From dee9495303f2c6d63a20c43a26420765909898eb Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 17 Jan 2019 09:10:03 +0900 Subject: kbuild: remove top-level built-in.a The symbol table in the final archive is unneeded; the linker does not require the symbol table after the --whole-archive option. Every object file in the archive is included in the link anyway. Pass thin archives from subdirectories directly to the linker, and remove the final archiving step. Fix up the document and comments as well. Signed-off-by: Masahiro Yamada Acked-by: Nicholas Piggin --- scripts/Makefile.build | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index fd03d60f6c5a..681ab58a1548 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -394,14 +394,10 @@ $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler $(sort $(subdir-obj-y)): $(subdir-ym) ; # -# Rule to compile a set of .o files into one .o file +# Rule to compile a set of .o files into one .a file (without symbol table) # ifdef builtin-target -# built-in.a archives are made with no symbol table or index which -# makes them small and fast, but unable to be used by the linker. -# scripts/link-vmlinux.sh builds an aggregate built-in.a with a symbol -# table and index. quiet_cmd_ar_builtin = AR $@ cmd_ar_builtin = rm -f $@; \ $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^) @@ -426,7 +422,7 @@ $(modorder-target): $(subdir-ym) FORCE $(Q)(cat /dev/null; $(modorder-cmds)) > $@ # -# Rule to compile a set of .o files into one .a file +# Rule to compile a set of .o files into one .a file (with symbol table) # ifdef lib-target quiet_cmd_link_l_target = AR $@ -- cgit v1.2.3 From afa974b771281fd89e8fdcb71152152f17fb8303 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 17 Jan 2019 19:02:43 +0900 Subject: kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^) In Kbuild, if_changed and friends must have FORCE as a prerequisite. Hence, $(filter-out FORCE,$^) or $(filter-out $(PHONY),$^) is a common idiom to get the names of all the prerequisites except phony targets. Add real-prereqs as a shorthand. Note: We cannot replace $(filter %.o,$^) in cmd_link_multi-m because $^ may include auto-generated dependencies from the .*.cmd file when a single object module is changed into a multi object module. Refer to commit 69ea912fda74 ("kbuild: remove unneeded link_multi_deps"). I added some comment to avoid accidental breakage. Signed-off-by: Masahiro Yamada Acked-by: Rob Herring --- scripts/Makefile.build | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 681ab58a1548..9800178fdcd2 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -399,8 +399,7 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ; ifdef builtin-target quiet_cmd_ar_builtin = AR $@ - cmd_ar_builtin = rm -f $@; \ - $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(filter $(real-obj-y), $^) + cmd_ar_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(real-prereqs) $(builtin-target): $(real-obj-y) FORCE $(call if_changed,ar_builtin) @@ -428,7 +427,7 @@ ifdef lib-target quiet_cmd_link_l_target = AR $@ # lib target archives do get a symbol table and index -cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(lib-y) +cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs) $(lib-target): $(lib-y) FORCE $(call if_changed,link_l_target) @@ -453,6 +452,10 @@ targets += $(obj)/lib-ksyms.o endif +# NOTE: +# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object +# module is turned into a multi object module, $^ will contain header file +# dependencies recorded in the .*.cmd file. quiet_cmd_link_multi-m = LD [M] $@ cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^) $(cmd_secanalysis) -- cgit v1.2.3 From b79c6aa6a1f111eab2fc08b92541c9e88824be72 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 17 Jan 2019 19:02:44 +0900 Subject: kbuild: remove unnecessary in-subshell execution The commands surrounded by ( ) are executed in a subshell, but in most cases, we do not need to spawn an extra subshell. Signed-off-by: Masahiro Yamada --- scripts/Makefile.build | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 9800178fdcd2..f8e2794107ed 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -312,11 +312,11 @@ $(real-obj-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE) # # These mirror gensymtypes_c and co above, keep them in synch. cmd_gensymtypes_S = \ - (echo "\#include " ; \ + { echo "\#include " ; \ echo "\#include " ; \ $(CPP) $(a_flags) $< | \ grep "\<___EXPORT_SYMBOL\>" | \ - sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \ + sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \ $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \ $(GENKSYMS) $(if $(1), -T $(2)) \ $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ -- cgit v1.2.3 From 1e88e415ebccb9013b92b55e7512938040c53b61 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 10 Feb 2019 15:51:00 +0900 Subject: kbuild: Disable extra debugging info in .s output Modern gcc adds view assignments, reset assertion checking in .loc directives and a couple more additional debug markers, which clutters the asm output unnecessarily: For example: bsp_resume: .LFB3466: .loc 1 1868 1 is_stmt 1 view -0 .cfi_startproc .loc 1 1869 2 view .LVU73 # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) .loc 1 1869 14 is_stmt 0 view .LVU74 movq this_cpu(%rip), %rax # this_cpu, this_cpu movq 64(%rax), %rax # this_cpu.94_1->c_bsp_resume, _2 # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) .loc 1 1869 5 view .LVU75 testq %rax, %rax # _2 je .L8 #, .loc 1 1870 3 is_stmt 1 view .LVU76 movq $boot_cpu_data, %rdi #, jmp __x86_indirect_thunk_rax or .loc 2 57 9 view .LVU478 .loc 2 57 9 view .LVU479 .loc 2 57 9 view .LVU480 .loc 2 57 9 view .LVU481 .LBB1385: .LBB1383: .LBB1379: .LBB1377: .LBB1375: .loc 2 57 9 view .LVU482 .loc 2 57 9 view .LVU483 movl %edi, %edx # cpu, cpu .LVL87: .loc 2 57 9 is_stmt 0 view .LVU484 That MOV in there is drowned in debugging information and latter makes it hard to follow the asm. And that DWARF info is not really needed for asm output staring. Disable the debug information generation which clutters the asm output unnecessarily: bsp_resume: # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) movq this_cpu(%rip), %rax # this_cpu, this_cpu movq 64(%rax), %rax # this_cpu.94_1->c_bsp_resume, _2 # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) testq %rax, %rax # _2 je .L8 #, # arch/x86/kernel/cpu/common.c:1870: this_cpu->c_bsp_resume(&boot_cpu_data); movq $boot_cpu_data, %rdi #, jmp __x86_indirect_thunk_rax .L8: # arch/x86/kernel/cpu/common.c:1871: } rep ret .size bsp_resume, .-bsp_resume [ bp: write commit message. ] Signed-off-by: Masahiro Yamada Signed-off-by: Borislav Petkov --- scripts/Makefile.build | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index f8e2794107ed..0a9d849d0fab 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -104,7 +104,7 @@ modkern_cflags = \ quiet_modtag = $(if $(part-of-module),[M], ) 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) $(filter-out $(DEBUG_CFLAGS), $(c_flags)) $(DISABLE_LTO) -fverbose-asm -S -o $@ $< $(obj)/%.s: $(src)/%.c FORCE $(call if_changed_dep,cc_s_c) -- cgit v1.2.3 From 1d8001ef358da16f0ca64ab7fae9f34d7b91101e Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 14 Feb 2019 12:05:15 +0900 Subject: kbuild: generate modules.order only when CONFIG_MODULES=y Do not generate pointless modules.order when the module support is disabled. Signed-off-by: Masahiro Yamada --- scripts/Makefile.build | 2 ++ 1 file changed, 2 insertions(+) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 0a9d849d0fab..b803233327d0 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -63,7 +63,9 @@ ifneq ($(strip $(real-obj-y) $(need-builtin)),) builtin-target := $(obj)/built-in.a endif +ifdef CONFIG_MODULES modorder-target := $(obj)/modules.order +endif # We keep a list of all modules in $(MODVERDIR) -- cgit v1.2.3 From 88110713ca9dfbb0b6cb8bbb46ef6ecb313d6681 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 20 Feb 2019 12:38:31 +0900 Subject: kbuild: hardcode genksyms path and remove GENKSYMS variable The genksyms source was integrated into the kernel tree in 2003. I do not expect anybody still using the external /sbin/genksyms. Kbuild does not need to provide the ability to override GENKSYMS. Let's remove the GENKSYMS variable, and use the hardcoded path. Since it occurred in the pre-git era, I attached the commit message in case somebody is interested in the historical background. | Author: Kai Germaschewski | Date: Wed Feb 19 04:17:28 2003 -0600 | | kbuild: [PATCH] put genksyms in scripts dir | | This puts genksyms into scripts/genksyms/. | | genksyms used to be maintained externally, though the only possible user | was the kernel build. Moving it into the kernel sources makes it easier to | keep it uptodate, like for example updating it to generate linker scripts | directly instead of postprocessing the generated header file fragments | with sed, as we do currently. | | Also, genksyms does not handle __typeof__, which needs to be fixed since | some of the exported symbol in the kernel are defined using __typeof__. | | (Rusty Russell/me) Signed-off-by: Masahiro Yamada --- scripts/Makefile.build | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'scripts/Makefile.build') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index b803233327d0..850b611f4aba 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -120,7 +120,7 @@ $(obj)/%.i: $(src)/%.c FORCE # These mirror gensymtypes_S and co below, keep them in synch. cmd_gensymtypes_c = \ $(CPP) -D__GENKSYMS__ $(c_flags) $< | \ - $(GENKSYMS) $(if $(1), -T $(2)) \ + scripts/genksyms/genksyms $(if $(1), -T $(2)) \ $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ $(if $(KBUILD_PRESERVE),-p) \ -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null)) @@ -320,7 +320,7 @@ cmd_gensymtypes_S = \ grep "\<___EXPORT_SYMBOL\>" | \ sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ; } | \ $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \ - $(GENKSYMS) $(if $(1), -T $(2)) \ + scripts/genksyms/genksyms $(if $(1), -T $(2)) \ $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ $(if $(KBUILD_PRESERVE),-p) \ -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null)) -- cgit v1.2.3