[PATCH] lib/Kconfig.debug: introduce CONFIG_CC_STACK_USAGE

[PATCH] lib/Kconfig.debug: introduce CONFIG_CC_STACK_USAGE

[Konstantin Khlebnikov]

This patch adds option for collecting stack usage statistics
via gcc option '-fstack-usage' (needs gcc 4.6 or newer).
For each .o file gcc dumps stack-frame sizes into .su file.

File format:
<file>:<line>:<column>:<function>	<size>	<qualifiers>

select.c:870:5:do_sys_poll	1040	static
rtnetlink.c:1880:12:rtnl_newlink        552     dynamic
random.c:1334:1:random_read	664     dynamic,bounded

Quote from the gcc manpage about qualifiers:

    The qualifier "static" means that the function
    manipulates the stack statically: a fixed number of bytes
    are allocated for the frame on function entry and
    released on function exit; no stack adjustments are
    otherwise made in the function.  The second field is this
    fixed number of bytes.

    The qualifier "dynamic" means that the function
    manipulates the stack dynamically: in addition to the
    static allocation described above, stack adjustments are
    made in the body of the function, for example to push/pop
    arguments around function calls.  If the qualifier
    "bounded" is also present, the amount of these
    adjustments is bounded at compile time and the second
    field is an upper bound of the total amount of stack used
    by the function.  If it is not present, the amount of
    these adjustments is not bounded at compile time and the
    second field only represents the bounded part.

In comparison to the scripts/checkstack.pl this method is more accurate.
It takes into account function arguments, push/pop pairs, frame
pointers and saved return address. It gives information about all
functions except purely assember (for example sha1_transform_avx2).

Also this patch adds make target 'stack-usage' which combines all .su
files into one sorted 'stack-usage'. Also prints top 100 and all unbounded
dynamic stack frames.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
---
 Makefile          |   22 +++++++++++++++++++++-
 lib/Kconfig.debug |    9 +++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 2167084..9ba61ee 100644
--- a/Makefile
+++ b/Makefile
@@ -635,6 +635,10 @@ ifneq ($(CONFIG_FRAME_WARN),0)
 KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
 endif
 
+ifdef CONFIG_CC_STACK_USAGE
+KBUILD_CFLAGS += $(call cc-option,-fstack-usage)
+endif
+
 # Handle stack protector mode.
 ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
   stackp-flag := -fstack-protector
@@ -1228,6 +1232,7 @@ help:
 	 echo  ''
 	@echo  'Static analysers'
 	@echo  '  checkstack      - Generate a list of stack hogs'
+	@echo  '  stack-usage     - Alternative list of stack hogs'
 	@echo  '  namespacecheck  - Name space analysis on compiled kernel'
 	@echo  '  versioncheck    - Sanity check on version.h usage'
 	@echo  '  includecheck    - Check for duplicate included header files'
@@ -1376,7 +1381,7 @@ clean: $(clean-dirs)
 	$(call cmd,rmfiles)
 	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
 		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
-		-o -name '*.ko.*' \
+		-o -name '*.ko.*' -o -name '*.su' \
 		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
 		-o -name '*.symtypes' -o -name 'modules.order' \
 		-o -name modules.builtin -o -name '.tmp_*.o.*' \
@@ -1432,6 +1437,21 @@ checkstack:
 	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
 	$(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
 
+quiet_cmd_cc_stack_usage = SORTING $@
+cmd_cc_stack_usage = find -name '*.su' | xargs cat | sort -k 2 -n -r > $@
+
+stack-usage: FORCE
+ifndef CONFIG_CC_STACK_USAGE
+	$(Q)echo >&2 'Please rebuild with CONFIG_CC_STACK_USAGE=y' && false
+endif
+	$(call cmd,cc_stack_usage)
+	$(Q)echo ''
+	$(Q)echo 'Unbounded dynamic stack frames:'
+	$(Q)grep '\bdynamic$$' $@
+	$(Q)echo ''
+	$(Q)echo 'Top 100 stack frames:'
+	$(Q)head -100 < $@
+
 kernelrelease:
 	@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 7a638aa..3b30853 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -170,6 +170,15 @@ config FRAME_WARN
 	  Setting it to 0 disables the warning.
 	  Requires gcc 4.4
 
