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c190fb35f3
Background: The pm_ev field of struct pmc_op_pmcallocate and struct pmc traditionally contains the index of the chosen event, corresponding to the __PMC_EVENTS array in pmc_events.h. This is a static list of events, maintained by FreeBSD. In the usual case, libpmc translates the user supplied event name (string) into the pm_ev index, which is passed as an argument to the allocation syscall. On the kernel side, the allocation method for the relevant hwpmc class translates the given index into the event code that will be written to an event selection register. In 2018, a new source of performance event definitions was introduced: the pmu-events json files, which are maintained by the Linux kernel. The result was better coverage for newer Intel processors with a reduced maintenance burden for libpmc/hwpmc. Intel and AMD CPUs were unconditionally switched to allocate events from pmu-events instead of the traditional scheme (959826ca1b,81eb4dcf9e). Under the pmu-events scheme, the pm_ev field contains an index corresponding to the selected event from the pmu-events table, something which the kernel has no knowledge of. The configuration for the performance counting registers is instead passed via class-dependent fields (struct pmc_md_op_pmcallocate). In 2021 I changed the allocation logic so that it would attempt to pull from the pmu-events table first, and fall-back to the traditional method (dfb4fb4116). Later, pmu-events support for arm64 and power8 CPUs was added (28dd6730a5andb48a2770d4). The problem that remains is that the pm_ev field is overloaded, without a definitive way to determine whether the event allocation came from the pmu-events table or FreeBSD's statically-defined PMC events. This resulted in a recent fix,21f7397a61. Change: To disambiguate these two supported but separate use-cases, add a new flag, PMC_F_EV_PMU, to be set as part of the allocation, indicating that the event index came from pmu-events. This is useful in two ways: 1. On the kernel side, we can validate the syscall arguments better. Some classes support only the traditional event scheme (e.g. hwpmc_armv7), while others support only the pmu-events method (e.g. hwpmc_core for Intel). We can now check for this. The hwpmc_arm64 class supports both methods, so the new flag supersedes the existing MD flag, PM_MD_EVENT_RAW. 2. The flag will be tracked in struct pmc for the duration of its lifetime, meaning it is communicated back to userspace. This allows libpmc to perform the reverse index-to-event-name translation without speculating about the meaning of the index value. Adding the flag is a backwards-incompatible ABI change. We recently bumped the major version of the hwpmc module, so this breakage is acceptable. Reviewed by: jkoshy MFC after: 3 days Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D40753
92 lines
3.1 KiB
C
92 lines
3.1 KiB
C
/*-
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* Copyright (c) 2009 Rui Paulo <rpaulo@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _MACHINE_PMC_MDEP_H_
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#define _MACHINE_PMC_MDEP_H_
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#define PMC_MDEP_CLASS_INDEX_ARMV8 1
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#define PMC_MDEP_CLASS_INDEX_DMC620_CD2 2
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#define PMC_MDEP_CLASS_INDEX_DMC620_C 3
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#define PMC_MDEP_CLASS_INDEX_CMN600 4
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/*
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* On the ARMv8 platform we support the following PMCs.
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*
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* ARMV8 ARM Cortex-A53/57/72 processors
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*/
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#include <dev/hwpmc/hwpmc_arm64.h>
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#include <dev/hwpmc/hwpmc_cmn600.h>
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#include <dev/hwpmc/hwpmc_dmc620.h>
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#include <dev/hwpmc/pmu_dmc620_reg.h>
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#include <machine/cmn600_reg.h>
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union pmc_md_op_pmcallocate {
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struct {
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uint32_t pm_md_config;
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};
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struct pmc_md_cmn600_pmu_op_pmcallocate pm_cmn600;
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struct pmc_md_dmc620_pmu_op_pmcallocate pm_dmc620;
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uint64_t __pad[4];
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};
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/* Logging */
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#define PMCLOG_READADDR PMCLOG_READ64
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#define PMCLOG_EMITADDR PMCLOG_EMIT64
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#ifdef _KERNEL
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union pmc_md_pmc {
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struct pmc_md_arm64_pmc pm_arm64;
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struct pmc_md_cmn600_pmc pm_cmn600;
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struct pmc_md_dmc620_pmc pm_dmc620;
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};
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#define PMC_IN_KERNEL_STACK(va) kstack_contains(curthread, (va), sizeof(va))
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#define PMC_IN_KERNEL(va) INKERNEL((va))
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#define PMC_IN_USERSPACE(va) ((va) <= VM_MAXUSER_ADDRESS)
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#define PMC_TRAPFRAME_TO_PC(TF) ((TF)->tf_elr)
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#define PMC_TRAPFRAME_TO_FP(TF) ((TF)->tf_x[29])
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/*
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* Prototypes
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*/
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struct pmc_mdep *pmc_arm64_initialize(void);
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void pmc_arm64_finalize(struct pmc_mdep *_md);
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/* Optional class for CMN-600 controler's PMU. */
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int pmc_cmn600_initialize(struct pmc_mdep *md);
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void pmc_cmn600_finalize(struct pmc_mdep *_md);
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int pmc_cmn600_nclasses(void);
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/* Optional class for DMC-620 controler's PMU. */
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int pmc_dmc620_initialize_cd2(struct pmc_mdep *md);
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void pmc_dmc620_finalize_cd2(struct pmc_mdep *_md);
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int pmc_dmc620_initialize_c(struct pmc_mdep *md);
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void pmc_dmc620_finalize_c(struct pmc_mdep *_md);
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int pmc_dmc620_nclasses(void);
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#endif /* _KERNEL */
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#endif /* !_MACHINE_PMC_MDEP_H_ */
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