From fed18b3aec0f575752eeca0ca8c24d7dd16dac78 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 31 Aug 2017 14:29:34 +0900 Subject: [PATCH] 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 --- include/common/asm_macros_common.S | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/include/common/asm_macros_common.S b/include/common/asm_macros_common.S index dbc9e2d30..6a02e18ee 100644 --- a/include/common/asm_macros_common.S +++ b/include/common/asm_macros_common.S @@ -12,11 +12,12 @@ * to enable elimination of unused code during linking. It also adds * basic debug information to enable call stack printing most of the * time. The optional _align parameter can be used to force a - * non-standard alignment (indicated in powers of 2). Do *not* try to - * use a raw .align directive. Since func switches to a new section, - * this would not have the desired effect. + * non-standard alignment (indicated in powers of 2). The default is + * _align=2 because both Aarch32 and Aarch64 instructions must be + * word aligned. Do *not* try to use a raw .align directive. Since func + * switches to a new section, this would not have the desired effect. */ - .macro func _name, _align=-1 + .macro func _name, _align=2 /* * Add Call Frame Information entry in the .debug_frame section for * debugger consumption. This enables callstack printing in debuggers. @@ -36,9 +37,7 @@ * .debug_frame */ .cfi_startproc - .if (\_align) != -1 - .align \_align - .endif + .align \_align \_name: .endm