devm_kasprintf() may return NULL on failure of internal allocation
thus the assignment to 'name' is not safe if unchecked. If NULL
is passed in for name then perf_pmu_register() would not fail
but rather silently jump to skip_type which is not the intent
here. As perf_pmu_register() may also return -ENOMEM returning
-ENOMEM in the (unlikely) failure case of devm_kasprintf() should
be fine here as well.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Fixes: d5d9696b03 ("drivers/perf: Add support for ARMv8.2 Statistical Profiling Extension")
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
[will: reworded error message]
Signed-off-by: Will Deacon <will.deacon@arm.com>
When built as a module, the spe driver isn't automatically
loaded on DT systems. Add the MODULE_DEVICE_TABLE entry.
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
We should get drvdata from struct device directly. Going via
platform_device is an unneeded step back and forth.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
On linux-next, I get a build failure in some configurations:
drivers/perf/arm_spe_pmu.c: In function 'arm_spe_pmu_setup_aux':
drivers/perf/arm_spe_pmu.c:857:14: error: implicit declaration of function 'vmap'; did you mean 'swap'? [-Werror=implicit-function-declaration]
buf->base = vmap(pglist, nr_pages, VM_MAP, PAGE_KERNEL);
^~~~
swap
drivers/perf/arm_spe_pmu.c:857:37: error: 'VM_MAP' undeclared (first use in this function); did you mean 'VM_MPX'?
buf->base = vmap(pglist, nr_pages, VM_MAP, PAGE_KERNEL);
^~~~~~
VM_MPX
drivers/perf/arm_spe_pmu.c:857:37: note: each undeclared identifier is reported only once for each function it appears in
drivers/perf/arm_spe_pmu.c: In function 'arm_spe_pmu_free_aux':
drivers/perf/arm_spe_pmu.c:878:2: error: implicit declaration of function 'vunmap'; did you mean 'iounmap'? [-Werror=implicit-function-declaration]
vmap() is declared in linux/vmalloc.h, so we should include that header file.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[will: add additional missing #includes reported by Mark]
Signed-off-by: Will Deacon <will.deacon@arm.com>
When running with the kernel unmapped whilst at EL0, the virtually-addressed
SPE buffer is also unmapped, which can lead to buffer faults if userspace
profiling is enabled and potentially also when writing back kernel samples
unless an expensive drain operation is performed on exception return.
For now, fail the SPE driver probe when arm64_kernel_unmapped_at_el0().
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
When the PMU driver is built as a module, the perf expects the
pmu->module to be valid, so that the driver is prevented from
being unloaded while it is in use. Fix the SPE pmu driver to
fill in this field.
Cc: Will Deacon <will.deacon@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The ARMv8.2 architecture introduces the optional Statistical Profiling
Extension (SPE).
SPE can be used to profile a population of operations in the CPU pipeline
after instruction decode. These are either architected instructions (i.e.
a dynamic instruction trace) or CPU-specific uops and the choice is fixed
statically in the hardware and advertised to userspace via caps/. Sampling
is controlled using a sampling interval, similar to a regular PMU counter,
but also with an optional random perturbation to avoid falling into patterns
where you continuously profile the same instruction in a hot loop.
After each operation is decoded, the interval counter is decremented. When
it hits zero, an operation is chosen for profiling and tracked within the
pipeline until it retires. Along the way, information such as TLB lookups,
cache misses, time spent to issue etc is captured in the form of a sample.
The sample is then filtered according to certain criteria (e.g. load
latency) that can be specified in the event config (described under
format/) and, if the sample satisfies the filter, it is written out to
memory as a record, otherwise it is discarded. Only one operation can
be sampled at a time.
The in-memory buffer is linear and virtually addressed, raising an
interrupt when it fills up. The PMU driver handles these interrupts to
give the appearance of a ring buffer, as expected by the AUX code.
The in-memory trace-like format is self-describing (though not parseable
in reverse) and written as a series of records, with each record
corresponding to a sample and consisting of a sequence of packets. These
packets are defined by the architecture, although some have CPU-specific
fields for recording information specific to the microarchitecture.
As a simple example, a record generated for a branch instruction may
consist of the following packets:
0 (Address) : Virtual PC of the branch instruction
1 (Type) : Conditional direct branch
2 (Counter) : Number of cycles taken from Dispatch to Issue
3 (Address) : Virtual branch target + condition flags
4 (Counter) : Number of cycles taken from Dispatch to Complete
5 (Events) : Mispredicted as not-taken
6 (END) : End of record
It is also possible to toggle properties such as timestamp packets in
each record.
This patch adds support for SPE in the form of a new perf driver.
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