+config CC_STACK_USAGE
+	bool "Collect statistics about stack usage (needs gcc 4.6)"
+	help
+	  This enables gcc option -fstack-usage which saves information
+	  about stack frames in per-function basis into '.su' files.
+
+	  Run 'make stack-usage' after building kernel and modules to
+	  combine all information in one file.
+
 config STRIP_ASM_SYMS
 	bool "Strip assembler-generated symbols during link"
 	default n

Re: [PATCH] lib/Kconfig.debug: introduce CONFIG_CC_STACK_USAGE

[Konstantin Khlebnikov]

Damn, I forget to add them to the .gitignore

On Sun, Jul 13, 2014 at 12:01 AM, Konstantin Khlebnikov
<koct9i@gmail.com> wrote:
> This patch adds option for collecting stack usage statistics
> via gcc option '-fstack-usage' (needs gcc 4.6 or newer).
> For each .o file gcc dumps stack-frame sizes into .su file.
>
> File format:
> <file>:<line>:<column>:<function>       <size>  <qualifiers>
>
> select.c:870:5:do_sys_poll      1040    static
> rtnetlink.c:1880:12:rtnl_newlink        552     dynamic
> random.c:1334:1:random_read     664     dynamic,bounded
>
> Quote from the gcc manpage about qualifiers:
>
>     The qualifier "static" means that the function
>     manipulates the stack statically: a fixed number of bytes
>     are allocated for the frame on function entry and
>     released on function exit; no stack adjustments are
>     otherwise made in the function.  The second field is this
>     fixed number of bytes.
>
>     The qualifier "dynamic" means that the function
>     manipulates the stack dynamically: in addition to the
>     static allocation described above, stack adjustments are
>     made in the body of the function, for example to push/pop
>     arguments around function calls.  If the qualifier
>     "bounded" is also present, the amount of these
>     adjustments is bounded at compile time and the second
>     field is an upper bound of the total amount of stack used
>     by the function.  If it is not present, the amount of
>     these adjustments is not bounded at compile time and the
>     second field only represents the bounded part.
>
> In comparison to the scripts/checkstack.pl this method is more accurate.
> It takes into account function arguments, push/pop pairs, frame
> pointers and saved return address. It gives information about all
> functions except purely assember (for example sha1_transform_avx2).
>
> Also this patch adds make target 'stack-usage' which combines all .su
> files into one sorted 'stack-usage'. Also prints top 100 and all unbounded
> dynamic stack frames.
>
> Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
> ---
>  Makefile          |   22 +++++++++++++++++++++-
>  lib/Kconfig.debug |    9 +++++++++
>  2 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 2167084..9ba61ee 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -635,6 +635,10 @@ ifneq ($(CONFIG_FRAME_WARN),0)
>  KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
>  endif
>
> +ifdef CONFIG_CC_STACK_USAGE
> +KBUILD_CFLAGS += $(call cc-option,-fstack-usage)
> +endif
> +
>  # Handle stack protector mode.
>  ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
>    stackp-flag := -fstack-protector
> @@ -1228,6 +1232,7 @@ help:
>          echo  ''
>         @echo  'Static analysers'
>         @echo  '  checkstack      - Generate a list of stack hogs'
> +       @echo  '  stack-usage     - Alternative list of stack hogs'
>         @echo  '  namespacecheck  - Name space analysis on compiled kernel'
>         @echo  '  versioncheck    - Sanity check on version.h usage'
>         @echo  '  includecheck    - Check for duplicate included header files'
> @@ -1376,7 +1381,7 @@ clean: $(clean-dirs)
>         $(call cmd,rmfiles)
>         @find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
>                 \( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
> -               -o -name '*.ko.*' \
> +               -o -name '*.ko.*' -o -name '*.su' \
>                 -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
>                 -o -name '*.symtypes' -o -name 'modules.order' \
>                 -o -name modules.builtin -o -name '.tmp_*.o.*' \
> @@ -1432,6 +1437,21 @@ checkstack:
>         $(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
>         $(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
>
> +quiet_cmd_cc_stack_usage = SORTING $@
> +cmd_cc_stack_usage = find -name '*.su' | xargs cat | sort -k 2 -n -r > $@
> +
> +stack-usage: FORCE
> +ifndef CONFIG_CC_STACK_USAGE
> +       $(Q)echo >&2 'Please rebuild with CONFIG_CC_STACK_USAGE=y' && false
> +endif
> +       $(call cmd,cc_stack_usage)
> +       $(Q)echo ''
> +       $(Q)echo 'Unbounded dynamic stack frames:'
> +       $(Q)grep '\bdynamic$$' $@
> +       $(Q)echo ''
> +       $(Q)echo 'Top 100 stack frames:'
> +       $(Q)head -100 < $@
> +
>  kernelrelease:
>         @echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 7a638aa..3b30853 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -170,6 +170,15 @@ config FRAME_WARN
>           Setting it to 0 disables the warning.
>           Requires gcc 4.4
>
> +config CC_STACK_USAGE
> +       bool "Collect statistics about stack usage (needs gcc 4.6)"
> +       help
> +         This enables gcc option -fstack-usage which saves information
> +         about stack frames in per-function basis into '.su' files.
> +
> +         Run 'make stack-usage' after building kernel and modules to
> +         combine all information in one file.
> +
>  config STRIP_ASM_SYMS
>         bool "Strip assembler-generated symbols during link"
>         default n
>

