riscv - What is the difference between mret and ret instruction in ...
Jul 25, 2022 · Is there any difference between mret and ret instruction when risc-v core is operating in machine mode?
How the RISC-V HW can determine the privilege level?
Feb 18, 2020 · Well, on interrupts - "xPP holds the previous privilege mode (x=M,S or U). The xPP fields can only hold privilege modes up to x, so MPP is two bits wide, SPP is one bit wide, and UPP is …
assembly - RISC-V Interrupt Handling Flow - Stack Overflow
The Instruction Set Manuals offer descriptions of say mret and mstatus, but fail to provide a holistic view. For a hypothetical architecture, interrupt processing might be described like this: If the IRQ line is …
riscv - How does a RISC-V processor handle a timer interrupt when ...
Jun 2, 2023 · When the timer interrupt is processed, the mret instruction is executed, MIE=MPIE=0, and the processor returns to S mode. I wonder if the above is a correct inference
RISC-V PMP instruction access fault when jumping to U mode
Aug 4, 2022 · Details: My program starts in M mode and at some point jump to U mode using mret. I am not using virtual memory for this test. Memory region that I want to protect starts at 0x80020180. I set …
riscv - Why would you sret from machine mode? - Stack Overflow
Sep 15, 2023 · You want it to either do what software wants, or raise a trap so the VMM can intervene. It would be a virtualization hole when classically virtualizing M-mode software within S-mode if …
riscv - If an interrupt signal lasts for multiple cycles, will it be ...
May 23, 2024 · So, when the current exception handling is completed and mret restores mstatus.mie to 1, the CPU will find a 1 in mip, and it seems the CPU will handle this exception again?
RISC-V return from exception handler with compressed instructions
Jun 3, 2020 · I see the standard way of exiting RISC-V exception handler is update mepc to mepc+4 before mret. But won't this cause problem if the next instruction is only 2-bytes long in compressed …
In RISCV Exception/Interrupt Handlers, how to return to the correct ...
Nov 10, 2023 · Suppose I have configured all exceptions and interrupts to be handled in machine-mode... How do my machine-mode handlers know to put PRV_U or PRV_M, etc. into mstatus.MPP …
RISC-V: Why does the mstatus include SIE, SPIE and SPP?
Jul 5, 2023 · MPP records the privilege level before the trap, so that the previous privilege level before trap can be restored when mret is executed later So what does mstatus.SIE/SPIE/SPP actually do?