Revert "kbuild: strip generated symbols from *.ko"

This reverts commit ad7a953.

And commit: ("allow stripping of generated symbols under CONFIG_KALLSYMS_ALL")
            9bb4824

These stripping patches has caused a set of issues:

1) People have reported compatibility issues with binutils due to
   lack of support for `--strip-unneeded-symbols' with objcopy 2.15.92.0.2
   Reported by: Wenji
2) ccache and distcc no longer works as expeced
   Reported by: Ted, Roland, + others
3) The installed modules increased a lot in size
   Reported by: Ted, Davej + others

Reported-by: Wenji Huang <wenji.huang@oracle.com>
Reported-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -606,25 +606,20 @@ export	INSTALL_PATH ?= /boot
 MODLIB	= $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
 export MODLIB
 
-strip-symbols := $(srctree)/scripts/strip-symbols \
-		 $(wildcard $(srctree)/arch/$(ARCH)/scripts/strip-symbols)
-
 #
-# INSTALL_MOD_STRIP, if defined, will cause modules to be stripped while
-# they get installed.  If INSTALL_MOD_STRIP is '1', then the default
-# options (see below) will be used.  Otherwise, INSTALL_MOD_STRIP will
-# be used as the option(s) to the objcopy command.
+#  INSTALL_MOD_STRIP, if defined, will cause modules to be
+#  stripped after they are installed.  If INSTALL_MOD_STRIP is '1', then
+#  the default option --strip-debug will be used.  Otherwise,
+#  INSTALL_MOD_STRIP will used as the options to the strip command.
+
 ifdef INSTALL_MOD_STRIP
 ifeq ($(INSTALL_MOD_STRIP),1)
-mod_strip_cmd = $(OBJCOPY) --strip-debug
-ifeq ($(CONFIG_KALLSYMS_ALL),$(CONFIG_KALLSYMS_STRIP_GENERATED))
-mod_strip_cmd += --wildcard $(addprefix --strip-symbols ,$(strip-symbols))
-endif
+mod_strip_cmd = $(STRIP) --strip-debug
 else
-mod_strip_cmd = $(OBJCOPY) $(INSTALL_MOD_STRIP)
+mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
 endif # INSTALL_MOD_STRIP=1
 else
-mod_strip_cmd = false
+mod_strip_cmd = true
 endif # INSTALL_MOD_STRIP
 export mod_strip_cmd
 
@@ -754,7 +749,6 @@ last_kallsyms := 2
 endif
 
 kallsyms.o := .tmp_kallsyms$(last_kallsyms).o
-kallsyms.h := $(wildcard include/config/kallsyms/*.h) $(wildcard include/config/kallsyms/*/*.h)
 
 define verify_kallsyms
 	$(Q)$(if $($(quiet)cmd_sysmap),                                      \
@@ -779,41 +773,24 @@ endef
 
 # Generate .S file with all kernel symbols
 quiet_cmd_kallsyms = KSYM    $@
-      cmd_kallsyms = { test $* -eq 0 || $(NM) -n $<; } \
-		     | $(KALLSYMS) $(if $(CONFIG_KALLSYMS_ALL),--all-symbols) >$@
-
-quiet_cmd_kstrip = STRIP   $@
-      cmd_kstrip = $(OBJCOPY) --wildcard $(addprefix --strip$(if $(CONFIG_RELOCATABLE),-unneeded)-symbols ,$(filter %/scripts/strip-symbols,$^)) $< $@
+      cmd_kallsyms = $(NM) -n $< | $(KALLSYMS) \
+                     $(if $(CONFIG_KALLSYMS_ALL),--all-symbols) > $@
 
-$(foreach n,0 1 2 3,.tmp_kallsyms$(n).o): KBUILD_AFLAGS += -Wa,--strip-local-absolute
-$(foreach n,0 1 2 3,.tmp_kallsyms$(n).o): %.o: %.S scripts FORCE
+.tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE
 	$(call if_changed_dep,as_o_S)
 
