Open access to monitoring for CAP_PERFMON privileged process. Providing
the access under CAP_PERFMON capability singly, without the rest of
CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials
and makes operation more secure.
CAP_PERFMON implements the principle of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
principle of least privilege: A security design principle that states
that a process or program be granted only those privileges (e.g.,
capabilities) necessary to accomplish its legitimate function, and only
for the time that such privileges are actually required)
For backward compatibility reasons access to the monitoring remains open
for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage for
secure monitoring is discouraged with respect to CAP_PERFMON capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/ac98cd9f-b59e-673c-c70d-180b3e7695d2@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
IMC(In-memory Collection Counters) does performance monitoring in
two different modes, i.e accumulation mode(core-imc and thread-imc events),
and trace mode(trace-imc events). A cpu thread can either be in
accumulation-mode or trace-mode at a time and this is done via the LDBAR
register in POWER architecture. The current design does not address the
races between thread-imc and trace-imc events.
Patch implements a global id and lock to avoid the races between
core, trace and thread imc events. With this global id-lock
implementation, the system can either run core, thread or trace imc
events at a time. i.e. to run any core-imc events, thread/trace imc events
should not be enabled/monitored.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200313055238.8656-1-anju@linux.vnet.ibm.com
The alloc_pages_node return value should be tested for failure
before being passed to page_address.
Tested-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190724084638.24982-3-npiggin@gmail.com
Nest and core IMC (In-Memory Collection counters) assigns a particular
cpu as the designated target for counter data collection. During
system boot, the first online cpu in a chip gets assigned as the
designated cpu for that chip(for nest-imc) and the first online cpu in
a core gets assigned as the designated cpu for that core(for
core-imc).
If the designated cpu goes offline, the next online cpu from the same
chip(for nest-imc)/core(for core-imc) is assigned as the next target,
and the event context is migrated to the target cpu. Currently,
cpumask_any_but() function is used to find the target cpu. Though this
function is expected to return a `random` cpu, this always returns the
next online cpu.
If all cpus in a chip/core is offlined in a sequential manner,
starting from the first cpu, the event migration has to happen for all
the cpus which goes offline. Since the migration process involves a
grace period, the total time taken to offline all the cpus will be
significantly high.
Example:
In a system which has 2 sockets, with
NUMA node0 CPU(s): 0-87
NUMA node8 CPU(s): 88-175
Time taken to offline cpu 88-175:
real 2m56.099s
user 0m0.191s
sys 0m0.000s
Use cpumask_last() to choose the target cpu, when the designated cpu
goes online, so the migration will happen only when the last_cpu in
the mask goes offline. This way the time taken to offline all cpus in
a chip/core can be reduced.
With the patch:
Time taken to offline cpu 88-175:
real 0m12.207s
user 0m0.171s
sys 0m0.000s
Offlining all cpus in reverse order is also taken care because,
cpumask_any_but() is used to find the designated cpu if the last cpu
in the mask goes offline. Since cpumask_any_but() always return the
first cpu in the mask, that becomes the designated cpu and migration
will happen only when the first_cpu in the mask goes offline.
Example: With the patch,
Time taken to offline cpu from 175-88:
real 0m9.330s
user 0m0.110s
sys 0m0.000s
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or
later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 4 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190523091650.480557885@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add PMU functions to support trace-imc.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Patch detects trace-imc events, does memory initilizations for each online
cpu, and registers cpuhotplug call-backs.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
LDBAR holds the memory address allocated for each cpu. For thread-imc
the mode bit (i.e bit 1) of LDBAR is set to accumulation.
Currently, ldbar is loaded with per cpu memory address and mode set to
accumulation at boot time.
To enable trace-imc, the mode bit of ldbar should be set to 'trace'. So to
accommodate trace-mode of IMC, reposition setting of ldbar for thread-imc
to thread_imc_event_add(). Also reset ldbar at thread_imc_event_del().
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The data structure (i.e struct imc_mem_info) to hold the memory address
information for nest imc units is allocated based on the number of nodes
in the system.
nest_imc_event_init() traverse this struct array to calculate the memory
base address for the event-cpu. If we fail to find a match for the event
cpu's chip-id in imc_mem_info struct array, then the do-while loop will
iterate until we crash.
Fix this by changing the loop exit condition based on the number of
non zero vbase elements in the array, since the allocation is done for
nr_chips + 1.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 885dcd709b ("powerpc/perf: Add nest IMC PMU support")
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nest hardware counter memory resides in a per-chip reserve-memory.
