Patch from Joel Vallier to add modules symbols to the kernel symbol

table in order to obtain better debug output from ksymoops.


git-svn-id: svn://busybox.net/trunk/busybox@6427 69ca8d6d-28ef-0310-b511-8ec308f3f277

2 files changed, 185 insertions, 2 deletions

diff --git a/modutils/Config.in b/modutils/Config.in
index 9af0ad6dc..98aef0032 100644
--- a/modutils/Config.in
+++ b/modutils/Config.in
@@ -40,6 +40,17 @@ config CONFIG_FEATURE_INSMOD_VERSION_CHECKING
         help
           Please submit a patch to add help text for this item.
 
+config CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS
+        bool "  Add module symbols to kernel symbol table"
+        default n
+        depends on CONFIG_INSMOD
+        help
+          By adding module symbols to the kernel symbol table, Oops messages 
+          occuring within kernel modules can be properly debugged.  By enabling
+          this feature, module symbols will always be added to the kernel symbol 
+          table for properly debugging support.  If you are not interested in
+          Oops messages from kernel modules, say N.
+
 config CONFIG_FEATURE_INSMOD_LOADINKMEM
         bool "  In kernel memory optimization (uClinux only)"
         default n
diff --git a/modutils/insmod.c b/modutils/insmod.c
index eda4e1a48..db9e1997e 100644
--- a/modutils/insmod.c
+++ b/modutils/insmod.c
@@ -234,7 +234,7 @@
 #ifndef MODUTILS_MODULE_H
 static const int MODUTILS_MODULE_H = 1;
 
-#ident "$Id: insmod.c,v 1.92 2002/11/28 11:27:27 aaronl Exp $"
+#ident "$Id: insmod.c,v 1.93 2003/01/23 04:48:34 andersen Exp $"
 
 /* This file contains the structures used by the 2.0 and 2.1 kernels.
    We do not use the kernel headers directly because we do not wish
@@ -455,7 +455,7 @@ int delete_module(const char *);
 #ifndef MODUTILS_OBJ_H
 static const int MODUTILS_OBJ_H = 1;
 
-#ident "$Id: insmod.c,v 1.92 2002/11/28 11:27:27 aaronl Exp $"
+#ident "$Id: insmod.c,v 1.93 2003/01/23 04:48:34 andersen Exp $"
 
 /* The relocatable object is manipulated using elfin types.  */
 
@@ -2654,6 +2654,37 @@ static int new_create_this_module(struct obj_file *f, const char *m_name)
         return 1;
 }
 
+#ifdef CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS
+/* add an entry to the __ksymtab section, creating it if necessary */
+static void new_add_ksymtab(struct obj_file *f, struct obj_symbol *sym)
+{
+        struct obj_section *sec;
+        ElfW(Addr) ofs;
+
+        /* ensure __ksymtab is allocated, EXPORT_NOSYMBOLS creates a non-alloc section.
+         * If __ksymtab is defined but not marked alloc, x out the first character
+         * (no obj_delete routine) and create a new __ksymtab with the correct
+         * characteristics.
+         */
+        sec = obj_find_section(f, "__ksymtab");
+        if (sec && !(sec->header.sh_flags & SHF_ALLOC)) {
+                *((char *)(sec->name)) = 'x';   /* override const */
+                sec = NULL;
+        }
+        if (!sec)
+                sec = obj_create_alloced_section(f, "__ksymtab",
+                                                 tgt_sizeof_void_p, 0);
+        if (!sec)
+                return;
+        sec->header.sh_flags |= SHF_ALLOC;
+        sec->header.sh_addralign = tgt_sizeof_void_p;   /* Empty section might
+                                                           be byte-aligned */
+        ofs = sec->header.sh_size;
+        obj_symbol_patch(f, sec->idx, ofs, sym);
+        obj_string_patch(f, sec->idx, ofs + tgt_sizeof_void_p, sym->name);
+        obj_extend_section(sec, 2 * tgt_sizeof_char_p);
+}
+#endif /* CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS */
 
 static int new_create_module_ksymtab(struct obj_file *f)
 {
@@ -2811,6 +2842,7 @@ new_init_module(const char *m_name, struct obj_file *f,
 
 #define new_init_module(x, y, z) TRUE
 #define new_create_this_module(x, y) 0
+#define new_add_ksymtab(x, y) -1
 #define new_create_module_ksymtab(x)
 #define query_module(v, w, x, y, z) -1
 
@@ -3538,6 +3570,142 @@ static void check_tainted_module(struct obj_file *f, char *m_name)
 #define check_tainted_module(x, y) do { } while(0);
 #endif /* CONFIG_FEATURE_CHECK_TAINTED_MODULE */
 
