Ksplice: Add functions for walking kallsyms symbols

Impact: New API

kallsyms_lookup_name only returns the first match that it finds.  Ksplice
needs information about all symbols with a given name in order to correctly
resolve local symbols.

kallsyms_on_each_symbol provides a generic mechanism for iterating over the
kallsyms table.

Cc: Jeff Arnold <jbarnold@mit.edu>
Cc: Tim Abbott <tabbott@mit.edu>
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index f3fe343..7922742 100644 (file)
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -13,10 +13,17 @@
 #define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s]") + (KSYM_NAME_LEN - 1) + \
                         2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + 1)
 
+struct module;
+
 #ifdef CONFIG_KALLSYMS
 /* Lookup the address for a symbol. Returns 0 if not found. */
 unsigned long kallsyms_lookup_name(const char *name);
 
+/* Call a function on each kallsyms symbol in the core kernel */
+int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
+                                     unsigned long),
+                           void *data);
+
 extern int kallsyms_lookup_size_offset(unsigned long addr,
                                  unsigned long *symbolsize,
                                  unsigned long *offset);
@@ -43,6 +50,14 @@ static inline unsigned long kallsyms_lookup_name(const char *name)
        return 0;
 }
 
+static inline int kallsyms_on_each_symbol(int (*fn)(void *, const char *,
+                                                   struct module *,
+                                                   unsigned long),
+                                         void *data)
+{
+       return 0;
+}
+
 static inline int kallsyms_lookup_size_offset(unsigned long addr,
                                              unsigned long *symbolsize,
                                              unsigned long *offset)

diff --git a/include/linux/module.h b/include/linux/module.h
index 69761ce..c3d3fc4 100644 (file)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -387,6 +387,10 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 /* Look for this name: can be of form module:name. */
 unsigned long module_kallsyms_lookup_name(const char *name);
 
+int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
+                                            struct module *, unsigned long),
+                                  void *data);
+
 extern void __module_put_and_exit(struct module *mod, long code)
        __attribute__((noreturn));
 #define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code);
@@ -566,6 +570,14 @@ static inline unsigned long module_kallsyms_lookup_name(const char *name)
        return 0;
 }
 
+static inline int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
+                                                          struct module *,
+                                                          unsigned long),
+                                                void *data)
+{
+       return 0;
+}
+
 static inline int register_module_notifier(struct notifier_block * nb)
 {
        /* no events will happen anyway, so this can always succeed */

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 7b8b0f2..374faf9 100644 (file)
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -161,6 +161,25 @@ unsigned long kallsyms_lookup_name(const char *name)
        return module_kallsyms_lookup_name(name);
 }
 
+int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
+                                     unsigned long),
+                           void *data)
+{
+       char namebuf[KSYM_NAME_LEN];
+       unsigned long i;
+       unsigned int off;
+       int ret;
+
+       for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
+               off = kallsyms_expand_symbol(off, namebuf);
+               ret = fn(data, namebuf, NULL, kallsyms_addresses[i]);
+               if (ret != 0)
+                       return ret;
+       }
+       return module_kallsyms_on_each_symbol(fn, data);
+}
+EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
+
 static unsigned long get_symbol_pos(unsigned long addr,
                                    unsigned long *symbolsize,
                                    unsigned long *offset)

diff --git a/kernel/module.c b/kernel/module.c
index 8ddca62..dd4389b 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2612,6 +2612,25 @@ unsigned long module_kallsyms_lookup_name(const char *name)
        preempt_enable();
        return ret;
 }
+
+int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
+                                            struct module *, unsigned long),
+                                  void *data)
+{
+       struct module *mod;
+       unsigned int i;
+       int ret;
+
+       list_for_each_entry(mod, &modules, list) {
+               for (i = 0; i < mod->num_symtab; i++) {
+                       ret = fn(data, mod->strtab + mod->symtab[i].st_name,
+                                mod, mod->symtab[i].st_value);
+                       if (ret != 0)
+                               return ret;
+               }
+       }
+       return 0;
+}
 #endif /* CONFIG_KALLSYMS */
 
 static char *module_flags(struct module *mod, char *buf)