Commit <684d984038aa> ('powerpc/powernv: Add debugfs interface for
imc-mode and imc') added debugfs interface for the nest imc pmu
devices to support changing of different ucode modes. Primarily adding
this capability for debug. But when doing so, the code did not
consider the case of cpu-less nodes. So when reading the _cmd_ or
_mode_ file of a cpu-less node will create this crash.
Faulting instruction address: 0xc0000000000d0d58
Oops: Kernel access of bad area, sig: 11 [#1]
...
CPU: 67 PID: 5301 Comm: cat Not tainted 5.2.0-rc6-next-20190627+ #19
NIP: c0000000000d0d58 LR: c00000000049aa18 CTR:c0000000000d0d50
REGS: c00020194548f9e0 TRAP: 0300 Not tainted (5.2.0-rc6-next-20190627+)
MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR:28022822 XER: 00000000
CFAR: c00000000049aa14 DAR: 000000000003fc08 DSISR:40000000 IRQMASK: 0
...
NIP imc_mem_get+0x8/0x20
LR simple_attr_read+0x118/0x170
Call Trace:
simple_attr_read+0x70/0x170 (unreliable)
debugfs_attr_read+0x6c/0xb0
__vfs_read+0x3c/0x70
vfs_read+0xbc/0x1a0
ksys_read+0x7c/0x140
system_call+0x5c/0x70
Patch fixes the issue with a more robust check for vbase to NULL.
Before patch, ls output for the debugfs imc directory
# ls /sys/kernel/debug/powerpc/imc/
imc_cmd_0 imc_cmd_251 imc_cmd_253 imc_cmd_255 imc_mode_0 imc_mode_251 imc_mode_253 imc_mode_255
imc_cmd_250 imc_cmd_252 imc_cmd_254 imc_cmd_8 imc_mode_250 imc_mode_252 imc_mode_254 imc_mode_8
After patch, ls output for the debugfs imc directory
# ls /sys/kernel/debug/powerpc/imc/
imc_cmd_0 imc_cmd_8 imc_mode_0 imc_mode_8
Actual bug here is that, we have two loops with potentially different
loop counts. That is, in imc_get_mem_addr_nest(), loop count is
obtained from the dt entries. But in case of export_imc_mode_and_cmd(),
loop was based on for_each_nid() count. Patch fixes the loop count in
latter based on the struct mem_info. Ideally it would be better to
have array size in struct imc_pmu.
Fixes: 684d984038 ('powerpc/powernv: Add debugfs interface for imc-mode and imc')
Reported-by: Qian Cai <cai@lca.pw>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190827101635.6942-1-maddy@linux.vnet.ibm.com
A minor fix to our IMC PMU code to print a less confusing error message when the
driver can't initialise properly.
A fix for a bug where a user requesting an unsupported branch sampling filter
can corrupt PMU state, preventing the PMU from counting properly.
And finally a fix for a bug in our support for kexec_file_load(), which
prevented loading a kernel and initramfs. Most versions of kexec don't yet use
kexec_file_load().
Thanks to:
Anju T Sudhakar, Dave Young, Madhavan Srinivasan, Ravi Bangoria, Thiago Jung
Bauermann.
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Merge tag 'powerpc-5.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
"A minor fix to our IMC PMU code to print a less confusing error
message when the driver can't initialise properly.
A fix for a bug where a user requesting an unsupported branch sampling
filter can corrupt PMU state, preventing the PMU from counting
properly.
And finally a fix for a bug in our support for kexec_file_load(),
which prevented loading a kernel and initramfs. Most versions of kexec
don't yet use kexec_file_load().
Thanks to: Anju T Sudhakar, Dave Young, Madhavan Srinivasan, Ravi
Bangoria, Thiago Jung Bauermann"
* tag 'powerpc-5.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/kexec: Fix loading of kernel + initramfs with kexec_file_load()
powerpc/perf: Fix MMCRA corruption by bhrb_filter
powerpc/powernv: Return for invalid IMC domain
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>
Currently init_imc_pmu() can fail either because we try to register an
IMC unit with an invalid domain (i.e an IMC node not supported by the
kernel) or something went wrong while registering a valid IMC unit. In
both the cases kernel provides a 'Register failed' error message.
For example when trace-imc node is not supported by the kernel, but
skiboot advertises a trace-imc node we print:
IMC Unknown Device type
IMC PMU (null) Register failed
To avoid confusion just print the unknown device type message, before
attempting PMU registration, so the second message isn't printed.
