On Wed, Aug 24, 2022 at 11:43:10AM -0700, Dave Hansen wrote:
> So, we don't have *ANY* control over where the compiler uses jump
> tables. The kernel just happened to add some code that uses them, fell
> over, and this adds a hack to get booting again.
>
> Isn't this a bigger problem?
I had the same question already. Was thinking of maybe disabling
the compiler from producing jump tables in the ident-mapped code.
Tom's argument is that that might prevent the compiler from doing
optimizations but I haven't talked to compiler folks whether those
optimizations are even worth the effort.
Regardless, the potential problem is limited:
"# (jump-tables are implicitly disabled by RETPOLINE)"
i.e., only RETPOLINE=n builds for now which should be a minority?
I guess when this explodes somewhere else again, we will have to
generalize a fix.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
