Patchwork [3/3] perf, x86, lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL

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Submitter Michael Neuling
Date May 16, 2013, 10:15 a.m.
Message ID <8578.1368699317@ale.ozlabs.ibm.com>
Download mbox | patch
Permalink /patch/244258/
State Not Applicable
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Comments

Michael Neuling - May 16, 2013, 10:15 a.m.
Peter Zijlstra <peterz@infradead.org> wrote:

> On Wed, May 15, 2013 at 03:37:22PM +0200, Stephane Eranian wrote:
> > On Fri, May 3, 2013 at 2:11 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> > > We should always have proper privileges when requesting kernel data.
> > >
> > > Cc: Andi Kleen <ak@linux.intel.com>
> > > Cc: eranian@google.com
> > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > > Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
> > > ---
> > >  arch/x86/kernel/cpu/perf_event_intel_lbr.c |    5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> > > +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
> > > @@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filte
> > >         if (br_type & PERF_SAMPLE_BRANCH_USER)
> > >                 mask |= X86_BR_USER;
> > >
> > > -       if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
> > > +       if (br_type & PERF_SAMPLE_BRANCH_KERNEL) {
> > > +               if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
> > > +                       return -EACCES;
> > >                 mask |= X86_BR_KERNEL;
> > > +       }
> > >
> > This will prevent regular users from capturing kernel -> kernel branches.
> > But it won't prevent users from getting kernel -> user branches. Thus
> > some kernel address will still be captured. I guess they could be eliminated
> > by the sw_filter.
> > 
> > When using LBR priv level filtering, the filter applies to the branch target
> > only.
> 
> How about something like the below? It also adds the branch flags
> Mikey wanted for PowerPC.

Peter,

BTW PowerPC also has the ability to filter on conditional branches.  Any
chance we could add something like the follow to perf also?

Mikey
Peter Zijlstra - May 16, 2013, 11:16 a.m.
On Thu, May 16, 2013 at 08:15:17PM +1000, Michael Neuling wrote:
> Peter,
> 
> BTW PowerPC also has the ability to filter on conditional branches.  Any
> chance we could add something like the follow to perf also?
> 

I don't see an immediate problem with that except that we on x86 need to
implement that in the software filter. Stephane do you see any
fundamental issue with that?

> 
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index fb104e5..891c769 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -157,8 +157,9 @@ enum perf_branch_sample_type {
>  	PERF_SAMPLE_BRANCH_ANY_CALL	= 1U << 4, /* any call branch */
>  	PERF_SAMPLE_BRANCH_ANY_RETURN	= 1U << 5, /* any return branch */
>  	PERF_SAMPLE_BRANCH_IND_CALL	= 1U << 6, /* indirect calls */
> +	PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
>  
> -	PERF_SAMPLE_BRANCH_MAX		= 1U << 7, /* non-ABI */
> +	PERF_SAMPLE_BRANCH_MAX		= 1U << 8, /* non-ABI */
>  };
>  
>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index cdf58ec..5b0b89d 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -676,6 +676,7 @@ static const struct branch_mode branch_modes[] = {
>  	BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
>  	BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
>  	BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
> +	BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),
>  	BRANCH_END
>  };
>
Stephane Eranian - May 16, 2013, 3:36 p.m.
On Thu, May 16, 2013 at 1:16 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, May 16, 2013 at 08:15:17PM +1000, Michael Neuling wrote:
>> Peter,
>>
>> BTW PowerPC also has the ability to filter on conditional branches.  Any
>> chance we could add something like the follow to perf also?
>>
>
> I don't see an immediate problem with that except that we on x86 need to
> implement that in the software filter. Stephane do you see any
> fundamental issue with that?
>
On X86, the LBR cannot filter on conditional in HW. Thus as Peter said, it would
have to be done in SW. I did not add that because I think those branches are
not necessarily useful for tools.

