asm_macros: set the default assembly code alignment to 4 byte
Assembly routines are usually defined by using "func" and "endfunc":
func foo
...
endfunc foo
Currently, the "func" macro does not specify ".align" directive
by default. It causes unaligned instruction under some circumstances.
As far as I tested, this problem happens for GCC 5 or older. It did
not happen for GCC 6 or newer. Taking into account that GCC 4.x / 5.x
is still used, make sure that assembly code is at least 4 byte aligned.
[ How to reproduce the problem ]
For example, use GCC 5.3 downloaded from Linaro:
http://releases.linaro.org/components/toolchain/binaries/5.3-2016.05/
aarch64-linux-gnu/gcc-linaro-5.3.1-2016.05-x86_64_aarch64-linux-gnu.tar.xz
Expand mbedtls-2.4.2 to the current directory.
Try the following:
$ git log --oneline -1
77544ef
Merge pull request #1071 from jeenu-arm/syntax-fix
$ aarch64-linux-gnu-gcc --version | head -1
aarch64-linux-gnu-gcc (Linaro GCC 5.3-2016.05) 5.3.1 20160412
$ make CROSS_COMPILE=aarch64-linux-gnu- PLAT=uniphier \
TRUSTED_BOARD_BOOT=1 MBEDTLS_DIR=mbedtls-2.4.2
( snip build log )
$ aarch64-linux-gnu-nm build/uniphier/release/bl1/bl1.elf | grep handler
00000000800088f4 T bl1_fwu_smc_handler
00000000800084c8 T bl1_smc_handler
000000008000a6e0 t _panic_handler
000000008000a8e0 W plat_error_handler
000000008000a8e8 W plat_panic_handler
000000008000a8d8 W plat_reset_handler
000000008000a39f T reset_handler
000000008000a367 t smc_handler
000000008000a2ef t smc_handler64
You will notice "smc_handler64", "reset_handler", etc. are not properly
aligned.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
parent
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@ -12,11 +12,12 @@
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* to enable elimination of unused code during linking. It also adds
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* basic debug information to enable call stack printing most of the
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* time. The optional _align parameter can be used to force a
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* non-standard alignment (indicated in powers of 2). Do *not* try to
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* use a raw .align directive. Since func switches to a new section,
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* this would not have the desired effect.
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* non-standard alignment (indicated in powers of 2). The default is
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* _align=2 because both Aarch32 and Aarch64 instructions must be
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* word aligned. Do *not* try to use a raw .align directive. Since func
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* switches to a new section, this would not have the desired effect.
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*/
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.macro func _name, _align=-1
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.macro func _name, _align=2
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/*
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* Add Call Frame Information entry in the .debug_frame section for
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* debugger consumption. This enables callstack printing in debuggers.
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@ -36,9 +37,7 @@
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* .debug_frame
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*/
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.cfi_startproc
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.if (\_align) != -1
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.align \_align
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.endif
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.align \_align
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\_name:
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.endm
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