Messages in this thread | | | Date | Mon, 17 May 2021 13:23:59 -0700 | Subject | Re: [PATCH v3 1/4] x86/syscall: sign-extend system calls on entry to int | From | "H. Peter Anvin" <> |
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No, this is what the Linux kernel did for a very long time.
On May 16, 2021 12:48:19 AM PDT, Ingo Molnar <mingo@kernel.org> wrote: > >* H. Peter Anvin <hpa@zytor.com> wrote: > >> This is an ABI change, but is in fact a revert to the original x86-64 >> ABI. The original assembly entry code would zero-extend the system >> call number; this patch uses sign extend to be explicit that this is >> treated as a signed number (although in practice it makes no >> difference, of course) and to avoid people getting the idea of >> "optimizing" it, as has happened on at least two(!) separate >> occasions. > >The original x86-64 ABI as documented by AMD, as we (probably) never >had >this in Linux, right? > >Sounds sensible to do this, assuming nothing relies on the weirdness. > >Thanks, > > Ingo
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