Re: [PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition

2019-07-11 Thread Masami Hiramatsu 
Hi Anshuman,

On Mon, 8 Jul 2019 09:03:13 +0530
Anshuman Khandual  wrote:

> >> Architectures like parisc enable CONFIG_KROBES without having a definition
> >> for kprobe_fault_handler() which results in a build failure.
> > 
> > Hmm, as far as I can see, kprobe_fault_handler() is closed inside each arch
> > specific code. The reason why include/linux/kprobes.h defines
> > dummy inline function is only for !CONFIG_KPROBES case.
> 
> IIRC Andrew mentioned [1] that we should remove this stub from the generic 
> kprobes
> header because this is very much architecture specific. As we see in this 
> proposed
> patch, except x86 there is no other current user which actually calls this 
> from
> some where when CONFIG_KPROBES is not enabled.
> 
> [1] https://www.spinics.net/lists/linux-mm/msg182649.html

Ah, OK. I saw another branch. Also, this is a bugfix patch against
commit 4dd635bce90e ("mm, kprobes: generalize and rename notify_page_fault() as
 kprobe_page_fault()"), please add Fixes: tag on it.

In this case, we should just add a prototype of kprobe_fault_handler() in
include/linux/kprobes.h, and maybe add a stub of kprobe_fault_handler()
as a weak function, something like below.

int __weak kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
/*
 * Each architecture which uses kprobe_page_fault() must define
 * a fault handler to handle page fault in kprobe correctly.
 */
WARN_ON_ONCE(1);
return 0;
}

> >> Arch needs to
> >> provide kprobe_fault_handler() as it is platform specific and cannot have
> >> a generic working alternative. But in the event when platform lacks such a
> >> definition there needs to be a fallback.
> > 
> > Wait, indeed that each arch need to implement it, but that is for calling
> > kprobe->fault_handler() as user expected.
> > Hmm, why not fixing those architecture implementations?
> 
> After the recent change which introduced a generic kprobe_page_fault() every
> architecture enabling CONFIG_KPROBES must have a kprobe_fault_handler() which
> was not the case earlier.

As far as I can see, gcc complains it because there is no prototype of
kprobe_fault_handler(). Actually no need to define empty kprobe_fault_handler()
on each arch. If we have a prototype, but no actual function, gcc stops the
error unless the arch depending code uses it. So actually, we don't need above
__weak function.

> Architectures like parisc which does enable KPROBES but
> never used (kprobe_page_fault or kprobe->fault_handler) 
> kprobe_fault_handler() now
> needs one as well.

(Hmm, it sounds like the kprobes porting is incomplete on parisc...)

> I am not sure and will probably require inputs from arch parsic
> folks whether it at all needs one. We dont have a stub or fallback definition 
> for
> kprobe_fault_handler() when CONFIG_KPROBES is enabled just to prevent a build
> failure in such cases.

Yeah, that is a bug, and fixed by adding a prototype, not introducing new macro.

> 
> In such a situation it might be better defining a stub symbol fallback than 
> to try
> to implement one definition which the architecture previously never needed or 
> used.
> AFAICS there is no generic MM callers for kprobe_fault_handler() as well 
> which would
> have made it mandatory for parisc to define a real one.
> 
> > 
> >> This adds a stub kprobe_fault_handler() definition which not only prevents
> >> a build failure but also makes sure that kprobe_page_fault() if called will
> >> always return negative in absence of a sane platform specific alternative.
> > 
> > I don't like introducing this complicated macro only for avoiding (not 
> > fixing)
> > build error. To fix that, kprobes on parisc should implement 
> > kprobe_fault_handler
> > correctly (and call kprobe->fault_handler).
> 
> As I mentioned before parsic might not need a real one. But you are right this
> complicated (if perceived as such) change can be just avoided at least for the
> build failure problem by just defining a stub definition 
> kprobe_fault_handler()
> for arch parsic when CONFIG_KPROBES is enabled. But this patch does some more
> and solves the kprobe_fault_handler() symbol dependency in a more generic way 
> and
> forces kprobe_page_fault() to fail in absence a real arch 
> kprobe_fault_handler().
> Is not it worth solving in this way ?
> 
> > 
> > BTW, even if you need such generic stub, please use a weak function instead
> > of macros for every arch headers.
> 
> There is a bit problem with that. The existing definitions are with different
> signatures and an weak function will need them to be exact same for override
> requiring more code changes. Hence choose to go with a macro in each header.
> 
> arch/arc/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
> unsigned long cause);
> arch/arm/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
> unsigned int fsr);
> arch/arm64/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs 
> *regs,

