...

Updates

04 Oct 2023

• glibc study to support setjmp/longjmp for Zicfiss is ongoing. It looks that there are many system-related details to consider.
• Update upstream and community activities related to Zicfiss:
  • Spike PR for Zimop and Zcmop, which Zicfiss depends on, have been submitted by Ved (Rivos):
    https://github.com/riscv-software-src/riscv-isa-sim/pull/1467
    https://github.com/riscv-software-src/riscv-isa-sim/pull/1468
  • The best place to put the flag for object compiled with Zicfiss on was discussed by the psABI group. Thank you, Kito (SiFive) and psABI group!
    We will implement this in LLVM when the final decision is made.
    https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/395
  • LLVM PR for Zicfiss v0.3.1 is posted by Yeting (SiFive). Thank Yeting again!
    https://github.com/llvm/llvm-project/pull/68075
    https://github.com/llvm/llvm-project/pull/66043

20 Sep 2023

• The investigation on the 6 run failures is done. It turns out they are not Oz-specific failures, i.e. these 6 test cases failed for all optimization levels but our error reporting mechanism didn't catch the failures because we only checked the "passed" output string but didn't check shadow stack fault. We've fixed the error reporting system.
  The root cause of the shadow stack fault on the 6 test cases is due to a lack of setjmp/longjmp support to save and restore shadow stack pointer.
• We will study glibc and try to add the support. We will also add Zicfiss instructions that are required by setjmp/longjmp into Spike for validation purpose, such as ssrdp, ssld, etc. 
  An example glibc patch for x86 shadow stack can be found here: https://github.com/bminor/glibc/commit/faaee1f07ed25b2779bfd935ffb29f431b80d6d3
  ABI discussions on jmp_buf can be found here: https://github.com/riscv/riscv-cfi/issues/142

...