[PATCH] Handle C symbols with leading underscore (HAVE_ASM_USCORE)

[Christian Franke]

HAVE_ASM_USCORE is checked by configure, but module loader does not work 
in this case.

This patch fixes this by ignoring the difference. It actually works to 
load modules compiled on Linux by a kernel compiled on Cygwin (with 
underscores) and vice versa.

It also prepares the grub_mod_init/finit search for modules converted 
from non-ELF format (which do not support the "function" symbol type).

A bug in symbol table scan is fixed.

Christian

2007-11-10  Christian Franke  <address@hidden>

        * genkernsyms.sh.in: Handle HAVE_ASM_USCORE case.

        * genmk.rb: Handle HAVE_ASM_USCORE case in strip command.
        Add $EXEEXT to CLEANFILES.

        * kern/dl.c (grub_dl_resolve_symbol): Handle HAVE_ASM_USCORE case,
        ignore leading underscore.
        (grub_dl_register_symbol): Likewise.
        (grub_dl_resolve_symbols): Likewise.
	Add check for grub_mod_init/fini for symbols without type. 
	(grub_dl_resolve_dependencies): Add check for trailing nullbytes
        in symbol table. This fixes an infinite loop if stab is zero filled.


diff -rup grub2.orig/genkernsyms.sh.in grub2/genkernsyms.sh.in
--- grub2.orig/genkernsyms.sh.in        2006-07-12 22:42:52.000000000 +0200
+++ grub2/genkernsyms.sh.in     2007-10-06 12:59:29.000000000 +0200
@@ -16,9 +16,12 @@
 address@hidden@
 CC="@CC@"
 
+u=
+grep "^#define HAVE_ASM_USCORE" config.h >/dev/null 2>&1 && u="_"
+
 $CC -DGRUB_SYMBOL_GENERATOR=1 -E -I. -Iinclude -I$srcdir/include $* \
   | grep -v '^#' \
   | sed -n \
-        -e '/EXPORT_FUNC *([a-zA-Z0-9_]*)/{s/.*EXPORT_FUNC 
*(\([a-zA-Z0-9_]*\)).*/\1 kernel/;p;}' \
-        -e '/EXPORT_VAR *([a-zA-Z0-9_]*)/{s/.*EXPORT_VAR 
*(\([a-zA-Z0-9_]*\)).*/\1 kernel/;p;}' \
+        -e '/EXPORT_FUNC *([a-zA-Z0-9_]*)/{s/.*EXPORT_FUNC 
*(\([a-zA-Z0-9_]*\)).*/'"$u"'\1 kernel/;p;}' \
+        -e '/EXPORT_VAR *([a-zA-Z0-9_]*)/{s/.*EXPORT_VAR 
*(\([a-zA-Z0-9_]*\)).*/'"$u"'\1 kernel/;p;}' \
   | sort -u
diff -rup grub2.orig/genmk.rb grub2/genmk.rb
--- grub2.orig/genmk.rb 2007-10-20 22:49:38.968750000 +0200
+++ grub2/genmk.rb      2007-11-10 19:37:17.562500000 +0100
@@ -115,7 +115,7 @@ UNDSYMFILES += #{undsym}
 address@hidden: #{pre_obj} #{mod_obj}
        -rm -f $@
        $(TARGET_CC) $(#{prefix}_LDFLAGS) $(TARGET_LDFLAGS) -Wl,-r,-d -o $@ $^
-       $(STRIP) --strip-unneeded -K grub_mod_init -K grub_mod_fini -R .note -R 
.comment $@
+       $(STRIP) --strip-unneeded -K grub_mod_init -K grub_mod_fini -K 
_grub_mod_init -K _grub_mod_fini -R .note -R .comment $@
 
 #{pre_obj}: $(#{prefix}_DEPENDENCIES) #{objs_str}
        -rm -f $@
@@ -187,7 +187,7 @@ class Utility
     deps = objs.collect {|obj| obj.suffix('d')}
     deps_str = deps.join(' ');
 
