Free_sampling_buffer() releases the Sampling Data Buffers (SDBs)
and Sampling Data Buffer Table (SDBTs) allocated at event
initialization. Both buffers are of PAGE_SIZE bytes. Each SDBT
consists of 512 entries. The first 511 entries point to SDBs
the last entry points to a successor SDBT. The last SDBT in
the list points to the origin of all SDBTs. SDBTs do not
contain holes, that is an entry always points to a SDB.
If less than 511 SDBs have been allocation, the last entry
points to the origin SDBT.
Simplify the release of the SDBs and SDBTs, walk along the
SDBT chain, release SDBs and SDBTs and stop when reaching
the origin again.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Convert cmpxchg128() usages to try_cmpxchg128() in order to generate
slightly better code.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reservation of the PMU hardware is done at first event creation
and is protected by a pair of mutex_lock() and mutex_unlock().
After reservation of the PMU hardware the memory
required for the PMUs the event is to be installed on is
allocated by allocate_buffers() and alloc_sampling_buffer().
This done outside of the mutex protection.
Without mutex protection two or more concurrent invocations of
perf_event_init() may run in parallel.
This can lead to allocation of Sample Data Blocks (SDBs)
multiple times for the same PMU.
Prevent this and protect memory allocation of SDBs by
mutex.
Fixes: 8a6fe8f21e ("s390/cpum_sf: Use refcount_t instead of atomic_t")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Setup_pmc_cpu() function body consists of one single switch
statement with two cases PMC_INIT and PMC_RELEASE.
In both of these cases sf_disable() is invoked to turn off the
CPU Measurement sampling facility.
Move sf_disable() out of the switch statement.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
CPU hotplug remove handling triggers the following function
call sequence:
CPUHP_AP_PERF_S390_SF_ONLINE --> s390_pmu_sf_offline_cpu()
...
CPUHP_AP_PERF_ONLINE --> perf_event_exit_cpu()
The s390 CPUMF sampling CPU hotplug handler invokes:
s390_pmu_sf_offline_cpu()
+--> cpusf_pmu_setup()
+--> setup_pmc_cpu()
+--> deallocate_buffers()
This function de-allocates all sampling data buffers (SDBs) allocated
for that CPU at event initialization. It also clears the
PMU_F_RESERVED bit. The CPU is gone and can not be sampled.
With the event still being active on the removed CPU, the CPU event
hotplug support in kernel performance subsystem triggers the
following function calls on the removed CPU:
perf_event_exit_cpu()
+--> perf_event_exit_cpu_context()
+--> __perf_event_exit_context()
+--> __perf_remove_from_context()
+--> event_sched_out()
+--> cpumsf_pmu_del()
+--> cpumsf_pmu_stop()
+--> hw_perf_event_update()
to stop and remove the event. During removal of the event, the
sampling device driver tries to read out the remaining samples from
the sample data buffers (SDBs). But they have already been freed
(and may have been re-assigned). This may lead to a use after free
situation in which case the samples are most likely invalid. In the
best case the memory has not been reassigned and still contains
valid data.
Remedy this situation and check if the CPU is still in reserved
state (bit PMU_F_RESERVED set). In this case the SDBs have not been
released an contain valid data. This is always the case when
the event is removed (and no CPU hotplug off occured).
If the PMU_F_RESERVED bit is not set, the SDB buffers are gone.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Fix format string in pr_err() and use the built-in
hexadecimal prefix %#x to display a number with a leading
hexadecimal indicator 0x.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use sf_buffer_available() consistently throughtout the code
to test for the existence of sampling buffer.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
When the sampling buffer allocation fails in
__hw_perf_event_init(), jump to the end of the function
and return the result. This is consistent with the other
error handling and return conditions in this function.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-By: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Event delete removes an event from the event list, but common
code invokes the PMU's enable function later on. This happens
in event_sched_out() and leads to the following call sequence:
event_sched_out()
+--> cpumsf_pmu_del()
+--> cpumsf_pmu_enable()
In cpumsf_pmu_enable() return immediately when the event is not
active. Also remove an unneeded if clause. That if() statement
is only reached when flag PMU_F_IN_USE has been set in
cpumsf_pmu_add(). And this function also sets cpuhw->event
to a valid value.
Remove WARN_ON_ONCE() statement which never triggered.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Set PMU enabled bit after lpp() call. This ensures the proper
task PID is loaded by the llp instruction into Program Parameter
register from where it is copied to each sampling data buffer
(SDB) sample entry after the sampling was enabled.
