Speculative architecture is a collaborative studio practice, led by dirk yates, that specialises in the design and delivery of public and educational buildings. This exploit, coupled with a sidechannel attack, can lead to the exposure and theft of critical secret information. Another form of spec exec is branch prediction, another is walking the page tables ahead of time. This approach is different than that taken in any other computer architecture text, and it is a bold step. Speculative execution in high performance computer architectures describes many recent advances in speculative execution techniques. Processors can take more risks with instruction ordering when it comes to execution because, if things dont work out as planned, they can roll. And speculative execution, while implemented differently from company to company, is. Until now, there were few textbooks that focused on the dynamic subject of speculative execution, a topic that is crucial to the development of. Almost none of the major computer architecture conferences in recent years can go without including some papers touched on the subject of speculative execution.
While speculative execution never hurts performance, it can be poorly utilized by software, leading to a high performance opportunity cost, that is, the performance that could have been achieved had the code been tuned better. On july 9, 2019 we released security updates for the windows operating system to help mitigate this issue. Every single highend cpu architecture today amd, arm, ibm, intel, sparc uses outoforder execution. Speculative execution is extensive in modern processors. Computer architecture download ebook pdf, epub, tuebl, mobi.
Speculative execution has been in the news of late, typically when. Speculative execution an overview sciencedirect topics. If youre looking for a free download links of inside the machine. Speculative execution is an optimization technique where a computer system performs some task that may not be needed. Incidentally, the purpose of the mill deferred load facility is to mask the l1 and l2 latencies, not to mask the dram latency. May 16, 2019 every single highend cpu architecture today amd, arm, ibm, intel, sparc uses outoforder execution. Jan 22, 2018 speculative execution plays a key role in the meltdown and spectre attacks. From microprocessors to supercomputers provides a comprehensive introduction to this thriving and exciting field. May 14, 2019 this vulnerability is a variant of the spectre variant 1 speculative execution side channel vulnerability and has been assigned cve20191125. Introduction 11 it deals with data path design and data ow control concepts and introduces the need of microoperations for a processor.
Well have compiler bugs for sure i write compilers but we fix them. Every single highend cpu architecture today amd, arm, ibm. Note that speculative execution can be applied even if there isnt an actual conditional branch in the code. Decoupled memory access architectures with speculative pre. Speculative execution is an optimization technique where a computer system performs some. Speculative execution in high performance computer architectures. Speculative execution plays a key role in the meltdown and spectre attacks. This vulnerability is a variant of the spectre variant 1 speculative execution side channel vulnerability and has been assigned cve20191125. Jan 04, 2018 were all getting quite the lesson in speculative execution today, and why faster isnt always better. If the branch prediction was correct, the result is used, otherwise it is discarded. Brief history of computer architecture predication and speculation compiling for ia64 b a s1 c move code above a split cs553 lecture predication and speculation 3 a brief history of computer architecture the early years.
We have developed projects with institutional organisations including the queensland government, brisbane city council, museum of brisbane. Parts of the computer and microprocessor programming fundamentals arithmetic instructions, memory accesses, control flow instructions, and data types intermediate and advanced microprocessor concepts branch prediction and speculative execution. At this stage the processor has two choices, either wait for the preceding instructions to complete and incur a huge. The first book to describe some of the speculative execution techniques used to overcome performance problems in modern computer architectures, this book discusses research projects and commercial. When they generate code, compilers take a best guess at the best order for instructions but have to err on the safe side. One could design a processor this ooo but not speculative or speculative but inorder. Computer architecture books meet your next favorite book. This book examines computer architecture, computability theory, and the history of computers from the perspective of minimalist computing a framework in which the instruction set consists of a single instruction.
Swarup bhunia, mark tehranipoor, in hardware security, 2019. Ooo execution is an execution model in which instructions can be executed in an order that is potentially different from the program order. If the compiler did not hoist that code then there is a compiler bug, not an architecture problem. Speculative execution and outoforder execution are orthogonal. Speculation also known as speculative loading, is a process implemented in explicitly parallel instruction computing epic processors and their compiler s to reduce processormemory exchanging bottlenecks or latency by putting all the data into memory in advance of an actual load instruction. Technically, ooo is the ability to move execution between different dependency chains, so skipping an inst and moving to the next one. These modifications are layered on top of the sanctum secure processor architecture that offers strong provable isolation of software modules running concurrently and sharing resources.
A handson approach utilizing the 80x86 microprocessor family 3rd edition computer organization and design, fourth edition. All that is technically meant by the term is that the execution of machine instructions on a computer is not actually intended to be all that secure or reliable. Speculative execution in a distributed file system edmund b. Intel analysis of speculative execution side channels download pdf white paper. Its the oldest story in technology and perhaps in human existence. Outoforder execution an overview sciencedirect topics. Part of the lecture notes in computer science book series lncs, volume 0. Speculative execution arvind computer science and artificial intelligence laboratory m. The concept behind speculative execution is that instructions are executed ahead of knowing that they are required. This text will also serve as a useful resource for all computer professionals and engineers who need an overview or introduction to computer architecture. A meltdown in computer architecture, as spectre haunts. Memory address prediction for data speculation springerlink. Data speculation refers to the execution of an instruction before some logically.
