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Date: Tue, 10 Nov 2020 09:20:48 +0100
From: Harald Hoyer <>
Subject: Re: x86_64/__set_thread_area clobber of rcx and r11

Am 09.11.20 um 22:59 schrieb Hydro Flask:
> On 2020-11-09 13:48, Harald Hoyer wrote:
>> In src/thread/x86_64/__set_thread_area.s, I don't see any special
>> handling of the registers rcx and r11,
>> which will be clobbered by the syscall. Is that an oversight, or am I
>> missing something?
> The x86_64 ABI states that code should assume all caller-saved registers, which include rcx and r11, are clobbered
> after the function call. __set_thread_area itself doesn't use rcx or r11, so no other special handling is needed.

Yeah, sorry, memorized half an hour later also. I guess it was too much inline assembly in the last weeks.

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