[PATCH v2] lib/Kconfig.debug: introduce CONFIG_CC_STACK_USAGE

[Konstantin Khlebnikov]

This patch adds option for collecting stack usage statistics
via gcc option '-fstack-usage' (needs gcc 4.6 or newer).
For each .o file gcc dumps stack-frame sizes into .su file.

File format:
<file>:<line>:<column>:<function>	<size>	<qualifiers>

select.c:870:5:do_sys_poll	1040	static
rtnetlink.c:1880:12:rtnl_newlink        552     dynamic
random.c:1334:1:random_read	664     dynamic,bounded

Quote from the gcc manpage about qualifiers:

    The qualifier "static" means that the function
    manipulates the stack statically: a fixed number of bytes
    are allocated for the frame on function entry and
    released on function exit; no stack adjustments are
    otherwise made in the function.  The second field is this
    fixed number of bytes.

    The qualifier "dynamic" means that the function
    manipulates the stack dynamically: in addition to the
    static allocation described above, stack adjustments are
    made in the body of the function, for example to push/pop
    arguments around function calls.  If the qualifier
    "bounded" is also present, the amount of these
    adjustments is bounded at compile time and the second
    field is an upper bound of the total amount of stack used
    by the function.  If it is not present, the amount of
    these adjustments is not bounded at compile time and the
    second field only represents the bounded part.

In comparison to the scripts/checkstack.pl this method is more accurate.
It takes into account function arguments, push/pop pairs, frame
pointers and saved return address. It gives information about all
functions except purely assember (for example sha1_transform_avx2).

Also this patch adds make target 'stack-usage' which combines all .su
files into one sorted 'stack-usage'. Also prints top 100 and all unbounded
dynamic stack frames.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
---
 .gitignore        |    3 +++
 Makefile          |   23 ++++++++++++++++++++++-
 lib/Kconfig.debug |    9 +++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index f4c0b09..96b8984 100644
--- a/.gitignore
+++ b/.gitignore
@@ -85,6 +85,9 @@ GTAGS
 *~
 \#*#
 
+*.su
+/stack-usage
+
 #
 # Leavings from module signing
 #
diff --git a/Makefile b/Makefile
index 2167084..29fe588 100644
--- a/Makefile
+++ b/Makefile
@@ -635,6 +635,11 @@ ifneq ($(CONFIG_FRAME_WARN),0)
 KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
 endif
 
+ifdef CONFIG_CC_STACK_USAGE
+KBUILD_CFLAGS += $(call cc-option,-fstack-usage)
+endif
+CLEAN_FILES += stack-usage
+
 # Handle stack protector mode.
 ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
   stackp-flag := -fstack-protector
@@ -1228,6 +1233,7 @@ help:
 	 echo  ''
 	@echo  'Static analysers'
 	@echo  '  checkstack      - Generate a list of stack hogs'
+	@echo  '  stack-usage     - Alternative list of stack hogs'
 	@echo  '  namespacecheck  - Name space analysis on compiled kernel'
 	@echo  '  versioncheck    - Sanity check on version.h usage'
 	@echo  '  includecheck    - Check for duplicate included header files'
@@ -1376,7 +1382,7 @@ clean: $(clean-dirs)
 	$(call cmd,rmfiles)
 	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
 		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
-		-o -name '*.ko.*' \
+		-o -name '*.ko.*' -o -name '*.su' \
 		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
 		-o -name '*.symtypes' -o -name 'modules.order' \
 		-o -name modules.builtin -o -name '.tmp_*.o.*' \
@@ -1432,6 +1438,21 @@ checkstack:
 	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
 	$(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
 