During nest_imc_event_init(), chip-id of the event-cpu is considered to
calculate the base memory addresss for that cpu. Return, proper error
condition if the chip_id calculated is invalid.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 885dcd709b ("powerpc/perf: Add nest IMC PMU support")
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
For PowerPC PMUs that do not support context exclusion let's
advertise the PERF_PMU_CAP_NO_EXCLUDE capability. This ensures that
perf will prevent us from handling events where any exclusion flags
are set. Let's also remove the now unnecessary check for exclusion
flags.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: robin.murphy@arm.com
Cc: suzuki.poulose@arm.com
Link: https://lkml.kernel.org/r/1547128414-50693-10-git-send-email-andrew.murray@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are three symbols (two variables and a function) that are being used
solely in the same file (imc-pmu.c), thus, these symbols should be static,
but they are not. This was detected by sparse:
arch/powerpc/perf/imc-pmu.c:31:20: warning: symbol 'nest_imc_refc' was not declared. Should it be static?
arch/powerpc/perf/imc-pmu.c:37:20: warning: symbol 'core_imc_refc' was not declared. Should it be static?
arch/powerpc/perf/imc-pmu.c:46:16: warning: symbol 'imc_event_to_pmu' was not declared. Should it be static?
This patch simply adds the 'static' storage-class definition to these
symbols, thus, restricting their usage only in the imc-pmu.c file.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
On a Power9 box we get a few screens full of these on boot. Drop
them to pr_debug.
[ 5.993645] nest_centaur6_imc performance monitor hardware support registered
[ 5.993728] nest_centaur7_imc performance monitor hardware support registered
[ 5.996510] core_imc performance monitor hardware support registered
[ 5.996569] nest_mba0_imc performance monitor hardware support registered
[ 5.996631] nest_mba1_imc performance monitor hardware support registered
[ 5.996685] nest_mba2_imc performance monitor hardware support registered
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Reviewed-by: Stewart Smith <stewart@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Since thread-imc internally use the core-imc hardware infrastructure
and is depended on it, having thread-imc in the kernel in the
absence of core-imc is trivial. Patch disables thread-imc, if
core-imc is not registered.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Replace the direct return statement in imc_mem_init() with goto, to adhere
to the kernel coding style.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When any of the IMC (In-Memory Collection counter) devices fail
to initialize, imc_common_mem_free() frees set of memory. In doing so,
pmu_ptr pointer is also freed. But pmu_ptr pointer is used in subsequent
function (imc_common_cpuhp_mem_free()) which is wrong. Patch here reorders
the code to avoid such access.
Also free the memory which is dynamically allocated during imc
initialization, wherever required.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently memory is allocated for core-imc based on cpu_present_mask,
which has bit 'cpu' set iff cpu is populated. We use (cpu number / threads
per core) as the array index to access the memory.
Under some circumstances firmware marks a CPU as GUARDed CPU and boot the
system, until cleared of errors, these CPU's are unavailable for all
subsequent boots. GUARDed CPUs are possible but not present from linux
view, so it blows a hole when we assume the max length of our allocation
is driven by our max present cpus, where as one of the cpus might be online
and be beyond the max present cpus, due to the hole.
So (cpu number / threads per core) value bounds the array index and leads
to memory overflow.
Call trace observed during a guard test:
Faulting instruction address: 0xc000000000149f1c
cpu 0x69: Vector: 380 (Data Access Out of Range) at [c000003fea303420]
pc:c000000000149f1c: prefetch_freepointer+0x14/0x30
lr:c00000000014e0f8: __kmalloc+0x1a8/0x1ac
sp:c000003fea3036a0
msr:9000000000009033
dar:c9c54b2c91dbf6b7
current = 0xc000003fea2c0000
paca = 0xc00000000fddd880 softe: 3 irq_happened: 0x01
pid = 1, comm = swapper/104
Linux version 4.16.7-openpower1 (smc@smc-desktop) (gcc version 6.4.0
(Buildroot 2018.02.1-00006-ga8d1126)) #2 SMP Fri May 4 16:44:54 PDT 2018
enter ? for help
call trace:
__kmalloc+0x1a8/0x1ac
(unreliable)
init_imc_pmu+0x7f4/0xbf0
opal_imc_counters_probe+0x3fc/0x43c
platform_drv_probe+0x48/0x80
driver_probe_device+0x22c/0x308
__driver_attach+0xa0/0xd8
bus_for_each_dev+0x88/0xb4
driver_attach+0x2c/0x40
bus_add_driver+0x1e8/0x228
driver_register+0xd0/0x114
__platform_driver_register+0x50/0x64
opal_imc_driver_init+0x24/0x38
do_one_initcall+0x150/0x15c
kernel_init_freeable+0x250/0x254
kernel_init+0x1c/0x150
ret_from_kernel_thread+0x5c/0xc8
Allocating memory for core-imc based on cpu_possible_mask, which has
bit 'cpu' set iff cpu is populatable, will fix this issue.
