Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 4 Feb 2021 09:18:38 -0600 | From | Rob Herring <> | Subject | Re: [PATCH v5 0/9] libperf and arm64 userspace counter access support |
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On Wed, Jan 13, 2021 at 08:05:56PM -0600, Rob Herring wrote: > Hi all, > > Another version of libperf and arm64 userspace counter access support. > This originally resurrected Raphael's series[1] to enable userspace counter > access on arm64. My previous versions are here[2][3][4][5]. A git branch is > here[6].
Ping.
Will, Mark, comments on the Arm bits?
> > Changes in v5: > - Limit enabling/disabling access to CPUs associated with the PMU > (supported_cpus) and with the mm_struct matching current->active_mm. > The x86 method of using mm_cpumask doesn't work for arm64 as it is not > updated. > - Only set cap_user_rdpmc if event is on current cpu. See patch 2. > - Create an mmap for every event in an evsel. This results in some changes > to the libperf mmap API from the last version. > - Rebase to v5.11-rc2 > > Changes in v4: > - Dropped 'arm64: pmu: Add hook to handle pmu-related undefined instructions'. > The onus is on userspace to pin itself to a homogeneous subset of CPUs > and avoid any aborts on heterogeneous systems, so the hook is not needed. > - Make perf_evsel__mmap() take pages rather than bytes for size > - Fix building arm64 heterogeneous test. > > Changes in v3: > - Dropped removing x86 rdpmc test until libperf tests can run via 'perf test' > - Added verbose prints for tests > - Split adding perf_evsel__mmap() to separate patch > > > The following changes to the arm64 support have been made compared to > Raphael's last version: > > The major change is support for heterogeneous systems with some > restrictions. Specifically, userspace must pin itself to like CPUs, open > a specific PMU by type, and use h/w specific events. The tests have been > reworked to demonstrate this. > > Chained events are not supported. The problem with supporting chained > events was there's no way to distinguish between a chained event and a > native 64-bit counter. We could add some flag, but do self monitoring > processes really need that? Native 64-bit counters are supported if the > PMU h/w has support. As there's already an explicit ABI to request 64-bit > counters, userspace can request 64-bit counters and if user > access is not enabled, then it must retry with 32-bit counters. > > Prior versions broke the build on arm32 (surprisingly never caught by > 0-day). As a result, event_mapped and event_unmapped implementations have > been moved into the arm64 code. > > There was a bug in that pmc_width was not set in the user page. The tests > now check for this. > > The documentation has been converted to rST. I've added sections on > chained events and heterogeneous. > > The tests have been expanded to test the cycle counter access. > > Rob > > [1] https://lore.kernel.org/r/20190822144220.27860-1-raphael.gault@arm.com/ > [2] https://lore.kernel.org/r/20200707205333.624938-1-robh@kernel.org/ > [3] https://lore.kernel.org/r/20200828205614.3391252-1-robh@kernel.org/ > [4] https://lore.kernel.org/r/20200911215118.2887710-1-robh@kernel.org/ > [5] https://lore.kernel.org/r/20201001140116.651970-1-robh@kernel.org/ > [6] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git user-perf-event-v5 > > > Raphael Gault (3): > arm64: pmu: Add function implementation to update event index in > userpage > arm64: perf: Enable PMU counter direct access for perf event > Documentation: arm64: Document PMU counters access from userspace > > Rob Herring (6): > tools/include: Add an initial math64.h > libperf: Add evsel mmap support > libperf: tests: Add support for verbose printing > libperf: Add support for user space counter access > libperf: Add arm64 support to perf_mmap__read_self() > perf: arm64: Add test for userspace counter access on heterogeneous > systems > > Documentation/arm64/index.rst | 1 + > .../arm64/perf_counter_user_access.rst | 56 ++++++ > arch/arm64/include/asm/mmu.h | 5 + > arch/arm64/include/asm/mmu_context.h | 2 + > arch/arm64/include/asm/perf_event.h | 14 ++ > arch/arm64/kernel/perf_event.c | 68 +++++++ > include/linux/perf/arm_pmu.h | 2 + > tools/include/linux/math64.h | 75 +++++++ > tools/lib/perf/Documentation/libperf.txt | 2 + > tools/lib/perf/evsel.c | 50 ++++- > tools/lib/perf/include/internal/evsel.h | 2 + > tools/lib/perf/include/internal/mmap.h | 3 + > tools/lib/perf/include/internal/tests.h | 32 +++ > tools/lib/perf/include/perf/evsel.h | 2 + > tools/lib/perf/libperf.map | 2 + > tools/lib/perf/mmap.c | 186 ++++++++++++++++++ > tools/lib/perf/tests/Makefile | 6 +- > tools/lib/perf/tests/test-evsel.c | 65 ++++++ > tools/perf/arch/arm64/include/arch-tests.h | 7 + > tools/perf/arch/arm64/tests/Build | 1 + > tools/perf/arch/arm64/tests/arch-tests.c | 4 + > tools/perf/arch/arm64/tests/user-events.c | 170 ++++++++++++++++ > 22 files changed, 751 insertions(+), 4 deletions(-) > create mode 100644 Documentation/arm64/perf_counter_user_access.rst > create mode 100644 tools/include/linux/math64.h > create mode 100644 tools/perf/arch/arm64/tests/user-events.c > > -- > 2.27.0
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