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kmod/core: add ftrace helper functions 

Move all the ftrace filtering and registering logic into a couple of new
helper functions.  Change kpatch_num_registered to kpatch_num_patched,
which now tracks the number of patched functions rather than the number
of patch modules.

This simplifies the code a bit and will also prevent a future loaded
module scenario where ftrace_ops can be registered with an empty filter,
resulting in _all_ kernel functions getting registered with ftrace.
This commit is contained in:
Josh Poimboeuf 2014-06-13 09:49:37 -05:00
parent dfc2641de2
commit c61fb88a23
1 changed files with 67 additions and 68 deletions
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135
kmod/core/core.c
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@ -58,7 +58,7 @@ static DEFINE_HASHTABLE(kpatch_func_hash, KPATCH_HASH_BITS);
static DEFINE_SEMAPHORE(kpatch_mutex);
static int kpatch_num_registered;
static int kpatch_num_patched;
static struct kobject *kpatch_root_kobj;
struct kobject *kpatch_patches_kobj;
@ -406,6 +406,60 @@ static struct ftrace_ops kpatch_ftrace_ops __read_mostly = {
.flags = FTRACE_OPS_FL_SAVE_REGS,
};
static int kpatch_ftrace_add_func(unsigned long ip)
{
int ret;
/* check if any other patch modules have also patched this func */
if (kpatch_get_func(ip))
return 0;
ret = ftrace_set_filter_ip(&kpatch_ftrace_ops, ip, 0, 0);
if (ret) {
pr_err("can't set ftrace filter at address 0x%lx\n", ip);
return ret;
}
if (!kpatch_num_patched) {
ret = register_ftrace_function(&kpatch_ftrace_ops);
if (ret) {
pr_err("can't register ftrace handler\n");
ftrace_set_filter_ip(&kpatch_ftrace_ops, ip, 1, 0);
return ret;
}
}
kpatch_num_patched++;
return 0;
}
static int kpatch_ftrace_remove_func(unsigned long ip)
{
int ret;
/* check if any other patch modules have also patched this func */
if (kpatch_get_func(ip))
return 0;
ret = ftrace_set_filter_ip(&kpatch_ftrace_ops, ip, 1, 0);
if (ret) {
pr_err("can't remove ftrace filter at address 0x%lx\n", ip);
return ret;
}
if (kpatch_num_patched == 1) {
ret = unregister_ftrace_function(&kpatch_ftrace_ops);
if (ret) {
pr_err("can't unregister ftrace handler\n");
ftrace_set_filter_ip(&kpatch_ftrace_ops, ip, 0, 0);
return ret;
}
}
kpatch_num_patched--;
return 0;
}
static void kpatch_put_modules(struct kpatch_func *funcs, int num_funcs)
{
int i;
@ -418,31 +472,6 @@ static void kpatch_put_modules(struct kpatch_func *funcs, int num_funcs)
}
}
/* Remove kpatch_funcs from ftrace filter */
static void kpatch_remove_funcs_from_filter(struct kpatch_func *funcs,
int num_funcs)
{
int i, ret = 0;
for (i = 0; i < num_funcs; i++) {
struct kpatch_func *func = &funcs[i];
/*
* If any other modules have also patched this function, don't
* remove its ftrace handler.
*/
if (kpatch_get_func(func->old_addr))
continue;
/* Remove the ftrace handler for this function. */
ret = ftrace_set_filter_ip(&kpatch_ftrace_ops,
func->old_addr, 1, 0);
WARN(ret, "can't remove ftrace filter at address 0x%lx (rc=%d)",
func->old_addr, ret);
}
}
static int kpatch_kallsyms_callback(void *data, const char *name,
struct module *mod,
unsigned long addr)
@ -662,34 +691,13 @@ int kpatch_register(struct kpatch_module *kpmod, bool replace)
goto err_rollback;
}
/*
* If any other modules have also patched this function, it
* already has an ftrace handler.
*/
if (kpatch_get_func(func->old_addr))
continue;
/* Add an ftrace handler for this function. */
ret = ftrace_set_filter_ip(&kpatch_ftrace_ops,
func->old_addr, 0, 0);
ret = kpatch_ftrace_add_func(func->old_addr);
if (ret) {
pr_err("can't set ftrace filter at address 0x%lx\n",
func->old_addr);
num_funcs = i;
goto err_rollback;
}
}
/* Register the ftrace handler if it hasn't been done already. */
if (!kpatch_num_registered) {
ret = register_ftrace_function(&kpatch_ftrace_ops);
if (ret) {
pr_err("can't register ftrace handler\n");
goto err_rollback;
}
}
kpatch_num_registered++;
if (replace)
hash_for_each_rcu(kpatch_func_hash, i, func, node)
func->op = KPATCH_OP_UNPATCH;
@ -715,9 +723,8 @@ int kpatch_register(struct kpatch_module *kpmod, bool replace)
if (func->op != KPATCH_OP_UNPATCH)
continue;
hash_del_rcu(&func->node);
kpatch_remove_funcs_from_filter(func, 1);
WARN_ON(kpatch_ftrace_remove_func(func->old_addr));
if (func->kpmod->enabled) {
kpatch_num_registered--;
func->kpmod->enabled = false;
pr_notice("unloaded patch module '%s'\n",
func->kpmod->mod->name);
@ -741,7 +748,7 @@ int kpatch_register(struct kpatch_module *kpmod, bool replace)
synchronize_rcu();
if (ret)
goto err_unregister;
goto err_ops;
for (i = 0; i < num_funcs; i++)
funcs[i].op = KPATCH_OP_NONE;
@ -757,20 +764,13 @@ int kpatch_register(struct kpatch_module *kpmod, bool replace)
up(&kpatch_mutex);
return 0;
err_unregister:
err_ops:
if (replace)
hash_for_each_rcu(kpatch_func_hash, i, func, node)
func->op = KPATCH_OP_NONE;
if (kpatch_num_registered == 1) {
int ret2 = unregister_ftrace_function(&kpatch_ftrace_ops);
if (ret2) {
pr_err("ftrace unregister failed (%d)\n", ret2);
goto err_rollback;
}
}
kpatch_num_registered--;
err_rollback:
kpatch_remove_funcs_from_filter(funcs, num_funcs);
for (i = 0; i < num_funcs; i++)
kpatch_ftrace_remove_func(funcs[i].old_addr);
kpatch_put_modules(funcs, kpmod->patches_nr);
err_put:
module_put(kpmod->mod);
@ -821,16 +821,15 @@ int kpatch_unregister(struct kpatch_module *kpmod)
goto out;
}
kpatch_num_registered--;
if (!kpatch_num_registered) {
ret = unregister_ftrace_function(&kpatch_ftrace_ops);
for (i = 0; i < num_funcs; i++) {
ret = kpatch_ftrace_remove_func(funcs[i].old_addr);
if (ret) {
WARN(1, "can't unregister ftrace handler");
kpatch_num_registered++;
WARN(1, "can't unregister ftrace for address 0x%lx\n",
funcs[i].old_addr);
goto out;
}
}
kpatch_remove_funcs_from_filter(funcs, num_funcs);
kpatch_put_modules(funcs, num_funcs);
kfree(kpmod->internal->funcs);
@ -863,7 +862,7 @@ static int kpatch_init(void)
static void kpatch_exit(void)
{
WARN_ON(kpatch_num_registered != 0);
WARN_ON(kpatch_num_patched != 0);
kobject_put(kpatch_patches_kobj);
kobject_put(kpatch_root_kobj);
}