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ARM: use arch_extension directive instead of arch argument

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The LLVM Target parser currently does not allow to specify the security
extension as part of -march (see also LLVM Bug 40186 [0]). When trying
to use Clang with LLVM's integrated assembler, this leads to build
errors such as this:
  clang-8: error: the clang compiler does not support '-Wa,-march=armv7-a+sec'

Use ".arch_extension sec" to enable the security extension in a more
portable fasion. Also make sure to use ".arch armv7-a" in case a v6/v7
multi-platform kernel is being built.

Note that this is technically not exactly the same as the old code
checked for availabilty of the security extension by calling as-instr.
However, there are already other sites which use ".arch_extension sec"
unconditionally, hence de-facto we need an assembler capable of
".arch_extension sec" already today (arch/arm/mm/proc-v7.S). The
arch extension "sec" is available since binutils 2.21 according to
its documentation [1].

[0] https://bugs.llvm.org/show_bug.cgi?id=40186
[1] https://sourceware.org/binutils/docs-2.21/as/ARM-Options.html

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Mans Rullgard <mans@mansr.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
This commit is contained in:
Stefan Agner
2019-05-28 00:40:50 +02:00
committed by Olof Johansson
parent 24cb4bc8f0
commit 3fe1ee40b2
18 changed files with 21 additions and 30 deletions
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3
arch/arm/mach-bcm/Makefile
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@@ -40,9 +40,6 @@ obj-$(CONFIG_ARCH_BCM_MOBILE_L2_CACHE) += kona_l2_cache.o
# Support for secure monitor traps
obj-$(CONFIG_ARCH_BCM_MOBILE_SMC) += bcm_kona_smc.o
ifeq ($(call as-instr,.arch_extension sec,as_has_sec),as_has_sec)
CFLAGS_bcm_kona_smc.o += -Wa,-march=armv7-a+sec -DREQUIRES_SEC
endif
# BCM2835
obj-$(CONFIG_ARCH_BCM2835) += board_bcm2835.o

2
arch/arm/mach-bcm/bcm_kona_smc.c
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@@ -125,9 +125,7 @@ static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
__asmeq("%2", "r4")
__asmeq("%3", "r5")
__asmeq("%4", "r6")
#ifdef REQUIRES_SEC
".arch_extension sec\n"
#endif
" smc #0\n"
: "=r" (ip), "=r" (r0)
: "r" (r4), "r" (r5), "r" (r6)