linux-kernel - Re: [PATCH -tip tracing/kprobes 3/6] kprobes/x86: Fix to add __kprobes to in-kernel fault handing functions

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Message-ID: <4A99E755.8000700@redhat.com>
Date:	Sat, 29 Aug 2009 22:43:33 -0400
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, lkml <linux-kernel@...r.kernel.org>,
	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>
Subject: Re: [PATCH -tip tracing/kprobes 3/6] kprobes/x86: Fix to add	__kprobes
 to in-kernel fault handing functions

Frederic Weisbecker wrote:
> On Thu, Aug 27, 2009 at 01:23:11PM -0400, Masami Hiramatsu wrote:
>> Add __kprobes to the functions which handles in-kernel fixable page faults.
>> Since kprobes can cause those in-kernel page faults by accessing kprobe data
>> structures, probing those fault functions will cause fault-int3-loop
>> (do_page_fault has already been marked as __kprobes).
>>
>> Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
>> Cc: Frederic Weisbecker <fweisbec@...il.com>
>> Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
>> Cc: Ingo Molnar <mingo@...e.hu>
>> ---
>>
>>  arch/x86/mm/fault.c |   11 ++++++-----
>>  1 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
>> index bfae139..c322e59 100644
>> --- a/arch/x86/mm/fault.c
>> +++ b/arch/x86/mm/fault.c
>> @@ -38,7 +38,8 @@ enum x86_pf_error_code {
>>   * Returns 0 if mmiotrace is disabled, or if the fault is not
>>   * handled by mmiotrace:
>>   */
>> -static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
>> +static inline int __kprobes
>> +kmmio_fault(struct pt_regs *regs, unsigned long addr)
>>  {
>>  	if (unlikely(is_kmmio_active()))
>>  		if (kmmio_handler(regs, addr) == 1)
> 
> 
> I guess the problem also resides in a lot of subfunctions such as kmmio_handler
> and such...

Hmm, sure.
kmmio functions should be marked as __kprobes( or __kmmio or __debug? :)).

Thank you,

>> @@ -46,7 +47,7 @@ static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
>>  	return 0;
>>  }
>>  
>> -static inline int notify_page_fault(struct pt_regs *regs)
>> +static inline int __kprobes notify_page_fault(struct pt_regs *regs)
>>  {
>>  	int ret = 0;
>>  
>> @@ -239,7 +240,7 @@ void vmalloc_sync_all(void)
>>   *
>>   *   Handle a fault on the vmalloc or module mapping area
>>   */
>> -static noinline int vmalloc_fault(unsigned long address)
>> +static noinline __kprobes int vmalloc_fault(unsigned long address)
>>  {
>>  	unsigned long pgd_paddr;
>>  	pmd_t *pmd_k;
>> @@ -361,7 +362,7 @@ void vmalloc_sync_all(void)
>>   *
>>   * This assumes no large pages in there.
>>   */
>> -static noinline int vmalloc_fault(unsigned long address)
>> +static noinline __kprobes int vmalloc_fault(unsigned long address)
>>  {
>>  	pgd_t *pgd, *pgd_ref;
>>  	pud_t *pud, *pud_ref;
>> @@ -858,7 +859,7 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte)
>>   * There are no security implications to leaving a stale TLB when
>>   * increasing the permissions on a page.
>>   */
>> -static noinline int
>> +static noinline __kprobes int
>>  spurious_fault(unsigned long error_code, unsigned long address)
>>  {
>>  	pgd_t *pgd;
>>
>>
>> -- 
>> Masami Hiramatsu
>>
>> Software Engineer
>> Hitachi Computer Products (America), Inc.
>> Software Solutions Division
>>
>> e-mail: mhiramat@...hat.com
> 

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

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