+#ifdef CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS
+/* add module source, timestamp, kernel version and a symbol for the
+ * start of some sections.  this info is used by ksymoops to do better
+ * debugging.
+ */
+static int
+get_module_version(struct obj_file *f, char str[STRVERSIONLEN])
+{
+#ifdef CONFIG_FEATURE_INSMOD_VERSION_CHECKING
+  if (get_modinfo_value(f, "kernel_version") == NULL)
+    return old_get_module_version(f, str);
+  else
+    return new_get_module_version(f, str);
+#else  /* CONFIG_FEATURE_INSMOD_VERSION_CHECKING */
+    strncpy(str, "???", sizeof(str));
+    return -1;
+#endif /* CONFIG_FEATURE_INSMOD_VERSION_CHECKING */
+}
+
+/* add module source, timestamp, kernel version and a symbol for the
+ * start of some sections.  this info is used by ksymoops to do better
+ * debugging.
+ */
+static void 
+add_ksymoops_symbols(struct obj_file *f, const char *filename,
+                                 const char *m_name)
+{
+        static const char symprefix[] = "__insmod_";
+        struct obj_section *sec;
+        struct obj_symbol *sym;
+        char *name, *absolute_filename;
+        char str[STRVERSIONLEN], real[PATH_MAX];
+        int i, l, lm_name, lfilename, use_ksymtab, version;
+        struct stat statbuf;
+
+        static const char *section_names[] = {
+                ".text",
+                ".rodata",
+                ".data",
+                ".bss"
+                ".sbss"
+        };
+
+        if (realpath(filename, real)) {
+                absolute_filename = xstrdup(real);
+        }
+        else {
+                int save_errno = errno;
+                error_msg("cannot get realpath for %s", filename);
+                errno = save_errno;
+                perror("");
+                absolute_filename = xstrdup(filename);
+        }
+
+        lm_name = strlen(m_name);
+        lfilename = strlen(absolute_filename);
+
+        /* add to ksymtab if it already exists or there is no ksymtab and other symbols
+         * are not to be exported.  otherwise leave ksymtab alone for now, the
+         * "export all symbols" compatibility code will export these symbols later.
+         */
+        use_ksymtab =  obj_find_section(f, "__ksymtab") || !flag_export;
+
+        if ((sec = obj_find_section(f, ".this"))) {
+                /* tag the module header with the object name, last modified
+                 * timestamp and module version.  worst case for module version
+                 * is 0xffffff, decimal 16777215.  putting all three fields in
+                 * one symbol is less readable but saves kernel space.
+                 */
+                l = sizeof(symprefix)+                  /* "__insmod_" */
+                    lm_name+                            /* module name */
+                    2+                                  /* "_O" */
+                    lfilename+                          /* object filename */
+                    2+                                  /* "_M" */
+                    2*sizeof(statbuf.st_mtime)+         /* mtime in hex */
+                    2+                                  /* "_V" */
+                    8+                                  /* version in dec */
+                    1;                                  /* nul */
+                name = xmalloc(l);
+                if (stat(absolute_filename, &statbuf) != 0)
+                        statbuf.st_mtime = 0;
+                version = get_module_version(f, str);   /* -1 if not found */
+                snprintf(name, l, "%s%s_O%s_M%0*lX_V%d",
+                         symprefix, m_name, absolute_filename,
+                         (int)(2*sizeof(statbuf.st_mtime)), statbuf.st_mtime,
+                         version);
+                sym = obj_add_symbol(f, name, -1,
+                                     ELFW(ST_INFO) (STB_GLOBAL, STT_NOTYPE),
+                                     sec->idx, sec->header.sh_addr, 0);
+                if (use_ksymtab)
+                    new_add_ksymtab(f, sym);
+        }
+        free(absolute_filename);
+#ifdef _NOT_SUPPORTED_
+        /* record where the persistent data is going, same address as previous symbol */
+
+        if (f->persist) {
+                l = sizeof(symprefix)+          /* "__insmod_" */
+                        lm_name+                /* module name */
+                        2+                      /* "_P" */
+                        strlen(f->persist)+     /* data store */
+                        1;                      /* nul */
+                name = xmalloc(l);
+                snprintf(name, l, "%s%s_P%s",
+                         symprefix, m_name, f->persist);
+                sym = obj_add_symbol(f, name, -1, ELFW(ST_INFO) (STB_GLOBAL, STT_NOTYPE),
+                                     sec->idx, sec->header.sh_addr, 0);
+                if (use_ksymtab)
+                    new_add_ksymtab(f, sym);
+        }
+#endif /* _NOT_SUPPORTED_ */
+        /* tag the desired sections if size is non-zero */
+
+        for (i = 0; i < sizeof(section_names)/sizeof(section_names[0]); ++i) {
+                if ((sec = obj_find_section(f, section_names[i])) &&
+                    sec->header.sh_size) {
+                        l = sizeof(symprefix)+          /* "__insmod_" */
+                                lm_name+                /* module name */
+                                2+                      /* "_S" */
+                                strlen(sec->name)+      /* section name */
+                                2+                      /* "_L" */
+                                8+                      /* length in dec */
+                                1;                      /* nul */
+                        name = xmalloc(l);
+                        snprintf(name, l, "%s%s_S%s_L%ld",
+                                 symprefix, m_name, sec->name,
+                                 (long)sec->header.sh_size);
+                        sym = obj_add_symbol(f, name, -1, ELFW(ST_INFO) (STB_GLOBAL, STT_NOTYPE),
+                                             sec->idx, sec->header.sh_addr, 0);
+                        if (use_ksymtab)
+                            new_add_ksymtab(f, sym);
+                }
+        }
+}
+#endif /* CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS */
+
 extern int insmod_main( int argc, char **argv)
 {
         int opt;
@@ -3788,6 +3956,10 @@ extern int insmod_main( int argc, char **argv)
         arch_create_got(f);
         hide_special_symbols(f);
 
+#ifdef CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS
+        add_ksymoops_symbols(f, m_filename, m_name);
+#endif /* CONFIG_FEATURE_INSMOD_KSYMOOPS_SYMBOLS */
+
         if (k_new_syscalls)
                 new_create_module_ksymtab(f);