Re: [PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition

2019-07-11 Thread Anshuman Khandual 



On 07/05/2019 11:00 AM, Anshuman Khandual wrote:
> Architectures like parisc enable CONFIG_KROBES without having a definition
> for kprobe_fault_handler() which results in a build failure. Arch needs to
> provide kprobe_fault_handler() as it is platform specific and cannot have
> a generic working alternative. But in the event when platform lacks such a
> definition there needs to be a fallback.
> 
> This adds a stub kprobe_fault_handler() definition which not only prevents
> a build failure but also makes sure that kprobe_page_fault() if called will
> always return negative in absence of a sane platform specific alternative.
> 
> While here wrap kprobe_page_fault() in CONFIG_KPROBES. This enables stud
> definitions for generic kporbe_fault_handler() and kprobes_built_in() can
> just be dropped. Only on x86 it needs to be added back locally as it gets
> used in a !CONFIG_KPROBES function do_general_protection().
> 
> Cc: Vineet Gupta 
> Cc: Russell King 
> Cc: Catalin Marinas 
> Cc: Will Deacon 
> Cc: Tony Luck 
> Cc: Fenghua Yu 
> Cc: Ralf Baechle 
> Cc: Paul Burton 
> Cc: James Hogan 
> Cc: Benjamin Herrenschmidt 
> Cc: Paul Mackerras 
> Cc: Michael Ellerman 
> Cc: Heiko Carstens 
> Cc: Vasily Gorbik 
> Cc: Christian Borntraeger 
> Cc: Yoshinori Sato 
> Cc: Rich Felker 
> Cc: "David S. Miller" 
> Cc: Thomas Gleixner 
> Cc: Ingo Molnar 
> Cc: Borislav Petkov 
> Cc: "H. Peter Anvin" 
> Cc: "Naveen N. Rao" 
> Cc: Anil S Keshavamurthy 
> Cc: Masami Hiramatsu 
> Cc: Allison Randal 
> Cc: Greg Kroah-Hartman 
> Cc: Enrico Weigelt 
> Cc: Richard Fontana 
> Cc: Kate Stewart 
> Cc: Mark Rutland 
> Cc: Andrew Morton 
> Cc: Guenter Roeck 
> Cc: x...@kernel.org
> Cc: linux-snps-...@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-arm-ker...@lists.infradead.org
> Cc: linux-i...@vger.kernel.org
> Cc: linux-m...@vger.kernel.org
> Cc: linuxppc-...@lists.ozlabs.org
> Cc: linux-s...@vger.kernel.org
> Cc: linux...@vger.kernel.org
> Cc: sparcli...@vger.kernel.org
> 
> Signed-off-by: Anshuman Khandual 
> ---

Any updates or suggestions on this patch ? Currently there is a build failure on
parisc architecture due to the lack of a kprobe_fault_handler() definition when
CONFIG_KPROBES is enabled and this build failure needs to be fixed.

This patch solves the build problem. But otherwise I am also happy to just 
define
a stub definition for kprobe_fault_handler() on parisc arch when CONFIG_KPROBES
is enabled, which will avoid the build failure. Please suggest.

