From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6
Date: Fri, 19 Mar 2010 08:53:17 +0000 [thread overview]
Message-ID: <20100319085317.GA8451@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20100319013521.GP2900@atomide.com>
On Thu, Mar 18, 2010 at 06:35:21PM -0700, Tony Lindgren wrote:
> -#if defined(CONFIG_HAS_TLS_REG)
> - mcr p15, 0, r3, c13, c0, 3 @ set TLS register
> -#elif !defined(CONFIG_TLS_REG_EMUL)
> - mov r4, #0xffff0fff
> - str r3, [r4, #-15] @ TLS val at 0xffff0ff0
> +#if !defined(CONFIG_TLS_REG_EMUL)
> + ldr r4, =elf_hwcap
> + ldr r4, [r4, #0]
> + tst r4, #HWCAP_TLS @ hardware with TLS?
This is really really inefficient. Both the second ldr and tst will stall
the pipeline because they need to wait for the result of the precending
ldr. Can we do better by re-ordering some instructions?
Also, the ifndef seems incorrect - if we have TLS_REG_EMUL we seem to omit
all this code.
next prev parent reply other threads:[~2010-03-19 8:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-17 17:57 [PATCH] arm: Fix mounting root on omaps with CPU_V6 and CPU_V7 Tony Lindgren
2010-03-17 18:07 ` Catalin Marinas
2010-03-17 19:11 ` Tony Lindgren
2010-03-18 11:13 ` Catalin Marinas
2010-03-18 17:00 ` Tony Lindgren
2010-03-19 1:35 ` [PATCH] arm: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6 Tony Lindgren
2010-03-19 3:24 ` Tony Lindgren
2010-03-19 3:46 ` Jamie Lokier
2010-03-19 8:54 ` Russell King - ARM Linux
2010-03-19 15:32 ` Tony Lindgren
2010-03-19 8:53 ` Russell King - ARM Linux [this message]
2010-03-19 15:58 ` Tony Lindgren
2010-03-23 0:16 ` Russell King - ARM Linux
2010-03-23 0:54 ` Tony Lindgren
-- strict thread matches above, loose matches on Subject: below --
2010-03-18 19:02 Tony Lindgren
2010-06-29 10:34 Tony Lindgren
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