Work is done before it is known whether it is actually needed, so as to prevent a delay that would have to be incurred by doing the work after it is known that it is needed. We define boosting, an architectural mechanism for speculative execution, that allows us to uncover. Computer systems, computer programming, computer science book 1 introduction to the intel family of microprocessors. Speculative execution in high performance computer. While performing outoforder execution, it may happen that the processor arrives at a branch for which the condition is dependent on values that are yet to be computed in preceding instructions. The spear speculative pre execution assisted by compiler is a further variation of the hidisc architecture. The concept behind speculative execution is that instructions. Warter n, chang p, mahlke s, chen w and hwu w 1995 three architectural models for compilercontrolled speculative execution, ieee transactions on computers, 44. Speculative execution is not really about computer machine architecture at all. Palnitkar prentice hall, 2003 provides a good introduction to verilog2001 well suited for the beginner. A meltdown in computer architecture, as spectre haunts intel.
Ece 4750 computer architecture, fall 2019 course syllabus. Speculative execution article about speculative execution. Spring 2020 cs3853 computer architecture speculative execution and security 34 speculative execution is an optimization technique where a computer system performs some task that may not be needed or should not be executed. It is developed to use the benefit of prefetching capability of the hidisc on the current multithreaded processors such as simultaneous multithreading or chip multiprocessor. Were all getting quite the lesson in speculative execution today, and why faster isnt always better. To me, outoforder execution is a form of speculative execution speculating that the inflight insts wont have side effects relevant to the new insts.
Description structured computer organization, specifically written for undergraduate students, is a bestselling guide that provides an accessible introduction to computer hardware and architecture. Speculative execution goes one step further and determines what the result would be from executing the next instructions. By exploiting the speculative execution of modern processors, spectre attack can trick the system into executing instructions that are not supposed to be executed given the current system state 22. Branch prediction is a type of speculative execution. Amazon unveils new fire hd 8 tablet with faster processor, usbc may. In a race to make things faster and better and stronger, weve once again stumbled into danger, or flown too close to the sun. Intel analysis of speculative execution side channels. The spear speculative preexecution assisted by compiler is a further variation of the hidisc architecture. Aws recently published aws security bulletin aws20180 for the newly disclosed research regarding sidechannel analysis via speculative execution on modern computer processors. Emphasizing both underlying theory and actual designs, the book covers a wide array of topics and links computer architecture to other subfields of computing. Listen up, you computer nerds and programmming cattle. Computer architecture and parallel processing guide books.
In general, the optimizations discussed in this chapter focus on avoiding the overhead associated with a branch. A superscalar processor can fetch, decode, execute, and retire, e. Speculative execution in modern computer architectures. However, there has been no reference book so far that attempts to summarize and.
The next chapter, chapter 10, uses selection from computer architecture and organization book. All that is technically meant by the term is that the execution of machine instructions on a computer is not actually intended to. Spring 2020 cs3853 computer architecture speculative execution and security 39 speculative execution is an optimization technique where a computer system performs some task that may not be needed or should not be executed. It covers cuttingedge research projects, as well as numerous commercial implementations that demonstrate the value of this latencyhiding technique. Predication and speculation department of computer.
By exploiting the speculative execution of modern processors, spectre attack can trick the system into executing instructions that are not supposed to. Chen, and jason flinn department of electrical engineering and computer science university of michigan abstract speculator provides linux kernel support for speculative execution. Architecture of the hewlettpackards pa8200 processor. Processor speculative execution operating system updates aws recently published aws security bulletin aws20180 for the newly disclosed research regarding sidechannel analysis via speculative execution on modern computer processors. Speculative execution in highperformance computer architectures. Until now, there were few textbooks that focused on the dynamic subject of speculative execution, a topic that is crucial to the development of high performance computer architectures. An illustrated introduction to microprocessors and computer architecture pdf, epub, docx and torrent then this site is not for you. Speculative execution in high performance computer architectures describes many recent advances in speculative exec. Provides an analysis of speculative execution security risks based on sidechannel analysis methods documented by. Sep 26, 2014 if the compiler did not hoist that code then there is a compiler bug, not an architecture problem. Provide many instructions provide many addressing modes. Pipelining 387 next two stages, indicated as trace cache fetch gathers the decoded microoperations guided by branch prediction strategy from the instruction decoder and places in sequence of selection from computer architecture and organization book. Ece 4750 computer architecture, fall 2019 course syllabus verilog book verilog hdl.
1053 1581 349 1553 1029 1157 47 333 28 1382 524 1428 618 1403 598 905 175 762 651 1412 6 392 1253 1475 684 569 102 667 139 959 667 43 380 413