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?
> @@ -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
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