Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1366692 > unrolled thread

[PATCH v7 0/8]/[PULL REQUEST] Trim unused exported kernel symbols

Back to article view | Back to linux.kernel

Contents

  [PATCH v7 0/8]/[PULL REQUEST] Trim unused exported kernel symbols Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 2/8] export.h: allow for per-symbol configurable EXPORT_SYMBOL() Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 3/8] fixdep: accept extra dependencies on stdin Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 4/8] kbuild: de-duplicate fixdep usage Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 1/8] kbuild: record needed exported symbols for modules Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 8/8] kconfig option for TRIM_UNUSED_KSYMS Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 6/8] kbuild: create/adjust generated/autoksyms.h Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200
    [PATCH v7 7/8] kbuild: build sample modules along with the rest of the kernel Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-03-29 22:50 +0200

#1366692 — [PATCH v7 0/8]/[PULL REQUEST] Trim unused exported kernel symbols

This patch series provides the option to omit exported symbols from
the kernel and modules that are never referenced by any of the selected
modules in the current kernel configuration. this allows for optimizing
the compiled code and reducing final binaries' size. When using LTO the
binary size reduction is even more effective. It could also be argued
that this could bring some security advantages.

The original cover letter with lots of test results can be found here:

	https://lkml.org/lkml/2016/2/8/813

Please consider for merging into your tree.

Alternately, the following branch can be pulled:

	http://git.linaro.org/people/nicolas.pitre/linux.git autoksyms

Thanks.

Changes from v6:

- Rebased on v4.6-rc1, including adjustments to the recently introduced
  rule_as_o_S.

- Explicitly ignored more if_changed_dep callers for which no EXPORT_SYMBOL
  can be parsed.

Changes from v5:

- Disable automatic dependency file generation during the preprocessor
  pass when gathering exported symbol names.  Not only it is redundant
  but in some conditions this crashes fixdep that might be reading the
  previous dependency file at the same time. Reported by Michal Marek.

- Redirect error messages to stderr rather than pass it as a symbol name
  dependency.

Changes from v4:

- Correctness changes plus small cleanup to adjust_autoksyms.sh as
  suggested by Michal Marek.

- Changed ksym build dependency generation by re-running the preprocessor
  rather than collecting those dependencies as warnings through stderr
  which was too fragile.

Changes from v3:

- Shell portability changes to adjust_autoksyms.sh, partly from
  suggestions by Zev Weiss.

- Fix sample modules by building them before adjust_autoksyms.sh is run.

Changes from v2:

- Generating the build dependencies by parsing the source with fixdep
  turned out to be unreliable due to all the EXPORT_SYMBOL() variants,
  and especially their use within macros where the actual symbol name
  is known only after running the preprocessor. This list of symbol names
  is now obtained from the preprocessor directly, fixing allmodconfig
  builds.

Changes from v1:

- Replaced "exp" that doesn't convey the right meaning as noted by
  Sam Ravnborg. The "ksym" identifier is actually what the kernel
  already uses for this. Therefore:
  - CONFIG_TRIM_UNUSED_EXPSYMS --> CONFIG_TRIM_UNUSED_KSYMS
  - include/generated/expsyms.h --> include/generated/autoksyms.h
  - #define __EXPSYM_* --> #define __KSYM_*

- Some sed regexp improvements as suggested by Al Viro.

- Renamed vmlinux_recursive target to autoksyms_recursive.

- Accept EXPORT_SYMBOL variants with a prefix, e.g. ACPI_EXPORT_SYMBOL.

- Minor commit log clarifications.

