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Subject[PATCH 2/9] module: __module_address

Impact: New API, cleanup

ksplice wants to know the bounds of a module, not just the module text.

It makes sense to have __module_address. We then implement
is_module_address and __module_text_address in terms of this (and
change is_module_text_address() to bool while we're at it).

Also, add proper kerneldoc for them all.

Cc: Anders Kaseorg <andersk@mit.edu>
Cc: Jeff Arnold <jbarnold@mit.edu>
Cc: Tim Abbott <tabbott@mit.edu>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
include/linux/module.h | 20 +++++++++---
kernel/module.c | 76 +++++++++++++++++++++++++++++++++++++------------
2 files changed, 73 insertions(+), 23 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -361,7 +361,9 @@ static inline int module_is_live(struct
/* Is this address in a module? (second is with no locks, for oops) */
struct module *module_text_address(unsigned long addr);
struct module *__module_text_address(unsigned long addr);
-int is_module_address(unsigned long addr);
+struct module *__module_address(unsigned long addr);
+bool is_module_address(unsigned long addr);
+bool is_module_text_address(unsigned long addr);

static inline int within_module_core(unsigned long addr, struct module *mod)
{
@@ -490,21 +492,29 @@ search_module_extables(unsigned long add
return NULL;
}

-/* Is this address in a module? */
static inline struct module *module_text_address(unsigned long addr)
{
return NULL;
}

-/* Is this address in a module? (don't take a lock, we're oopsing) */
+static inline struct module *__module_address(unsigned long addr)
+{
+ return NULL;
+}
+
static inline struct module *__module_text_address(unsigned long addr)
{
return NULL;
}

-static inline int is_module_address(unsigned long addr)
+static inline bool is_module_address(unsigned long addr)
{
- return 0;
+ return false;
+}
+
+static inline bool is_module_text_address(unsigned long addr)
+{
+ return false;
}

/* Get/put a kernel symbol (calls should be symmetric) */
diff --git a/kernel/module.c b/kernel/module.c
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -75,7 +75,7 @@ static DECLARE_WAIT_QUEUE_HEAD(module_wq

static BLOCKING_NOTIFIER_HEAD(module_notify_list);

-/* Bounds of module allocation, for speeding __module_text_address */
+/* Bounds of module allocation, for speeding __module_address */
static unsigned long module_addr_min = -1UL, module_addr_max = 0;

int register_module_notifier(struct notifier_block * nb)
@@ -2712,29 +2712,31 @@ const struct exception_table_entry *sear
}

/*
- * Is this a valid module address?
+ * is_module_address - is this address inside a module?
+ * @addr: the address to check.
+ *
+ * See is_module_text_address() if you simply want to see if the address
+ * is code (not data).
*/
-int is_module_address(unsigned long addr)
+bool is_module_address(unsigned long addr)
{
- struct module *mod;
+ bool ret;

preempt_disable();
-
- list_for_each_entry_rcu(mod, &modules, list) {
- if (within_module_core(addr, mod)) {
- preempt_enable();
- return 1;
- }
- }
-
+ ret = __module_address(addr) != NULL;
preempt_enable();

- return 0;
+ return ret;
}

-
-/* Is this a valid kernel address? */
-__notrace_funcgraph struct module *__module_text_address(unsigned long addr)
+/*
+ * __module_address - get the module which contains an address.
+ * @addr: the address.
+ *
+ * Must be called with preempt disabled or module mutex held so that
+ * module doesn't get freed during this.
+ */
+__notrace_funcgraph struct module *__module_address(unsigned long addr)
{
struct module *mod;

@@ -2742,10 +2744,48 @@ __notrace_funcgraph struct module *__mod
return NULL;

list_for_each_entry_rcu(mod, &modules, list)
- if (within(addr, mod->module_init, mod->init_text_size)
- || within(addr, mod->module_core, mod->core_text_size))
+ if (within_module_core(addr, mod)
+ || within_module_init(addr, mod))
return mod;
return NULL;
+}
+
+/*
+ * is_module_text_address - is this address inside module code?
+ * @addr: the address to check.
+ *
+ * See is_module_address() if you simply want to see if the address is
+ * anywhere in a module. See kernel_text_address() for testing if an
+ * address corresponds to kernel or module code.
+ */
+bool is_module_text_address(unsigned long addr)
+{
+ bool ret;
+
+ preempt_disable();
+ ret = __module_text_address(addr) != NULL;
+ preempt_enable();
+
+ return ret;
+}
+
+/*
+ * __module_text_address - get the module whose code contains an address.
+ * @addr: the address.
+ *
+ * Must be called with preempt disabled or module mutex held so that
+ * module doesn't get freed during this.
+ */
+struct module *__module_text_address(unsigned long addr)
+{
+ struct module *mod = __module_address(addr);
+ if (mod) {
+ /* Make sure it's within the text section. */
+ if (!within(addr, mod->module_init, mod->init_text_size)
+ && !within(addr, mod->module_core, mod->core_text_size))
+ mod = NULL;
+ }
+ return mod;
}

struct module *module_text_address(unsigned long addr)


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