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Date: Mon, 09 Nov 2020 13:59:34 -0800
From: Hydro Flask <hydroflask@yqxmail.com>
To: musl@lists.openwall.com
In-Reply-To: <ed5fc497-3225-efb4-4ca9-31142ac3e749@redhat.com>
References: <ed5fc497-3225-efb4-4ca9-31142ac3e749@redhat.com>
Message-ID: <c7fc041cc9f112e595ef236882ae1975@yqxmail.com>
Subject: Re: [musl] x86_64/__set_thread_area clobber of rcx and r11

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.