User-level hardware branch records

摘要

A processor, a method and a computer-readable medium for recording branch addresses are provided. The processor comprises hardware registers and first and second circuitry. The first circuitry is configured to store a first address associated with a branch instruction in the hardware registers. The first circuitry is further configured to store a second address that indicates where the processor execution is redirected to as a result of the branch instruction in the hardware registers. The second circuitry is configured to, in response to a second instruction, retrieve a value of at least one of the registers. The second instruction can be a user-level instruction.

主权项

1. A processor comprising:
at least one bit configured to indicate whether the processor is operating in a kernel mode or a user mode, wherein the processor in the kernel mode allows access to read and write to registers that are inaccessible in the user mode; a plurality of hardware registers configured to store one or more branch tracing addresses when a branch instruction is executed, wherein the hardware registers may be read by both a kernel mode instruction and a user mode instruction; circuitry configured to, in response to executing a branch instruction, store a branch-from address and a branch-to address in the hardware registers; and a control bit that indicates whether to maintain the stored branch tracing addresses in the plurality of hardware registers when the processor switches between the kernel mode and the user mode.