Re: [PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition

2019-07-07 Thread Anshuman Khandual 



On 07/05/2019 04:00 PM, Masami Hiramatsu wrote:
> Hi Anshuman,


Hello Masami,

> 
> On Fri,  5 Jul 2019 11:00:29 +0530
> Anshuman Khandual  wrote:
> 
>> Architectures like parisc enable CONFIG_KROBES without having a definition
>> for kprobe_fault_handler() which results in a build failure.
> 
> Hmm, as far as I can see, kprobe_fault_handler() is closed inside each arch
> specific code. The reason why include/linux/kprobes.h defines
> dummy inline function is only for !CONFIG_KPROBES case.

IIRC Andrew mentioned [1] that we should remove this stub from the generic 
kprobes
header because this is very much architecture specific. As we see in this 
proposed
patch, except x86 there is no other current user which actually calls this from
some where when CONFIG_KPROBES is not enabled.

[1] https://www.spinics.net/lists/linux-mm/msg182649.html
> 
>> Arch needs to
>> provide kprobe_fault_handler() as it is platform specific and cannot have
>> a generic working alternative. But in the event when platform lacks such a
>> definition there needs to be a fallback.
> 
> Wait, indeed that each arch need to implement it, but that is for calling
> kprobe->fault_handler() as user expected.
> Hmm, why not fixing those architecture implementations?

After the recent change which introduced a generic kprobe_page_fault() every
architecture enabling CONFIG_KPROBES must have a kprobe_fault_handler() which
was not the case earlier. Architectures like parisc which does enable KPROBES 
but
never used (kprobe_page_fault or kprobe->fault_handler) kprobe_fault_handler() 
now
needs one as well. I am not sure and will probably require inputs from arch 
parsic
folks whether it at all needs one. We dont have a stub or fallback definition 
for
kprobe_fault_handler() when CONFIG_KPROBES is enabled just to prevent a build
failure in such cases.

In such a situation it might be better defining a stub symbol fallback than to 
try
to implement one definition which the architecture previously never needed or 
used.
AFAICS there is no generic MM callers for kprobe_fault_handler() as well which 
would
have made it mandatory for parisc to define a real one.

> 
>> This adds a stub kprobe_fault_handler() definition which not only prevents
>> a build failure but also makes sure that kprobe_page_fault() if called will
>> always return negative in absence of a sane platform specific alternative.
> 
> I don't like introducing this complicated macro only for avoiding (not fixing)
> build error. To fix that, kprobes on parisc should implement 
> kprobe_fault_handler
> correctly (and call kprobe->fault_handler).

As I mentioned before parsic might not need a real one. But you are right this
complicated (if perceived as such) change can be just avoided at least for the
build failure problem by just defining a stub definition kprobe_fault_handler()
for arch parsic when CONFIG_KPROBES is enabled. But this patch does some more
and solves the kprobe_fault_handler() symbol dependency in a more generic way 
and
forces kprobe_page_fault() to fail in absence a real arch 
kprobe_fault_handler().
Is not it worth solving in this way ?

> 
> BTW, even if you need such generic stub, please use a weak function instead
> of macros for every arch headers.

There is a bit problem with that. The existing definitions are with different
signatures and an weak function will need them to be exact same for override
requiring more code changes. Hence choose to go with a macro in each header.

arch/arc/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
unsigned long cause);
arch/arm/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
unsigned int fsr);
arch/arm64/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
unsigned int fsr);
arch/ia64/include/asm/kprobes.h:extern int kprobe_fault_handler(struct pt_regs 
*regs, int trapnr);
arch/powerpc/include/asm/kprobes.h:extern int kprobe_fault_handler(struct 
pt_regs *regs, int trapnr);
arch/s390/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
int trapnr);
arch/sh/include/asm/kprobes.h:extern int kprobe_fault_handler(struct pt_regs 
*regs, int trapnr);
arch/sparc/include/asm/kprobes.h:int kprobe_fault_handler(struct pt_regs *regs, 
int trapnr);
arch/x86/include/asm/kprobes.h:extern int kprobe_fault_handler(struct pt_regs 
*regs, int trapnr);

> 
>> While here wrap kprobe_page_fault() in CONFIG_KPROBES. This enables stud
>> definitions for generic kporbe_fault_handler() and kprobes_built_in() can
>> just be dropped. Only on x86 it needs to be added back locally as it gets
>> used in a !CONFIG_KPROBES function do_general_protection().
> 
> If you want to remove kprobes_built_in(), you should replace it with
> IS_ENABLED(CONFIG_KPROBES), instead of this...

