Add option to enable -Wframe-larger-than= on gcc 4.4 (35bb5b1e) · Commits · 戴 / test

Add option to enable -Wframe-larger-than= on gcc 4.4 gcc mainline (upcoming 4.4) added a new -Wframe-larger-than=... option to warn at build time about too large stack frames. Add a config option to enable this warning, since this very useful for the kernel. I choose (somewhat arbitarily) 2048 as default warning threshold for 64bit and 1024 as default for 32bit architectures. With some research and fixing all the code for smaller values these defaults should be probably lowered. With the default allyesconfigs have some new warnings, but I think that is all code that should be just fixed. At some point (when gcc 4.4 is released and widely used) this should obsolete make checkstack Signed-off-by:

Andi Kleen <ak@suse.de> Signed-off-by:

Sam Ravnborg <sam@ravnborg.org>

Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -507,6 +507,10 @@ else
		KBUILD_CFLAGS += -O2
		endif

		ifneq (CONFIG_FRAME_WARN,0)
		KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
		endif

		# Force gcc to behave correct even for buggy distributions
		# Arch Makefiles may override this setting
		KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)

lib/Kconfig.debug

+11 −0

Original line number	Diff line number	Diff line
		@@ -25,6 +25,17 @@ config ENABLE_MUST_CHECK
		suppress the "warning: ignoring return value of 'foo', declared with
		attribute warn_unused_result" messages.

		config FRAME_WARN
		int "Warn for stack frames larger than (needs gcc 4.4)"
		range 0 8192
		default 1024 if !64BIT
		default 2048 if 64BIT
		help
		Tell gcc to warn at build time for stack frames larger than this.
		Setting this too low will cause a lot of warnings.
		Setting it to 0 disables the warning.
		Requires gcc 4.4

		config MAGIC_SYSRQ
		bool "Magic SysRq key"
		depends on !UML

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