+quiet_cmd_cc_stack_usage = SORTING $@
+cmd_cc_stack_usage = find -name '*.su' | xargs cat | sort -k 2 -n -r > $@
+
+stack-usage: FORCE
+ifndef CONFIG_CC_STACK_USAGE
+	$(Q)echo >&2 'Please rebuild with CONFIG_CC_STACK_USAGE=y' && false
+endif
+	$(call cmd,cc_stack_usage)
+	$(Q)echo ''
+	$(Q)echo 'Unbounded dynamic stack frames:'
+	$(Q)grep '\bdynamic$$' $@ || true
+	$(Q)echo ''
+	$(Q)echo 'Top 100 stack frames:'
+	$(Q)head -100 < $@
+
 kernelrelease:
 	@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 7a638aa..3b30853 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -170,6 +170,15 @@ config FRAME_WARN
 	  Setting it to 0 disables the warning.
 	  Requires gcc 4.4
 
+config CC_STACK_USAGE
+	bool "Collect statistics about stack usage (needs gcc 4.6)"
+	help
+	  This enables gcc option -fstack-usage which saves information
+	  about stack frames in per-function basis into '.su' files.
+
+	  Run 'make stack-usage' after building kernel and modules to
+	  combine all information in one file.
+
 config STRIP_ASM_SYMS
 	bool "Strip assembler-generated symbols during link"
 	default n

Re: [PATCH v2] lib/Kconfig.debug: introduce CONFIG_CC_STACK_USAGE

[Sam Ravnborg]

Hi Konstantin.

On Sun, Jul 13, 2014 at 12:24:50AM +0400, Konstantin Khlebnikov wrote:
> This patch adds option for collecting stack usage statistics
> via gcc option '-fstack-usage' (needs gcc 4.6 or newer).
> For each .o file gcc dumps stack-frame sizes into .su file.
> 
> File format:
> <file>:<line>:<column>:<function>	<size>	<qualifiers>
> 
> select.c:870:5:do_sys_poll	1040	static
> rtnetlink.c:1880:12:rtnl_newlink        552     dynamic
> random.c:1334:1:random_read	664     dynamic,bounded
> 
> Quote from the gcc manpage about qualifiers:
> 
>     The qualifier "static" means that the function
>     manipulates the stack statically: a fixed number of bytes
>     are allocated for the frame on function entry and
>     released on function exit; no stack adjustments are
>     otherwise made in the function.  The second field is this
>     fixed number of bytes.
> 
>     The qualifier "dynamic" means that the function
>     manipulates the stack dynamically: in addition to the
>     static allocation described above, stack adjustments are
>     made in the body of the function, for example to push/pop
>     arguments around function calls.  If the qualifier
>     "bounded" is also present, the amount of these
>     adjustments is bounded at compile time and the second
>     field is an upper bound of the total amount of stack used
>     by the function.  If it is not present, the amount of
>     these adjustments is not bounded at compile time and the
>     second field only represents the bounded part.
> 
> In comparison to the scripts/checkstack.pl this method is more accurate.
> It takes into account function arguments, push/pop pairs, frame
> pointers and saved return address. It gives information about all
> functions except purely assember (for example sha1_transform_avx2).
> 
> Also this patch adds make target 'stack-usage' which combines all .su
> files into one sorted 'stack-usage'. Also prints top 100 and all unbounded
> dynamic stack frames.
> 
> Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
> ---
>  .gitignore        |    3 +++
>  Makefile          |   23 ++++++++++++++++++++++-
>  lib/Kconfig.debug |    9 +++++++++
>  3 files changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/.gitignore b/.gitignore
> index f4c0b09..96b8984 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -85,6 +85,9 @@ GTAGS
>  *~
>  \#*#
>  
> +*.su
> +/stack-usage
> +
>  #
>  # Leavings from module signing
>  #
> diff --git a/Makefile b/Makefile
> index 2167084..29fe588 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -635,6 +635,11 @@ ifneq ($(CONFIG_FRAME_WARN),0)
>  KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
>  endif
>  
> +ifdef CONFIG_CC_STACK_USAGE
> +KBUILD_CFLAGS += $(call cc-option,-fstack-usage)
> +endif
> +CLEAN_FILES += stack-usage
> +
>  # Handle stack protector mode.
>  ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
>    stackp-flag := -fstack-protector
> @@ -1228,6 +1233,7 @@ help:
>  	 echo  ''
>  	@echo  'Static analysers'
>  	@echo  '  checkstack      - Generate a list of stack hogs'
> +	@echo  '  stack-usage     - Alternative list of stack hogs'
>  	@echo  '  namespacecheck  - Name space analysis on compiled kernel'
>  	@echo  '  versioncheck    - Sanity check on version.h usage'
>  	@echo  '  includecheck    - Check for duplicate included header files'
The other "check" targets have check in their name.
Can we follow this naming convention and call it checkstackusage?


