From 4460fdad85becd569f11501ad5b91814814335ff Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Fri, 6 Mar 2009 10:36:38 -0500 Subject: 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 Acked-by: Ananth N Mavinakayanahalli Acked-by: Masami Hiramatsu LKML-Reference: <49B14306.2080202@redhat.com> Signed-off-by: Ingo Molnar --- kernel/kprobes.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'kernel/kprobes.c') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 7ba8cd9845c..479d4d5672f 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -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(); -- cgit v1.2.3 From f02b8624fedca39886b0eef770dca70c2f0749b3 Mon Sep 17 00:00:00 2001 From: Ananth N Mavinakayanahalli Date: Wed, 18 Mar 2009 17:06:21 +0530 Subject: kprobes: Fix locking imbalance in kretprobes Fix locking imbalance in kretprobes: ===================================== [ BUG: bad unlock balance detected! ] ------------------------------------- kthreadd/2 is trying to release lock (&rp->lock) at: [] pre_handler_kretprobe+0xea/0xf4 but there are no more locks to release! other info that might help us debug this: 1 lock held by kthreadd/2: #0: (rcu_read_lock){..--}, at: [] __atomic_notifier_call_chain+0x0/0x5a stack backtrace: Pid: 2, comm: kthreadd Not tainted 2.6.29-rc8 #1 Call Trace: [] ? printk+0xf/0x17 [] ? pre_handler_kretprobe+0xea/0xf4 [] print_unlock_inbalance_bug+0xc3/0xce [] ? clocksource_read+0x7/0xa [] ? getnstimeofday+0x5f/0xf6 [] ? register_lock_class+0x17/0x293 [] ? mark_lock+0x1e/0x30b [] ? tick_dev_program_event+0x4a/0xbc [] ? __slab_alloc+0xa5/0x415 [] ? pre_handler_kretprobe+0x28/0xf4 [] ? pre_handler_kretprobe+0xea/0xf4 [] lock_release_non_nested+0xa4/0x1a5 [] ? pre_handler_kretprobe+0xea/0xf4 [] lock_release+0x141/0x166 [] _spin_unlock_irqrestore+0x19/0x50 [] pre_handler_kretprobe+0xea/0xf4 [] kprobe_exceptions_notify+0x1c9/0x43e [] notifier_call_chain+0x26/0x48 [] __atomic_notifier_call_chain+0x37/0x5a [] ? __atomic_notifier_call_chain+0x0/0x5a [] atomic_notifier_call_chain+0xc/0xe [] notify_die+0x2d/0x2f [] do_int3+0x1f/0x71 [] int3+0x2c/0x34 [] ? do_fork+0x1/0x288 [] ? kernel_thread+0x71/0x79 [] ? kthread+0x0/0x60 [] ? kthread+0x0/0x60 [] ? kernel_thread_helper+0x0/0x10 [] kthreadd+0xac/0x148 [] ? kthreadd+0x0/0x148 [] kernel_thread_helper+0x7/0x10 Signed-off-by: Ananth N Mavinakayanahalli Tested-by: Bharata B Rao Cc: Masami Hiramatsu Cc: Jim Keniston Cc: Linus Torvalds Cc: Andrew Morton Cc: [2.6.29.x, 2.6.28.x, 2.6.27.x] LKML-Reference: <20090318113621.GB4129@in.ibm.com> Signed-off-by: Ingo Molnar --- kernel/kprobes.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'kernel/kprobes.c') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 479d4d5672f..5016bfb682b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -919,10 +919,8 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, ri->rp = rp; ri->task = current; - if (rp->entry_handler && rp->entry_handler(ri, regs)) { - spin_unlock_irqrestore(&rp->lock, flags); + if (rp->entry_handler && rp->entry_handler(ri, regs)) return 0; - } arch_prepare_kretprobe(ri, regs); -- cgit v1.2.3