diff options
author | Keshavamurthy Anil S <anil.s.keshavamurthy@intel.com> | 2006-01-11 12:17:41 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-11 18:42:12 -0800 |
commit | df019b1d8b893d0f0ee5a9b0f71486f0892561ae (patch) | |
tree | 9d2ced14291502af1ca687b5d854d8394cbfb84d /kernel/kprobes.c | |
parent | ef43bc4fc32bec8fda7bae8948b774616dc9e496 (diff) | |
download | linux-df019b1d8b893d0f0ee5a9b0f71486f0892561ae.tar.bz2 |
[PATCH] kprobes: fix unloading of self probed module
When a kprobes modules is written in such a way that probes are inserted on
itself, then unload of that moudle was not possible due to reference
couning on the same module.
The below patch makes a check and incrementes the module refcount only if
it is not a self probed module.
We need to allow modules to probe themself for kprobes performance
measurements
This patch has been tested on several x86_64, ppc64 and IA64 architectures.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r-- | kernel/kprobes.c | 42 |
1 files changed, 32 insertions, 10 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 34a885bb82e0..3ea6325228da 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -449,19 +449,32 @@ static int __kprobes in_kprobes_functions(unsigned long addr) return 0; } -int __kprobes register_kprobe(struct kprobe *p) +static int __kprobes __register_kprobe(struct kprobe *p, + unsigned long called_from) { int ret = 0; struct kprobe *old_p; - struct module *mod; + struct module *probed_mod; if ((!kernel_text_address((unsigned long) p->addr)) || in_kprobes_functions((unsigned long) p->addr)) return -EINVAL; - if ((mod = module_text_address((unsigned long) p->addr)) && - (unlikely(!try_module_get(mod)))) - return -EINVAL; + p->mod_refcounted = 0; + /* Check are we probing a module */ + if ((probed_mod = module_text_address((unsigned long) p->addr))) { + struct module *calling_mod = module_text_address(called_from); + /* We must allow modules to probe themself and + * in this case avoid incrementing the module refcount, + * so as to allow unloading of self probing modules. + */ + if (calling_mod && (calling_mod != probed_mod)) { + if (unlikely(!try_module_get(probed_mod))) + return -EINVAL; + p->mod_refcounted = 1; + } else + probed_mod = NULL; + } p->nmissed = 0; down(&kprobe_mutex); @@ -483,11 +496,17 @@ int __kprobes register_kprobe(struct kprobe *p) out: up(&kprobe_mutex); - if (ret && mod) - module_put(mod); + if (ret && probed_mod) + module_put(probed_mod); return ret; } +int __kprobes register_kprobe(struct kprobe *p) +{ + return __register_kprobe(p, + (unsigned long)__builtin_return_address(0)); +} + void __kprobes unregister_kprobe(struct kprobe *p) { struct module *mod; @@ -524,7 +543,8 @@ valid_p: up(&kprobe_mutex); synchronize_sched(); - if ((mod = module_text_address((unsigned long)p->addr))) + if (p->mod_refcounted && + (mod = module_text_address((unsigned long)p->addr))) module_put(mod); if (cleanup_p) { @@ -547,7 +567,8 @@ int __kprobes register_jprobe(struct jprobe *jp) jp->kp.pre_handler = setjmp_pre_handler; jp->kp.break_handler = longjmp_break_handler; - return register_kprobe(&jp->kp); + return __register_kprobe(&jp->kp, + (unsigned long)__builtin_return_address(0)); } void __kprobes unregister_jprobe(struct jprobe *jp) @@ -587,7 +608,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp) rp->nmissed = 0; /* Establish function entry probe point */ - if ((ret = register_kprobe(&rp->kp)) != 0) + if ((ret = __register_kprobe(&rp->kp, + (unsigned long)__builtin_return_address(0))) != 0) free_rp_inst(rp); return ret; } |