On Fri, Nov 15, 2024 at 10:41:04AM -0800, Josh Poimboeuf wrote: > On Mon, Nov 11, 2024 at 12:59:47PM +0100, Peter Zijlstra wrote: > > Since there is only a single fastop() function, convert the FASTOP > > stuff from CALL_NOSPEC+RET to JMP_NOSPEC+JMP, avoiding the return > > thunks and all that jazz. > > > > Specifically FASTOPs rely on the return thunk to preserve EFLAGS, > > which not all of them can trivially do (call depth tracing suffers > > here). > > > > Objtool strenuously complains about this: > > > > - indirect call without a .rodata, fails to determine JUMP_TABLE, > > annotate > > - fastop functions fall through, exception > > - unreachable instruction after fastop_return, save/restore > > This wording makes it sound like this patch triggers objtool warnings, > which I'm guessing is not true? Right, no, it did without the fixups. This was a (poorly worder) attempt at explaining the reasons for the various annotations in the patch.
