tracing, Text Edit Lock - kprobes architecture independent support

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@polymtl.ca>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <49B14306.2080202@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 2 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 7ba8cd9845cb..479d4d5672f9 100644
--- a/kernel/kprobes.c
+++ b/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 kprobe *p)
                 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 kprobe *p)
         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(void)
         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_kprobes(void)
 
         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_kprobes(void)
                 }
         }
 
+        mutex_unlock(&text_mutex);
         mutex_unlock(&kprobe_mutex);
         /* Allow all currently running kprobes to complete */
         synchronize_sched();