The barrier() instruction is not needed as cpumsf_pmu_enable()
changes a CPU specific variable. Only the CPU that task is
running on changes structure members.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Remove WARN_ON_ONCE statements. These have not triggered in the
past.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Rework debug messages:
- Remove most of the debug_sprintf_event() invocations.
- Do not split string format statements
- Remove colon after function name.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
qsi() executes the instruction qsi (query sample information)
and stores the result of the query in a sample information block
pointed to by the function argument. The instruction does not
change the condition code register. The return code is always
zero. No need to check for errors. Remove now unreferenced
macros PMC_FAILURE and RS_INIT_FAILURE_QSI.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
sf_disable() returns the condition code of instruction lsctl (load
sampling controls). However the parameter to lsctl() in
sf_disable() is a sample control block containing
all zeroes. This invocation of lsctl() does not fail and returns
always zero even when there is no authorization for sampling
on the machine. In short, sampling can be always turned off.
Ignore the return code of sf_disable() and change the function
return to void.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
All functions but setup_pmc_cpu() use a local variable named
cpuhw to refer to struct cpu_hw_sf.
In setup_pmc_cpu() rename variable cpusf to cpuhw. This makes
the naming scheme consistent with all other functions.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Define and initialize a variable in one place.
Remove space between cast and variable.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Some defines in common header file arch/s390/include/asm/perf_event.h
are only used in one source file arch/s390/kernel/perf_cpum_sf.c.
Move these defines from header to source file.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Rename macro SAMPLE_FREQ_MODE to SAMPL_FREQ_MODE to make its
prefix consistent with all other macro starting with prefix
SAMPL_XXX.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Member hw_perf_event::reg.reg is set but never used, so remove it.
Defines REG_NONE and REG_OVERFLOW are not referenced anymore.
The initialization to zero takes place in function
perf_event_alloc() where
...
event = kmem_cache_alloc_node(perf_event_cache,
GFP_KERNEL | __GFP_ZERO, node);
...
makes sure memory allocated for the event is zero'ed.
This is done in the kernel's common code in kernel/events/core.c
The struct perf_event contains member hw_perf_event as in
struct perf_event {
....
struct hw_perf_event hw;
....
};
This contained sub-structure is also initialized to zero.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Replace all S390_lowcore usages in arch/s390/ by get_lowcore().
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
During sampling event initialization, a check is done if that
particular CPU the event is to be installed on is actually online.
This check is not necessary, as it is also performed in the
system call entry point. Therefore remove this check.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
The casts are written in two different notations:
(cast) expression
and
(cast)expression
Convert statements with the first notation to the second notation.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Remove debug_sprint_event() statement right after an pr_err()
statement. No additional debug information is generated.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
The op argument is hardcoded in the parameter list of function pr_err.
Make the op code part of the text printed by pr_err.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Print the error message when the FAILURE flag is set.
This saves on pr_err statement as the text of the error message
is identical in both failures.
Also observe reverse Xmas tree variable declarations in this function.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Include linux/io.h instead of asm/io.h everywhere. linux/io.h includes
asm/io.h, so this shouldn't cause any problems. Instead this might help for
some randconfig build errors which were reported due to some undefined io
related functions.
Also move the changed include so it stays grouped together with other
includes from the same directory.
For ctcm_mpc.c also remove not needed comments (actually questions).
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Now that there is a cross arch u128 and cmpxchg128(), use those
instead of the custom CDSG helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230531132324.058821078@infradead.org
This flag is used to process only fully populated sampling buffers
when an sampling event is stopped on a CPU. By default the last sampling
buffer is also scanned for samples even if the sampling block full
indicator is not set in the trailer entry of a sampling buffer page.
This flag can be set via perf_event_attr::config1 field. It was never
used and never documented. It is useless now.
With PERF_CPUM_SF_FULL_BLOCKS:
When a process is scheduled off the CPU, the sampling is stopped and
the samples are copied to the perf ring buffer and marked invalid.
When stopped at the last full sample buffer page (which is
achieved with the PERF_CPUM_SF_FULL_BLOCKS options), the hardware
sampling will resume at the first free sample entry in the current,
partially filled sample buffer.
Without PERF_CPUM_SF_FULL_BLOCKS (default behavior):
The partially filled last sample buffer is scanned and valid samples
are saved to the perf ring buffer. The valid samples are marked invalid.
The sampling is resumed when the process is scheduled on this CPU.
Again the hardware sampling will resume at the first free sample entry in
the current, partially filled sample buffer.
Now the next interrupt handler invocation scans the
full sample block and saves the valid samples to the ring buffer.
It omits the invalid samples at the top of the buffer.
