Messages in this thread |  | | Date | Sun, 16 May 2021 09:48:19 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v3 1/4] x86/syscall: sign-extend system calls on entry to int |
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* 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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