-    "CLEANFILES += address@hidden #{objs_str}
+    "CLEANFILES += address@hidden(EXEEXT) #{objs_str}
 MOSTLYCLEANFILES += #{deps_str}
 
 address@hidden: $(#{prefix}_DEPENDENCIES) #{objs_str}
diff -rup grub2.orig/kern/dl.c grub2/kern/dl.c
--- grub2.orig/kern/dl.c        2007-07-22 01:32:26.000000000 +0200
+++ grub2/kern/dl.c     2007-11-10 19:44:34.140625000 +0100
@@ -156,6 +156,9 @@ grub_dl_resolve_symbol (const char *name
 {
   grub_symbol_t sym;
 
+  if (*name == '_')
+    name++;
+
   for (sym = grub_symtab[grub_symbol_hash (name)]; sym; sym = sym->next)
     if (grub_strcmp (sym->name, name) == 0)
       return sym->addr;
@@ -169,6 +172,11 @@ grub_dl_register_symbol (const char *nam
 {
   grub_symbol_t sym;
   unsigned k;
+
+  /* Ignore leading underscore used for C symbols.
+     Done at runtime to allow loading modules compiled on other OS.  */
+  if (*name == '_')
+    name++;
   
   sym = (grub_symbol_t) grub_malloc (sizeof (*sym));
   if (! sym)
@@ -347,6 +355,7 @@ grub_dl_resolve_symbols (grub_dl_t mod, 
       unsigned char type = ELF_ST_TYPE (sym->st_info);
       unsigned char bind = ELF_ST_BIND (sym->st_info);
       const char *name = str + sym->st_name;
+      int check_mod_func = 0;
       
       switch (type)
        {
@@ -359,6 +368,12 @@ grub_dl_resolve_symbols (grub_dl_t mod, 
                return grub_error (GRUB_ERR_BAD_MODULE,
                                   "the symbol `%s' not found", name);
            }
+         else if (sym->st_name != 0 && bind == STB_LOCAL)
+           { /* Static functions have no type if initial format was not ELF.  
*/
+             sym->st_value += (Elf_Addr) grub_dl_get_section_addr (mod,
+                                                                   
sym->st_shndx);
+             check_mod_func = 1;
+           }
          else
            sym->st_value = 0;
          break;
@@ -374,14 +389,11 @@ grub_dl_resolve_symbols (grub_dl_t mod, 
        case STT_FUNC:
          sym->st_value += (Elf_Addr) grub_dl_get_section_addr (mod,
                                                                sym->st_shndx);
-         if (bind != STB_LOCAL)
+         if (bind == STB_LOCAL)
+           check_mod_func = 1;
+         else  
            if (grub_dl_register_symbol (name, (void *) sym->st_value, mod))
              return grub_errno;
-         
-         if (grub_strcmp (name, "grub_mod_init") == 0)
-           mod->init = (void (*) (grub_dl_t)) sym->st_value;
-         else if (grub_strcmp (name, "grub_mod_fini") == 0)
-           mod->fini = (void (*) (void)) sym->st_value;
          break;
 
        case STT_SECTION:
@@ -397,6 +409,15 @@ grub_dl_resolve_symbols (grub_dl_t mod, 
          return grub_error (GRUB_ERR_BAD_MODULE,
                             "unknown symbol type `%d'", (int) type);
        }
+      if (check_mod_func)
+        {
+         if (*name == '_')
+           name++;
+         if (grub_strcmp (name, "grub_mod_init") == 0)
+           mod->init = (void (*) (grub_dl_t)) sym->st_value;
+         else if (grub_strcmp (name, "grub_mod_fini") == 0)
+           mod->fini = (void (*) (void)) sym->st_value;
+        }
     }
 
   return GRUB_ERR_NONE;
@@ -454,7 +475,7 @@ grub_dl_resolve_dependencies (grub_dl_t 
        const char *name = (char *) e + s->sh_offset;
        const char *max = name + s->sh_size;
 
-       while (name < max)
+       while (name < max && *name) /* Segment may contain trailing 0.  */
          {
            grub_dl_t m;
            grub_dl_dep_t dep;