Messages in this thread | | | Date | Wed, 24 Aug 2022 20:48:44 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/sev: Don't use cc_platform_has() for early SEV-SNP calls |
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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
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