what is get_irq_regs() in linux kernel

In the Linux kernel, `get_irq_regs()` is a function that returns a pointer to the structure representing the register state of the processor at the time of the interrupt.

When an interrupt occurs, the processor saves the current register state onto the stack and loads the register state associated with the interrupt handler. The `get_irq_regs()` function retrieves a pointer to the saved register state on the stack, which can be used by the interrupt handler to access the values of the registers at the time of the interrupt.

The register state includes the values of the general-purpose registers, such as the program counter, stack pointer, and other registers that were in use at the time of the interrupt. This information is useful for debugging purposes, as it can help developers understand the state of the system at the time of the interrupt and diagnose any issues that may have occurred.

It's important to note that `get_irq_regs()` should only be called within the context of an interrupt handler. Calling it outside of an interrupt context can result in undefined behavior.