-ifeq ($(CONFIG_KALLSYMS_STRIP_GENERATED),y)
-strip-ext := .stripped
-endif
-
-.tmp_kallsyms%.S: .tmp_vmlinux%$(strip-ext) $(KALLSYMS) $(kallsyms.h)
+.tmp_kallsyms%.S: .tmp_vmlinux% $(KALLSYMS)
 	$(call cmd,kallsyms)
 
-# make -jN seems to have problems with intermediate files, see bug #3330.
-.SECONDARY: $(foreach n,1 2 3,.tmp_vmlinux$(n).stripped)
-.tmp_vmlinux%.stripped: .tmp_vmlinux% $(strip-symbols) $(kallsyms.h)
-	$(call cmd,kstrip)
-
-ifneq ($(CONFIG_DEBUG_INFO),y)
-.tmp_vmlinux%: LDFLAGS_vmlinux += -S
-endif
 # .tmp_vmlinux1 must be complete except kallsyms, so update vmlinux version
-.tmp_vmlinux%: $(vmlinux-lds) $(vmlinux-all) FORCE
-	$(if $(filter 1,$*),$(call if_changed_rule,ksym_ld),$(call if_changed,vmlinux__))
+.tmp_vmlinux1: $(vmlinux-lds) $(vmlinux-all) FORCE
+	$(call if_changed_rule,ksym_ld)
 
-.tmp_vmlinux0$(strip-ext):
-	$(Q)echo "placeholder" >$@
+.tmp_vmlinux2: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms1.o FORCE
+	$(call if_changed,vmlinux__)
 
-.tmp_vmlinux1: .tmp_kallsyms0.o
-.tmp_vmlinux2: .tmp_kallsyms1.o
-.tmp_vmlinux3: .tmp_kallsyms2.o
+.tmp_vmlinux3: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms2.o FORCE
+	$(call if_changed,vmlinux__)
 
 # Needs to visit scripts/ before $(KALLSYMS) can be used.
 $(KALLSYMS): scripts ;

init/Kconfig

@@ -626,13 +626,6 @@ config KALLSYMS_ALL
 
 	   Say N.
 
-config KALLSYMS_STRIP_GENERATED
-	bool "Strip machine generated symbols from kallsyms"
-	depends on KALLSYMS_ALL
-	default y
-	help
-	  Say N if you want kallsyms to retain even machine generated symbols.
-
 config KALLSYMS_EXTRA_PASS
 	bool "Do an extra kallsyms pass"
 	depends on KALLSYMS

kernel/kallsyms.c

@@ -30,19 +30,20 @@
 #define all_var 0
 #endif
 
-extern const unsigned long kallsyms_addresses[];
-extern const u8 kallsyms_names[];
+/* These will be re-linked against their real values during the second link stage */
+extern const unsigned long kallsyms_addresses[] __attribute__((weak));
+extern const u8 kallsyms_names[] __attribute__((weak));
 
 /* tell the compiler that the count isn't in the small data section if the arch
  * has one (eg: FRV)
  */
 extern const unsigned long kallsyms_num_syms
-	__attribute__((__section__(".rodata")));
+__attribute__((weak, section(".rodata")));
 
-extern const u8 kallsyms_token_table[];
-extern const u16 kallsyms_token_index[];
+extern const u8 kallsyms_token_table[] __attribute__((weak));
+extern const u16 kallsyms_token_index[] __attribute__((weak));
 
-extern const unsigned long kallsyms_markers[];
+extern const unsigned long kallsyms_markers[] __attribute__((weak));
 
 static inline int is_kernel_inittext(unsigned long addr)
 {
@@ -167,6 +168,9 @@ static unsigned long get_symbol_pos(unsigned long addr,
 	unsigned long symbol_start = 0, symbol_end = 0;
 	unsigned long i, low, high, mid;
 
+	/* This kernel should never had been booted. */
+	BUG_ON(!kallsyms_addresses);
+
 	/* do a binary search on the sorted kallsyms_addresses array */
 	low = 0;
 	high = kallsyms_num_syms;

scripts/Makefile.build

@@ -151,16 +151,16 @@ cmd_cc_i_c       = $(CPP) $(c_flags)   -o $@ $<
 $(obj)/%.i: $(src)/%.c FORCE
 	$(call if_changed_dep,cc_i_c)
 
