Messages in this thread | | | Date | Wed, 13 Oct 2021 16:20:55 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] tools/nolibc: x86: Remove `r8`, `r9` and `r10` from the clobber list |
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On Wed, Oct 13, 2021 at 04:07:23PM +0200, Willy Tarreau wrote: > Yes I agree with the "potentially" here. If it can potentially be (i.e. > the kernel is allowed by contract to later change the way it's currently > done) then we have to save them even if it means lower code efficiency. > > If, however, the kernel performs such savings on purpose because it is > willing to observe a stricter saving than the AMD64 ABI, we can follow > it but only once it's written down somewhere that it is by contract and > will not change.
Right, and Micha noted that such a change to the document can be done. And we're basically doing that registers restoring anyway, in POP_REGS.
I'm not the least bit convinced it is worth enforcing that stricter register saving, though.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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