Reported-by: Pridhiviraj Paidipeddi <ppaidipe@linux.vnet.ibm.com>
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Tested-by: Pridhiviraj Paidipeddi <ppaidipe@linux.vnet.ibm.com>
Fixes: 39a846db1d ("powerpc/perf: Add core IMC PMU support")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Merge our fixes branch from the 4.15 cycle.
Unusually the fixes branch saw some significant features merged,
notably the RFI flush patches, so we want the code in next to be
tested against that, to avoid any surprises when the two are merged.
There's also some other work on the panic handling that was reverted
in fixes and we now want to do properly in next, which would conflict.
And we also fix a few other minor merge conflicts.
Change the data type for the variable 'ncpu' in ppc_core_imc_cpu_offline(),
since cpumask_any_but() returns an 'int' value.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Remove the allocation of struct imc_events from imc_parse_event().
Instead pass imc_events as a parameter to imc_parse_event(), which is
a pointer to a slot in the array allocated in
update_events_in_group().
Reported-by: Dan Carpenter ("powerpc/perf: Fix a sizeof() typo so we allocate less memory")
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Factor out memory freeing part for attribute elements from
imc_common_cpuhp_mem_free().
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Remove the global variable 'thread_imc_pmu', since it is not used in the code.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
imc_common_cpuhp_mem_free() is the common function for all
IMC (In-memory Collection counters) domains to unregister cpuhotplug
callback and free memory. Since kfree of memory allocated for
nest-imc (per_nest_pmu_arr) is in the common code, all
domains (core/nest/thread) can do the kfree in the failure case.
This could potentially create a call trace as shown below, where
core(/thread/nest) imc pmu initialization fails and in the failure
path imc_common_cpuhp_mem_free() free the memory(per_nest_pmu_arr),
which is allocated by successfully registered nest units.
The call trace is generated in a scenario where core-imc
initialization is made to fail and a cpuhotplug is performed in a p9
system. During cpuhotplug ppc_nest_imc_cpu_offline() tries to access
per_nest_pmu_arr, which is already freed by core-imc.
NIP [c000000000cb6a94] mutex_lock+0x34/0x90
LR [c000000000cb6a88] mutex_lock+0x28/0x90
Call Trace:
mutex_lock+0x28/0x90 (unreliable)
perf_pmu_migrate_context+0x90/0x3a0
ppc_nest_imc_cpu_offline+0x190/0x1f0
cpuhp_invoke_callback+0x160/0x820
cpuhp_thread_fun+0x1bc/0x270
smpboot_thread_fn+0x250/0x290
kthread+0x1a8/0x1b0
ret_from_kernel_thread+0x5c/0x74
To address this scenario do the kfree(per_nest_pmu_arr) only in case
of nest-imc initialization failure, and when there is no other nest
units registered.
Fixes: 73ce9aec65 ("powerpc/perf: Fix IMC_MAX_PMU macro")
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Oops is observed during boot:
Faulting instruction address: 0xc000000000248340
cpu 0x0: Vector: 380 (Data Access Out of Range) at [c000000ff66fb850]
pc: c000000000248340: event_function_call+0x50/0x1f0
lr: c00000000024878c: perf_remove_from_context+0x3c/0x100
sp: c000000ff66fbad0
msr: 9000000000009033
dar: 7d20e2a6f92d03c0
pid = 14, comm = cpuhp/0
While registering the cpuhotplug callbacks for nest-imc, if we fail in
the cpuhotplug online path for any random node in a multi node
system (because the opal call to stop nest-imc counters fails for that
node), ppc_nest_imc_cpu_offline() will get invoked for other nodes who
successfully returned from cpuhotplug online path.
This call trace is generated since in the ppc_nest_imc_cpu_offline()
path we are trying to migrate the event context, when nest-imc
counters are not even initialized.
Patch to add a check to ensure that nest-imc is registered before
migrating the event context.
