Add option to enable -Wframe-larger-than= on gcc 4.4

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>

Add option to enable -Wframe-larger-than= on gcc 4.4
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>
Andi Kleen · Sam Ravnborg
1 parent 80ff262416
Showing 2 changed files with 15 additions and 0 deletions Side-by-side Diff
Makefile
lib/Kconfig.debug
@@ -507,6 +507,10 @@
 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)
@@ -25,6 +25,17 @@
 	  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
...	...	@@ -507,6 +507,10 @@
507	507	KBUILD_CFLAGS += -O2
508	508	endif
509	509
	510	+ifneq (CONFIG_FRAME_WARN,0)
	511	+KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
	512	+endif
	513	+
510	514	# Force gcc to behave correct even for buggy distributions
511	515	# Arch Makefiles may override this setting
512	516	KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
...	...	@@ -25,6 +25,17 @@
25	25	suppress the "warning: ignoring return value of 'foo', declared with
26	26	attribute warn_unused_result" messages.
27	27
	28	+config FRAME_WARN
	29	+ int "Warn for stack frames larger than (needs gcc 4.4)"
	30	+ range 0 8192
	31	+ default 1024 if !64BIT
	32	+ default 2048 if 64BIT
	33	+ help
	34	+ Tell gcc to warn at build time for stack frames larger than this.
	35	+ Setting this too low will cause a lot of warnings.
	36	+ Setting it to 0 disables the warning.
	37	+ Requires gcc 4.4
	38	+
28	39	config MAGIC_SYSRQ
29	40	bool "Magic SysRq key"
30	41	depends on !UML