[PATCH] Text Edit Lock - kprobes architecture independent support (v3)

Mathieu Desnoyers
2009-03-03T14:33:50Z

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>
CC: ananth@in.ibm.com
CC: anil.s.keshavamurthy@intel.com
CC: davem@davemloft.net
CC: Roel Kluin <12o3l@tiscali.nl>
---
kernel/kprobes.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

Index: linux-2.6-lttng/kernel/kprobes.c
===================================================================
--- linux-2.6-lttng.orig/kernel/kprobes.c 2009-03-02 19:22:51.000000000 -0500
+++ linux-2.6-lttng/kernel/kprobes.c 2009-03-03 09:11:17.000000000 -0500
@@ -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();

--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68