- Added Rusty's ACK.

diffstat:

 Makefile                    |  23 +++++++--
 include/linux/export.h      |  33 ++++++++++++-
 init/Kconfig                |  16 ++++++
 scripts/Kbuild.include      |  32 +++++++++++-
 scripts/Makefile.build      |  32 ++++++------
 scripts/adjust_autoksyms.sh | 101 ++++++++++++++++++++++++++++++++++++++
 scripts/basic/fixdep.c      |  61 +++++++++++++++++------
 7 files changed, 261 insertions(+), 37 deletions(-)

[toc] | [next] | [standalone]

#1366693 — [PATCH v7 2/8] export.h: allow for per-symbol configurable EXPORT_SYMBOL()

Similar to include/generated/autoconf.h, include/generated/autoksyms.h
will contain a list of defines for each EXPORT_SYMBOL() that we want
active. The format is:

  #define __KSYM_<symbol_name> 1

This list will be auto-generated with another patch.  For now we only
include the preprocessor magic to automatically create or omit the
corresponding struct kernel_symbol declaration.

Given the content of include/generated/autoksyms.h may not be known in
advance, an empty file is created early on to let the build proceed.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
---
 Makefile               |  2 ++
 include/linux/export.h | 22 ++++++++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 916b26e999..451acbebee 100644
--- a/Makefile
+++ b/Makefile
@@ -998,6 +998,8 @@ prepare2: prepare3 outputmakefile asm-generic
 prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
                    include/config/auto.conf
 	$(cmd_crmodverdir)
+	$(Q)test -e include/generated/autoksyms.h || \
+	    touch   include/generated/autoksyms.h
 
 archprepare: archheaders archscripts prepare1 scripts_basic
 
diff --git a/include/linux/export.h b/include/linux/export.h
index 96e45ea463..77afdb2a25 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -38,7 +38,7 @@ extern struct module __this_module;
 
 #ifdef CONFIG_MODULES
 
-#ifndef __GENKSYMS__
+#if defined(__KERNEL__) && !defined(__GENKSYMS__)
 #ifdef CONFIG_MODVERSIONS
 /* Mark the CRC weak since genksyms apparently decides not to
  * generate a checksums for some symbols */
@@ -53,7 +53,7 @@ extern struct module __this_module;
 #endif
 
 /* For every exported symbol, place a struct in the __ksymtab section */
-#define __EXPORT_SYMBOL(sym, sec)				\
+#define ___EXPORT_SYMBOL(sym, sec)				\
 	extern typeof(sym) sym;					\
 	__CRC_SYMBOL(sym, sec)					\
 	static const char __kstrtab_##sym[]			\
@@ -65,6 +65,24 @@ extern struct module __this_module;
 	__attribute__((section("___ksymtab" sec "+" #sym), unused))	\
 	= { (unsigned long)&sym, __kstrtab_##sym }
 
+#ifdef CONFIG_TRIM_UNUSED_KSYMS
+
+#include <linux/kconfig.h>
+#include <generated/autoksyms.h>
+
+#define __EXPORT_SYMBOL(sym, sec)				\
+	__cond_export_sym(sym, sec, config_enabled(__KSYM_##sym))
+#define __cond_export_sym(sym, sec, conf)			\
+	___cond_export_sym(sym, sec, conf)
+#define ___cond_export_sym(sym, sec, enabled)			\
+	__cond_export_sym_##enabled(sym, sec)
+#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
+#define __cond_export_sym_0(sym, sec) /* nothing */
+
+#else
+#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
+#endif
+
 #define EXPORT_SYMBOL(sym)					\
 	__EXPORT_SYMBOL(sym, "")
 
-- 
2.5.5

[toc] | [prev] | [next] | [standalone]

#1366694 — [PATCH v7 3/8] fixdep: accept extra dependencies on stdin

... and merge them in the list of parsed dependencies.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 scripts/basic/fixdep.c | 60 +++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 45 insertions(+), 15 deletions(-)

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index caef815d17..7e90a1f7de 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -120,13 +120,15 @@
 #define INT_NFIG ntohl(0x4e464947)
 #define INT_FIG_ ntohl(0x4649475f)
 
+int insert_extra_deps;
 char *target;
 char *depfile;
 char *cmdline;
 
 static void usage(void)
 {
-	fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
+	fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
+	fprintf(stderr, " -e  insert extra dependencies given on stdin\n");
 	exit(1);
 }
 
