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4f79a5dd7c
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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| .. | ||
| .gitignore | ||
| armksyms.c | ||
| arthur.c | ||
| asm-offsets.c | ||
| atags.c | ||
| atags.h | ||
| bios32.c | ||
| calls.S | ||
| compat.c | ||
| compat.h | ||
| crash_dump.c | ||
| crunch-bits.S | ||
| crunch.c | ||
| debug.S | ||
| dma-isa.c | ||
| dma.c | ||
| early_printk.c | ||
| ecard.c | ||
| ecard.h | ||
| elf.c | ||
| entry-armv.S | ||
| entry-common.S | ||
| entry-header.S | ||
| etm.c | ||
| fiq.c | ||
| ftrace.c | ||
| head-common.S | ||
| head-nommu.S | ||
| head.S | ||
| hw_breakpoint.c | ||
| init_task.c | ||
| io.c | ||
| irq.c | ||
| isa.c | ||
| iwmmxt.S | ||
| kgdb.c | ||
| kprobes-decode.c | ||
| kprobes.c | ||
| leds.c | ||
| machine_kexec.c | ||
| Makefile | ||
| module.c | ||
| perf_event.c | ||
| pmu.c | ||
| process.c | ||
| ptrace.c | ||
| ptrace.h | ||
| relocate_kernel.S | ||
| return_address.c | ||
| setup.c | ||
| signal.c | ||
| signal.h | ||
| smp_scu.c | ||
| smp_twd.c | ||
| smp.c | ||
| stacktrace.c | ||
| sys_arm.c | ||
| sys_oabi-compat.c | ||
| tcm.c | ||
| tcm.h | ||
| thumbee.c | ||
| time.c | ||
| traps.c | ||
| unwind.c | ||
| vmlinux.lds.S | ||
| xscale-cp0.c | ||