kbuild: __crc_* symbols in System.map

David S. Miller <davem@redhat.com> wrote:
Shouldn't we be grepping __crc_ symbols out of the System.map file?

For one thing, these can confuse readprofile.  It's algorithm is
to start at _stext, then stop when it sees a line in the System.map
which is not text (mode is one of 'T' 't' 'W' or 'w')

It will exit early if there are some intermixed __crc_* things in
there (since they are are mode 'A').

For example, in my current sparc64 kernel I have this:

00000000004cef80 t do_split
00000000004cf2a0 t add_dirent_to_buf
00000000004cf5a7 A __crc_init_special_inode
00000000004cf640 t make_indexed_dir
00000000004cf900 t ext3_add_entry

So no symbols after add_dirent_to_buf will be shown in the profiling
output of readprofile.

Implementation ported to mksysmap by Sam.
Included two System.map related fixes:
- Print "SYSMAP  System.map" during build
- Sort symbols in System.map
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -609,7 +609,7 @@ endif
 define rule_vmlinux
 	$(rule_vmlinux__);
 	$(Q)$(if $($(quiet)cmd_sysmap),                  \
-	  echo '  $($(quiet)cmd_sysmap) $@' &&)  \
+	  echo '  $($(quiet)cmd_sysmap) System.map' &&)  \
 	$(cmd_sysmap) $@ System.map;                     \
 	if [ $$? -ne 0 ]; then                           \
 		rm -f $@;                                \

scripts/mksysmap

@@ -51,4 +51,11 @@ fi
 #   U - undefined global symbols
 #   w - local weak symbols
 
-nm $1 | grep -v ' [aUw] ' > $2
+# readprofile starts reading symbols when _stext is found, and
+# continue until it finds a symbol which is not either of 'T', 't',
+# 'W' or 'w'. __crc_ are 'A' and placed in the middle
+# so we just ignore them to let readprofile continue to work.
+# (At least sparc64 has __crc_ in the middle).
+
+$NM -n $1 | grep -v '\( [aUw] \)\|\(__crc_\)' > $2
+