@@ -138,6 +140,40 @@ static void print_cmdline(void)
 	printf("cmd_%s := %s\n\n", target, cmdline);
 }
 
+/*
+ * Print out a dependency path from a symbol name
+ */
+static void print_config(const char *m, int slen)
+{
+	int c, i;
+
+	printf("    $(wildcard include/config/");
+	for (i = 0; i < slen; i++) {
+		c = m[i];
+		if (c == '_')
+			c = '/';
+		else
+			c = tolower(c);
+		putchar(c);
+	}
+	printf(".h) \\\n");
+}
+
+static void do_extra_deps(void)
+{
+	if (insert_extra_deps) {
+		char buf[80];
+		while(fgets(buf, sizeof(buf), stdin)) {
+			int len = strlen(buf);
+			if (len < 2 || buf[len-1] != '\n') {
+				fprintf(stderr, "fixdep: bad data on stdin\n");
+				exit(1);
+			}
+			print_config(buf, len-1);
+		}
+	}
+}
+
 struct item {
 	struct item	*next;
 	unsigned int	len;
@@ -197,23 +233,12 @@ static void define_config(const char *name, int len, unsigned int hash)
 static void use_config(const char *m, int slen)
 {
 	unsigned int hash = strhash(m, slen);
-	int c, i;
 
 	if (is_defined_config(m, slen, hash))
 	    return;
 
 	define_config(m, slen, hash);
-
-	printf("    $(wildcard include/config/");
-	for (i = 0; i < slen; i++) {
-		c = m[i];
-		if (c == '_')
-			c = '/';
-		else
-			c = tolower(c);
-		putchar(c);
-	}
-	printf(".h) \\\n");
+	print_config(m, slen);
 }
 
 static void parse_config_file(const char *map, size_t len)
@@ -250,7 +275,7 @@ static void parse_config_file(const char *map, size_t len)
 	}
 }
 
-/* test is s ends in sub */
+/* test if s ends in sub */
 static int strrcmp(const char *s, const char *sub)
 {
 	int slen = strlen(s);
@@ -378,6 +403,8 @@ static void parse_dep_file(void *map, size_t len)
 		exit(1);
 	}
 
+	do_extra_deps();
+
 	printf("\n%s: $(deps_%s)\n\n", target, target);
 	printf("$(deps_%s):\n", target);
 }
@@ -434,7 +461,10 @@ int main(int argc, char *argv[])
 {
 	traps();
 
-	if (argc != 4)
+	if (argc == 5 && !strcmp(argv[1], "-e")) {
+		insert_extra_deps = 1;
+		argv++;
+	} else if (argc != 4)
 		usage();
 
 	depfile = argv[1];
-- 
2.5.5

[toc] | [prev] | [next] | [standalone]

#1366698 — [PATCH v7 4/8] kbuild: de-duplicate fixdep usage

The generation and postprocessing of automatic dependency rules is
duplicated in rule_cc_o_c, rule_as_o_S and if_changed_dep. Since
this is not a trivial one-liner action, it is now abstracted under
cmd_and_fixdep to simplify things and make future changes in this area
easier.

In the rule_cc_o_c and rule_as_o_S cases that means the order of some
commands has been altered, namely fixdep and related file manipulations
are executed earlier, but they didn't depend on those commands that now
execute later.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 scripts/Kbuild.include |  5 ++++-
 scripts/Makefile.build | 19 +++++--------------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index b2ab2a92a3..80ca538bfb 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -256,10 +256,13 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)),                       \
 # Execute the command and also postprocess generated .d dependencies file.
 if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ),                  \
 	@set -e;                                                             \
+	$(cmd_and_fixdep), @:)
+
+cmd_and_fixdep =                                                             \
 	$(echo-cmd) $(cmd_$(1));                                             \
 	scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
 	rm -f $(depfile);                                                    \
-	mv -f $(dot-target).tmp $(dot-target).cmd, @:)
+	mv -f $(dot-target).tmp $(dot-target).cmd;
 