> @@ -1376,7 +1382,7 @@ clean: $(clean-dirs)
>  	$(call cmd,rmfiles)
>  	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
>  		\( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
> -		-o -name '*.ko.*' \
> +		-o -name '*.ko.*' -o -name '*.su' \
>  		-o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
>  		-o -name '*.symtypes' -o -name 'modules.order' \
>  		-o -name modules.builtin -o -name '.tmp_*.o.*' \
> @@ -1432,6 +1438,21 @@ checkstack:
>  	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
>  	$(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
>  
> +quiet_cmd_cc_stack_usage = SORTING $@
> +cmd_cc_stack_usage = find -name '*.su' | xargs cat | sort -k 2 -n -r > $@
> +
> +stack-usage: FORCE
> +ifndef CONFIG_CC_STACK_USAGE
> +	$(Q)echo >&2 'Please rebuild with CONFIG_CC_STACK_USAGE=y' && false
> +endif
> +	$(call cmd,cc_stack_usage)
> +	$(Q)echo ''
> +	$(Q)echo 'Unbounded dynamic stack frames:'
> +	$(Q)grep '\bdynamic$$' $@ || true
> +	$(Q)echo ''
> +	$(Q)echo 'Top 100 stack frames:'
> +	$(Q)head -100 < $@
> +

All this belongs to a script - for example named

    scripts/checkstackusage.sh

The top-level Makefile shall be a thin driver and there are too much functionality
in that file. but this is no excuse for adding more.

	Sam

Re: [PATCH v2] lib/Kconfig.debug: introduce CONFIG_CC_STACK_USAGE

[Konstantin Khlebnikov]

