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| author | Nathan Chancellor <natechancellor@gmail.com> | 2019-09-04 01:13:15 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-07 18:59:34 +0200 |
| commit | 68a14319be3875022cd8b8e9548b46825923693c (patch) | |
| tree | 90c7fa5c509222e21f3122a6a24f841f6cbad05f | |
| parent | b10ee427091597699b83ea8bb454ae72e0fe43e9 (diff) | |
| download | linux-stable-68a14319be3875022cd8b8e9548b46825923693c.tar.gz linux-stable-68a14319be3875022cd8b8e9548b46825923693c.tar.bz2 linux-stable-68a14319be3875022cd8b8e9548b46825923693c.zip | |
ARM: 8905/1: Emit __gnu_mcount_nc when using Clang 10.0.0 or newer
[ Upstream commit b0fe66cf095016e0b238374c10ae366e1f087d11 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/arm/Kconfig | 2 | ||||
| -rw-r--r-- | arch/arm/Makefile | 4 |
2 files changed, 5 insertions, 1 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 3539be870055..6029d324911c 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -75,7 +75,7 @@ config ARM select HAVE_EXIT_THREAD select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG - select HAVE_FUNCTION_TRACER if !XIP_KERNEL + select HAVE_FUNCTION_TRACER if !XIP_KERNEL && (CC_IS_GCC || CLANG_VERSION >= 100000) select HAVE_GCC_PLUGINS select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7) select HAVE_IDE if PCI || ISA || PCMCIA diff --git a/arch/arm/Makefile b/arch/arm/Makefile index f863c6935d0e..c0b278358301 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -112,6 +112,10 @@ 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) |