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Subject[PATCH v15 01/11] livepatch: Change unsigned long old_addr -> void *old_func in struct klp_func
Date
The address of the to be patched function and new function is stored
in struct klp_func as:

void *new_func;
unsigned long old_addr;

The different naming scheme and type are derived from the way
the addresses are set. @old_addr is assigned at runtime using
kallsyms-based search. @new_func is statically initialized,
for example:

static struct klp_func funcs[] = {
{
.old_name = "cmdline_proc_show",
.new_func = livepatch_cmdline_proc_show,
}, { }
};

This patch changes unsigned long old_addr -> void *old_func. It removes
some confusion when these address are later used in the code. It is
motivated by a followup patch that adds special NOP struct klp_func
where we want to assign func->new_func = func->old_addr respectively
func->new_func = func->old_func.

This patch does not modify the existing behavior.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Alice Ferrazzi <alice.ferrazzi@gmail.com>
---
include/linux/livepatch.h | 4 ++--
kernel/livepatch/core.c | 6 +++---
kernel/livepatch/patch.c | 18 ++++++++++--------
kernel/livepatch/patch.h | 4 ++--
kernel/livepatch/transition.c | 4 ++--
5 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index aec44b1d9582..634e13876380 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -40,7 +40,7 @@
* @new_func: pointer to the patched function code
* @old_sympos: a hint indicating which symbol position the old function
* can be found (optional)
- * @old_addr: the address of the function being patched
+ * @old_func: pointer to the function being patched
* @kobj: kobject for sysfs resources
* @stack_node: list node for klp_ops func_stack list
* @old_size: size of the old function
@@ -77,7 +77,7 @@ struct klp_func {
unsigned long old_sympos;

/* internal */
- unsigned long old_addr;
+ void *old_func;
struct kobject kobj;
struct list_head stack_node;
unsigned long old_size, new_size;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 5b77a7314e01..cb59c7fb94cb 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -648,7 +648,7 @@ static void klp_free_object_loaded(struct klp_object *obj)
obj->mod = NULL;

klp_for_each_func(obj, func)
- func->old_addr = 0;
+ func->old_func = NULL;
}

/*
@@ -721,11 +721,11 @@ static int klp_init_object_loaded(struct klp_patch *patch,
klp_for_each_func(obj, func) {
ret = klp_find_object_symbol(obj->name, func->old_name,
func->old_sympos,
- &func->old_addr);
+ (unsigned long *)&func->old_func);
if (ret)
return ret;

- ret = kallsyms_lookup_size_offset(func->old_addr,
+ ret = kallsyms_lookup_size_offset((unsigned long)func->old_func,
&func->old_size, NULL);
if (!ret) {
pr_err("kallsyms size lookup failed for '%s'\n",
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 7702cb4064fc..825022d70912 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -34,7 +34,7 @@

static LIST_HEAD(klp_ops);

-struct klp_ops *klp_find_ops(unsigned long old_addr)
+struct klp_ops *klp_find_ops(void *old_func)
{
struct klp_ops *ops;
struct klp_func *func;
@@ -42,7 +42,7 @@ struct klp_ops *klp_find_ops(unsigned long old_addr)
list_for_each_entry(ops, &klp_ops, node) {
func = list_first_entry(&ops->func_stack, struct klp_func,
stack_node);
- if (func->old_addr == old_addr)
+ if (func->old_func == old_func)
return ops;
}

@@ -142,17 +142,18 @@ static void klp_unpatch_func(struct klp_func *func)

if (WARN_ON(!func->patched))
return;
- if (WARN_ON(!func->old_addr))
+ if (WARN_ON(!func->old_func))
return;

- ops = klp_find_ops(func->old_addr);
+ ops = klp_find_ops(func->old_func);
if (WARN_ON(!ops))
return;

if (list_is_singular(&ops->func_stack)) {
unsigned long ftrace_loc;

- ftrace_loc = klp_get_ftrace_location(func->old_addr);
+ ftrace_loc =
+ klp_get_ftrace_location((unsigned long)func->old_func);
if (WARN_ON(!ftrace_loc))
return;

@@ -174,17 +175,18 @@ static int klp_patch_func(struct klp_func *func)
struct klp_ops *ops;
int ret;

- if (WARN_ON(!func->old_addr))
+ if (WARN_ON(!func->old_func))
return -EINVAL;

if (WARN_ON(func->patched))
return -EINVAL;

- ops = klp_find_ops(func->old_addr);
+ ops = klp_find_ops(func->old_func);
if (!ops) {
unsigned long ftrace_loc;

- ftrace_loc = klp_get_ftrace_location(func->old_addr);
+ ftrace_loc =
+ klp_get_ftrace_location((unsigned long)func->old_func);
if (!ftrace_loc) {
pr_err("failed to find location for function '%s'\n",
func->old_name);
diff --git a/kernel/livepatch/patch.h b/kernel/livepatch/patch.h
index e72d8250d04b..a9b16e513656 100644
--- a/kernel/livepatch/patch.h
+++ b/kernel/livepatch/patch.h
@@ -10,7 +10,7 @@
* struct klp_ops - structure for tracking registered ftrace ops structs
*
* A single ftrace_ops is shared between all enabled replacement functions
- * (klp_func structs) which have the same old_addr. This allows the switch
+ * (klp_func structs) which have the same old_func. This allows the switch
* between function versions to happen instantaneously by updating the klp_ops
* struct's func_stack list. The winner is the klp_func at the top of the
* func_stack (front of the list).
@@ -25,7 +25,7 @@ struct klp_ops {
struct ftrace_ops fops;
};

-struct klp_ops *klp_find_ops(unsigned long old_addr);
+struct klp_ops *klp_find_ops(void *old_func);

int klp_patch_object(struct klp_object *obj);
void klp_unpatch_object(struct klp_object *obj);
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 304d5eb8a98c..f27a378ad5e1 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -224,11 +224,11 @@ static int klp_check_stack_func(struct klp_func *func,
* Check for the to-be-patched function
* (the previous func).
*/
- ops = klp_find_ops(func->old_addr);
+ ops = klp_find_ops(func->old_func);

if (list_is_singular(&ops->func_stack)) {
/* original function */
- func_addr = func->old_addr;
+ func_addr = (unsigned long)func->old_func;
func_size = func->old_size;
} else {
/* previously patched function */
--
2.13.7
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