On Mon, Oct 12, 2026 at 08:05:21PM +0100, Andrew Cooper wrote: > > On Mon, Oct 12, 2026 at 02:04:25AM -0700, Kees Cook wrote: > >> The "cs" prefix on the LEA in the FineIBT paranoid caller template is > >> padding: it places the LEA's 0xf0 immediate byte where it doubles as the > >> LOCK prefix that makes the failing Jcc raise #UD. GNU as warns about it > >> in every CONFIG_FINEIBT=y build: > >> > >> Warning: segment override on `lea' is ineffectual > > Shees... > > This is a binutils bug. Can't we fix it here?
I can try to send a binutils bug fix? > The claim in the warning is simply not true. This is an example where > it absolutely does matter, and it also matters for legibility that we > can avoid writing raw hex. Well, we'd have to keep some kind of work-around for earlier binutils for a long while... -- Kees Cook
