[PATCH 14/14] [RFC] ARM: forbid ftrace with clang and thumb2_kernel
From: Arnd Bergmann <arnd@kernel.org>
Date: 2021-09-28 15:42:46
Also in:
lkml, llvm
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
From: Arnd Bergmann <arnd@arndb.de> clang fails to build kernels with THUMB2 and FUNCTION_TRACER enabled when there is any inline asm statement containing the frame pointer register r7: arch/arm/mach-versatile/dcscb.c:95:2: error: inline asm clobber list contains reserved registers: R7 [-Werror,-Winline-asm] arch/arm/mach-exynos/mcpm-exynos.c:154:2: error: inline asm clobber list contains reserved registers: R7 [-Werror,-Winline-asm] arch/arm/probes/kprobes/actions-thumb.c:449:3: error: inline asm clobber list contains reserved registers: R7 [-Werror,-Winline-asm] Apparently gcc should also have warned about this, and the configuration is actually invalid, though there is some disagreement on the bug trackers about this. Link: https://bugs.llvm.org/show_bug.cgi?id=45826 Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94986 Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- arch/arm/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0d4f3e2d50ad..7ea95bb40004 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig@@ -91,7 +91,7 @@ config ARM select HAVE_FAST_GUP if ARM_LPAE 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 && !(THUMB2_KERNEL && CC_IS_CLANG) select HAVE_GCC_PLUGINS select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7) select HAVE_IRQ_TIME_ACCOUNTING
--
2.29.2
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