[PATCH 6/7] Ksplice: Export symbols needed for Ksplice

Jeff Arnold
2008-12-06T00:10:46Z

From: Tim Abbott <tabbott@mit.edu>

Ksplice uses several functions from module.c in order to resolve
symbols and implement dependency handling. Calling these functions
requires holding module_mutex, so it is exported.

Ksplice uses task_curr in order to confirm that no other tasks are
executing during Ksplice's kernel stack check.

Ksplice uses find_bug and search_exception_tables as part of its
conservative check that the user provided the correct source code for
the running kernel.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
---
include/linux/module.h | 28 ++++++++++++++++++++++++++++
kernel/extable.c | 3 +++
kernel/module.c | 41 +++++++++++++++++------------------------
kernel/sched.c | 1 +
lib/bug.c | 1 +
5 files changed, 50 insertions(+), 24 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 29972a2..cc613f6 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -355,6 +355,8 @@ struct module
#define MODULE_ARCH_INIT {}
#endif

+extern struct mutex module_mutex;
+
/* FIXME: It'd be nice to isolate modules during init, too, so they
aren't used before they (may) fail. But presently too much code
(IDE & SCSI) require entry into the module during init.*/
@@ -370,6 +372,31 @@ struct module *module_data_address(unsigned long addr);
struct module *__module_data_address(unsigned long addr);
int is_module_address(unsigned long addr);

+/* Search for module by name: must hold module_mutex. */
+struct module *find_module(const char *name);
+
+struct symsearch {
+ const struct kernel_symbol *start, *stop;
+ const unsigned long *crcs;
+ enum {
+ NOT_GPL_ONLY,
+ GPL_ONLY,
+ WILL_BE_GPL_ONLY,
+ } licence;
+ bool unused;
+};
+
+/* Search for an exported symbol by name. */
+const struct kernel_symbol *find_symbol(const char *name,
+ struct module **owner,
+ const unsigned long **crc,
+ bool gplok,
+ bool warn);
+
+/* Walk the exported symbol table */
+bool each_symbol(bool (*fn)(const struct symsearch *arr, struct module *owner,
+ unsigned int symnum, void *data), void *data);
+
/* Returns 0 and fills in value, defined and namebuf, or -ERANGE if
symnum out of range. */
int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
@@ -435,6 +462,7 @@ static inline void __module_get(struct module *module)
#define symbol_put_addr(p) do { } while(0)

#endif /* CONFIG_MODULE_UNLOAD */
+int use_module(struct module *a, struct module *b);

/* This is a #define so the string doesn't get put in every .o file */
#define module_name(mod) \
diff --git a/kernel/extable.c b/kernel/extable.c
index a26cb2e..f7740b1 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -39,6 +39,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
e = search_module_extables(addr);
return e;
}
+EXPORT_SYMBOL_GPL(search_exception_tables);

int core_kernel_text(unsigned long addr)
{
@@ -59,6 +60,7 @@ int __kernel_text_address(unsigned long addr)
return 1;
return __module_text_address(addr) != NULL;
}
+EXPORT_SYMBOL_GPL(__kernel_text_address);

int kernel_text_address(unsigned long addr)
{
@@ -66,3 +68,4 @@ int kernel_text_address(unsigned long addr)
return 1;
return module_text_address(addr) != NULL;
}
+EXPORT_SYMBOL_GPL(kernel_text_address);
diff --git a/kernel/module.c b/kernel/module.c
index 8839d40..b109aae 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -67,7 +67,8 @@

/* List of modules, protected by module_mutex or preempt_disable
* (delete uses stop_machine/add uses RCU list operations). */
-static DEFINE_MUTEX(module_mutex);
+DEFINE_MUTEX(module_mutex);
+EXPORT_SYMBOL_GPL(module_mutex);
static LIST_HEAD(modules);

/* Waiting for a module to finish initializing? */
@@ -185,17 +186,6 @@ extern const unsigned long __start___kcrctab_unused_gpl[];
#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)
#endif