 # Usage: $(call if_changed_rule,foo)
 # Will check if $(cmd_foo) or any of the prerequisites changed,
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 74556e5e4e..12821d9eae 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -266,24 +266,15 @@ endif # CONFIG_STACK_VALIDATION
 
 define rule_cc_o_c
 	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
-	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
+	$(call cmd_and_fixdep,cc_o_c)					  \
 	$(cmd_modversions)						  \
-	$(cmd_objtool)						  \
-	$(call echo-cmd,record_mcount)					  \
-	$(cmd_record_mcount)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
-	                                              $(dot-target).tmp;  \
-	rm -f $(depfile);						  \
-	mv -f $(dot-target).tmp $(dot-target).cmd
+	$(cmd_objtool)						          \
+	$(call echo-cmd,record_mcount) $(cmd_record_mcount)
 endef
 
 define rule_as_o_S
-	$(call echo-cmd,as_o_S) $(cmd_as_o_S);				  \
-	$(cmd_objtool)						  \
-	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' >    \
-	                                              $(dot-target).tmp;  \
-	rm -f $(depfile);						  \
-	mv -f $(dot-target).tmp $(dot-target).cmd
+	$(call cmd_and_fixdep,as_o_S)					  \
+	$(cmd_objtool)
 endef
 
 # List module undefined symbols (or empty line if not enabled)
-- 
2.5.5

[toc] | [prev] | [next] | [standalone]

#1366699 — [PATCH v7 1/8] kbuild: record needed exported symbols for modules

Kernel modules are partially linked object files with some undefined
symbols that are expected to be matched with EXPORT_SYMBOL() entries
from elsewhere.

Each .tmp_versions/*.mod file currently contains two line of text
separated by a newline character. The first line has the actual module
file name while the second line has a list of object files constituting
that module. Those files are parsed by modpost (scripts/mod/sumversion.c),
scripts/Makefile.modpost, scripts/Makefile.modsign, etc.  Only the
modpost utility cares about the second line while the others retrieve
only the first line.

Therefore we can add a third line to record the list of undefined symbols
aka required EXPORT_SYMBOL() entries for each module into that file
without breaking anything. Like for the second line, symbols are separated
by a blank and the list is terminated with a newline character.

To avoid needless build overhead, the undefined symbols extraction is
performed only when CONFIG_TRIM_UNUSED_KSYMS is selected.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
---
 scripts/Makefile.build | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index e1bc190709..74556e5e4e 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -286,6 +286,13 @@ define rule_as_o_S
 	mv -f $(dot-target).tmp $(dot-target).cmd
 endef
 
+# List module undefined symbols (or empty line if not enabled)
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+cmd_undef_syms = $(NM) $@ | sed -n 's/^ \+U //p' | xargs echo
+else
+cmd_undef_syms = echo
+endif
+
 # Built-in and composite module parts
 $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
@@ -296,7 +303,8 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 $(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
-	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
+	@{ echo $(@:.o=.ko); echo $@; \
+	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
 
 quiet_cmd_cc_lst_c = MKLST   $@
       cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
@@ -426,7 +434,8 @@ $(call multi_depend, $(multi-used-y), .o, -objs -y)
 
 $(multi-used-m): FORCE
 	$(call if_changed,link_multi-m)
-	@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
+	@{ echo $(@:.o=.ko); echo $(link_multi_deps); \
+	   $(cmd_undef_syms); } > $(MODVERDIR)/$(@F:.o=.mod)
 $(call multi_depend, $(multi-used-m), .o, -objs -y -m)
 
 targets += $(multi-used-y) $(multi-used-m)
-- 
2.5.5

[toc] | [prev] | [next] | [standalone]

