kernel.git/arch/arc/kernel/perf_event.c, branch linux-4.19.y

ARC: perf: Accommodate big-endian CPU

2019-12-01T08:17:37Z

commit 5effc09c4907901f0e71e68e5f2e14211d9a203f upstream. 8-letter strings representing ARC perf events are stores in two 32-bit registers as ASCII characters like that: "IJMP", "IALL", "IJMPTAK" etc. And the same order of bytes in the word is used regardless CPU endianness. Which means in case of big-endian CPU core we need to swap bytes to get the same order as if it was on little-endian CPU. Otherwise we're seeing the following error message on boot: ------------------------->8---------------------- ARC perf : 8 counters (32 bits), 40 conditions, [overflow IRQ support] sysfs: cannot create duplicate filename '/devices/arc_pct/events/pmji' CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.18 #3 Stack Trace: arc_unwind_core+0xd4/0xfc dump_stack+0x64/0x80 sysfs_warn_dup+0x46/0x58 sysfs_add_file_mode_ns+0xb2/0x168 create_files+0x70/0x2a0 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at kernel/events/core.c:12144 perf_event_sysfs_init+0x70/0xa0 Failed to register pmu: arc_pct, reason -17 Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.18 #3 Stack Trace: arc_unwind_core+0xd4/0xfc dump_stack+0x64/0x80 __warn+0x9c/0xd4 warn_slowpath_fmt+0x22/0x2c perf_event_sysfs_init+0x70/0xa0 ---[ end trace a75fb9a9837bd1ec ]--- ------------------------->8---------------------- What happens here we're trying to register more than one raw perf event with the same name "PMJI". Why? Because ARC perf events are 4 to 8 letters and encoded into two 32-bit words. In this particular case we deal with 2 events: * "IJMP____" which counts all jump & branch instructions * "IJMPC___" which counts only conditional jumps & branches Those strings are split in two 32-bit words this way "IJMP" + "____" & "IJMP" + "C___" correspondingly. Now if we read them swapped due to CPU core being big-endian then we read "PMJI" + "____" & "PMJI" + "___C". And since we interpret read array of ASCII letters as a null-terminated string on big-endian CPU we end up with 2 events of the same name "PMJI". Signed-off-by: Alexey Brodkin Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

ARCv2: perf: optimize given that num counters <= 32

2017-11-21T23:20:55Z

use ffz primitive which maps to ARCv2 instruction, vs. non atomic __test_and_set_bit It is unlikely if we will even have more than 32 counters, but still add a BUILD_BUG to catch that Acked-by: Peter Zijlstra (Intel) Signed-off-by: Vineet Gupta

ARCv2: perf: tweak overflow interrupt

2017-11-21T23:20:31Z

Current perf ISR loops thru all 32 counters, checking for each if it caused the interrupt. Instead only loop thru counters which actually interrupted (typically 1). Acked-by: Peter Zijlstra (Intel) Signed-off-by: Vineet Gupta

arc: perf: Enable generic "cache-references" and "cache-misses" events

2016-09-30T21:48:18Z

We used to live with PERF_COUNT_HW_CACHE_REFERENCES and PERF_COUNT_HW_CACHE_REFERENCES not specified on ARC. Those events are actually aliases to 2 cache events that we do support and so this change sets "cache-reference" and "cache-misses" events in the same way as "L1-dcache-loads" and L1-dcache-load-misses. And while at it adding debug info for cache events as well as doing a subtle fix in HW events debug info - config value is much better represented by hex so we may see not only event index but as well other control bits set (if they exist). Signed-off-by: Alexey Brodkin Cc: Vineet Gupta Cc: Thomas Gleixner Cc: linux-snps-arc@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: Arnaldo Carvalho de Melo Cc: Peter Zijlstra Signed-off-by: Vineet Gupta

Fix typos

2016-05-30T04:37:32Z

Signed-off-by: Andrea Gelmini Signed-off-by: Vineet Gupta

perf core: Pass max stack as a perf_callchain_entry context

2016-05-17T02:11:50Z

This makes perf_callchain_{user,kernel}() receive the max stack as context for the perf_callchain_entry, instead of accessing the global sysctl_perf_event_max_stack. Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: David Ahern Cc: Frederic Weisbecker Cc: He Kuang Cc: Jiri Olsa Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Milian Wolff Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: Wang Nan Cc: Zefan Li Link: http://lkml.kernel.org/n/tip-kolmn1yo40p7jhswxwrc7rrd@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo

ARCv2: perf: Ensure perf intr gets enabled on all cores

2015-12-12T10:33:59Z

This was the second perf intr issue perf sampling on multicore requires intr to be enabled on all cores. ARC perf probe code used helper arc_request_percpu_irq() which calls - request_percpu_irq() on core0 - enable_percpu_irq() on all all cores (including core0) genirq requires that request be made ahead of enable call. However if perf probe happened on non core0 (observed on a 3.18 kernel), enable would get called ahead of request, failing obviously and rendering perf intr disabled on all such cores [ 11.120000] 1 ARC perf : 8 counters (48 bits), 113 conditions, [overflow IRQ support] [ 11.130000] 1 -----> enable_percpu_irq() IRQ 20 failed [ 11.140000] 3 -----> enable_percpu_irq() IRQ 20 failed [ 11.140000] 2 -----> enable_percpu_irq() IRQ 20 failed [ 11.140000] 0 =====> request_percpu_irq() IRQ 20 [ 11.140000] 0 -----> enable_percpu_irq() IRQ 20 Fix this fragility, by calling request_percpu_irq() on whatever core calls probe (there is no requirement on which core calls this anyways) and then calling enable on each cores. Interestingly this started as invesigation of STAR 9000838902: "sporadically IRQs enabled on perf prob" which was about occassional boot spew as request_percpu_irq got called non-locally (from an IPI), and re-enabled interrupts in following path proc_mkdir -> spin_unlock_irq() which the irq work code didn't like. | ARC perf : 8 counters (48 bits), 113 conditions, [overflow IRQ support] | | BUG: failure at ../kernel/irq_work.c:135/irq_work_run_list()! | CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.18.10-01127-g285efb8e66d1 #2 | | Stack Trace: | arc_unwind_core.constprop.1+0x94/0x104 | dump_stack+0x62/0x98 | irq_work_run_list+0xb0/0xb4 | irq_work_run+0x22/0x3c | do_IPI+0x74/0x9c | handle_irq_event_percpu+0x34/0x164 | handle_percpu_irq+0x58/0x78 | generic_handle_irq+0x1e/0x2c | arch_do_IRQ+0x3c/0x60 | ret_from_exception+0x0/0x8 Cc: Marc Zyngier Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-snps-arc@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: Alexey Brodkin Cc: #4.2+ Signed-off-by: Vineet Gupta

ARCv2: perf: Finally introduce HS perf unit

2015-08-27T09:29:07Z

With all features in place, the ARC HS pct block can now be effectively allowed to be probed/used Acked-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Signed-off-by: Alexey Brodkin Signed-off-by: Vineet Gupta

ARCv2: perf: SMP support

2015-08-27T09:28:42Z

* split off pmu info into singleton and per-cpu bits * setup PMU on all cores Acked-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Signed-off-by: Alexey Brodkin Signed-off-by: Vineet Gupta

ARCv2: perf: implement exclusion of event counting in user or kernel mode

2015-08-27T09:28:14Z

Acked-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Signed-off-by: Alexey Brodkin Signed-off-by: Vineet Gupta