Apart from kprobes_built_in() the intent was to remove !CONFIG_KPROBES
stub for kprobe_fault_handler() as well which required making generic
kprobe_page_fault() to be empty in such case.

Re: [PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition

2019-07-05 Thread Masami Hiramatsu 
Hi Anshuman,

On Fri,  5 Jul 2019 11:00:29 +0530
Anshuman Khandual  wrote:

> Architectures like parisc enable CONFIG_KROBES without having a definition
> for kprobe_fault_handler() which results in a build failure.

Hmm, as far as I can see, kprobe_fault_handler() is closed inside each arch
specific code. The reason why include/linux/kprobes.h defines
dummy inline function is only for !CONFIG_KPROBES case.

> Arch needs to
> provide kprobe_fault_handler() as it is platform specific and cannot have
> a generic working alternative. But in the event when platform lacks such a
> definition there needs to be a fallback.

Wait, indeed that each arch need to implement it, but that is for calling
kprobe->fault_handler() as user expected.
Hmm, why not fixing those architecture implementations?

> This adds a stub kprobe_fault_handler() definition which not only prevents
> a build failure but also makes sure that kprobe_page_fault() if called will
> always return negative in absence of a sane platform specific alternative.

I don't like introducing this complicated macro only for avoiding (not fixing)
build error. To fix that, kprobes on parisc should implement 
kprobe_fault_handler
correctly (and call kprobe->fault_handler).

BTW, even if you need such generic stub, please use a weak function instead
of macros for every arch headers.

> While here wrap kprobe_page_fault() in CONFIG_KPROBES. This enables stud
> definitions for generic kporbe_fault_handler() and kprobes_built_in() can
> just be dropped. Only on x86 it needs to be added back locally as it gets
> used in a !CONFIG_KPROBES function do_general_protection().

If you want to remove kprobes_built_in(), you should replace it with
IS_ENABLED(CONFIG_KPROBES), instead of this...