Fixes: 885dcd709b ("powerpc/perf: Add nest IMC PMU support")
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
IMC_MAX_PMU is used for static storage (per_nest_pmu_arr) which holds
nest pmu information. Current value for the macro is 32 based on
the initial number of nest pmu units supported by the nest microcode.
But going forward, microcode could support more nest units. Instead
of static storage, patch to fix the code to dynamically allocate an
array based on the number of nest imc units found in the device tree.
Fixes:8f95faaac56c1 ('powerpc/powernv: Detect and create IMC device')
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
init_imc_pmu() uses topology_physical_package_id() to detect the
node id of the processor it is on to get local memory, but that's
wrong, and can lead to crashes. Fix it to use cpu_to_node().
Fixes: 885dcd709b ("powerpc/perf: Add nest IMC PMU support")
Cc: stable@vger.kernel.org # v4.14+
Reported-By: Rob Lippert <rlippert@google.com>
Tested-By: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Call trace observed during boot:
nest_capp0_imc performance monitor hardware support registered
nest_capp1_imc performance monitor hardware support registered
core_imc memory allocation for cpu 56 failed
Unable to handle kernel paging request for data at address 0xffa400010
Faulting instruction address: 0xc000000000bf3294
0:mon> e
cpu 0x0: Vector: 300 (Data Access) at [c000000ff38ff8d0]
pc: c000000000bf3294: mutex_lock+0x34/0x90
lr: c000000000bf3288: mutex_lock+0x28/0x90
sp: c000000ff38ffb50
msr: 9000000002009033
dar: ffa400010
dsisr: 80000
current = 0xc000000ff383de00
paca = 0xc000000007ae0000 softe: 0 irq_happened: 0x01
pid = 13, comm = cpuhp/0
Linux version 4.11.0-39.el7a.ppc64le (mockbuild@ppc-058.build.eng.bos.redhat.com) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) ) #1 SMP Tue Oct 3 07:42:44 EDT 2017
0:mon> t
[c000000ff38ffb80] c0000000002ddfac perf_pmu_migrate_context+0xac/0x470
[c000000ff38ffc40] c00000000011385c ppc_core_imc_cpu_offline+0x1ac/0x1e0
[c000000ff38ffc90] c000000000125758 cpuhp_invoke_callback+0x198/0x5d0
[c000000ff38ffd00] c00000000012782c cpuhp_thread_fun+0x8c/0x3d0
[c000000ff38ffd60] c0000000001678d0 smpboot_thread_fn+0x290/0x2a0
[c000000ff38ffdc0] c00000000015ee78 kthread+0x168/0x1b0
[c000000ff38ffe30] c00000000000b368 ret_from_kernel_thread+0x5c/0x74
While registering the cpuhoplug callbacks for core-imc, if we fails
in the cpuhotplug online path for any random core (either because opal call to
initialize the core-imc counters fails or because memory allocation fails for
that core), ppc_core_imc_cpu_offline() will get invoked for other cpus who
successfully returned from cpuhotplug online path.
But in the ppc_core_imc_cpu_offline() path we are trying to migrate the event
context, when core-imc counters are not even initialized. Thus creating the
above stack dump.
Add a check to see if core-imc counters are enabled or not in the cpuhotplug
offline path before migrating the context to handle this failing scenario.
Fixes: 885dcd709b ("powerpc/perf: Add nest IMC PMU support")
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When setting nr_cpus=1, we observed a crash in IMC code during boot
due to a missing allocation: basically, IMC code is taking the number
of threads into account in imc_mem_init() and if we manually set
nr_cpus for a value that is not multiple of the number of threads per
core, an integer division in that function will discard the decimal
portion, leading IMC to not allocate one mem_info struct. This causes
a NULL pointer dereference later, on is_core_imc_mem_inited().
This patch just rounds that division up, fixing the bug.
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Acked-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Panic observed with latest firmware, and upstream kernel:
NIP init_imc_pmu+0x8c/0xcf0
LR init_imc_pmu+0x2f8/0xcf0
Call Trace:
init_imc_pmu+0x2c8/0xcf0 (unreliable)
opal_imc_counters_probe+0x300/0x400
platform_drv_probe+0x64/0x110
driver_probe_device+0x3d8/0x580
__driver_attach+0x14c/0x1a0
bus_for_each_dev+0x8c/0xf0
driver_attach+0x34/0x50
bus_add_driver+0x298/0x350
driver_register+0x9c/0x180
__platform_driver_register+0x5c/0x70
opal_imc_driver_init+0x2c/0x40
do_one_initcall+0x64/0x1d0
kernel_init_freeable+0x280/0x374
kernel_init+0x24/0x160
ret_from_kernel_thread+0x5c/0x74
While registering nest imc at init, cpu-hotplug callback
nest_pmu_cpumask_init() makes an OPAL call to stop the engine. And if
the OPAL call fails, imc_common_cpuhp_mem_free() is invoked to cleanup
memory and cpuhotplug setup.
