[PATCH -tip 2/4]Text Edit Lock - kprobes architecture independentsupport (v3)

[Masami Hiramatsu]

From: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>

Use the mutual exclusion provided by the text edit lock in the kprobes code. It
allows coherent manipulation of the kernel code by other subsystems.

Changelog:

Move the kernel_text_lock/unlock out of the for loops.
Use text_mutex directly instead of a function.
Remove whitespace modifications.

(note : kprobes_mutex is always taken outside of text_mutex)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
Acked-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
CC: ananth@xxxxxxxxxx
CC: anil.s.keshavamurthy@xxxxxxxxx
CC: davem@xxxxxxxxxxxxx
CC: Roel Kluin <12o3l@xxxxxxxxxx>
---
 kernel/kprobes.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Index: 2.6.29-rc7/kernel/kprobes.c
===================================================================
--- 2.6.29-rc7.orig/kernel/kprobes.c
+++ 2.6.29-rc7/kernel/kprobes.c
@@ -43,6 +43,7 @@
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <linux/kdebug.h>
+#include <linux/memory.h>

 #include <asm-generic/sections.h>
 #include <asm/cacheflush.h>
@@ -699,9 +700,10 @@ int __kprobes register_kprobe(struct kpr
 		goto out;
 	}

+	mutex_lock(&text_mutex);
 	ret = arch_prepare_kprobe(p);
 	if (ret)
-		goto out;
+		goto out_unlock_text;

 	INIT_HLIST_NODE(&p->hlist);
 	hlist_add_head_rcu(&p->hlist,
@@ -710,6 +712,8 @@ int __kprobes register_kprobe(struct kpr
 	if (kprobe_enabled)
 		arch_arm_kprobe(p);

+out_unlock_text:
+	mutex_unlock(&text_mutex);
 out:
 	mutex_unlock(&kprobe_mutex);

@@ -746,8 +750,11 @@ valid_p:
 		 * enabled and not gone - otherwise, the breakpoint would
 		 * already have been removed. We save on flushing icache.
 		 */
-		if (kprobe_enabled && !kprobe_gone(old_p))
+		if (kprobe_enabled && !kprobe_gone(old_p)) {
+			mutex_lock(&text_mutex);
 			arch_disarm_kprobe(p);
+			mutex_unlock(&text_mutex);
+		}
 		hlist_del_rcu(&old_p->hlist);
 	} else {
 		if (p->break_handler && !kprobe_gone(p))
@@ -1280,12 +1287,14 @@ static void __kprobes enable_all_kprobes
 	if (kprobe_enabled)
 		goto already_enabled;

+	mutex_lock(&text_mutex);
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
 		hlist_for_each_entry_rcu(p, node, head, hlist)
 			if (!kprobe_gone(p))
 				arch_arm_kprobe(p);
 	}
+	mutex_unlock(&text_mutex);

 	kprobe_enabled = true;
 	printk(KERN_INFO "Kprobes globally enabled\n");
@@ -1310,6 +1319,7 @@ static void __kprobes disable_all_kprobe

 	kprobe_enabled = false;
 	printk(KERN_INFO "Kprobes globally disabled\n");
+	mutex_lock(&text_mutex);
 	for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
 		head = &kprobe_table[i];
 		hlist_for_each_entry_rcu(p, node, head, hlist) {
@@ -1318,6 +1328,7 @@ static void __kprobes disable_all_kprobe
 		}
 	}

+	mutex_unlock(&text_mutex);
 	mutex_unlock(&kprobe_mutex);
 	/* Allow all currently running kprobes to complete */
 	synchronize_sched();
-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@xxxxxxxxxx


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