• Dave Martin's avatar
    ARM: mxc: Correct data alignment in headsmp.S for CONFIG_THUMB2_KERNEL · 0575b4b8
    Dave Martin authored
    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: default avatarDave Martin <dave.martin@linaro.org>
    Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
    LAKML-Reference: 1289913217-8672-1-git-send-email-dave.martin@linaro.org
    Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
    Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
    0575b4b8
ssi-fiq.S 2.5 KB