kbuild: include symbol names in section mismatch warnings

Try to look up the symbol that is referenced. Include the symbol
name in the warning message.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 47 insertions, 17 deletions

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index eeaf57476820..844f84b0818a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -451,6 +451,29 @@ static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
         return NULL;
 }
 
+/**
+ * Find symbol based on relocation record info.
+ * In some cases the symbol supplied is a valid symbol so
+ * return refsym. If st_name != 0 we assume this is a valid symbol.
+ * In other cases the symbol needs to be looked up in the symbol table
+ * based on section and address.
+ *  **/
+static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf_Addr addr,
+                                Elf_Sym *relsym)
+{
+        Elf_Sym *sym;
+
+        if (relsym->st_name != 0)
+                return relsym;
+        for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
+                if (sym->st_shndx != relsym->st_shndx)
+                        continue;
+                if (sym->st_value == addr)
+                        return sym;
+        }
+        return NULL;
+}
+
 /*
  * Find symbols before or equal addr and after addr - in the section sec
  **/
@@ -499,8 +522,9 @@ static void find_symbols_between(struct elf_info *elf, Elf_Addr addr,
 static void warn_sec_mismatch(const char *modname, const char *fromsec,
                               struct elf_info *elf, Elf_Sym *sym, Elf_Rela r)
 {
-        Elf_Sym *before;
-        Elf_Sym *after;
+        const char *refsymname = "";
+        Elf_Sym *before, *after;
+        Elf_Sym *refsym;
         Elf_Ehdr *hdr = elf->hdr;
         Elf_Shdr *sechdrs = elf->sechdrs;
         const char *secstrings = (void *)hdr +
@@ -509,29 +533,34 @@ static void warn_sec_mismatch(const char *modname, const char *fromsec,
         
         find_symbols_between(elf, r.r_offset, fromsec, &before, &after);
 
+        refsym = find_elf_symbol(elf, r.r_addend, sym);
+        if (refsym && strlen(elf->strtab + refsym->st_name))
+                refsymname = elf->strtab + refsym->st_name;
+        
         if (before && after) {
-                warn("%s - Section mismatch: reference to %s from %s "
-                     "between '%s' (at offset 0x%lx) and '%s'\n",
-                     modname, secname, fromsec,
+                warn("%s - Section mismatch: reference to %s:%s from %s "
+                     "between '%s' (at offset 0x%llx) and '%s'\n",
+                     modname, secname, refsymname, fromsec,
                      elf->strtab + before->st_name,
-                     (long)(r.r_offset - before->st_value),
+                     (long long)r.r_offset,
                      elf->strtab + after->st_name);
         } else if (before) {
-                warn("%s - Section mismatch: reference to %s from %s "
-                     "after '%s' (at offset 0x%lx)\n",
-                     modname, secname, fromsec, 
+                warn("%s - Section mismatch: reference to %s:%s from %s "
+                     "after '%s' (at offset 0x%llx)\n",
+                     modname, secname, refsymname, fromsec, 
                      elf->strtab + before->st_name,
-                     (long)(r.r_offset - before->st_value));
+                     (long long)r.r_offset);
         } else if (after) {
-                warn("%s - Section mismatch: reference to %s from %s "
-                     "before '%s' (at offset -0x%lx)\n",
-                     modname, secname, fromsec, 
+                warn("%s - Section mismatch: reference to %s:%s from %s "
+                     "before '%s' (at offset -0x%llx)\n",
+                     modname, secname, refsymname, fromsec, 
                      elf->strtab + before->st_name,
-                     (long)(before->st_value - r.r_offset));
+                     (long long)r.r_offset);
         } else {
-                warn("%s - Section mismatch: reference to %s from %s "
-                     "(offset 0x%lx)\n",
-                     modname, secname, fromsec, (long)r.r_offset);
+                warn("%s - Section mismatch: reference to %s:%s from %s "
+                     "(offset 0x%llx)\n",
+                     modname, secname, fromsec, refsymname,
+                     (long long)r.r_offset);
         }
 }
 
@@ -575,6 +604,7 @@ static void check_sec_ref(struct module *mod, const char *modname,
                         const char *secname;
                         r.r_offset = TO_NATIVE(rela->r_offset);
                         r.r_info   = TO_NATIVE(rela->r_info);
+                        r.r_addend = TO_NATIVE(rela->r_addend);
                         sym = elf->symtab_start + ELF_R_SYM(r.r_info);
                         /* Skip special sections */
                         if (sym->st_shndx >= SHN_LORESERVE)