But when cleaning up the attribute group, we are dereferencing the
attribute element array without checking whether the backing element
is not NULL. This causes the kernel panic.
Add a check for the backing element prior to dereferencing the
attribute element, to handle the failing case gracefully.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reported-by: Pridhiviraj Paidipeddi <ppaidipe@linux.vnet.ibm.com>
[mpe: Trim change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Nest/core pmu units are enabled only when it is used. A reference count is
maintained for the events which uses the nest/core pmu units. Currently in
*_imc_counters_release function a WARN() is used for notification of any
underflow of ref count.
The case where event ref count hit a negative value is, when perf session is
started, followed by offlining of all cpus in a given core.
i.e. in cpuhotplug offline path ppc_core_imc_cpu_offline() function set the
ref->count to zero, if the current cpu which is about to offline is the last
cpu in a given core and make an OPAL call to disable the engine in that core.
And on perf session termination, perf->destroy (core_imc_counters_release) will
first decrement the ref->count for this core and based on the ref->count value
an opal call is made to disable the core-imc engine.
Now, since cpuhotplug path already clears the ref->count for core and disabled
the engine, perf->destroy() decrementing again at event termination make it
negative which in turn fires the WARN_ON. The same happens for nest units.
Add a check to see if the reference count is alreday zero, before decrementing
the count, so that the ref count will not hit a negative value.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Santosh Sivaraj <santosh@fossix.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
nest_imc_refc is a reference count struct, used to track number of
active perf sessions using the nest units.
Currently the code accesses nest_imc_refc using node_id, which is
incorrect, the array is indexed by node number. Meaning in the case of
sparse node ids we index off the end of the array.
Fix it to use get_nest_pmu_ref() which uses the existing per-cpu
variable local_nest_imc_refc.
Fixes: 885dcd709b ('powerpc/perf: Add nest IMC PMU support')
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Tweak change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In a multi node system with discontiguous node ids, nest event values
are not showing up properly. eg. lscpu output:
NUMA node0 CPU(s): 0-15
NUMA node8 CPU(s): 16-31
Nest event values on such systems can be counted on CPUs <= 15:
$./perf stat -e 'nest_powerbus0_imc/PM_PB_CYC/' -C 0-14 -I 1000 sleep 1000
# time counts unit events
1.000294577 30,17,24,42,880 nest_powerbus0_imc/PM_PB_CYC/
But not on CPUs >= 16:
$./perf stat -e 'nest_powerbus0_imc/PM_PB_CYC/' -C 16-28 -I 1000 sleep 1000
# time counts unit events
1.000049902 <not supported> nest_powerbus0_imc/PM_PB_CYC/
This is because, when fetching the reference count, the node id (which
may be sparse) is used as the array index, not the node number (which
is 0 based and contiguous).
Fix it by using the node number as the array index.
$./perf stat -e 'nest_powerbus0_imc/PM_PB_CYC/' -C 16-28 -I 1000 sleep 1000
# time counts unit events
1.000241961 26,12,35,28,704 nest_powerbus0_imc/PM_PB_CYC/
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
[mpe: Change log tweaks for clarity and brevity]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This function is not called with the nest_init_lock held, and it also
unlocks the nest_init_lock immediately below, so it's fairly clear
that this is a typo and should be locking the lock.
Fixes: 885dcd709b ("powerpc/perf: Add nest IMC PMU support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add support to register Thread In-Memory Collection PMU counters.
Patch adds thread IMC specific data structures, along with memory
init functions and CPU hotplug support.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add support to register Core In-Memory Collection PMU counters.
Patch adds core IMC specific data structures, along with memory
init functions and CPU hotplug support.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add support to register Nest In-Memory Collection PMU counters.
Patch adds a new device file called "imc-pmu.c" under powerpc/perf
folder to contain all the device PMU functions.
Device tree parser code added to parse the PMU events information
and create sysfs event attributes for the PMU.
Cpumask attribute added along with Cpu hotplug online/offline functions
specific for nest PMU. A new state "CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE"
added for the cpu hotplug callbacks. Error handle path frees the memory
and unregisters the CPU hotplug callbacks.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Alexey Budankov