On Sun, Jul 13, 2014 at 1:31 PM, Sam Ravnborg <sam@ravnborg.org> wrote:
> Hi Konstantin.
>
> On Sun, Jul 13, 2014 at 12:24:50AM +0400, Konstantin Khlebnikov wrote:
>> This patch adds option for collecting stack usage statistics
>> via gcc option '-fstack-usage' (needs gcc 4.6 or newer).
>> For each .o file gcc dumps stack-frame sizes into .su file.
>>
>> File format:
>> <file>:<line>:<column>:<function>     <size>  <qualifiers>
>>
>> select.c:870:5:do_sys_poll    1040    static
>> rtnetlink.c:1880:12:rtnl_newlink        552     dynamic
>> random.c:1334:1:random_read   664     dynamic,bounded
>>
>> Quote from the gcc manpage about qualifiers:
>>
>>     The qualifier "static" means that the function
>>     manipulates the stack statically: a fixed number of bytes
>>     are allocated for the frame on function entry and
>>     released on function exit; no stack adjustments are
>>     otherwise made in the function.  The second field is this
>>     fixed number of bytes.
>>
>>     The qualifier "dynamic" means that the function
>>     manipulates the stack dynamically: in addition to the
>>     static allocation described above, stack adjustments are
>>     made in the body of the function, for example to push/pop
>>     arguments around function calls.  If the qualifier
>>     "bounded" is also present, the amount of these
>>     adjustments is bounded at compile time and the second
>>     field is an upper bound of the total amount of stack used
>>     by the function.  If it is not present, the amount of
>>     these adjustments is not bounded at compile time and the
>>     second field only represents the bounded part.
>>
>> In comparison to the scripts/checkstack.pl this method is more accurate.
>> It takes into account function arguments, push/pop pairs, frame
>> pointers and saved return address. It gives information about all
>> functions except purely assember (for example sha1_transform_avx2).
>>
>> Also this patch adds make target 'stack-usage' which combines all .su
>> files into one sorted 'stack-usage'. Also prints top 100 and all unbounded
>> dynamic stack frames.
>>
>> Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
>> ---
>>  .gitignore        |    3 +++
>>  Makefile          |   23 ++++++++++++++++++++++-
>>  lib/Kconfig.debug |    9 +++++++++
>>  3 files changed, 34 insertions(+), 1 deletion(-)
>>
>> diff --git a/.gitignore b/.gitignore
>> index f4c0b09..96b8984 100644
>> --- a/.gitignore
>> +++ b/.gitignore
>> @@ -85,6 +85,9 @@ GTAGS
>>  *~
>>  \#*#
>>
>> +*.su
>> +/stack-usage
>> +
>>  #
>>  # Leavings from module signing
>>  #
>> diff --git a/Makefile b/Makefile
>> index 2167084..29fe588 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -635,6 +635,11 @@ ifneq ($(CONFIG_FRAME_WARN),0)
>>  KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
>>  endif
>>
>> +ifdef CONFIG_CC_STACK_USAGE
>> +KBUILD_CFLAGS += $(call cc-option,-fstack-usage)
>> +endif
>> +CLEAN_FILES += stack-usage
>> +
>>  # Handle stack protector mode.
>>  ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
>>    stackp-flag := -fstack-protector
>> @@ -1228,6 +1233,7 @@ help:
>>        echo  ''
>>       @echo  'Static analysers'
>>       @echo  '  checkstack      - Generate a list of stack hogs'
>> +     @echo  '  stack-usage     - Alternative list of stack hogs'
>>       @echo  '  namespacecheck  - Name space analysis on compiled kernel'
>>       @echo  '  versioncheck    - Sanity check on version.h usage'
>>       @echo  '  includecheck    - Check for duplicate included header files'
> The other "check" targets have check in their name.
> Can we follow this naming convention and call it checkstackusage?

Most of them, not all of them. export_report and headerdep dont have it.
And it's not just a check it generates file as result.
So, since I haven't found better name I decided to use the same words
as in the gcc option.

>
>
>> @@ -1376,7 +1382,7 @@ clean: $(clean-dirs)
>>       $(call cmd,rmfiles)
>>       @find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
>>               \( -name '*.[oas]' -o -name '*.ko' -o -name '.*.cmd' \
>> -             -o -name '*.ko.*' \
>> +             -o -name '*.ko.*' -o -name '*.su' \
>>               -o -name '.*.d' -o -name '.*.tmp' -o -name '*.mod.c' \
>>               -o -name '*.symtypes' -o -name 'modules.order' \
>>               -o -name modules.builtin -o -name '.tmp_*.o.*' \
>> @@ -1432,6 +1438,21 @@ checkstack:
>>       $(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
>>       $(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
>>
>> +quiet_cmd_cc_stack_usage = SORTING $@
>> +cmd_cc_stack_usage = find -name '*.su' | xargs cat | sort -k 2 -n -r > $@
>> +
>> +stack-usage: FORCE
>> +ifndef CONFIG_CC_STACK_USAGE
>> +     $(Q)echo >&2 'Please rebuild with CONFIG_CC_STACK_USAGE=y' && false
>> +endif
>> +     $(call cmd,cc_stack_usage)
>> +     $(Q)echo ''
>> +     $(Q)echo 'Unbounded dynamic stack frames:'
>> +     $(Q)grep '\bdynamic$$' $@ || true
>> +     $(Q)echo ''
>> +     $(Q)echo 'Top 100 stack frames:'
>> +     $(Q)head -100 < $@
>> +
>
> All this belongs to a script - for example named
>
>     scripts/checkstackusage.sh
>
> The top-level Makefile shall be a thin driver and there are too much functionality
> in that file. but this is no excuse for adding more.

Ok, I'll think about it.

>
>         Sam