On Thu, May 16, 2013 at 12:15 PM, Michael Neuling <mi...@neuling.org> wrote:
> Peter Zijlstra <pet...@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.zijls...@chello.nl>
>> > wrote:
>> > > We should always have proper privileges when requesting kernel data.
>> > >
>> > > Cc: Andi Kleen <a...@linux.intel.com>
>> > > Cc: eran...@google.com
>> > > Signed-off-by: Peter Zijlstra <a.p.zijls...@chello.nl>
>> > > Link:
>> > > http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwr...@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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
