+arm64 people...

On Mon, Mar 28, 2022 at 10:14:38PM +0200, Peter Zijlstra wrote:

On Mon, Mar 28, 2022 at 12:59:20PM -0700, Josh Poimboeuf wrote:

quoted

I'm not making any major changes to the code, just shuffling things
around to make the interface more modular.  I hope to have something
soon (this week).  Peter recently added a big feature (Intel IBT) which
is already in -next.

Hit Linus' tree yesterday :-)

quoted

Some years ago Kamalesh Babulal had a prototype of objtool for ppc64le
which did the full stack validation.  I'm not sure what ever became of
that.

I've also heard chatter about s390.

quoted

FWIW, there have been some objtool patches for arm64 stack validation,
but the arm64 maintainers have been hesitant to get on board with
objtool, as it brings a certain maintenance burden.  Especially for the
full stack validation and ORC unwinder.  But if you only want inline
static calls and/or mcount then it'd probably be much easier to
maintain.

IIRC the major stumbling block for arm64 is the whole jump-table thing.
Either they need to rely on compiler plugins to provide objtool that
data (yuck, since we support at least 2 different compilers), disable
jump-tables (yuck, for that limits code-gen just to please a tool) or
use DWARF (yuck, because build times).

There was a little talk about an impromptu 'abi' to communicate
jump-table details to objtool without going full on DWARF, but that
seems to have hit a dead end again.