On Sun, Jul 13, 2014 at 1:31 PM, Sam Ravnborg <sam@xxxxxxxxxxxx> 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@xxxxxxxxx>
>> ---
>> .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
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