mirror of https://gitee.com/openkylin/linux.git
725ca4adae
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.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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| .. | ||
| include/mach | ||
| Kconfig | ||
| Makefile | ||
| Makefile.boot | ||
| core.c | ||
| core.h | ||
| headsmp.S | ||
| hotplug.c | ||
| localtimer.c | ||
| platsmp.c | ||
| realview_eb.c | ||
| realview_pb11mp.c | ||
| realview_pb1176.c | ||
| realview_pba8.c | ||
| realview_pbx.c | ||