Thank you,

> 
> Cc: Vineet Gupta 
> Cc: Russell King 
> Cc: Catalin Marinas 
> Cc: Will Deacon 
> Cc: Tony Luck 
> Cc: Fenghua Yu 
> Cc: Ralf Baechle 
> Cc: Paul Burton 
> Cc: James Hogan 
> Cc: Benjamin Herrenschmidt 
> Cc: Paul Mackerras 
> Cc: Michael Ellerman 
> Cc: Heiko Carstens 
> Cc: Vasily Gorbik 
> Cc: Christian Borntraeger 
> Cc: Yoshinori Sato 
> Cc: Rich Felker 
> Cc: "David S. Miller" 
> Cc: Thomas Gleixner 
> Cc: Ingo Molnar 
> Cc: Borislav Petkov 
> Cc: "H. Peter Anvin" 
> Cc: "Naveen N. Rao" 
> Cc: Anil S Keshavamurthy 
> Cc: Masami Hiramatsu 
> Cc: Allison Randal 
> Cc: Greg Kroah-Hartman 
> Cc: Enrico Weigelt 
> Cc: Richard Fontana 
> Cc: Kate Stewart 
> Cc: Mark Rutland 
> Cc: Andrew Morton 
> Cc: Guenter Roeck 
> Cc: x...@kernel.org
> Cc: linux-snps-...@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-arm-ker...@lists.infradead.org
> Cc: linux-i...@vger.kernel.org
> Cc: linux-m...@vger.kernel.org
> Cc: linuxppc-...@lists.ozlabs.org
> Cc: linux-s...@vger.kernel.org
> Cc: linux...@vger.kernel.org
> Cc: sparcli...@vger.kernel.org
> 
> Signed-off-by: Anshuman Khandual 
> ---
>  arch/arc/include/asm/kprobes.h |  1 +
>  arch/arm/include/asm/kprobes.h |  1 +
>  arch/arm64/include/asm/kprobes.h   |  1 +
>  arch/ia64/include/asm/kprobes.h|  1 +
>  arch/mips/include/asm/kprobes.h|  1 +
>  arch/powerpc/include/asm/kprobes.h |  1 +
>  arch/s390/include/asm/kprobes.h|  1 +
>  arch/sh/include/asm/kprobes.h  |  1 +
>  arch/sparc/include/asm/kprobes.h   |  1 +
>  arch/x86/include/asm/kprobes.h |  6 ++
>  include/linux/kprobes.h| 32 ++
>  11 files changed, 34 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arc/include/asm/kprobes.h b/arch/arc/include/asm/kprobes.h
> index 2134721dce44..ee8efe256675 100644
> --- a/arch/arc/include/asm/kprobes.h
> +++ b/arch/arc/include/asm/kprobes.h
> @@ -45,6 +45,7 @@ struct kprobe_ctlblk {
>   struct prev_kprobe prev_kprobe;
>  };
>  
> +#define kprobe_fault_handler kprobe_fault_handler
>  int kprobe_fault_handler(struct pt_regs *regs, unsigned long cause);
>  void kretprobe_trampoline(void);
>  void trap_is_kprobe(unsigned long address, struct pt_regs *regs);
> diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
> index 213607a1f45c..660f877b989f 100644
> --- a/arch/arm/include/asm/kprobes.h
> +++ b/arch/arm/include/asm/kprobes.h
> @@ -38,6 +38,7 @@ struct kprobe_ctlblk {
>   struct prev_kprobe prev_kprobe;
>  };
>  
> +#define kprobe_fault_handler kprobe_fault_handler
>  void arch_remove_kprobe(struct kprobe *);
>  int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
>  int kprobe_exceptions_notify(struct notifier_block *self,
> diff --git a/arch/arm64/include/asm/kprobes.h 
> b/arch/arm64/include/asm/kprobes.h
> index 97e511d645a2..667773f75616 100644
> --- a/arch/arm64/include/asm/kprobes.h
> +++ b/arch/arm64/include/asm/kprobes.h
> @@ -42,6 +42,7 @@ struct kprobe_ctlblk {
>   struct kprobe_step_ctx ss_ctx;
>  };
>  
> +#define kprobe_fault_handler kprobe_fault_handler
>  void arch_remove_kprobe(struct kprobe *);
>  int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
>  int

[PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition

2019-07-04 Thread Anshuman Khandual 
Architectures like parisc enable CONFIG_KROBES without having a definition
for kprobe_fault_handler() which results in a build failure. Arch needs to
provide kprobe_fault_handler() as it is platform specific and cannot have
a generic working alternative. But in the event when platform lacks such a
definition there needs to be a fallback.

This adds a stub kprobe_fault_handler() definition which not only prevents
a build failure but also makes sure that kprobe_page_fault() if called will
always return negative in absence of a sane platform specific alternative.

While here wrap kprobe_page_fault() in CONFIG_KPROBES. This enables stud
definitions for generic kporbe_fault_handler() and kprobes_built_in() can
just be dropped. Only on x86 it needs to be added back locally as it gets
used in a !CONFIG_KPROBES function do_general_protection().