The default behavior is fully sufficient, therefore remove this feature.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Use READ_ONCE_ALIGNED_128() to read the previous value in front of a
128-bit cmpxchg loop, instead of (mis-)using a 128-bit cmpxchg operation to
do the same.
This makes the code more readable and is faster.
Link: https://lore.kernel.org/r/20230224100237.3247871-3-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
- Large cleanup of the con3270/tty3270 driver. Among others this fixes:
* Background Color Support
* ASCII Line Character Support
* VT100 Support
* Geometries other than 80x24
- Cleanup and improve cmpxchg() code. Also add cmpxchg_user_key() to
uaccess functions, which will be used by KVM to access KVM guest memory
with a specific storage key.
- Add support for user space events counting to CPUMF.
- Cleanup the vfio/ccw code, which also allows now to properly support 2K
Format-2 IDALs.
- Move kernel page table allocation and initialization to decompressor,
which finally allows to enter the kernel with dynamic address translation
enabled. This in turn allows to get rid of code with special handling in
the kernel, which has to distinguish if DAT is on or off.
- Replace kretprobe with rethook.
- Various improvements to vfio/ap queue resets:
* Use TAPQ to verify completion of a reset in progress rather than
multiple invocations of ZAPQ.
* Check TAPQ response codes when verifying successful completion of ZAPQ.
* Fix erroneous handling of some error response codes.
* Increase the maximum amount of time to wait for successful completion
of ZAPQ.
- Rework system call wrappers to get rid of alias functions, which were
only left on s390.
- Cleanup diag288_wdt watchdog driver. It has been agreed on with Guenter
Roeck that this goes upstream via the s390 tree.
- Add missing loadparm parameter handling for list-directed ECKD ipl/reipl.
- Various improvements to memory detection code.
- Remove arch_cpu_idle_time() since the current implementation is broken,
and allows user space observable accounted idle times which can
temporarily decrease.
- Add Reset DAT-Protection support: (only) allow to change PTEs from RO to
RW with a new RDP instruction. Unlike the currently used IPTE
instruction, this does not necessarily guarantee that TLBs of all CPUs
are synchronously flushed; and that remote CPUs can see spurious
protection faults. The overall improvement for not requiring an all CPU
synchronization, like it is required with IPTE, should be beneficial.
- Fix KFENCE page fault reporting.
- Smaller cleanups and improvement all over the place.
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Merge tag 's390-6.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Heiko Carstens:
- Large cleanup of the con3270/tty3270 driver. Among others this fixes:
- Background Color Support
- ASCII Line Character Support
- VT100 Support
- Geometries other than 80x24
- Cleanup and improve cmpxchg() code. Also add cmpxchg_user_key() to
uaccess functions, which will be used by KVM to access KVM guest
memory with a specific storage key
- Add support for user space events counting to CPUMF
- Cleanup the vfio/ccw code, which also allows now to properly support
2K Format-2 IDALs
- Move kernel page table allocation and initialization to decompressor,
which finally allows to enter the kernel with dynamic address
translation enabled. This in turn allows to get rid of code with
special handling in the kernel, which has to distinguish if DAT is on
or off
- Replace kretprobe with rethook
- Various improvements to vfio/ap queue resets:
- Use TAPQ to verify completion of a reset in progress rather than
multiple invocations of ZAPQ.
- Check TAPQ response codes when verifying successful completion of
ZAPQ.
- Fix erroneous handling of some error response codes.
- Increase the maximum amount of time to wait for successful
completion of ZAPQ
- Rework system call wrappers to get rid of alias functions, which were
only left on s390
- Cleanup diag288_wdt watchdog driver. It has been agreed on with
Guenter Roeck that this goes upstream via the s390 tree
- Add missing loadparm parameter handling for list-directed ECKD
ipl/reipl
- Various improvements to memory detection code
- Remove arch_cpu_idle_time() since the current implementation is
broken, and allows user space observable accounted idle times which
can temporarily decrease
- Add Reset DAT-Protection support: (only) allow to change PTEs from RO
to RW with a new RDP instruction. Unlike the currently used IPTE
instruction, this does not necessarily guarantee that TLBs of all
CPUs are synchronously flushed; and that remote CPUs can see spurious
protection faults. The overall improvement for not requiring an all
CPU synchronization, like it is required with IPTE, should be
beneficial
- Fix KFENCE page fault reporting
- Smaller cleanups and improvement all over the place
* tag 's390-6.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (182 commits)
s390/irq,idle: simplify idle check
s390/processor: add test_and_set_cpu_flag() and test_and_clear_cpu_flag()
s390/processor: let cpu helper functions return boolean values
s390/kfence: fix page fault reporting
s390/zcrypt: introduce ctfm field in struct CPRBX
s390: remove confusing comment from uapi types header file
vfio/ccw: remove WARN_ON during shutdown
s390/entry: remove toolchain dependent micro-optimization
s390/mem_detect: do not truncate online memory ranges info
s390/vx: remove __uint128_t type from __vector128 struct again
s390/mm: add support for RDP (Reset DAT-Protection)
s390/mm: define private VM_FAULT_* reasons from top bits
Documentation: s390: correct spelling
s390/ap: fix status returned by ap_qact()
s390/ap: fix status returned by ap_aqic()
s390: vfio-ap: tighten the NIB validity check
Revert "s390/mem_detect: do not update output parameters on failure"
s390/idle: remove arch_cpu_idle_time() and corresponding code
s390/vx: use simple assignments to access __vector128 members
s390/vx: add 64 and 128 bit members to __vector128 struct
...
