objtool: Ignore unreachable trap after call to noreturn functions

With CONFIG_UBSAN_TRAP enabled, the compiler may insert a trap
instruction after a call to a noreturn function. In this case, objtool
warns that the UD2 instruction is unreachable.

This is a behavior seen with Clang, from the oldest version capable of
building the mainline x64_64 kernel (9.0), to the latest experimental
version (12.0).

Objtool silences similar warnings (trap after dead end instructions), so
so expand that check to include dead end functions.

Cc: Nick Desaulniers <[email protected]>
Cc: Rong Chen <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Philip Li <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
BugLink: https://github.com/ClangBuiltLinux/linux/issues/1148
Link: https://lore.kernel.org/lkml/CAKwvOdmptEpi8fiOyWUo=AiZJiX+Z+VHJOM2buLPrWsMTwLnyw@mail.gmail.com
Suggested-by: Nick Desaulniers <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Tested-by: Nick Desaulniers <[email protected]>
Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Ilie Halip <[email protected]>
Tested-by: Sedat Dilek <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>

0 files changed, 0 insertions, 0 deletions