Fixes: 8f95faaac5 ("powerpc/powernv: Detect and create IMC device")
Reported-by: Pavaman Subramaniyam <pavsubra@in.ibm.com>
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Reword change log a bit]
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>
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>
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>
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>
It's slightly less error prone to use sizeof(*foo) rather than
specifying the type.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
[mpe: Consolidate into one patch, rewrite change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The OPAL IMC driver's shutdown handler disables nest PMU counters by
walking nodes and taking the first CPU out of their cpumask, which is
used to index into the paca (get_hard_smp_processor_id()). This does
not always do the right thing, and in particular for CPU-less nodes it
returns NR_CPUS and that overruns the paca and dereferences random
memory.
Fix it by being more careful about checking returned CPU, and only
using online CPUs. It's not clear this shutdown code makes sense after
commit 885dcd709b ("powerpc/perf: Add nest IMC PMU support"), but this
should not make things worse
Currently the bug causes us to call OPAL with a junk CPU number. A
separate patch in development to change the way pacas are allocated
escalates this bug into a crash:
Unable to handle kernel paging request for data at address 0x2a21af1eeb000076
Faulting instruction address: 0xc0000000000a5468
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP opal_imc_counters_shutdown+0x148/0x1d0
LR opal_imc_counters_shutdown+0x134/0x1d0
Call Trace:
opal_imc_counters_shutdown+0x134/0x1d0 (unreliable)
platform_drv_shutdown+0x44/0x60
device_shutdown+0x1f8/0x350
kernel_restart_prepare+0x54/0x70
kernel_restart+0x28/0xc0
SyS_reboot+0x1d0/0x2c0
system_call+0x58/0x6c
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In memory Collection (IMC) counter pmu driver controls the ucode's
execution state. At the system boot, IMC perf driver pause the ucode.
Ucode state is changed to "running" only when any of the nest units
are monitored or profiled using perf tool.
Nest units support only limited set of hardware counters and ucode is
always programmed in the "production mode" ("accumulation") mode. This
mode is configured to provide key performance metric data for most of
the nest units.
But ucode also supports other modes which would be used for "debug" to
drill down specific nest units. That is, ucode when switched to
"powerbus" debug mode (for example), will dynamically reconfigure the
nest counters to target only "powerbus" related events in the hardware
counters. This allows the IMC nest unit to focus on powerbus related
transactions in the system in more detail. At this point, production
mode events may or may not be counted.
IMC nest counters has both in-band (ucode access) and out of band
access to it. Since not all nest counter configurations are supported
by ucode, out of band tools are used to characterize other nest
counter configurations.
Patch provides an interface via "debugfs" to enable the switching of
ucode modes in the system. To switch ucode mode, one has to first
pause the microcode (imc_cmd), and then write the target mode value to
the "imc_mode" file.
Proposed Approach:
In the proposed approach, the function (export_imc_mode_and_cmd) which
creates the debugfs interface for imc mode and command is implemented
in opal-imc.c. Thus we can use imc_get_mem_addr() to get the homer
base address for each chip.
The interface to expose imc mode and command is required only if we
have nest pmu units registered. Employing the existing data structures
to track whether we have any nest units registered will require to
extend data from perf side to opal-imc.c. Instead an integer is
introduced to hold that information by counting successful nest unit
registration. Debugfs interface is removed based on the integer count.
Example for the interface:
$ ls /sys/kernel/debug/imc
imc_cmd_0 imc_cmd_8 imc_mode_0 imc_mode_8
Signed-off-by: Anju T Sudhakar <anju@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>
"pmu_count" in opal_imc_counters_probe() is intended to hold
the number of successful nest imc pmu registerations. But
current code also counts other imc units like core_imc and
thread_imc. Patch add a check to count only nest imc pmus.
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When building a random powerpc kernel I hit this build error:
arch/powerpc/platforms/powernv/opal-imc.c:130:13: error : assignment
discards « const » qualifier from pointer target type
[-Werror=discarded-qualifiers]
l_cpumask = cpumask_of_node(nid);
^
This happens because when CONFIG_NUMA=n cpumask_of_node() returns a
const pointer.
This patch simply adds const to l_cpumask to fix this issue.
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Flesh out change log]
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>
Code to create platform device for the In-Memory Collection (IMC)
counters. Platform devices are created based on the IMC compatibility.
New header file created to contain the data structures and macros
needed for In-Memory Collection (IMC) counter pmu devices.
The device tree for IMC counters starts at the node "imc-counters".
This node contains all the IMC PMU nodes and event nodes for these IMC
PMUs. Device probe() parses the device to locate three possible IMC
device types (Nest/Core/Thread). Function then branch to parse each
unit nodes to populate vital information such as device memory sizes,
event nodes information, base address for reserve memory access (if
any) and so on. Simple bare-minimum shutdown function added which only
"stops" the engines.
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>
[mpe: Fix build with CONFIG_PERF_EVENTS=n]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
