From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Prasanna S Panchamukhi <prasanna@in.ibm.com>,
Jim Keniston <jkenisto@us.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
Maneesh Soni <maneesh@in.ibm.com>
Subject: Re: [PATCH] Kprobes: Print details of kretprobe on assertion failure
Date: Tue, 3 Apr 2007 11:19:43 +0530 [thread overview]
Message-ID: <20070403054943.GA18459@in.ibm.com> (raw)
In-Reply-To: <20070402141732.166f50bd.akpm@linux-foundation.org>
On Mon, Apr 02, 2007 at 02:17:32PM -0700, Andrew Morton wrote:
> On Mon, 2 Apr 2007 14:56:36 +0530
> Ananth N Mavinakayanahalli <ananth@in.ibm.com> wrote:
>
> > From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> >
> > In certain cases like when the real return address can't be found or
> > when the number of tracked calls to a kretprobed function is less than
> > the number of returns, we may not be able to find the correct return
> > address after processing a kretprobe. Currently we just do a BUG_ON, but
> > no information is provided about the actual failing kretprobe.
> >
> > Print out details of the kretprobe before calling BUG().
> >
> > Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> >
> > ---
> > arch/i386/kernel/kprobes.c | 6 +++++-
> > arch/ia64/kernel/kprobes.c | 7 ++++++-
> > arch/powerpc/kernel/kprobes.c | 7 ++++++-
> > arch/x86_64/kernel/kprobes.c | 7 ++++++-
> > 4 files changed, 23 insertions(+), 4 deletions(-)
> >
> > Index: linux-2.6.21-rc5/arch/i386/kernel/kprobes.c
> > ===================================================================
> > --- linux-2.6.21-rc5.orig/arch/i386/kernel/kprobes.c
> > +++ linux-2.6.21-rc5/arch/i386/kernel/kprobes.c
> > @@ -440,7 +440,11 @@ fastcall void *__kprobes trampoline_hand
> > break;
> > }
> >
> > - BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
> > + if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
> > + printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
> > + ri->rp, ri->rp->kp.addr);
> > + BUG();
> > + }
> >
> > spin_unlock_irqrestore(&kretprobe_lock, flags);
> >
> > Index: linux-2.6.21-rc5/arch/ia64/kernel/kprobes.c
> > ===================================================================
> > --- linux-2.6.21-rc5.orig/arch/ia64/kernel/kprobes.c
> > +++ linux-2.6.21-rc5/arch/ia64/kernel/kprobes.c
> > @@ -444,7 +444,12 @@ int __kprobes trampoline_probe_handler(s
> > break;
> > }
> >
> > - BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
> > + if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
> > + printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
> > + ri->rp, ri->rp->kp.addr);
> > + BUG();
> > + }
> > +
> > regs->cr_iip = orig_ret_address;
> >
> > reset_current_kprobe();
> > Index: linux-2.6.21-rc5/arch/powerpc/kernel/kprobes.c
> > ===================================================================
> > --- linux-2.6.21-rc5.orig/arch/powerpc/kernel/kprobes.c
> > +++ linux-2.6.21-rc5/arch/powerpc/kernel/kprobes.c
> > @@ -293,7 +293,12 @@ int __kprobes trampoline_probe_handler(s
> > break;
> > }
> >
> > - BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
> > + if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
> > + printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
> > + ri->rp, ri->rp->kp.addr);
> > + BUG();
> > + }
> > +
> > regs->nip = orig_ret_address;
> >
> > reset_current_kprobe();
> > Index: linux-2.6.21-rc5/arch/x86_64/kernel/kprobes.c
> > ===================================================================
> > --- linux-2.6.21-rc5.orig/arch/x86_64/kernel/kprobes.c
> > +++ linux-2.6.21-rc5/arch/x86_64/kernel/kprobes.c
> > @@ -438,7 +438,12 @@ int __kprobes trampoline_probe_handler(s
> > break;
> > }
> >
> > - BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
> > + if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
> > + printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
> > + ri->rp, ri->rp->kp.addr);
> > + BUG();
> > + }
> > +
> > regs->rip = orig_ret_address;
> >
>
> A lot of copying-and-pasting there. Would it be better if this assertion
> was performed in a library function in kernel/kprobes.c?
