kbuild: strip generated symbols from *.ko

This patch changes the way __crc_ symbols are being resolved from
using ld to do so to using the assembler, thus allowing these symbols
to be marked local (the linker creates then as global ones) and hence
allow stripping (for modules) or ignoring (for vmlinux) them. While at
this, also strip other generated symbols during module installation.

One potentially debatable point is the handling of the flags passeed
to gcc when translating the intermediate assembly file into an object:
passing $(c_flags) unchanged doesn't work as gcc passes --gdwarf2 to
gas whenever is sees any -g* option, even for -g0, and despite the
fact that the compiler would have already produced all necessary debug
info in the C->assembly translation phase. I took the approach of just
filtering out all -g* options, but an alternative to such negative
filtering might be to have a positive filter which might, in the ideal
case allow just all the -Wa,* options to pass through.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/Makefile b/Makefile
index e1c5ae8a8162..5dd0ed3b12c6 100644
--- a/Makefile
+++ b/Makefile
@@ -605,19 +605,19 @@ MODLIB	= $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
 export MODLIB
 
 #
-#  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.
-
+# 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.
 ifdef INSTALL_MOD_STRIP
 ifeq ($(INSTALL_MOD_STRIP),1)
-mod_strip_cmd = $(STRIP) --strip-debug
+mod_strip_cmd = $(OBJCOPY) --strip-debug --strip-symbols \
+                $(srctree)/scripts/strip-symbols --wildcard
 else
-mod_strip_cmd = $(STRIP) $(INSTALL_MOD_STRIP)
+mod_strip_cmd = $(OBJCOPY) $(INSTALL_MOD_STRIP)
 endif # INSTALL_MOD_STRIP=1
 else
-mod_strip_cmd = true
+mod_strip_cmd = false
 endif # INSTALL_MOD_STRIP
 export mod_strip_cmd