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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-16 14:31:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-16 14:31:40 -0700
commite77fafe9afb53b7f4d8176c5cd5c10c43a905bc8 (patch)
tree828ad771a2951f7ac06111c3a9a30e0f368a9b5e /Documentation/admin-guide
parent52a5525214d0d612160154d902956eca0558b7c0 (diff)
parente376897f424a1c807779a2635f62eb02d7e382f9 (diff)
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon: "Although there isn't tonnes of code in terms of line count, there are a fair few headline features which I've noted both in the tag and also in the merge commits when I pulled everything together. The part I'm most pleased with is that we had 35 contributors this time around, which feels like a big jump from the usual small group of core arm64 arch developers. Hopefully they all enjoyed it so much that they'll continue to contribute, but we'll see. It's probably worth highlighting that we've pulled in a branch from the risc-v folks which moves our CPU topology code out to where it can be shared with others. Summary: - 52-bit virtual addressing in the kernel - New ABI to allow tagged user pointers to be dereferenced by syscalls - Early RNG seeding by the bootloader - Improve robustness of SMP boot - Fix TLB invalidation in light of recent architectural clarifications - Support for i.MX8 DDR PMU - Remove direct LSE instruction patching in favour of static keys - Function error injection using kprobes - Support for the PPTT "thread" flag introduced by ACPI 6.3 - Move PSCI idle code into proper cpuidle driver - Relaxation of implicit I/O memory barriers - Build with RELR relocations when toolchain supports them - Numerous cleanups and non-critical fixes" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (114 commits) arm64: remove __iounmap arm64: atomics: Use K constraint when toolchain appears to support it arm64: atomics: Undefine internal macros after use arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP_LABEL arm64: asm: Kill 'asm/atomic_arch.h' arm64: lse: Remove unused 'alt_lse' assembly macro arm64: atomics: Remove atomic_ll_sc compilation unit arm64: avoid using hard-coded registers for LSE atomics arm64: atomics: avoid out-of-line ll/sc atomics arm64: Use correct ll/sc atomic constraints jump_label: Don't warn on __exit jump entries docs/perf: Add documentation for the i.MX8 DDR PMU perf/imx_ddr: Add support for AXI ID filtering arm64: kpti: ensure patched kernel text is fetched from PoU arm64: fix fixmap copy for 16K pages and 48-bit VA perf/smmuv3: Validate groups for global filtering perf/smmuv3: Validate group size arm64: Relax Documentation/arm64/tagged-pointers.rst arm64: kvm: Replace hardcoded '1' with SYS_PAR_EL1_F arm64: mm: Ignore spurious translation faults taken from the kernel ...
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+=====================================================
+Freescale i.MX8 DDR Performance Monitoring Unit (PMU)
+=====================================================
+
+There are no performance counters inside the DRAM controller, so performance
+signals are brought out to the edge of the controller where a set of 4 x 32 bit
+counters is implemented. This is controlled by the CSV modes programed in counter
+control register which causes a large number of PERF signals to be generated.
+
+Selection of the value for each counter is done via the config registers. There
+is one register for each counter. Counter 0 is special in that it always counts
+“time” and when expired causes a lock on itself and the other counters and an
+interrupt is raised. If any other counter overflows, it continues counting, and
+no interrupt is raised.
+
+The "format" directory describes format of the config (event ID) and config1
+(AXI filtering) fields of the perf_event_attr structure, see /sys/bus/event_source/
+devices/imx8_ddr0/format/. The "events" directory describes the events types
+hardware supported that can be used with perf tool, see /sys/bus/event_source/
+devices/imx8_ddr0/events/.
+ e.g.::
+ perf stat -a -e imx8_ddr0/cycles/ cmd
+ perf stat -a -e imx8_ddr0/read/,imx8_ddr0/write/ cmd
+
+AXI filtering is only used by CSV modes 0x41 (axid-read) and 0x42 (axid-write)
+to count reading or writing matches filter setting. Filter setting is various
+from different DRAM controller implementations, which is distinguished by quirks
+in the driver.
+
+* With DDR_CAP_AXI_ID_FILTER quirk.
+ Filter is defined with two configuration parts:
+ --AXI_ID defines AxID matching value.
+ --AXI_MASKING defines which bits of AxID are meaningful for the matching.
+ 0:corresponding bit is masked.
+ 1: corresponding bit is not masked, i.e. used to do the matching.
+
+ AXI_ID and AXI_MASKING are mapped on DPCR1 register in performance counter.
+ When non-masked bits are matching corresponding AXI_ID bits then counter is
+ incremented. Perf counter is incremented if
+ AxID && AXI_MASKING == AXI_ID && AXI_MASKING
+
+ This filter doesn't support filter different AXI ID for axid-read and axid-write
+ event at the same time as this filter is shared between counters.
+ e.g.::
+ perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
+ perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
+
+ NOTE: axi_mask is inverted in userspace(i.e. set bits are bits to mask), and
+ it will be reverted in driver automatically. so that the user can just specify
+ axi_id to monitor a specific id, rather than having to specify axi_mask.
+ e.g.::
+ perf stat -a -e imx8_ddr0/axid-read,axi_id=0x12/ cmd, which will monitor ARID=0x12