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Subject[PATCH] Kbuild: Check for CONFIG_READABLE_ASM when building .s targets
Date
From: Borislav Petkov <bp@suse.de>

We do need to look at the asm output of c files for various reasons. In
order to do so, we do make <path-to-filename>.s.

However, it can happen that the Kconfig option which enables the
creation of readable asm CONFIG_READABLE_ASM is disabled. What is more,
we want this option enabled because it indirectly enables the issue of
line numbers in the asm done by gcc's switch -g.

So issue a warning that the asm output might not be optimally readable
if that option is disabled.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
Makefile | 2 +-
scripts/Makefile.build | 7 ++++++-
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index e43244263306..d9b505360c2a 100644
--- a/Makefile
+++ b/Makefile
@@ -1513,7 +1513,7 @@ else
endif

%.s: %.c prepare scripts FORCE
- $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
+ $(Q)$(MAKE) $(build)=$(build-dir) asm_target=$@ $(target-dir)$(notdir $@)
%.i: %.c prepare scripts FORCE
$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
%.o: %.c prepare scripts FORCE
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index bf3e6778cd71..8aaf1c04fe18 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -147,7 +147,12 @@ $(multi-objs-y:.o=.s) : modname = $(modname-multi)
$(multi-objs-y:.o=.lst) : modname = $(modname-multi)

quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
-cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $<
+cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $< \
+ $(if $(findstring $(asm_target),$@),\
+ $(if $(__cmd_cc_s_c_once),,\
+ $(if $(CONFIG_READABLE_ASM),,\
+ $(warning Enable CONFIG_READABLE_ASM for more helpful asm); \
+ $(eval __cmd_cc_s_c_once=1)))) \

$(obj)/%.s: $(src)/%.c FORCE
$(call if_changed_dep,cc_s_c)
--
2.0.0


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