From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 3/8] ARM: add macro to perform far branches (b/bl)
Date: Fri, 13 Mar 2015 16:40:06 +0000 [thread overview]
Message-ID: <20150313164005.GU8656@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1426248452-4773-4-git-send-email-ard.biesheuvel@linaro.org>
On Fri, Mar 13, 2015 at 01:07:27PM +0100, Ard Biesheuvel wrote:
> + .macro bl_abs, target, c=
> +#if defined(CONFIG_CPU_32v7) || defined(CONFIG_CPU_32v7M)
> + movt\c lr, #:upper16:\target
> + movw\c lr, #:lower16:\target
> + blx\c lr
So I've looked this up, and it's valid, which is surprising because BLX
itself writes to LR - the read from LR must happen before BLX itself
writes to LR. Thankfully, because of the pipelining, this is probably
guaranteed.
I wonder whether there will be any errata on this... maybe on non-ARM
CPUs? It'll be interesting to find out what happens once we merge
this... :)
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2015-03-13 16:40 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-13 12:07 [PATCH v2 0/8] ARM kernel size fixes Ard Biesheuvel
2015-03-13 12:07 ` [PATCH v2 1/8] ARM: replace PROCINFO embedded branch with relative offset Ard Biesheuvel
2015-04-19 16:59 ` Joachim Eastwood
2015-04-19 17:08 ` Russell King - ARM Linux
2015-04-19 17:41 ` Ard Biesheuvel
2015-04-19 19:28 ` Russell King - ARM Linux
2015-04-19 19:45 ` Joachim Eastwood
2015-04-19 21:52 ` Ard Biesheuvel
2015-04-19 19:24 ` Joachim Eastwood
2015-03-13 12:07 ` [PATCH v2 2/8] ARM: move HYP text to end of .text section Ard Biesheuvel
2015-03-13 12:07 ` [PATCH v2 3/8] ARM: add macro to perform far branches (b/bl) Ard Biesheuvel
2015-03-13 16:40 ` Russell King - ARM Linux [this message]
2015-03-17 20:35 ` Ard Biesheuvel
2015-03-18 10:07 ` Ard Biesheuvel
2015-03-19 9:01 ` [PATCH] " Ard Biesheuvel
2015-03-13 12:07 ` [PATCH v2 4/8] ARM: use bl_far to call __hyp_stub_install_secondary from the .data section Ard Biesheuvel
2015-03-13 12:07 ` [PATCH v2 5/8] ARM: move the .idmap.text section closer to .head.text Ard Biesheuvel
2015-03-13 12:07 ` [PATCH v2 6/8] asm-generic: introduce .text.fixup input section Ard Biesheuvel
2015-03-18 18:58 ` Arnd Bergmann
2015-03-13 12:07 ` [PATCH v2 7/8] ARM: keep .text and .fixup regions together Ard Biesheuvel
2015-03-13 12:07 ` [PATCH v2 8/8] kallsyms: allow kallsyms data to reside in the .data section Ard Biesheuvel
2015-03-18 7:54 ` [PATCH v2 0/8] ARM kernel size fixes Ard Biesheuvel
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