The CPU Measurement Sampling Facility (CPUM_SF) installs large buffers
to save samples collected by hardware. These buffers are organized
as Sample Data Buffer Tables (SDBT) and Sample Data Buffers (SDB).
SDBs contain the samples which are extracted and saved in the perf
ring buffer.
The SDBTs are chained using real addresses and refer to SDBs using
real addresses.
The diagnostic sampling setup uses buffers provided by the process
which invokes perf_event_open system call. The buffers are memory
mapped. The buffers have been allocated by the kernel event
subsystem.
Add proper virtual to phyiscal address translation to the buffer
chaining. The current constraint which requires virtual equals
real address layout is removed.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Macro AUX_SDB_NUM() has three parameters. The first one is not used.
Remove the first parameter. Also convert the macros to inline functions.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The CPU Measurement Sampling Facility (CPUM_SF) installs large buffers
to save samples collected by hardware. These buffers are organized
as Sample Data Buffer Tables (SDBT) and Sample Data Buffers (SDB).
SDBs contain the samples which are extracted and saved in the perf
ring buffer.
The SDBTs are chained using real addresses and refer to SDBs using
real addresses.
Adds proper virtual to phyiscal address translation to the buffer
chaining. The current constraint which requires virtual equals real
address layout is removed.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Remove debug statements from function setup_pmc_cpu().
The debug statement displays a pointer value to a per cpu variable.
This pointer value is printed nowhere else, so it has no use for
cross reference.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Some inline helper functions are defined in a header file but used
in only one source file. Move these functions to the source file.
No functional change.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Factor out perf_prepare_header() so that it can call
perf_prepare_sample() without a header if not needed.
Also it checks the filtered_sample_type to avoid duplicate
work when perf_prepare_sample() is called twice (or more).
Suggested-by: Peter Zijlstr <peterz@infradead.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230118060559.615653-8-namhyung@kernel.org
The current cmpxchg_double() loops within the perf hw sampling code do not
have READ_ONCE() semantics to read the old value from memory. This allows
the compiler to generate code which reads the "old" value several times
from memory, which again allows for inconsistencies.
For example:
/* Reset trailer (using compare-double-and-swap) */
do {
te_flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
te_flags |= SDB_TE_ALERT_REQ_MASK;
} while (!cmpxchg_double(&te->flags, &te->overflow,
te->flags, te->overflow,
te_flags, 0ULL));
The compiler could generate code where te->flags used within the
cmpxchg_double() call may be refetched from memory and which is not
necessarily identical to the previous read version which was used to
generate te_flags. Which in turn means that an incorrect update could
happen.
Fix this by adding READ_ONCE() semantics to all cmpxchg_double()
loops. Given that READ_ONCE() cannot generate code on s390 which atomically
reads 16 bytes, use a private compare-and-swap-double implementation to
achieve that.
Also replace cmpxchg_double() with the private implementation to be able to
re-use the old value within the loops.
As a side effect this converts the whole code to only use bit fields
to read and modify bits within the hws trailer header.
Reported-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/linux-s390/Y71QJBhNTIatvxUT@osiris/T/#ma14e2a5f7aa8ed4b94b6f9576799b3ad9c60f333
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Adds support for the CPU Measurement Sampling Facility limit sampling
bit in the sampling device driver.
Limited samples have no valueable information are not collected.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Convert tod_clock_base to union tod_clock. This simplifies quite a bit
of code and also fixes a bug in read_persistent_clock64();
void read_persistent_clock64(struct timespec64 *ts)
{
__u64 delta;
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
get_tod_clock_ext(clk);
*(__u64 *) &clk[1] -= delta;
if (*(__u64 *) &clk[1] > delta)
clk[0]--;
ext_to_timespec64(clk, ts);
}
Assume &clk[1] == 3 and delta == 2; then after the substraction the if
condition becomes true and the epoch part of the clock is decremented
by one because of an assumed overflow, even though there is none.