>>
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index fb104e5..891c769 100644
>> --- a/include/uapi/linux/perf_event.h
>> +++ b/include/uapi/linux/perf_event.h
>> @@ -157,8 +157,9 @@ enum perf_branch_sample_type {
>>       PERF_SAMPLE_BRANCH_ANY_CALL     = 1U << 4, /* any call branch */
>>       PERF_SAMPLE_BRANCH_ANY_RETURN   = 1U << 5, /* any return branch */
>>       PERF_SAMPLE_BRANCH_IND_CALL     = 1U << 6, /* indirect calls */
>> +     PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
>>
>> -     PERF_SAMPLE_BRANCH_MAX          = 1U << 7, /* non-ABI */
>> +     PERF_SAMPLE_BRANCH_MAX          = 1U << 8, /* non-ABI */
>>  };
>>
>>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index cdf58ec..5b0b89d 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -676,6 +676,7 @@ static const struct branch_mode branch_modes[] = {
>>       BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
>>       BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
>>       BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
>> +     BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),
>>       BRANCH_END
>>  };
>>
Stephane Eranian - May 21, 2013, 1:55 p.m.
On Thu, May 16, 2013 at 12:15 PM, Michael Neuling <mikey@neuling.org> wrote:
> Peter Zijlstra <peterz@infradead.org> wrote:
>
>> On Wed, May 15, 2013 at 03:37:22PM +0200, Stephane Eranian wrote:
>> > On Fri, May 3, 2013 at 2:11 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>> > > We should always have proper privileges when requesting kernel data.
>> > >
>> > > Cc: Andi Kleen <ak@linux.intel.com>
>> > > Cc: eranian@google.com
>> > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> > > Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
>> > > ---
>> > >  arch/x86/kernel/cpu/perf_event_intel_lbr.c |    5 ++++-
>> > >  1 file changed, 4 insertions(+), 1 deletion(-)
>> > >
>> > > --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>> > > +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>> > > @@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filte
>> > >         if (br_type & PERF_SAMPLE_BRANCH_USER)
>> > >                 mask |= X86_BR_USER;
>> > >
>> > > -       if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
>> > > +       if (br_type & PERF_SAMPLE_BRANCH_KERNEL) {
>> > > +               if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
>> > > +                       return -EACCES;
>> > >                 mask |= X86_BR_KERNEL;
>> > > +       }
>> > >
>> > This will prevent regular users from capturing kernel -> kernel branches.
>> > But it won't prevent users from getting kernel -> user branches. Thus
>> > some kernel address will still be captured. I guess they could be eliminated
>> > by the sw_filter.
>> >
>> > When using LBR priv level filtering, the filter applies to the branch target
>> > only.
>>
>> How about something like the below? It also adds the branch flags
>> Mikey wanted for PowerPC.
>
> Peter,
>
> BTW PowerPC also has the ability to filter on conditional branches.  Any
> chance we could add something like the follow to perf also?
>
> Mikey
>
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index fb104e5..891c769 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -157,8 +157,9 @@ enum perf_branch_sample_type {
>         PERF_SAMPLE_BRANCH_ANY_CALL     = 1U << 4, /* any call branch */
>         PERF_SAMPLE_BRANCH_ANY_RETURN   = 1U << 5, /* any return branch */
>         PERF_SAMPLE_BRANCH_IND_CALL     = 1U << 6, /* indirect calls */
> +       PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
>
I would use PERF_SAMPLE_BRANCH_COND here.

