[PATCH] D106056: [CVP] processSwitch: Remove default case when switch cover all possible values.

Mon Aug 23 18:15:20 PDT 2021

junparser added a comment.

In D106056#2961447 <https://reviews.llvm.org/D106056#2961447>, @nathanchance wrote:

> I do not think that is the issue here. Adding `-mllvm -trap-unreachable` to the kernel's build flags does not silence `objtool` nor allows the kernel to boot. I switched over to `CONFIG_UNWINDER_FRAME_POINTER` instead of `CONFIG_UNWINDER_ORC` so `objtool` should only be running checks, not doing any sort of binary modifications, and I see the same warning. If the warning is not valid, then I can bring that up to the tool's author but it seems valid, given that it is pointing to the exact function that @junparser already identified as problematic.
>
>   + tools/objtool/objtool check --duplicate --vmlinux --no-unreachable --retpoline --uaccess vmlinux.o
>   vmlinux.o: warning: objtool: cfg80211_edmg_chandef_valid()+0x16e: can't find jump dest instruction at .text.cfg80211_edmg_chandef_valid+0x180

@nathanchance I can confirm that @efriedma is right.  since we are using lto, we need add `-mllvm -trap-unreachable` to link flags as well.  After that we can see `ud2 `at the jump dest, then there is no warning from libtool, also boot has been succeed.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106056/new/

https://reviews.llvm.org/D106056