two or more hierarchical ''levels'' or ''layers'' of privilege within the architecture of a computer system. This is generally hardware-enforced by some CPU architectures that provide different CPU modes at the hardware or microcode level. Rings are arranged in a hierarchy from most privileged (most trusted, usually numbered zero) to least privileged (least trusted, usually with the highest ring number). Ring 0 is the level with the most privileges and allows direct interaction with the physical hardware such as certain CPU functionality and chips on the motherboard. Special call gates between rings are provided to allow an outer ring to acces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Executable And Linkable Format
In computing, the Executable and Linkable FormatTool Interface Standard (TIS) Portable Formats SpecificationVersion 1.1'' (October 1993) (ELF, formerly named Extensible Linking Format), is a common standard file format for executable files, object code, shared libraries, and core dumps. First published in the specification for the application binary interface (ABI) of the Unix operating system version named System V Release 4 (SVR4), and later in the Tool Interface Standard,Tool Interface Standard (TIS) Executable and Linking Format (ELF) SpecificationVersion 1.2'' (May 1995) it was quickly accepted among different vendors of Unix systems. In 1999, it was chosen as the standard binary file format for Unix and Unix-like systems on x86 processors by the 86open project. By design, the ELF format is flexible, extensible, and cross-platform. For instance, it supports different endiannesses and address sizes so it does not exclude any particular central processing unit (CPU) or inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glibc
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by the Free Software Foundation (FSF) for the GNU operating system. Released under the GNU Lesser General Public License, glibc is free software. The GNU C Library project provides the core libraries for the GNU system, as well as many systems that use Linux as the kernel. These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread_create, crypt, login, exit and more. History The glibc project was initially written mostly by Roland McGrath, working for the Free Software Foundation (FSF) in the 1980s as a teenager. In February 1988, FSF described glibc as having nearly completed the func ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Application Binary Interface
In computer software, an application binary interface (ABI) is an interface between two binary program modules. Often, one of these modules is a library or operating system facility, and the other is a program that is being run by a user. An ''ABI'' defines how data structures or computational routines are accessed in machine code, which is a low-level, hardware-dependent format. In contrast, an ''API'' defines this access in source code, which is a relatively high-level, hardware-independent, often human-readable format. A common aspect of an ABI is the calling convention, which determines how data is provided as input to, or read as output from, computational routines. Examples of this are the x86 calling conventions. Adhering to an ABI (which may or may not be officially standardized) is usually the job of a compiler, operating system, or library author. However, an application programmer may have to deal with an ABI directly when writing a program in a mix of programming l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static Memory Allocation
In computer programming, a static variable is a variable that has been allocated "statically", meaning that its lifetime (or "extent") is the entire run of the program. This is in contrast to shorter-lived automatic variables, whose storage is stack allocated and deallocated on the call stack; and in contrast to objects, whose storage is dynamically allocated and deallocated in heap memory. Variable lifetime is contrasted with scope (where a variable can be used): "global" and "local" refer to scope, not lifetime, but scope often implies lifetime. In many languages, global variables are always static, but in some languages they are dynamic, while local variables are generally automatic, but may be static. In general, is the allocation of memory at compile time, before the associated program is executed, unlike dynamic memory allocation or automatic memory allocation where memory is allocated as required at run time. History Static variables date at least to ALGOL 60 (196 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DWARF
Dwarf or dwarves may refer to: Common uses *Dwarf (folklore), a being from Germanic mythology and folklore * Dwarf, a person or animal with dwarfism Arts, entertainment, and media Fictional entities * Dwarf (''Dungeons & Dragons''), a humanoid race *Dwarf (Middle-earth), a humanoid race in J. R. R. Tolkien's literature * Dwarf (''Warhammer''), a humanoid race * Dwarfs (''Discworld''), a race of characters * Dwarves (''Artemis Fowl''), a race of characters * Dwarves (''Warcraft''), a short, strong race *Dwarves (Marvel Comics) Literature * ''The Dwarf'' (Cho novel), a 1978 novel by Cho Se-hui * ''The Dwarf'' (Lagerkvist novel), a 1944 novel by Pär Lagerkvist Other arts, entertainment, and media * ''Dwarfs?!'' (video game) *Dwarves (band), American punk band *Killer Dwarfs, Canadian heavy metal band *Wrocław's dwarfs, small sculptures in Wrocław, Poland Biology *Phyletic dwarfism, an average decrease in size of animals **Insular dwarfism, a evolutionary condition caused by g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IA-32
