From: Szabolcs Nagy <nsz@port70.net>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Rich Felker <dalias@libc.org>,
musl@lists.openwall.com, Kees Cook <keescook@chromium.org>,
linux-arm-kernel@lists.infradead.org,
Andy Lutomirski <luto@amacapital.net>
Subject: Re: Re: Thread pointer changes
Date: Sat, 28 Jun 2014 00:40:17 +0200 [thread overview]
Message-ID: <20140627224017.GU23102@port70.net> (raw)
In-Reply-To: <20140627221744.GU32514@n2100.arm.linux.org.uk>
* Russell King - ARM Linux <linux@arm.linux.org.uk> [2014-06-27 23:17:44 +0100]:
> I think you're are missing one obvious solution to this which you can do:
> you are passed the HWCAP fields in the ELF auxinfo. This will tell you
> if the CPU has TLS support or not. If it has TLS support, then you don't
> need to use the kuser helpers, and you know that it is a CPU which is ARM
> architecture v6k or later, and it has things like the CP15 barrier
> instructions. If you want to know that the CPU supports the DMB
> instruction rather than the CP15 barrier instruction, then you have to
> check the uname details, or read /proc/cpuinfo (but I'd rather you
> didn't.)
>
but cp15 barrier is deprecated on armv7+
and i think the kernel can avoid the barriers on non-smp systems making
kuser helpers possibly preferable even if TLS HWCAP flag is set
next prev parent reply other threads:[~2014-06-27 22:40 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-10 7:28 Rich Felker
2014-06-11 14:55 ` Rich Felker
2014-06-27 19:27 ` Andy Lutomirski
2014-06-27 20:09 ` Russell King - ARM Linux
2014-06-27 21:09 ` Szabolcs Nagy
2014-06-27 21:30 ` Russell King - ARM Linux
2014-06-27 21:47 ` Andy Lutomirski
2014-06-27 21:58 ` Rich Felker
2014-06-27 21:55 ` Rich Felker
2014-06-27 22:17 ` Russell King - ARM Linux
2014-06-27 22:25 ` Andy Lutomirski
2014-06-27 22:54 ` Russell King - ARM Linux
2014-06-28 0:11 ` Rich Felker
2014-06-27 22:33 ` Rich Felker
2014-06-27 23:07 ` Russell King - ARM Linux
2014-06-27 23:17 ` Andy Lutomirski
2014-06-27 23:35 ` Russell King - ARM Linux
2014-06-27 23:40 ` Andy Lutomirski
2014-06-30 15:38 ` [musl] " Christopher Covington
2014-07-02 21:16 ` Rich Felker
2014-06-28 0:20 ` Rich Felker
2014-06-27 22:40 ` Szabolcs Nagy [this message]
2014-06-27 22:51 ` Andy Lutomirski
2014-06-27 23:12 ` Russell King - ARM Linux
2014-06-28 16:37 ` Szabolcs Nagy
2014-06-27 21:37 ` Rich Felker
2014-06-27 22:04 ` Russell King - ARM Linux
2014-06-27 22:26 ` Rich Felker
2014-06-27 23:03 ` Russell King - ARM Linux
2014-06-28 7:09 ` u-igbb
2014-06-27 23:20 ` Russell King - ARM Linux
2014-06-28 0:38 ` Rich Felker
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