From 0575b4b83edb0a766a9c1518a5da57780f386340 Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Tue, 16 Nov 2010 13:13:37 +0000 Subject: ARM: mxc: Correct data alignment in headsmp.S for CONFIG_THUMB2_KERNEL MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Directives such as .long and .word do not magically cause the assembler location counter to become aligned in gas. As a result, using these directives in code sections can result in misaligned data words when building a Thumb-2 kernel (CONFIG_THUMB2_KERNEL). This is a Bad Thing, since the ABI permits the compiler to assume that fundamental types of word size or above are word- aligned when accessing them from C. If the data is not really word-aligned, this can cause impaired performance and stray alignment faults in some circumstances. In general, the following rules should be applied when using data word declaration directives inside code sections: * .quad and .double: .align 3 * .long, .word, .single, .float: .align (or .align 2) * .short: No explicit alignment required, since Thumb-2 instructions are always 2 or 4 bytes in size. immediately after an instruction. Signed-off-by: Dave Martin Signed-off-by: Sascha Hauer LAKML-Reference: 1289913217-8672-1-git-send-email-dave.martin@linaro.org Signed-off-by: Uwe Kleine-König Signed-off-by: Sascha Hauer --- arch/arm/plat-mxc/ssi-fiq.S | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/arm/plat-mxc') diff --git a/arch/arm/plat-mxc/ssi-fiq.S b/arch/arm/plat-mxc/ssi-fiq.S index 4ddce565b353..8397a2dd19f2 100644 --- a/arch/arm/plat-mxc/ssi-fiq.S +++ b/arch/arm/plat-mxc/ssi-fiq.S @@ -124,6 +124,8 @@ imx_ssi_fiq_start: 1: @ return from FIQ subs pc, lr, #4 + + .align imx_ssi_fiq_base: .word 0x0 imx_ssi_fiq_rx_buffer: -- cgit v1.2.3