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Re: [PATCH 5/7] kprobes: Remove called_from argument
- From: Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: Andrew Morton <akpm at linux-foundation dot org>, Jim Keniston <jkenisto at us dot ibm dot com>, David Miller <davem at davemloft dot net>, Rusty Russell <rusty at rustcorp dot com dot au>, LKML <linux-kernel at vger dot kernel dot org>, systemtap-ml <systemtap at sources dot redhat dot com>
- Date: Wed, 12 Nov 2008 12:22:38 +0530
- Subject: Re: [PATCH 5/7] kprobes: Remove called_from argument
- References: <4919F1A9.5070601@redhat.com>
- Reply-to: ananth at in dot ibm dot com
On Tue, Nov 11, 2008 at 03:57:13PM -0500, Masami Hiramatsu wrote:
> Remove called_from argument from kprobes which had been used for preventing
> self-refering of kernel module. However, since we don't keep module's refcount
> after registering kprobe any more, there is no reason to check that.
>
> This patch also simplifies registering/unregistering functions because we don't
> need to use __builtin_return_address(0) which was passed to called_from.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> ---
> kernel/kprobes.c | 70 +++++++++++--------------------------------------------
> 1 file changed, 14 insertions(+), 56 deletions(-)
>
> Index: 2.6.28-rc4/kernel/kprobes.c
> ===================================================================
> --- 2.6.28-rc4.orig/kernel/kprobes.c
> +++ 2.6.28-rc4/kernel/kprobes.c
> @@ -641,8 +641,7 @@ static kprobe_opcode_t __kprobes *kprobe
> return (kprobe_opcode_t *)(((char *)addr) + p->offset);
> }
>
> -static int __kprobes __register_kprobe(struct kprobe *p,
> - unsigned long called_from)
> +int __kprobes register_kprobe(struct kprobe *p)
> {
> int ret = 0;
> struct kprobe *old_p;
> @@ -673,13 +672,10 @@ static int __kprobes __register_kprobe(s
> * We must hold a refcount of the probed module while updating
> * its code to prohibit unexpected unloading.
> */
> - if (calling_mod != probed_mod) {
> - if (unlikely(!try_module_get(probed_mod))) {
> - preempt_enable();
> - return -EINVAL;
> - }
> - } else
> - probed_mod = NULL;
> + if (unlikely(!try_module_get(probed_mod))) {
> + preempt_enable();
> + return -EINVAL;
> + }
You also need the following to get this to compile, don't you?
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Index: linux-2.6.28-rc4/kernel/kprobes.c
===================================================================
--- linux-2.6.28-rc4.orig/kernel/kprobes.c 2008-11-12 11:13:30.000000000 +0530
+++ linux-2.6.28-rc4/kernel/kprobes.c 2008-11-12 12:18:44.000000000 +0530
@@ -666,8 +666,6 @@
*/
probed_mod = __module_text_address((unsigned long) p->addr);
if (probed_mod) {
- struct module *calling_mod;
- calling_mod = __module_text_address(called_from);
/*
* We must hold a refcount of the probed module while updating
* its code to prohibit unexpected unloading.