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| author | Nathan Chancellor <natechancellor@gmail.com> | 2019-09-04 02:13:15 +0200 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2019-09-10 16:22:57 +0200 |
| commit | b0fe66cf095016e0b238374c10ae366e1f087d11 (patch) | |
| tree | 14d4d0933a72d71acf2bd02f07f424cd059d9980 /arch/arm/Makefile | |
| parent | ARM: 8904/1: skip nomap memblocks while finding the lowmem/highmem boundary (diff) | |
| download | linux-b0fe66cf095016e0b238374c10ae366e1f087d11.tar.xz linux-b0fe66cf095016e0b238374c10ae366e1f087d11.zip | |
ARM: 8905/1: Emit __gnu_mcount_nc when using Clang 10.0.0 or newer
Currently, multi_v7_defconfig + CONFIG_FUNCTION_TRACER fails to build
with clang:
arm-linux-gnueabi-ld: kernel/softirq.o: in function `_local_bh_enable':
softirq.c:(.text+0x504): undefined reference to `mcount'
arm-linux-gnueabi-ld: kernel/softirq.o: in function `__local_bh_enable_ip':
softirq.c:(.text+0x58c): undefined reference to `mcount'
arm-linux-gnueabi-ld: kernel/softirq.o: in function `do_softirq':
softirq.c:(.text+0x6c8): undefined reference to `mcount'
arm-linux-gnueabi-ld: kernel/softirq.o: in function `irq_enter':
softirq.c:(.text+0x75c): undefined reference to `mcount'
arm-linux-gnueabi-ld: kernel/softirq.o: in function `irq_exit':
softirq.c:(.text+0x840): undefined reference to `mcount'
arm-linux-gnueabi-ld: kernel/softirq.o:softirq.c:(.text+0xa50): more undefined references to `mcount' follow
clang can emit a working mcount symbol, __gnu_mcount_nc, when
'-meabi gnu' is passed to it. Until r369147 in LLVM, this was
broken and caused the kernel not to boot with '-pg' because the
calling convention was not correct. Always build with '-meabi gnu'
when using clang but ensure that '-pg' (which is added with
CONFIG_FUNCTION_TRACER and its prereq CONFIG_HAVE_FUNCTION_TRACER)
cannot be added with it unless this is fixed (which means using
clang 10.0.0 and newer).
Link: https://github.com/ClangBuiltLinux/linux/issues/35
Link: https://bugs.llvm.org/show_bug.cgi?id=33845
Link: https://github.com/llvm/llvm-project/commit/16fa8b09702378bacfa3d07081afe6b353b99e60
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/Makefile')
| -rw-r--r-- | arch/arm/Makefile | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 977f4e66f145..d6273b660629 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -115,6 +115,10 @@ ifeq ($(CONFIG_ARM_UNWIND),y) CFLAGS_ABI +=-funwind-tables endif +ifeq ($(CONFIG_CC_IS_CLANG),y) +CFLAGS_ABI += -meabi gnu +endif + # Accept old syntax despite ".syntax unified" AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W) |