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

This reverts commit ad7a953c522ceb496611d127e51e278bfe0ff483.

And commit: ("allow stripping of generated symbols under CONFIG_KALLSYMS_ALL")
            9bb482476c6c9d1ae033306440c51ceac93ea80c

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>

1 files changed, 20 insertions, 35 deletions

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 5d900307de3e..c7de8b39fcf1 100644
--- a/scripts/Makefile.build
+++ b/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