* [PATCH] Kprobes: Print details of kretprobe on assertion failure
@ 2007-04-02 9:26 Ananth N Mavinakayanahalli
2007-04-02 21:17 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: Ananth N Mavinakayanahalli @ 2007-04-02 9:26 UTC (permalink / raw)
To: lkml
Cc: akpm, Prasanna S Panchamukhi, Jim Keniston, Anil S Keshavamurthy,
Maneesh Soni
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;
reset_current_kprobe();
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] Kprobes: Print details of kretprobe on assertion failure 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 0 siblings, 1 reply; 3+ messages in thread From: Andrew Morton @ 2007-04-02 21:17 UTC (permalink / raw) To: ananth Cc: lkml, Prasanna S Panchamukhi, Jim Keniston, Anil S Keshavamurthy, Maneesh Soni 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? ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Kprobes: Print details of kretprobe on assertion failure 2007-04-02 21:17 ` Andrew Morton @ 2007-04-03 5:49 ` Ananth N Mavinakayanahalli 0 siblings, 0 replies; 3+ messages in thread From: Ananth N Mavinakayanahalli @ 2007-04-03 5:49 UTC (permalink / raw) To: Andrew Morton Cc: lkml, Prasanna S Panchamukhi, Jim Keniston, Anil S Keshavamurthy, Maneesh Soni 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); ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2007-04-03 5:46 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 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
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