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kmod/core: Handle registering error and unroll it

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Handle registering error to unroll the ftrace filter.
This also introduces get_kpatch_func() and
kpatch_remove_funcs_from_filter() for holding up
redundant loops.

Changes from v2:
 - Rebased on the latest kpatch.

Changes from v1:
 - Rename get_kpatch_func to kpatch_get_func.
 - Fix function definition style issue.
 - Do not jump to a label in "if" block.
 - Rollback the ftrace user counter if we hit an error.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
This commit is contained in:
Masami Hiramatsu 2014-04-23 10:58:45 +09:00 committed by Masami Hiramatsu
parent 2e607644e1
commit 79ca5dbfa7
1 changed files with 59 additions and 47 deletions
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106
kmod/core/core.c
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@ -169,6 +169,15 @@ out:
return ret;
}
static struct kpatch_func *kpatch_get_func(unsigned long ip)
{
struct kpatch_func *f;
hash_for_each_possible(kpatch_func_hash, f, node, ip)
if (f->old_addr == ip)
return f;
return NULL;
}
void notrace kpatch_ftrace_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct pt_regs *regs)
@ -198,6 +207,35 @@ static struct ftrace_ops kpatch_ftrace_ops __read_mostly = {
.flags = FTRACE_OPS_FL_SAVE_REGS,
};
/* Remove kpatch_funcs from ftrace filter */
static int 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);
if (ret) {
pr_err("can't remove ftrace filter at address 0x%lx\n",
func->old_addr);
break;
}
}
return ret;
}
int kpatch_register(struct module *mod, struct kpatch_func *funcs,
int num_funcs)
{
@ -210,8 +248,7 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
down(&kpatch_mutex);
for (i = 0; i < num_funcs; i++) {
struct kpatch_func *f, *func = &funcs[i];
bool found = false;
struct kpatch_func *func = &funcs[i];
func->mod = mod;
@ -219,14 +256,7 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
* If any other modules have also patched this function, it
* already has an ftrace handler.
*/
hash_for_each_possible(kpatch_func_hash, f, node,
func->old_addr) {
if (f->old_addr == func->old_addr) {
found = true;
break;
}
}
if (found)
if (kpatch_get_func(func->old_addr))
continue;
/* Add an ftrace handler for this function. */
@ -235,6 +265,7 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
if (ret) {
pr_err("can't set ftrace filter at address 0x%lx\n",
func->old_addr);
num_funcs = i;
goto out;
}
}
@ -244,6 +275,8 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
ret = register_ftrace_function(&kpatch_ftrace_ops);
if (ret) {
pr_err("can't register ftrace handler\n");
/* For the next time, the counter should be unrolled */
--kpatch_num_registered;
goto out;
}
}
@ -259,25 +292,30 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
if (ret2)
pr_err("ftrace unregister failed (%d)\n", ret2);
}
goto out;
}
/* TODO: need TAINT_KPATCH */
pr_notice_once("tainting kernel with TAINT_USER\n");
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
pr_notice("loaded patch module \"%s\"\n", mod->name);
out:
/* Rollback the filter if we get any error */
if (ret)
kpatch_remove_funcs_from_filter(funcs, num_funcs);
else {
/* TODO: need TAINT_KPATCH */
pr_notice_once("tainting kernel with TAINT_USER\n");
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
pr_notice("loaded patch module \"%s\"\n", mod->name);
}
up(&kpatch_mutex);
return ret;
}
EXPORT_SYMBOL(kpatch_register);
int kpatch_unregister(struct module *mod, struct kpatch_func *funcs,
int num_funcs)
{
int i, ret;
int ret;
struct kpatch_stop_machine_args args = {
.funcs = funcs,
.num_funcs = num_funcs,
@ -297,35 +335,9 @@ int kpatch_unregister(struct module *mod, struct kpatch_func *funcs,
}
}
for (i = 0; i < num_funcs; i++) {
struct kpatch_func *f, *func = &funcs[i];
bool found = false;
/*
* If any other modules have also patched this function, don't
* remove its ftrace handler.
*/
hash_for_each_possible(kpatch_func_hash, f, node,
func->old_addr) {
if (f->old_addr == func->old_addr) {
found = true;
break;
}
}
if (found)
continue;
/* Remove the ftrace handler for this function. */
ret = ftrace_set_filter_ip(&kpatch_ftrace_ops, func->old_addr,
1, 0);
if (ret) {
pr_err("can't remove ftrace filter at address 0x%lx\n",
func->old_addr);
goto out;
}
}
pr_notice("unloaded patch module \"%s\"\n", mod->name);
ret = kpatch_remove_funcs_from_filter(funcs, num_funcs);
if (ret == 0)
pr_notice("unloaded patch module \"%s\"\n", mod->name);
out:
up(&kpatch_mutex);