> -       PERF_SAMPLE_BRANCH_MAX          = 1U << 7, /* non-ABI */
> +       PERF_SAMPLE_BRANCH_MAX          = 1U << 8, /* non-ABI */
>  };
>
>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index cdf58ec..5b0b89d 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -676,6 +676,7 @@ static const struct branch_mode branch_modes[] = {
>         BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
>         BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
>         BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
> +       BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),

use "cond"

>         BRANCH_END
>  };
>

And if you do this, you also need to update the x86
perf_event_intel_lbr.c mapping
tables to fill out the entries for PERF_SAMPLE_BRANCH_COND:

        [PERF_SAMPLE_BRANCH_COND]       = LBR_JCC,

And you also need to update intel_pmu_setup_sw_lbr_filter()
to handle the conversion to x86 instructions:

       if (br_type & PERF_SAMPLE_BRANCH_COND)
                mask |= X86_BR_JCC;


You also need to update the perf-record.txt documentation to list cond
as a possible
branch filter.
Anshuman Khandual - May 22, 2013, 6:43 a.m.
On 05/21/2013 07:25 PM, Stephane Eranian wrote:
> On Thu, May 16, 2013 at 12:15 PM, Michael Neuling <mikey@neuling.org> wrote:
>> Peter Zijlstra <peterz@infradead.org> wrote:
>>
>>> On Wed, May 15, 2013 at 03:37:22PM +0200, Stephane Eranian wrote:
>>>> On Fri, May 3, 2013 at 2:11 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>>>>> We should always have proper privileges when requesting kernel data.
>>>>>
>>>>> Cc: Andi Kleen <ak@linux.intel.com>
>>>>> Cc: eranian@google.com
>>>>> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
>>>>> Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
>>>>> ---
>>>>>  arch/x86/kernel/cpu/perf_event_intel_lbr.c |    5 ++++-
>>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>>>
>>>>> --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>>>>> +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>>>>> @@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filte
>>>>>         if (br_type & PERF_SAMPLE_BRANCH_USER)
>>>>>                 mask |= X86_BR_USER;
>>>>>
>>>>> -       if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
>>>>> +       if (br_type & PERF_SAMPLE_BRANCH_KERNEL) {
>>>>> +               if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
>>>>> +                       return -EACCES;
>>>>>                 mask |= X86_BR_KERNEL;
>>>>> +       }
>>>>>
>>>> This will prevent regular users from capturing kernel -> kernel branches.
>>>> But it won't prevent users from getting kernel -> user branches. Thus
>>>> some kernel address will still be captured. I guess they could be eliminated
>>>> by the sw_filter.
>>>>
>>>> When using LBR priv level filtering, the filter applies to the branch target
>>>> only.
>>>
>>> How about something like the below? It also adds the branch flags
>>> Mikey wanted for PowerPC.
>>
>> Peter,
>>
>> BTW PowerPC also has the ability to filter on conditional branches.  Any
>> chance we could add something like the follow to perf also?
>>
>> Mikey
>>
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index fb104e5..891c769 100644
>> --- a/include/uapi/linux/perf_event.h
>> +++ b/include/uapi/linux/perf_event.h
>> @@ -157,8 +157,9 @@ enum perf_branch_sample_type {
>>         PERF_SAMPLE_BRANCH_ANY_CALL     = 1U << 4, /* any call branch */
>>         PERF_SAMPLE_BRANCH_ANY_RETURN   = 1U << 5, /* any return branch */
>>         PERF_SAMPLE_BRANCH_IND_CALL     = 1U << 6, /* indirect calls */
>> +       PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
>>
> I would use PERF_SAMPLE_BRANCH_COND here.
> 
>> -       PERF_SAMPLE_BRANCH_MAX          = 1U << 7, /* non-ABI */
>> +       PERF_SAMPLE_BRANCH_MAX          = 1U << 8, /* non-ABI */
>>  };
>>
>>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index cdf58ec..5b0b89d 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -676,6 +676,7 @@ static const struct branch_mode branch_modes[] = {
>>         BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
>>         BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
>>         BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
>> +       BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),
> 
> use "cond"
> 
>>         BRANCH_END
>>  };
>>
> 
> And if you do this, you also need to update the x86
> perf_event_intel_lbr.c mapping
> tables to fill out the entries for PERF_SAMPLE_BRANCH_COND:
> 
>         [PERF_SAMPLE_BRANCH_COND]       = LBR_JCC,
> 
> And you also need to update intel_pmu_setup_sw_lbr_filter()
> to handle the conversion to x86 instructions:
> 
>        if (br_type & PERF_SAMPLE_BRANCH_COND)
>                 mask |= X86_BR_JCC;
> 
> 
> You also need to update the perf-record.txt documentation to list cond
> as a possible
> branch filter.