Fix this by using 128 bit arithmetics and let the compiler do the
right thing:
void read_persistent_clock64(struct timespec64 *ts)
{
union tod_clock clk;
u64 delta;
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
store_tod_clock_ext(&clk);
clk.eitod -= delta;
ext_to_timespec64(&clk, ts);
}
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
any TIF/CIF/PIF set
- fix file permission for cpum_sfb_size parameter
- another small defconfig update
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Merge tag 's390-5.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 fixes from Heiko Carstens:
- fix system call exit path; avoid return to user space with any
TIF/CIF/PIF set
- fix file permission for cpum_sfb_size parameter
- another small defconfig update
* tag 's390-5.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/cpum_sf.c: fix file permission for cpum_sfb_size
s390: update defconfigs
s390: fix system call exit path
This file is installed by the s390 CPU Measurement sampling
facility device driver to export supported minimum and
maximum sample buffer sizes.
This file is read by lscpumf tool to display the details
of the device driver capabilities. The lscpumf tool might
be invoked by a non-root user. In this case it does not
print anything because the file contents can not be read.
Fix this by allowing read access for all users. Reading
the file contents is ok, changing the file contents is
left to the root user only.
For further reference and details see:
[1] https://github.com/ibm-s390-tools/s390-tools/issues/97
Fixes: 69f239ed33 ("s390/cpum_sf: Dynamically extend the sampling buffer if overflows occur")
Cc: <stable@vger.kernel.org> # 3.14
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
__perf_output_begin() has an on-stack struct perf_sample_data in the
unlikely case it needs to generate a LOST record. However, every call
to perf_output_begin() must already have a perf_sample_data on-stack.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201030151954.985416146@infradead.org
CPU Measurement sampling facility on s390 does not support
perf tool collection of callchain data using --call-graph
option. The sampling facility collects samples in a ring
buffer which includes only the instruction address the
samples were taken. When the ring buffer hits a watermark,
a measurement alert interrupt is triggered and handled
by the performance measurement unit (PMU) device driver.
It collects the samples and feeds each sample to the
perf ring buffer in the common code via functions
perf_prepare_sample()/perf_output_sample(). When function
perf_prepare_sample() is called to collect sample data's
callchain, user register values or stack area, invalid
data is picked, because the context of the collected
information does not match the context when the sample
was taken.
There is currently no way to provide the callchain and other
information, because the hardware sampler does not collect this
information.
Therefore prohibit sampling when the user requests a callchain graph
from the hardware sampler. Return -EOPNOTSUPP to the user in this
case.
If call chains are really wanted, users need to specify software
event cpu-clock to get the callchain information from a
software event.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
When perf record -e SF_CYCLES_BASIC_DIAG runs with very high
frequency, the samples arrive faster than the perf process can
save them to file. Eventually, for longer running processes, this
leads to the siutation where the trace buffers allocated by perf
slowly fills up. At one point the auxiliary trace buffer is full
and the CPU Measurement sampling facility is turned off. Furthermore
a warning is printed to the kernel log buffer:
cpum_sf: The AUX buffer with 0 pages for the diagnostic-sampling
mode is full
The number of allocated pages for the auxiliary trace buffer is shown
as zero pages. That is wrong.
Fix this by saving the number of allocated pages before entering the
work loop in the interrupt handler. When the interrupt handler processes
the samples, it may detect the buffer full condition and stop sampling,
reducing the buffer size to zero.
Print the correct value in the error message:
cpum_sf: The AUX buffer with 256 pages for the diagnostic-sampling
mode is full
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Adjust sampling buffer allocation depending on
frequency and correct comments. Investigation on the
interrupt handler revealed that almost always one interupt
services one SDB, even when running with the maximum frequency
of 100000. Very rarely there have been 2 SBD serviced per
interrupt.
Therefore reduce the number of SBD per CPU. Each SDB is one
page in size. The new formula results in
freq:4000 n_sdb:32 new:16
freq:10000 n_sdb:80 new:16
freq:20000 n_sdb:159 new:17
freq:40000 n_sdb:318 new:19
freq:50000 n_sdb:397 new:20
freq:62500 n_sdb:497 new:22
freq:83333 n_sdb:662 new:24
freq:100000 n_sdb:794 new:25
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Use macro DIV_ROUND_UP() for calculation of number of SDBT
SDBT pages required for index pages. This macro is already
used throughout the file.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