-cmd_genksyms =                                                              \
+cmd_gensymtypes =                                                           \
     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
-    $(GENKSYMS) -T $@ -A -a $(ARCH)                                         \
+    $(GENKSYMS) -T $@ -a $(ARCH)                                            \
      $(if $(KBUILD_PRESERVE),-p)                                            \
      $(if $(1),-r $(firstword $(wildcard $(@:.symtypes=.symref) /dev/null)))
 
 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 cmd_cc_symtypes_c =                                                         \
     set -e;                                                                 \
-    $(call cmd_genksyms, true) >/dev/null;                                  \
+    $(call cmd_gensymtypes, true) >/dev/null;                               \
     test -s $@ || rm -f $@
 
 $(obj)/%.symtypes : $(src)/%.c FORCE
@@ -177,38 +177,28 @@ cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
 
 else
 # When module versioning is enabled the following steps are executed:
-# o compile a .tmp_<file>.s from <file>.c
-# o if .tmp_<file>.s doesn't contain a __ksymtab version, i.e. does
-#   not export symbols, we just assemble .tmp_<file>.s to <file>.o and
+# o compile a .tmp_<file>.o from <file>.c
+# o if .tmp_<file>.o doesn't contain a __ksymtab version, i.e. does
+#   not export symbols, we just rename .tmp_<file>.o to <file>.o and
 #   are done.
 # o otherwise, we calculate symbol versions using the good old
 #   genksyms on the preprocessed source and postprocess them in a way
-#   that they are usable as assembly source
-# o assemble <file>.o from .tmp_<file>.s forcing inclusion of directives
-#   defining the actual values of __crc_*, followed by objcopy-ing them
-#   to force these symbols to be local to permit stripping them later.
-s_file = $(@D)/.tmp_$(@F:.o=.s)
-v_file = $(@D)/.tmp_$(@F:.o=.v)
-tmp_o_file = $(@D)/.tmp_$(@F)
-no_g_c_flags = $(filter-out -g%,$(c_flags))
-
-cmd_cc_o_c = $(CC) $(c_flags) -S -o $(s_file) $<
+#   that they are usable as a linker script
+# o generate <file>.o from .tmp_<file>.o using the linker to
+#   replace the unresolved symbols __crc_exported_symbol with
+#   the actual value of the checksum generated by genksyms
 
+cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
 cmd_modversions =							\
-	if grep -q __ksymtab $(s_file); then				\
-		if $(call cmd_genksyms, $(KBUILD_SYMTYPES)) > $(v_file) \
-		   && $(CC) $(no_g_c_flags) -c -Wa,$(v_file)		\
-			    -o $(tmp_o_file) $(s_file)			\
-		   && $(OBJCOPY) -L '__crc_*' -L '___crc_*' -w		\
-				 $(tmp_o_file) $@;			\
-		then							\
-			: ;						\
-		else							\
-			rm -f $@; exit 1;				\
-		fi;							\
+	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then	\
+		$(call cmd_gensymtypes, $(KBUILD_SYMTYPES))		\
+		    > $(@D)/.tmp_$(@F:.o=.ver);				\
+									\
+		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 		\
+			-T $(@D)/.tmp_$(@F:.o=.ver);			\
+		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);	\
 	else								\
-		rm -f $(v_file);					\
-		$(CC) $(no_g_c_flags) -c -o $@ $(s_file);		\
+		mv -f $(@D)/.tmp_$(@F) $@;				\
 	fi;
 endif
 
@@ -225,12 +215,7 @@ define rule_cc_o_c
 	$(cmd_record_mcount)						  \
 	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
 	                                              $(dot-target).tmp;  \
-	if [ -r $(@D)/.tmp_$(@F:.o=.v) ]; then				  \
-		echo >> $(dot-target).tmp;				  \
-		echo '$@: $(GENKSYMS)' >> $(dot-target).tmp;		  \
-		echo '$(GENKSYMS):: ;' >> $(dot-target).tmp;		  \
-	fi;								  \
-	rm -f $(depfile) $(@D)/.tmp_$(@F:.o=.?);			  \
+	rm -f $(depfile);						  \
 	mv -f $(dot-target).tmp $(dot-target).cmd
 endef
 

scripts/Makefile.modinst

@@ -17,8 +17,7 @@ __modinst: $(modules)
 	@:
 
 quiet_cmd_modules_install = INSTALL $@
-      cmd_modules_install = mkdir -p $(2); \
-			    $(mod_strip_cmd) $@ $(2)/$(notdir $@) || cp $@ $(2)
+      cmd_modules_install = mkdir -p $(2); cp $@ $(2) ; $(mod_strip_cmd) $(2)/$(notdir $@)
 
