On 05/21/2013 07:25 PM, Stephane Eranian wrote: > 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.
Hey Stephane, I have incorporated all the review comments into the patch series https://lkml.org/lkml/2013/5/22/51. Regards Anshuman -- 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/
