OpenSBI should emulate fence.tso for the D1 soc

[Alexandre Ghiti]

[ Impact ]

As reported in https://bugs.launchpad.net/ubuntu/+source/llvm-defaults/+bug/1994071, clang triggers an illegal instruction trap and is killed after it tries to execute a fence.tso instruction. This is a known bug in the core of this soc, and a fix exists upstream which consists in emulating this instruction in opensbi.

[ Test Plan ]

Patch opensbi with both commits c919f684d95f ("lib: sbi_illegal_insn: Add emulation for fence.tso") and 51074432b233 ("lib: sbi_illegal_insn: Fix FENCE.TSO emulation infinite trap loop"), rebuild a u-boot-nezha package with this opensbi and install it on the nezha board. Finally reboot, and just execute the following command:

$ clang --version

Which should output the current clang version and not get killed.

[ Where problems could occur ]

This could break opensbi on all the RISC-V boards, even though the patches have been in upstream for a few months.

[Alexandre Ghiti (alexghiti)]

Please find attached a debdiff that was successfully tested on the Nezha board.

[Heinrich Schuchardt (xypron)]

The patch is only needed for OpenSBI 1.0. In Kinetic we use OpenSBI 1.1.

It seems easier to just SRU OpenSBI 1.1 to Jammy and rebuild U-Boot.