[SPARC32]: Update module linking for symbols starting with "."

Rusty did not like the __dot_sym approach and suggested instead:

1) make rem, urem, mul, umul, div and udiv aliases to .rem, .urem etc:

   extern int rem(int, int) __attribute__((weak,alias(".rem")));

2) EXPORT_SYMBOL(rem) etc.
3) Check genksyms recognises that prototype (it should).
4) Copy "dedotify" from ppc64 to handle them on load.

The only real downside is the risk that someone else will export
those names, but I think that's pretty unlikely.

arch/sparc/kernel/module.c

@@ -36,7 +36,9 @@ void module_free(struct module *mod, void *module_region)
            table entries. */
 }
 
-/* Make generic code ignore STT_REGISTER dummy undefined symbols.  */
+/* Make generic code ignore STT_REGISTER dummy undefined symbols,
+ * and replace references to .func with func as in ppc64's dedotify.
+ */
 int module_frob_arch_sections(Elf_Ehdr *hdr,
 			      Elf_Shdr *sechdrs,
 			      char *secstrings,
@@ -44,7 +46,7 @@ int module_frob_arch_sections(Elf_Ehdr *hdr,
 {
 	unsigned int symidx;
 	Elf32_Sym *sym;
-	const char *strtab;
+	char *strtab;
 	int i;
 
 	for (symidx = 0; sechdrs[symidx].sh_type != SHT_SYMTAB; symidx++) {
@@ -57,9 +59,15 @@ int module_frob_arch_sections(Elf_Ehdr *hdr,
 	strtab = (char *)sechdrs[sechdrs[symidx].sh_link].sh_addr;
 
 	for (i = 1; i < sechdrs[symidx].sh_size / sizeof(Elf_Sym); i++) {
-		if (sym[i].st_shndx == SHN_UNDEF &&
-		    ELF32_ST_TYPE(sym[i].st_info) == STT_REGISTER)
-			sym[i].st_shndx = SHN_ABS;
+		if (sym[i].st_shndx == SHN_UNDEF) {
+			if (ELF32_ST_TYPE(sym[i].st_info) == STT_REGISTER)
+				sym[i].st_shndx = SHN_ABS;
+			else {
+				char *name = strtab + sym[i].st_name;
+				if (name[0] == '.')
+					memmove(name, name+1, strlen(name));
+			}
+		}
 	}
 	return 0;
 }

arch/sparc/kernel/sparc_ksyms.c

@@ -92,31 +92,21 @@ extern void ___set_bit(void);
 extern void ___clear_bit(void);
 extern void ___change_bit(void);
 
-/* One thing to note is that the way the symbols of the mul/div
- * support routines are named is a mess, they all start with
- * a '.' which makes it a bitch to export, here is the trick:
+/* Alias functions whose names begin with "." and export the aliases.
+ * The module references will be fixed up by module_frob_arch_sections.
  */
+#define DOT_ALIAS2(__ret, __x, __arg1, __arg2) \
+	extern __ret __x(__arg1, __arg2) \
+	             __attribute__((weak, alias("." # __x)));
 
-/* If the interface of any of these special functions does ever
- * change in an incompatible way, you must modify this.
- */
-#define DOT_PROTO(sym) extern int __dot_##sym(int, int)
-
-#ifdef __GENKSYMS__
-#define EXPORT_SYMBOL_DOT(sym)						\
-	DOT_PROTO(sym);							\
-	EXPORT_SYMBOL(__dot_ ## sym)
-#else /* !__GENKSYMS__ */
-#define EXPORT_SYMBOL_DOT(sym)						\
-	DOT_PROTO(sym) __asm__("." # sym);				\
-	__CRC_SYMBOL(__dot_##sym, "")					\
-	static const char __kstrtab___dot_##sym[]			\
-	__attribute__((section("__ksymtab_strings")))			\
-	= "." #sym;							\
-	static const struct kernel_symbol __ksymtab___dot_##sym		\
-	__attribute__((section("__ksymtab")))				\
-	= { (unsigned long)&__dot_##sym, __kstrtab___dot_##sym }
-#endif
+DOT_ALIAS2(int, div, int, int)
+DOT_ALIAS2(int, mul, int, int)
+DOT_ALIAS2(int, rem, int, int)
+DOT_ALIAS2(unsigned, udiv, unsigned, unsigned)
+DOT_ALIAS2(unsigned, umul, unsigned, unsigned)
+DOT_ALIAS2(unsigned, urem, unsigned, unsigned)
+
+#undef DOT_ALIAS2
 
 /* used by various drivers */
 EXPORT_SYMBOL(sparc_cpu_model);
@@ -325,12 +315,12 @@ EXPORT_SYMBOL_NOVERS(__lshrdi3);
 EXPORT_SYMBOL_NOVERS(__muldi3);
 EXPORT_SYMBOL_NOVERS(__divdi3);
 
-EXPORT_SYMBOL_DOT(rem);
-EXPORT_SYMBOL_DOT(urem);
-EXPORT_SYMBOL_DOT(mul);
-EXPORT_SYMBOL_DOT(umul);
-EXPORT_SYMBOL_DOT(div);
-EXPORT_SYMBOL_DOT(udiv);
+EXPORT_SYMBOL(rem);
+EXPORT_SYMBOL(urem);
+EXPORT_SYMBOL(mul);
+EXPORT_SYMBOL(umul);
+EXPORT_SYMBOL(div);
+EXPORT_SYMBOL(udiv);
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 EXPORT_SYMBOL(do_BUG);

scripts/modpost.c

@@ -141,26 +141,14 @@ new_symbol(const char *name, struct module *module, unsigned int *crc)
 	symbolhash[hash] = new;
 }
 
-#define DOTSYM_PFX "__dot_"
-
 struct symbol *
 find_symbol(const char *name)
 {
 	struct symbol *s;
-	char dotname[64 + sizeof(DOTSYM_PFX)];
 
-	/* .foo matches foo.  PPC64 needs this. */
-	if (name[0] == '.') {
+	/* For our purposes, .foo matches foo.  PPC64 needs this. */
+	if (name[0] == '.')
 		name++;
-		strcpy(dotname, DOTSYM_PFX);
-		strncat(dotname, name, sizeof(dotname) - sizeof(DOTSYM_PFX) - 1);
-		dotname[sizeof(dotname)-1] = 0;
-		/* Sparc32 wants .foo to match __dot_foo, try this first. */
-		for (s = symbolhash[tdb_hash(dotname) % SYMBOL_HASH_SIZE]; s; s=s->next) {
-			if (strcmp(s->name, dotname) == 0)
-				return s;
-		}
-	}
 
 	for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s=s->next) {
 		if (strcmp(s->name, name) == 0)