Vmware, Inc.

Cadence Design Systems, Inc.

Kabushiki Kaisha Toshiba

Rakesh Agarwal

Wei Xu

Naresh Kumar

Alok Nemchand Kataria

Umesh Gupta

Kamran Malik

David A Dunn

Jeffrey W Sheldon

Frederick Joseph Jacobs

Radu Rugina

Prashant Sethia

Tatsuo Teruyama

Martim Carbone

Masashi Sasahara

Ritika Govila

Manish Bansal

Oana Baltaretu

Jayant Sharma

Marut Agarwal

Michael Raam

James S Mattson

Ajay Tomar

Kaustav Guha

James S Mattson, Jr

Sourabh Kumar Verma

Sukriti Khanna

A static timing analysis system for finding and reporting timing violations in a digital circuit design prior to circuit fabrication, and associated methods, use exhaustive path-based analysis (EPBA) that is informed by infinite-depth path-based analysis (IPBA) to provide analysis results that are driven full-depth, in contrast to conventional EPBA systems and methods, which can terminate after reaching a maximum depth of analysis as a way of avoiding prolonged or infinite runtimes. The IPBA-driven full-depth EPBA functions for hold-mode as well as setup-mode analysis and achieves reduced pessimism as compared to systems or methods employing IPBA alone, and more complete analysis of designs as compared to systems or methods employing EPBA alone. Improved IPBA signal merging using multidimensional zones for thresholding of signal clustering mitigates the occasional optimism of IPBA.

IPBA-driven full-depth EPBA of operational timing for circuit design

Mechanisms to protect the integrity of memory of a virtual machine are provided. The mechanisms involve utilizing certain capabilities of the hypervisor underlying the virtual machine to monitor writes to memory pages of the virtual machine. A guest integrity driver communicates with the hypervisor to request such functionality. Additional protections are provided for protecting the guest integrity driver and associated data, as well as for preventing use of these mechanisms by malicious software. These additional protections include an elevated execution mode, termed 'integrity mode,' which can only be entered from a specified entry point, as well as protections on the memory pages that store the guest integrity driver and associated data.

Techniques for protecting memory pages of a virtual computing instance

In a computer system operable at more than one privilege level, an interrupt security module handles interrupts without exposing a secret value of a register to virtual interrupt handling code that executes at a lower privilege level than the interrupt security module. The interrupt security module is configured to intercept interrupts generated while executing code at lower privilege levels. Upon receiving such an interrupt, the interrupt security module overwrites the secret value of the register with an unrelated constant. Subsequently, the interrupt security module generates a virtual interrupt corresponding to the interrupt and forwards the virtual interrupt to the virtual interrupt handling code. Advantageously, although the virtual interrupt handling code is able to determine the value of the register and consequently the unrelated constant, the virtual interrupt handling code is unable to determine the secret value.

Securing secret data embedded in code against compromised interrupt and exception handlers

The present embodiments relate to static timing analysis (STA) of circuits. The STA can include determining graph based analysis (GBA) delays of timing paths within the circuit. Path based analysis (PBA) delays of a subset of timing paths can be determined to generate circuit stage credit values for circuit stages in the circuit. The circuit stage credit values can be used to adjust GBA delays of the timing paths. Prediction functions can be utilized to predict or estimate PBA delays of timing paths thereby avoiding the determination of actual PBA delays of the timing paths.

Circuit stage credit based approaches to static timing analysis of integrated circuits

The present disclosure relates to a system and method for electronic design automation. Embodiments may include receiving, using at least one processor, an electronic design and determining one or more graph based analysis ('GBA') violating nodes associated with the electronic design. Embodiments may include identifying a non-covered violating node from the GBA violating nodes and determining a worst timing path through the non-covered violating node. Embodiments may further include invoking a path-based analysis ('PBA') on the worst timing path and determining if the worst timing path satisfies the PBA analysis.