-struct symsearch {
- const struct kernel_symbol *start, *stop;
- const unsigned long *crcs;
- enum {
- NOT_GPL_ONLY,
- GPL_ONLY,
- WILL_BE_GPL_ONLY,
- } licence;
- bool unused;
-};
-
static bool each_symbol_in_section(const struct symsearch *arr,
unsigned int arrsize,
struct module *owner,
@@ -216,10 +206,8 @@ static bool each_symbol_in_section(const struct symsearch *arr,
}

/* Returns true as soon as fn returns true, otherwise false. */
-static bool each_symbol(bool (*fn)(const struct symsearch *arr,
- struct module *owner,
- unsigned int symnum, void *data),
- void *data)
+bool each_symbol(bool (*fn)(const struct symsearch *arr, struct module *owner,
+ unsigned int symnum, void *data), void *data)
{
struct module *mod;
const struct symsearch arr[] = {
@@ -272,6 +260,7 @@ static bool each_symbol(bool (*fn)(const struct symsearch *arr,
}
return false;
}
+EXPORT_SYMBOL_GPL(each_symbol);

struct find_symbol_arg {
/* Input */
@@ -329,11 +318,11 @@ static bool find_symbol_in_section(const struct symsearch *syms,

/* Find a symbol and return it, along with, (optional) crc and
* (optional) module which owns it */
-static const struct kernel_symbol *find_symbol(const char *name,
- struct module **owner,
- const unsigned long **crc,
- bool gplok,
- bool warn)
+const struct kernel_symbol *find_symbol(const char *name,
+ struct module **owner,
+ const unsigned long **crc,
+ bool gplok,
+ bool warn)
{
struct find_symbol_arg fsa;

@@ -352,9 +341,10 @@ static const struct kernel_symbol *find_symbol(const char *name,
DEBUGP("Failed to find symbol %s\n", name);
return NULL;
}
+EXPORT_SYMBOL_GPL(find_symbol);

/* Search for module by name: must hold module_mutex. */
-static struct module *find_module(const char *name)
+struct module *find_module(const char *name)
{
struct module *mod;

@@ -364,6 +354,7 @@ static struct module *find_module(const char *name)
}
return NULL;
}
+EXPORT_SYMBOL_GPL(find_module);

#ifdef CONFIG_SMP
/* Number of blocks used and allocated. */
@@ -607,7 +598,7 @@ static int already_uses(struct module *a, struct module *b)
}

/* Module a uses b */
-static int use_module(struct module *a, struct module *b)
+int use_module(struct module *a, struct module *b)
{
struct module_use *use;
int no_warn, err;
@@ -640,6 +631,7 @@ static int use_module(struct module *a, struct module *b)
no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
return 1;
}
+EXPORT_SYMBOL_GPL(use_module);

/* Clear the unload stuff of the module. */
static void module_unload_free(struct module *mod)
@@ -903,10 +895,11 @@ static inline void module_unload_free(struct module *mod)
{
}

-static inline int use_module(struct module *a, struct module *b)
+int use_module(struct module *a, struct module *b)
{
return strong_try_module_get(b) == 0;
}
+EXPORT_SYMBOL_GPL(use_module);

static inline void module_unload_init(struct module *mod)
{
diff --git a/kernel/sched.c b/kernel/sched.c
index b7480fb..970e034 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1770,6 +1770,7 @@ inline int task_curr(const struct task_struct *p)
{
return cpu_curr(task_cpu(p)) == p;
}
+EXPORT_SYMBOL_GPL(task_curr);

static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
{
diff --git a/lib/bug.c b/lib/bug.c
index bfeafd6..b5c0659 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -113,6 +113,7 @@ const struct bug_entry *find_bug(unsigned long bugaddr)

return module_find_bug(bugaddr);
}
+EXPORT_SYMBOL_GPL(find_bug);

enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
{
--
1.5.6.3