Hey Stephane,

I have incorporated all the review comments into the patch series
https://lkml.org/lkml/2013/5/22/51.

Regards
Anshuman
Stephane Eranian - May 22, 2013, 12:23 p.m.
Hi,



On Wed, May 22, 2013 at 8:43 AM, Anshuman Khandual
<khandual@linux.vnet.ibm.com> wrote:
> On 05/21/2013 07:25 PM, Stephane Eranian wrote:
>> On Thu, May 16, 2013 at 12:15 PM, Michael Neuling <mikey@neuling.org> wrote:
>>> Peter Zijlstra <peterz@infradead.org> wrote:
>>>
>>>> On Wed, May 15, 2013 at 03:37:22PM +0200, Stephane Eranian wrote:
>>>>> On Fri, May 3, 2013 at 2:11 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>>>>>> We should always have proper privileges when requesting kernel data.
>>>>>>
>>>>>> Cc: Andi Kleen <ak@linux.intel.com>
>>>>>> Cc: eranian@google.com
>>>>>> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
>>>>>> Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
>>>>>> ---
>>>>>>  arch/x86/kernel/cpu/perf_event_intel_lbr.c |    5 ++++-
>>>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>>>>>> +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>>>>>> @@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filte
>>>>>>         if (br_type & PERF_SAMPLE_BRANCH_USER)
>>>>>>                 mask |= X86_BR_USER;
>>>>>>
>>>>>> -       if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
>>>>>> +       if (br_type & PERF_SAMPLE_BRANCH_KERNEL) {
>>>>>> +               if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
>>>>>> +                       return -EACCES;
>>>>>>                 mask |= X86_BR_KERNEL;
>>>>>> +       }
>>>>>>
>>>>> This will prevent regular users from capturing kernel -> kernel branches.
>>>>> But it won't prevent users from getting kernel -> user branches. Thus
>>>>> some kernel address will still be captured. I guess they could be eliminated
>>>>> by the sw_filter.
>>>>>
>>>>> When using LBR priv level filtering, the filter applies to the branch target
>>>>> only.
>>>>
>>>> How about something like the below? It also adds the branch flags
>>>> Mikey wanted for PowerPC.
>>>
>>> Peter,
>>>
>>> BTW PowerPC also has the ability to filter on conditional branches.  Any
>>> chance we could add something like the follow to perf also?
>>>
>>> Mikey
>>>
>>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>>> index fb104e5..891c769 100644
>>> --- a/include/uapi/linux/perf_event.h
>>> +++ b/include/uapi/linux/perf_event.h
>>> @@ -157,8 +157,9 @@ enum perf_branch_sample_type {
>>>         PERF_SAMPLE_BRANCH_ANY_CALL     = 1U << 4, /* any call branch */
>>>         PERF_SAMPLE_BRANCH_ANY_RETURN   = 1U << 5, /* any return branch */
>>>         PERF_SAMPLE_BRANCH_IND_CALL     = 1U << 6, /* indirect calls */
>>> +       PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
>>>
>> I would use PERF_SAMPLE_BRANCH_COND here.
>>
>>> -       PERF_SAMPLE_BRANCH_MAX          = 1U << 7, /* non-ABI */
>>> +       PERF_SAMPLE_BRANCH_MAX          = 1U << 8, /* non-ABI */
>>>  };
>>>
>>>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
>>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>>> index cdf58ec..5b0b89d 100644
>>> --- a/tools/perf/builtin-record.c
>>> +++ b/tools/perf/builtin-record.c
>>> @@ -676,6 +676,7 @@ static const struct branch_mode branch_modes[] = {
>>>         BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
>>>         BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
>>>         BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
>>> +       BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),
>>
>> use "cond"
>>
>>>         BRANCH_END
>>>  };
>>>
>>
>> And if you do this, you also need to update the x86
>> perf_event_intel_lbr.c mapping
>> tables to fill out the entries for PERF_SAMPLE_BRANCH_COND:
>>
>>         [PERF_SAMPLE_BRANCH_COND]       = LBR_JCC,
>>
>> And you also need to update intel_pmu_setup_sw_lbr_filter()
>> to handle the conversion to x86 instructions:
>>
>>        if (br_type & PERF_SAMPLE_BRANCH_COND)
>>                 mask |= X86_BR_JCC;
>>
>>
>> You also need to update the perf-record.txt documentation to list cond
>> as a possible
>> branch filter.
>
> Hey Stephane,
>
> I have incorporated all the review comments into the patch series
> https://lkml.org/lkml/2013/5/22/51.
>
I don't see how you can compile Patch 3/5:

+ BRANCH_OPT("cond", PERF_SAMPLE_BRANCH_CONDITIONAL),

Needs to be PERF_SAMPLE_BRANCH_COND.
Anshuman Khandual - May 22, 2013, 2:51 p.m.
On 05/22/2013 05:53 PM, Stephane Eranian wrote:
> Hi,
> 
> 
> 
> On Wed, May 22, 2013 at 8:43 AM, Anshuman Khandual
> <khandual@linux.vnet.ibm.com> wrote:
>> On 05/21/2013 07:25 PM, Stephane Eranian wrote:
>>> On Thu, May 16, 2013 at 12:15 PM, Michael Neuling <mikey@neuling.org> wrote:
>>>> Peter Zijlstra <peterz@infradead.org> wrote:
>>>>
>>>>> On Wed, May 15, 2013 at 03:37:22PM +0200, Stephane Eranian wrote:
>>>>>> On Fri, May 3, 2013 at 2:11 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>>>>>>> We should always have proper privileges when requesting kernel data.
>>>>>>>
>>>>>>> Cc: Andi Kleen <ak@linux.intel.com>
>>>>>>> Cc: eranian@google.com
>>>>>>> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
>>>>>>> Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
>>>>>>> ---
>>>>>>>  arch/x86/kernel/cpu/perf_event_intel_lbr.c |    5 ++++-
>>>>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>>>>>>> +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>>>>>>> @@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filte
>>>>>>>         if (br_type & PERF_SAMPLE_BRANCH_USER)
>>>>>>>                 mask |= X86_BR_USER;
>>>>>>>
>>>>>>> -       if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
>>>>>>> +       if (br_type & PERF_SAMPLE_BRANCH_KERNEL) {
>>>>>>> +               if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
>>>>>>> +                       return -EACCES;
>>>>>>>                 mask |= X86_BR_KERNEL;
>>>>>>> +       }
>>>>>>>
>>>>>> This will prevent regular users from capturing kernel -> kernel branches.
>>>>>> But it won't prevent users from getting kernel -> user branches. Thus
>>>>>> some kernel address will still be captured. I guess they could be eliminated
>>>>>> by the sw_filter.
>>>>>>
>>>>>> When using LBR priv level filtering, the filter applies to the branch target
>>>>>> only.
>>>>>
>>>>> How about something like the below? It also adds the branch flags
>>>>> Mikey wanted for PowerPC.
>>>>
>>>> Peter,
>>>>
>>>> BTW PowerPC also has the ability to filter on conditional branches.  Any
>>>> chance we could add something like the follow to perf also?
>>>>
>>>> Mikey
>>>>
>>>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>>>> index fb104e5..891c769 100644
>>>> --- a/include/uapi/linux/perf_event.h
>>>> +++ b/include/uapi/linux/perf_event.h
>>>> @@ -157,8 +157,9 @@ enum perf_branch_sample_type {
>>>>         PERF_SAMPLE_BRANCH_ANY_CALL     = 1U << 4, /* any call branch */
>>>>         PERF_SAMPLE_BRANCH_ANY_RETURN   = 1U << 5, /* any return branch */
>>>>         PERF_SAMPLE_BRANCH_IND_CALL     = 1U << 6, /* indirect calls */
>>>> +       PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
>>>>
>>> I would use PERF_SAMPLE_BRANCH_COND here.
>>>
>>>> -       PERF_SAMPLE_BRANCH_MAX          = 1U << 7, /* non-ABI */
>>>> +       PERF_SAMPLE_BRANCH_MAX          = 1U << 8, /* non-ABI */
>>>>  };
>>>>
>>>>  #define PERF_SAMPLE_BRANCH_PLM_ALL \
>>>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>>>> index cdf58ec..5b0b89d 100644
>>>> --- a/tools/perf/builtin-record.c
>>>> +++ b/tools/perf/builtin-record.c
>>>> @@ -676,6 +676,7 @@ static const struct branch_mode branch_modes[] = {
>>>>         BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
>>>>         BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
>>>>         BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
>>>> +       BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),
>>>
>>> use "cond"
>>>
>>>>         BRANCH_END
>>>>  };
>>>>
>>>
>>> And if you do this, you also need to update the x86
>>> perf_event_intel_lbr.c mapping
>>> tables to fill out the entries for PERF_SAMPLE_BRANCH_COND:
>>>
>>>         [PERF_SAMPLE_BRANCH_COND]       = LBR_JCC,
>>>
>>> And you also need to update intel_pmu_setup_sw_lbr_filter()
>>> to handle the conversion to x86 instructions:
>>>
>>>        if (br_type & PERF_SAMPLE_BRANCH_COND)
>>>                 mask |= X86_BR_JCC;
>>>
>>>
>>> You also need to update the perf-record.txt documentation to list cond
>>> as a possible
>>> branch filter.
>>
>> Hey Stephane,
>>
>> I have incorporated all the review comments into the patch series
>> https://lkml.org/lkml/2013/5/22/51.
>>
> I don't see how you can compile Patch 3/5:
> 
> + BRANCH_OPT("cond", PERF_SAMPLE_BRANCH_CONDITIONAL),
> 
> Needs to be PERF_SAMPLE_BRANCH_COND.
> 

