ARM: always use ARM_UNWIND for thumb2 kernels (89bace65) · Commits · 戴 / test

Thumb2 kernels cannot be built with frame pointers, but can use the ARM_UNWIND feature for unwinding instead. This makes sure that all features that rely on unwinding includeing CONFIG_LATENCYTOP and FAULT_INJECTION_STACKTRACE_FILTER do not enable frame pointers when the unwinder is already selected, and we always build with the unwinder when we want a thumb2 kernel, to make sure we do not get the frame pointers instead. A different option would be to redefine the CONFIG_FRAME_POINTERS option on ARM to mean builing with either frame pointers or the unwinder, and then select which one to use based on the CPU architecture or another user option. That would still allow building thumb2 kernels without the unwinder but would also be more confusing. Signed-off-by:

Arnd Bergmann <arnd@arndb.de>

arch/arm/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -1457,6 +1457,7 @@ config THUMB2_KERNEL
		depends on CPU_V7 && !CPU_V6 && !CPU_V6K && EXPERIMENTAL
		select AEABI
		select ARM_ASM_UNIFIED
		select ARM_UNWIND
		help
		By enabling this option, the kernel will be compiled in
		Thumb-2 mode. A compiler/assembler that understand the unified

lib/Kconfig.debug

+2 −2

Original line number	Diff line number	Diff line
		@@ -1081,7 +1081,7 @@ config FAULT_INJECTION_STACKTRACE_FILTER
		depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
		depends on !X86_64
		select STACKTRACE
		select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
		select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
		help
		Provide stacktrace filter for fault-injection capabilities

		@@ -1091,7 +1091,7 @@ config LATENCYTOP
		depends on DEBUG_KERNEL
		depends on STACKTRACE_SUPPORT
		depends on PROC_FS
		select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
		select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
		select KALLSYMS
		select KALLSYMS_ALL
		select STACKTRACE

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