MIPS: Fix loading of modules with unresolved weak symbols

Loading of modules with unresolved weak symbols fails on MIPS
since '88173507e4fc1e7ecd111b0565e8cba0cb7dae6d'.

Modules: handle symbols that have a zero value

The module subsystem cannot handle symbols that are zero.  If symbols
are present that have a zero value then the module resolver prints out a
message that these symbols are unresolved.

We have to use IS_ERR_VALUE() to check that a symbol has been resolved
or not.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/module.c

@@ -301,7 +301,7 @@ int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 		/* This is the symbol it is referring to */
 		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 			+ ELF_MIPS_R_SYM(rel[i]);
-		if (!sym->st_value) {
+		if (IS_ERR_VALUE(sym->st_value)) {
 			/* Ignore unresolved weak symbol */
 			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 				continue;
@@ -341,7 +341,7 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 		/* This is the symbol it is referring to */
 		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 			+ ELF_MIPS_R_SYM(rel[i]);
-		if (!sym->st_value) {
+		if (IS_ERR_VALUE(sym->st_value)) {
 			/* Ignore unresolved weak symbol */
 			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 				continue;