Comprehensive path based analysis process

A hypervisor provides a guest operating system with a plurality of protection domains, including a root protection domain and one or more secure protection domains, and mechanisms for controlling the transitions between the protection domains. The guest physical memory region of a secure protection domain, which is mapped to host physical memory by secure nested page tables, stores secure guest code and data, and guest page tables for the secure guest code. When executing secure guest code, the guest page tables stored in the secure protection domain region are used for guest virtual to guest physical address translations, and the secure nested page tables are used for guest physical to host physical address translations.

Isolating guest code and data using multiple nested page tables

In a computer system operable at more than one privilege level, an application is securely customized to use secret data without disclosing the secret data to a managing operating system. In operation, an integrity module executes at a higher privilege level than both the managing operating system and the application. After the managing operating system loads the application executable code, the integrity module injects the secret data directly into the instruction stream of the application executable code and then sets the memory location of the secret data as executable-only. As the application executes at the assigned privilege level, the instruction in the application directly accesses the secret data without performing any indirect memory access, thereby protecting the secret data from malicious attempts to read the secret data at a privilege level lower than the integrity module.

Embedding secret data in code

In a computer system operable at more than one privilege level, confidential code is securely customized to use secret data to establish a code protection domain without disclosing the secret data to a managing operating system. In operation, a security module executes at a higher privilege level than both the managing operating system and the confidential code. After the managing operating system loads the executable of the confidential code, the security module injects the secret data directly into an authorization instruction and a verification instruction included in the confidential code and then sets both the authorization instruction and the verification instruction as executable-only. As the confidential code executes at the assigned privilege level, the authorization instruction and the verification instruction use the secret data to distinguish between unauthorized and authorized execution of the confidential code.

Verifying caller authorization using secret data embedded in code

A method of improved simulator processing is provided. The method according to the current invention includes grouping frequently accessed data into one set id to improve memory hierarchy performance. The method further includes simulating predication in a non-predicated architecture to improve CPU performance. The simulated predication includes pseudo-predicated implementation of read-operation vector element access pseudo-predicated implementation of write-operation vector element access, and predicated implementation of multi-way branches with assignment statements having a same left-hand-side (lhs). The method further includes determining a selection path in a multi-sensitive 'always' block to reduce taken branches. The multi-sensitive 'always' block selection path determination includes generating instance-specific code to save port allocation storage, and generating inlined instance-specific code to combine sensitive actions. The method further includes regenerating code affected by the assignment statement to implement value-change callback.

Methods for improved simulation of integrated circuit designs

A microprocessor includes an MMU which converts from a virtual address to a physical address, and an LSU which controls an execution of a load/store instruction. The LSU includes a DCACHE which temporarily stores data to read out from and to write into an external memory, an SPRAM used for a specific purpose besides caching, and an address generator which generates the virtual address to access the DCACHE and the SPRAM. The MMU generates a conversion table which performs a conversion from the virtual address to the physical address. A flag information showing whether or not the access to the SPRAM is performed is included in this conversion table. The LSU absolutely accesses the SPRAM if the flag is being set. Accordingly, it is unnecessary to allocate the SPRAM to a memory map of the main memory, and the allocation of the memory map simplifies.

Microprocessor with virtual-to-physical address translation using flags

A processor includes n-bit (e.g., 128-bit) register circuitry for holding instruction operands. Instruction decode circuitry decodes processor instructions from an instruction stream. Arithmetic logic (AL) circuitry is operable to perform one of a single operation on at least one m-bit maximum (e.g., 64-bit) operand provided from the n-bit register circuitry, responsive to a first single processor instruction decoded by the instruction decode circuitry, wherein m<n. In addition, the AL circuitry is operable to perform multiple parallel operations on at least two portions of one n-bit operand provided from the n-bit register circuitry. The multiple parallel operations are performed responsive to a second single instruction decoded by the instruction decode circuitry.

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Palo Alto, CA, United States of America

Rakesh Agarwal