From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH 3/3] ARM: tegra: make sure the pointer on 4 byte align when THUMB2_KERNEL enabled Date: Tue, 16 Apr 2013 10:20:11 -0600 Message-ID: <516D7A3B.9030404@wwwdotorg.org> References: <1366066255-18192-1-git-send-email-swarren@wwwdotorg.org> <1366066255-18192-3-git-send-email-swarren@wwwdotorg.org> <20130416141252.GA2229@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130416141252.GA2229-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dave Martin , arm-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Cc: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Joseph Lo List-Id: linux-tegra@vger.kernel.org On 04/16/2013 08:13 AM, Dave Martin wrote: > On Mon, Apr 15, 2013 at 04:50:55PM -0600, Stephen Warren wrote: >> From: Joseph Lo >> >> When building kernel with CONFIG_THUMB2_KERNEL, the data pointer in the >> assembly may not on the 4 byte alignment. Then causing a data abort when >> accessing the pointer. This patch add a ".align" flag in the head of the >> pointer. And always using 32-bit ADR Thumb instruction to make sure it >> won't build failure. >> >> Signed-off-by: Joseph Lo >> Signed-off-by: Stephen Warren >> --- >> arch/arm/mach-tegra/reset-handler.S | 1 + >> arch/arm/mach-tegra/sleep.h | 3 ++- >> 2 files changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm/mach-tegra/reset-handler.S b/arch/arm/mach-tegra/reset-handler.S >> index e6de88a..519a8c5 100644 >> --- a/arch/arm/mach-tegra/reset-handler.S >> +++ b/arch/arm/mach-tegra/reset-handler.S >> @@ -83,6 +83,7 @@ ENDPROC(tegra_resume) >> >> #ifdef CONFIG_CACHE_L2X0 >> .globl l2x0_saved_regs_addr >> + .align >> l2x0_saved_regs_addr: >> .long 0 >> #endif >> diff --git a/arch/arm/mach-tegra/sleep.h b/arch/arm/mach-tegra/sleep.h >> index 4ffae54..8e9b6af 100644 >> --- a/arch/arm/mach-tegra/sleep.h >> +++ b/arch/arm/mach-tegra/sleep.h >> @@ -92,7 +92,8 @@ >> >> #ifdef CONFIG_CACHE_L2X0 >> .macro l2_cache_resume, tmp1, tmp2, tmp3, phys_l2x0_saved_regs >> - adr \tmp1, \phys_l2x0_saved_regs >> + ARM( adr \tmp1, \phys_l2x0_saved_regs ) >> + THUMB( adr.w \tmp1, \phys_l2x0_saved_regs ) > > Can you give an example of the assembler error you get without this? arch/arm/mach-tegra/reset-handler.S: Assembler messages: arch/arm/mach-tegra/reset-handler.S:78: Error: invalid immediate for address calculation (value = 0x00000004) This is with gcc-4.5.3, as: GNU assembler (crosstool-NG hg_unknown-Y8jGNvr6ygZCnf0dxYVdog@public.gmane.org) 2.20.1.20100303 > The target symbol is local and the assembler can see where it is, > so it should choose the correct variant for the adr instruction > with no need for the ".w" suffix. > > If not, it could mean that there is a bug in the version of the > assembler you're using. True. Switching to the Ubuntu-packaged ARM cross-compiler that ships with Ubuntu 12.10, I do not see this problem. Still, many people probably still use older compilers. > If it's definitely needed, you can append a Thumb-only .w suffix with > > W(adr) \tmp1, \phys_l2x0_saved_regs > > ...which is slightly neater. Yes, that certainly works too, even without the .align change in reset-handler.S. Arnd, Olof, I guess let's drop this once patch from this series, but apply the other two, and I'll send an updated version of this one patch. Thanks.