 # Modules built outside the kernel source tree go into extra by default
 INSTALL_MOD_DIR ?= extra

scripts/genksyms/genksyms.c

@@ -43,7 +43,7 @@ int cur_line = 1;
 char *cur_filename;
 
 static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,
-	   flag_preserve, flag_warnings, flag_asm;
+	   flag_preserve, flag_warnings;
 static const char *arch = "";
 static const char *mod_prefix = "";
 
@@ -610,11 +610,8 @@ void export_symbol(const char *name)
 		if (flag_dump_defs)
 			fputs(">\n", debugfile);
 
-		/* Used as assembly source or a linker script. */
-		printf(flag_asm
-		       ? ".equiv %s__crc_%s, %#08lx\n"
-		       : "%s__crc_%s = %#08lx ;\n",
-		       mod_prefix, name, crc);
+		/* Used as a linker script. */
+		printf("%s__crc_%s = 0x%08lx ;\n", mod_prefix, name, crc);
 	}
 }
 
@@ -651,10 +648,9 @@ void error_with_pos(const char *fmt, ...)
 
 static void genksyms_usage(void)
 {
-	fputs("Usage:\n" "genksyms [-aAdDTwqhV] > /path/to/.tmp_obj.ver\n" "\n"
+	fputs("Usage:\n" "genksyms [-adDTwqhV] > /path/to/.tmp_obj.ver\n" "\n"
 #ifdef __GNU_LIBRARY__
 	      "  -a, --arch            Select architecture\n"
-	      "  -A, --asm             Generate assembly rather than linker script\n"
 	      "  -d, --debug           Increment the debug level (repeatable)\n"
 	      "  -D, --dump            Dump expanded symbol defs (for debugging only)\n"
 	      "  -r, --reference file  Read reference symbols from a file\n"
@@ -666,7 +662,6 @@ static void genksyms_usage(void)
 	      "  -V, --version         Print the release version\n"
 #else				/* __GNU_LIBRARY__ */
 	      "  -a                    Select architecture\n"
-	      "  -A                    Generate assembly rather than linker script\n"
 	      "  -d                    Increment the debug level (repeatable)\n"
 	      "  -D                    Dump expanded symbol defs (for debugging only)\n"
 	      "  -r file               Read reference symbols from a file\n"
@@ -688,7 +683,6 @@ int main(int argc, char **argv)
 #ifdef __GNU_LIBRARY__
 	struct option long_opts[] = {
 		{"arch", 1, 0, 'a'},
-		{"asm", 0, 0, 'A'},
 		{"debug", 0, 0, 'd'},
 		{"warnings", 0, 0, 'w'},
 		{"quiet", 0, 0, 'q'},
@@ -701,10 +695,10 @@ int main(int argc, char **argv)
 		{0, 0, 0, 0}
 	};
 
-	while ((o = getopt_long(argc, argv, "a:dwqVADr:T:ph",
+	while ((o = getopt_long(argc, argv, "a:dwqVDr:T:ph",
 				&long_opts[0], NULL)) != EOF)
 #else				/* __GNU_LIBRARY__ */
-	while ((o = getopt(argc, argv, "a:dwqVADr:T:ph")) != EOF)
+	while ((o = getopt(argc, argv, "a:dwqVDr:T:ph")) != EOF)
 #endif				/* __GNU_LIBRARY__ */
 		switch (o) {
 		case 'a':
@@ -722,9 +716,6 @@ int main(int argc, char **argv)
 		case 'V':
 			fputs("genksyms version 2.5.60\n", stderr);
 			break;
-		case 'A':
-			flag_asm = 1;
-			break;
 		case 'D':
 			flag_dump_defs = 1;
 			break;