Indeed. Here is the updated patch...
From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
In certain cases like when the real return address can't be found or
when the number of tracked calls to a kretprobed function is less than
the number of returns, we may not be able to find the correct return
address after processing a kretprobe. Currently we just do a BUG_ON, but
no information is provided about the actual failing kretprobe.
Print out details of the kretprobe before calling BUG().
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---
arch/i386/kernel/kprobes.c | 3 +--
arch/ia64/kernel/kprobes.c | 3 ++-
arch/powerpc/kernel/kprobes.c | 2 +-
arch/x86_64/kernel/kprobes.c | 2 +-
include/linux/kprobes.h | 10 ++++++++++
5 files changed, 15 insertions(+), 5 deletions(-)
Index: linux-2.6.21-rc5/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/i386/kernel/kprobes.c
+++ linux-2.6.21-rc5/arch/i386/kernel/kprobes.c
@@ -440,8 +440,7 @@ fastcall void *__kprobes trampoline_hand
break;
}
- BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
-
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
spin_unlock_irqrestore(&kretprobe_lock, flags);
hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
Index: linux-2.6.21-rc5/arch/ia64/kernel/kprobes.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/ia64/kernel/kprobes.c
+++ linux-2.6.21-rc5/arch/ia64/kernel/kprobes.c
@@ -444,7 +444,8 @@ int __kprobes trampoline_probe_handler(s
break;
}
- BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
+
regs->cr_iip = orig_ret_address;
reset_current_kprobe();
Index: linux-2.6.21-rc5/arch/powerpc/kernel/kprobes.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/powerpc/kernel/kprobes.c
+++ linux-2.6.21-rc5/arch/powerpc/kernel/kprobes.c
@@ -293,7 +293,7 @@ int __kprobes trampoline_probe_handler(s
break;
}
- BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
regs->nip = orig_ret_address;
reset_current_kprobe();
Index: linux-2.6.21-rc5/arch/x86_64/kernel/kprobes.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/x86_64/kernel/kprobes.c
+++ linux-2.6.21-rc5/arch/x86_64/kernel/kprobes.c
@@ -438,7 +438,7 @@ int __kprobes trampoline_probe_handler(s
break;
}
- BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
regs->rip = orig_ret_address;
reset_current_kprobe();
Index: linux-2.6.21-rc5/include/linux/kprobes.h
===================================================================
--- linux-2.6.21-rc5.orig/include/linux/kprobes.h
+++ linux-2.6.21-rc5/include/linux/kprobes.h
@@ -158,6 +158,16 @@ struct kretprobe_instance {
struct task_struct *task;
};
+static inline void kretprobe_assert(struct kretprobe_instance *ri,
+ unsigned long orig_ret_address, unsigned long trampoline_address)
+{
+ if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
+ printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
+ ri->rp, ri->rp->kp.addr);
+ BUG();
+ }
+}
+
extern spinlock_t kretprobe_lock;
extern struct mutex kprobe_mutex;
extern int arch_prepare_kprobe(struct kprobe *p);
prev parent reply other threads:[~2007-04-03 5:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-02 9:26 [PATCH] Kprobes: Print details of kretprobe on assertion failure Ananth N Mavinakayanahalli
2007-04-02 21:17 ` Andrew Morton
2007-04-03 5:49 ` Ananth N Mavinakayanahalli [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070403054943.GA18459@in.ibm.com \
--to=ananth@in.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=anil.s.keshavamurthy@intel.com \
--cc=jkenisto@us.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=maneesh@in.ibm.com \
--cc=prasanna@in.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.