Commit 4c3ef6d7 authored by Jason Baron's avatar Jason Baron Committed by Steven Rostedt
Browse files

jump label: Add jump_label_text_reserved() to reserve jump points 



Add a jump_label_text_reserved(void *start, void *end), so that other
pieces of code that want to modify kernel text, can first verify that
jump label has not reserved the instruction.

Acked-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: default avatarJason Baron <jbaron@redhat.com>
LKML-Reference: <06236663a3a7b1c1f13576bb9eccb6d9c17b7bfe.1284733808.git.jbaron@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent e0cf0cd4

arch/x86/kernel/kprobes.c

+2 −1
Original line number Diff line number Diff line
@@ -1218,7 +1218,8 @@ static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src) 
	}

	/* Check whether the address range is reserved */

	if (ftrace_text_reserved(src, src + len - 1) ||

	    alternatives_text_reserved(src, src + len - 1))

	    alternatives_text_reserved(src, src + len - 1) ||

	    jump_label_text_reserved(src, src + len - 1))

		return -EBUSY;



	return len;

include/linux/jump_label.h

+7 −1
Original line number Diff line number Diff line
@@ -20,9 +20,10 @@ extern struct jump_entry __stop___jump_table[]; 


extern void arch_jump_label_transform(struct jump_entry *entry,

				 enum jump_label_type type);

extern void arch_jump_label_text_poke_early(jump_label_t addr);

extern void jump_label_update(unsigned long key, enum jump_label_type type);

extern void jump_label_apply_nops(struct module *mod);

extern void arch_jump_label_text_poke_early(jump_label_t addr);

extern int jump_label_text_reserved(void *start, void *end);



#define enable_jump_label(key) \

	jump_label_update((unsigned long)key, JUMP_LABEL_ENABLE);
@@ -53,6 +54,11 @@ static inline int jump_label_apply_nops(struct module *mod) 
	return 0;

}



static inline int jump_label_text_reserved(void *start, void *end)

{

	return 0;

}



#endif



#endif

kernel/jump_label.c

+83 −0
Original line number Diff line number Diff line
@@ -177,6 +177,89 @@ void jump_label_update(unsigned long key, enum jump_label_type type) 
	mutex_unlock(&jump_label_mutex);

}



static int addr_conflict(struct jump_entry *entry, void *start, void *end)

{

	if (entry->code <= (unsigned long)end &&

		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)

		return 1;



	return 0;

}



#ifdef CONFIG_MODULES



static int module_conflict(void *start, void *end)

{

	struct hlist_head *head;

	struct hlist_node *node, *node_next, *module_node, *module_node_next;

	struct jump_label_entry *e;

	struct jump_label_module_entry *e_module;

	struct jump_entry *iter;

	int i, count;

	int conflict = 0;



	for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {

		head = &jump_label_table[i];

		hlist_for_each_entry_safe(e, node, node_next, head, hlist) {

			hlist_for_each_entry_safe(e_module, module_node,

							module_node_next,

							&(e->modules), hlist) {

				count = e_module->nr_entries;

				iter = e_module->table;

				while (count--) {

					if (addr_conflict(iter, start, end)) {

						conflict = 1;

						goto out;

					}

					iter++;

				}

			}

		}

	}

out:

	return conflict;

}



#endif



/***

 * jump_label_text_reserved - check if addr range is reserved

 * @start: start text addr

 * @end: end text addr

 *

 * checks if the text addr located between @start and @end

 * overlaps with any of the jump label patch addresses. Code

 * that wants to modify kernel text should first verify that

 * it does not overlap with any of the jump label addresses.

 *

 * returns 1 if there is an overlap, 0 otherwise

 */

int jump_label_text_reserved(void *start, void *end)

{

	struct jump_entry *iter;

	struct jump_entry *iter_start = __start___jump_table;

	struct jump_entry *iter_stop = __start___jump_table;

	int conflict = 0;



	mutex_lock(&jump_label_mutex);

	iter = iter_start;

	while (iter < iter_stop) {

		if (addr_conflict(iter, start, end)) {

			conflict = 1;

			goto out;

		}

		iter++;

	}



	/* now check modules */

#ifdef CONFIG_MODULES

	conflict = module_conflict(start, end);

#endif

out:

	mutex_unlock(&jump_label_mutex);

	return conflict;

}



static __init int init_jump_label(void)

{

	int ret;

kernel/kprobes.c

+2 −1
Original line number Diff line number Diff line
@@ -1147,7 +1147,8 @@ int __kprobes register_kprobe(struct kprobe *p) 
	preempt_disable();

	if (!kernel_text_address((unsigned long) p->addr) ||

	    in_kprobes_functions((unsigned long) p->addr) ||

	    ftrace_text_reserved(p->addr, p->addr)) {

	    ftrace_text_reserved(p->addr, p->addr) ||

	    jump_label_text_reserved(p->addr, p->addr)) {

		preempt_enable();

		return -EINVAL;

	}