#1366701 — [PATCH v7 8/8] kconfig option for TRIM_UNUSED_KSYMS

The config option to enable it all.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
---
 init/Kconfig | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index e0d2616243..29d74d3f80 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2012,6 +2012,22 @@ config MODULE_COMPRESS_XZ
 
 endchoice
 
+config TRIM_UNUSED_KSYMS
+	bool "Trim unused exported kernel symbols"
+	depends on MODULES && !UNUSED_SYMBOLS
+	help
+	  The kernel and some modules make many symbols available for
+	  other modules to use via EXPORT_SYMBOL() and variants. Depending
+	  on the set of modules being selected in your kernel configuration,
+	  many of those exported symbols might never be used.
+
+	  This option allows for unused exported symbols to be dropped from
+	  the build. In turn, this provides the compiler more opportunities
+	  (especially when using LTO) for optimizing the code and reducing
+	  binary size.  This might have some security advantages as well.
+
+	  If unsure say N.
+
 endif # MODULES
 
 config MODULES_TREE_LOOKUP
-- 
2.5.5

[toc] | [prev] | [next] | [standalone]

#1366703 — [PATCH v7 6/8] kbuild: create/adjust generated/autoksyms.h

Given the list of exported symbols needed by all modules, we can create
a header file containing preprocessor defines for each of those symbols.
Also, when some symbols are added and/or removed from the list, we can
update the time on the corresponding files used as build dependencies for
those symbols. And finally, if any symbol did change state, the
corresponding source files must be rebuilt.

The insertion or removal of an EXPORT_SYMBOL() entry within a module may
create or remove the need for another exported symbol.  This is why this
operation has to be repeated until the list of needed exported symbols
becomes stable. Only then the final kernel and modules link take place.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
---
 Makefile                    |  13 ++++++
 scripts/adjust_autoksyms.sh | 101 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100755 scripts/adjust_autoksyms.sh

diff --git a/Makefile b/Makefile
index 451acbebee..9f93d2595d 100644
--- a/Makefile
+++ b/Makefile
@@ -933,6 +933,10 @@ quiet_cmd_link-vmlinux = LINK    $@
 # Include targets which we want to
 # execute if the rest of the kernel build went well.
 vmlinux: scripts/link-vmlinux.sh $(vmlinux-deps) FORCE
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+	$(Q)$(CONFIG_SHELL) scripts/adjust_autoksyms.sh \
+	  "$(MAKE) KBUILD_MODULES=1 -f $(srctree)/Makefile autoksyms_recursive"
+endif
 ifdef CONFIG_HEADERS_CHECK
 	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
@@ -947,6 +951,15 @@ ifdef CONFIG_GDB_SCRIPTS
 endif
 	+$(call if_changed,link-vmlinux)
 