Cc: Vineet Gupta 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Ralf Baechle 
Cc: Paul Burton 
Cc: James Hogan 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: Yoshinori Sato 
Cc: Rich Felker 
Cc: "David S. Miller" 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Cc: "Naveen N. Rao" 
Cc: Anil S Keshavamurthy 
Cc: Masami Hiramatsu 
Cc: Allison Randal 
Cc: Greg Kroah-Hartman 
Cc: Enrico Weigelt 
Cc: Richard Fontana 
Cc: Kate Stewart 
Cc: Mark Rutland 
Cc: Andrew Morton 
Cc: Guenter Roeck 
Cc: x...@kernel.org
Cc: linux-snps-...@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-ker...@lists.infradead.org
Cc: linux-i...@vger.kernel.org
Cc: linux-m...@vger.kernel.org
Cc: linuxppc-...@lists.ozlabs.org
Cc: linux-s...@vger.kernel.org
Cc: linux...@vger.kernel.org
Cc: sparcli...@vger.kernel.org

Signed-off-by: Anshuman Khandual 
---
 arch/arc/include/asm/kprobes.h |  1 +
 arch/arm/include/asm/kprobes.h |  1 +
 arch/arm64/include/asm/kprobes.h   |  1 +
 arch/ia64/include/asm/kprobes.h|  1 +
 arch/mips/include/asm/kprobes.h|  1 +
 arch/powerpc/include/asm/kprobes.h |  1 +
 arch/s390/include/asm/kprobes.h|  1 +
 arch/sh/include/asm/kprobes.h  |  1 +
 arch/sparc/include/asm/kprobes.h   |  1 +
 arch/x86/include/asm/kprobes.h |  6 ++
 include/linux/kprobes.h| 32 ++
 11 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/arch/arc/include/asm/kprobes.h b/arch/arc/include/asm/kprobes.h
index 2134721dce44..ee8efe256675 100644
--- a/arch/arc/include/asm/kprobes.h
+++ b/arch/arc/include/asm/kprobes.h
@@ -45,6 +45,7 @@ struct kprobe_ctlblk {
struct prev_kprobe prev_kprobe;
 };
 
+#define kprobe_fault_handler kprobe_fault_handler
 int kprobe_fault_handler(struct pt_regs *regs, unsigned long cause);
 void kretprobe_trampoline(void);
 void trap_is_kprobe(unsigned long address, struct pt_regs *regs);
diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index 213607a1f45c..660f877b989f 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -38,6 +38,7 @@ struct kprobe_ctlblk {
struct prev_kprobe prev_kprobe;
 };
 
+#define kprobe_fault_handler kprobe_fault_handler
 void arch_remove_kprobe(struct kprobe *);
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
 int kprobe_exceptions_notify(struct notifier_block *self,
diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h
index 97e511d645a2..667773f75616 100644
--- a/arch/arm64/include/asm/kprobes.h
+++ b/arch/arm64/include/asm/kprobes.h
@@ -42,6 +42,7 @@ struct kprobe_ctlblk {
struct kprobe_step_ctx ss_ctx;
 };
 
+#define kprobe_fault_handler kprobe_fault_handler
 void arch_remove_kprobe(struct kprobe *);
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
 int kprobe_exceptions_notify(struct notifier_block *self,
diff --git a/arch/ia64/include/asm/kprobes.h b/arch/ia64/include/asm/kprobes.h
index c5cf5e4fb338..c321e8585089 100644
--- a/arch/ia64/include/asm/kprobes.h
+++ b/arch/ia64/include/asm/kprobes.h
@@ -106,6 +106,7 @@ struct arch_specific_insn {
unsigned short slot;
 };
 
+#define kprobe_fault_handler kprobe_fault_handler
 extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h
index 68b1e5d458cf..d1efe991ea22 100644
--- a/arch/mips/include/asm/kprobes.h
+++ b/arch/mips/include/asm/kprobes.h
@@ -40,6 +40,7 @@ do {  
\
 
 #define kretprobe_blacklist_size 0
 
+#define kprobe_fault_handler kprobe_fault_handler
 void arch_remove_kprobe(struct kprobe *p);
 int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 
diff --git a/arch/powerpc/include/asm/kprobes.h