IA-32 (short for "Intel Architecture, 32-bit", commonly called i386) is the 32-bit version of the x86 instruction set architecture, designed by Intel and first implemented in the 80386 microprocessor in 1985. IA-32 is the first incarnation of x86 that supports 32-bit computing; as a result, the "IA-32" term may be used as a metonym to refer to all x86 versions that support 32-bit computing. Within various programming language directives, IA-32 is still sometimes referred to as the "i386" architecture. In some other contexts, certain iterations of the IA-32 ISA are sometimes labelled i486, i586 and i686, referring to the instruction supersets offered by the 80486, the P5 and the P6 microarchitectures respectively. These updates offered numerous additions alongside the base IA-32 set including floating-point capabilities and the MMX extensions. Intel was historically the largest manufacturer of IA-32 processors, with the second biggest supplier having been AMD. During the 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Architectures
In computer engineering, computer architecture is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a more detailed level, the description may include the instruction set architecture design, microarchitecture design, logic design, and implementation. History The first documented computer architecture was in the correspondence between Charles Babbage and Ada Lovelace, describing the analytical engine. When building the computer Z1 in 1936, Konrad Zuse described in two patent applications for his future projects that machine instructions could be stored in the same storage used for data, i.e., the stored-program concept. Two other early and important examples are: * John von Neumann's 1945 paper, First Draft of a Report on the EDVAC, which described an organization of logical elements; and *Alan Turing's more detailed ''Proposed Electronic Calculator'' for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syscall
In computing, a system call (commonly abbreviated to syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, accessing a hard disk drive or accessing the device's camera), creation and execution of new processes, and communication with integral kernel services such as process scheduling. System calls provide an essential interface between a process and the operating system. In most systems, system calls can only be made from userspace processes, while in some systems, OS/360 and successors for example, privileged system code also issues system calls. Privileges The architecture of most modern processors, with the exception of some embedded systems, involves a security model. For example, the ''rings'' model specifies multiple privilege levels under which software may be executed: a program is usually limited to its own address space so that i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel Space
A modern computer operating system usually segregates virtual memory into user space and kernel space. Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour. Kernel space is strictly reserved for running a privileged operating system kernel, kernel extensions, and most device drivers. In contrast, user space is the memory area where application software and some drivers execute. Overview The term user space (or userland) refers to all code that runs outside the operating system's kernel. User space usually refers to the various programs and libraries that the operating system uses to interact with the kernel: software that performs input/output, manipulates file system objects, application software, etc. Each user space process normally runs in its own virtual memory space, and, unless explicitly allowed, cannot access the memory of other processes. This is the basis for memory protection in today' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Standard Libraries
The C standard library or libc is the standard library for the C programming language, as specified in the ISO C standard.ISO/IEC (2018). '' ISO/IEC 9899:2018(E): Programming Languages - C §7'' Starting from the original ANSI C standard, it was developed at the same time as the C library POSIX specification, which is a superset of it. Since ANSI C was adopted by the International Organization for Standardization, the C standard library is also called the ISO C library. The C standard library provides macros, type definitions and functions for tasks such as string handling, mathematical computations, input/output processing, memory management, and several other operating system services. Application programming interface Header files The application programming interface (API) of the C standard library is declared in a number of header files. Each header file contains one or more function declarations, data type definitions, and macros. After a long period of stabilit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