+autoksyms_recursive: $(vmlinux-deps)
+	$(Q)$(CONFIG_SHELL) scripts/adjust_autoksyms.sh \
+	  "$(MAKE) KBUILD_MODULES=1 -f $(srctree)/Makefile autoksyms_recursive"
+PHONY += autoksyms_recursive
+
+# standalone target for easier testing
+include/generated/autoksyms.h: FORCE
+	$(Q)$(CONFIG_SHELL) scripts/adjust_autoksyms.sh true
+
 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
 $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
new file mode 100755
index 0000000000..5bf538f1ed
--- /dev/null
+++ b/scripts/adjust_autoksyms.sh
@@ -0,0 +1,101 @@
+#!/bin/sh
+
+# Script to create/update include/generated/autoksyms.h and dependency files
+#
+# Copyright:	(C) 2016  Linaro Limited
+# Created by:	Nicolas Pitre, January 2016
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+
+# Create/update the include/generated/autoksyms.h file from the list
+# of all module's needed symbols as recorded on the third line of
+# .tmp_versions/*.mod files.
+#
+# For each symbol being added or removed, the corresponding dependency
+# file's timestamp is updated to force a rebuild of the affected source
+# file. All arguments passed to this script are assumed to be a command
+# to be exec'd to trigger a rebuild of those files.
+
+set -e
+
+cur_ksyms_file="include/generated/autoksyms.h"
+new_ksyms_file="include/generated/autoksyms.h.tmpnew"
+
+info() {
+	if [ "$quiet" != "silent_" ]; then
+		printf "  %-7s %s\n" "$1" "$2"
+	fi
+}
+
+info "CHK" "$cur_ksyms_file"
+
+# Use "make V=1" to debug this script.
+case "$KBUILD_VERBOSE" in
+*1*)
+	set -x
+	;;
+esac
+
+# We need access to CONFIG_ symbols
+case "${KCONFIG_CONFIG}" in
+*/*)
+	. "${KCONFIG_CONFIG}"
+	;;
+*)
+	# Force using a file from the current directory
+	. "./${KCONFIG_CONFIG}"
+esac
+
+# In case it doesn't exist yet...
+if [ -e "$cur_ksyms_file" ]; then touch "$cur_ksyms_file"; fi
+
+# Generate a new ksym list file with symbols needed by the current
+# set of modules.
+cat > "$new_ksyms_file" << EOT
+/*
+ * Automatically generated file; DO NOT EDIT.
+ */
+
+EOT
+sed -ns -e '3s/ /\n/gp' "$MODVERDIR"/*.mod | sort -u |
+while read sym; do
+	if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then
+		sym="${sym#_}"
+	fi
+	echo "#define __KSYM_${sym} 1"
+done >> "$new_ksyms_file"
+
+# Special case for modversions (see modpost.c)
+if [ -n "$CONFIG_MODVERSIONS" ]; then
+	echo "#define __KSYM_module_layout 1" >> "$new_ksyms_file"
+fi
+
+# Extract changes between old and new list and touch corresponding
+# dependency files.
+changed=$(
+count=0
+sort "$cur_ksyms_file" "$new_ksyms_file" | uniq -u |
+sed -n 's/^#define __KSYM_\(.*\) 1/\1/p' | tr "A-Z_" "a-z/" |
+while read sympath; do
+	if [ -z "$sympath" ]; then continue; fi
+	depfile="include/config/ksym/${sympath}.h"
+	mkdir -p "$(dirname "$depfile")"
+	touch "$depfile"
+	echo $((count += 1))
+done | tail -1 )
+changed=${changed:-0}
+
+if [ $changed -gt 0 ]; then
+	# Replace the old list with tne new one
+	old=$(grep -c "^#define __KSYM_" "$cur_ksyms_file" || true)
+	new=$(grep -c "^#define __KSYM_" "$new_ksyms_file" || true)
+	info "KSYMS" "symbols: before=$old, after=$new, changed=$changed"
+	info "UPD" "$cur_ksyms_file"
+	mv -f "$new_ksyms_file" "$cur_ksyms_file"
+	# Then trigger a rebuild of affected source files
+	exec $@
+else
+	rm -f "$new_ksyms_file"
+fi
-- 
2.5.5

[toc] | [prev] | [next] | [standalone]

#1366704 — [PATCH v7 7/8] kbuild: build sample modules along with the rest of the kernel

Make sample modules in parallel with the rest of the kernel rather
than having them built from the vmlinux target. This makes the build
slightly faster, and those modules are properly considered when
adjust_autoksyms.sh is executed.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 Makefile | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 9f93d2595d..cec9539d30 100644
--- a/Makefile
+++ b/Makefile
@@ -940,9 +940,6 @@ endif
 ifdef CONFIG_HEADERS_CHECK
 	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
-ifdef CONFIG_SAMPLES
-	$(Q)$(MAKE) $(build)=samples
-endif
 ifdef CONFIG_BUILD_DOCSRC
 	$(Q)$(MAKE) $(build)=Documentation
 endif
@@ -960,6 +957,11 @@ PHONY += autoksyms_recursive
 include/generated/autoksyms.h: FORCE
 	$(Q)$(CONFIG_SHELL) scripts/adjust_autoksyms.sh true
 
+# Build samples along the rest of the kernel
+ifdef CONFIG_SAMPLES
+vmlinux-dirs += samples
+endif
+
 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
 $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;
-- 
2.5.5

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web