Ahh, sorry missed it, will fix it.

Patch

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index fb104e5..891c769 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -157,8 +157,9 @@  enum perf_branch_sample_type {
 	PERF_SAMPLE_BRANCH_ANY_CALL	= 1U << 4, /* any call branch */
 	PERF_SAMPLE_BRANCH_ANY_RETURN	= 1U << 5, /* any return branch */
 	PERF_SAMPLE_BRANCH_IND_CALL	= 1U << 6, /* indirect calls */
+	PERF_SAMPLE_BRANCH_CONDITIONAL  = 1U << 7, /* conditional branches */
 
-	PERF_SAMPLE_BRANCH_MAX		= 1U << 7, /* non-ABI */
+	PERF_SAMPLE_BRANCH_MAX		= 1U << 8, /* non-ABI */
 };
 
 #define PERF_SAMPLE_BRANCH_PLM_ALL \
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index cdf58ec..5b0b89d 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -676,6 +676,7 @@  static const struct branch_mode branch_modes[] = {
 	BRANCH_OPT("any_call", PERF_SAMPLE_BRANCH_ANY_CALL),
 	BRANCH_OPT("any_ret", PERF_SAMPLE_BRANCH_ANY_RETURN),
 	BRANCH_OPT("ind_call", PERF_SAMPLE_BRANCH_IND_CALL),
+	BRANCH_OPT("cnd", PERF_SAMPLE_BRANCH_CONDITIONAL),
 	BRANCH_END
 };