From: Thomas Richter Date: Wed, 28 Apr 2021 11:30:56 +0000 (+0200) Subject: s390/cpumf: remove counter transaction call backs X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d552a58d708020963f6973a8b3b690f19ac81c99;p=linux.git s390/cpumf: remove counter transaction call backs The command 'perf stat -e cycles ...' triggers the following function sequence in the CPU Measurement Facility counter device driver: perf_pmu_event_init() __hw_perf_event_init() validate_ctr_auth() validate_ctr_version() During event creation, the counter number is checked in functions validate_ctr_auth() and validate_ctr_version() to verify it is a valid counter and supported by the hardware. If this is not the case, both functions return an error and the event is not created. System call perf_event_open() returns an error in this case. Later on the event is installed in the kernel event subsystem and the driver functions cpumf_pmu_add() and cpumf_pmu_commit_txn() are called to install the counter event by the hardware. Since both events have been verified at event creation, there is no need to re-evaluate the authorization state. This can not change since on * LPARs the authorization change requires a restart of the LPAR (and thus a reboot of the kernel) * DPMs can not take resources away, just add them. Also the sequence of CPU Measurement facility counter device driver calls is cpumf_pmu_start_txn cpumf_pmu_add cpumf_pmu_start cpumf_pmu_commit_txn for every single event. Which means the condition in cpumf_pmu_add() is never met and validate_ctr_auth() is never called. This leaves the counter device driver transaction functions with just one task: start_txn: Verify a transaction is not in flight and call perf_pmu_disable() cancel_txn, commit_txn: Verify a transaction is in flight and call perf_pmu_enable() The same functionality is provided by the default transaction handling functions in kernel/events/core.c. Use those by removing the counter device driver private call back functions. Suggested-by: Sumanth Korikkar Signed-off-by: Thomas Richter Reviewed-by: Sumanth Korikkar Signed-off-by: Vasily Gorbik --- diff --git a/arch/s390/include/asm/cpu_mcf.h b/arch/s390/include/asm/cpu_mcf.h index 3e4cbcb7c4cc1..4dcefddb77513 100644 --- a/arch/s390/include/asm/cpu_mcf.h +++ b/arch/s390/include/asm/cpu_mcf.h @@ -92,9 +92,8 @@ struct cpu_cf_events { struct cpumf_ctr_info info; atomic_t ctr_set[CPUMF_CTR_SET_MAX]; atomic64_t alert; - u64 state, tx_state; + u64 state; unsigned int flags; - unsigned int txn_flags; }; DECLARE_PER_CPU(struct cpu_cf_events, cpu_cf_events); diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c index 31a605bcbc6e3..91ee0f399aae4 100644 --- a/arch/s390/kernel/perf_cpum_cf.c +++ b/arch/s390/kernel/perf_cpum_cf.c @@ -413,15 +413,6 @@ static int cpumf_pmu_add(struct perf_event *event, int flags) { struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); - /* Check authorization for the counter set to which this - * counter belongs. - * For group events transaction, the authorization check is - * done in cpumf_pmu_commit_txn(). - */ - if (!(cpuhw->txn_flags & PERF_PMU_TXN_ADD)) - if (validate_ctr_auth(&event->hw)) - return -ENOENT; - ctr_set_enable(&cpuhw->state, event->hw.config_base); event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED; @@ -449,78 +440,6 @@ static void cpumf_pmu_del(struct perf_event *event, int flags) ctr_set_disable(&cpuhw->state, event->hw.config_base); } -/* - * Start group events scheduling transaction. - * Set flags to perform a single test at commit time. - * - * We only support PERF_PMU_TXN_ADD transactions. Save the - * transaction flags but otherwise ignore non-PERF_PMU_TXN_ADD - * transactions. - */ -static void cpumf_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags) -{ - struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); - - WARN_ON_ONCE(cpuhw->txn_flags); /* txn already in flight */ - - cpuhw->txn_flags = txn_flags; - if (txn_flags & ~PERF_PMU_TXN_ADD) - return; - - perf_pmu_disable(pmu); - cpuhw->tx_state = cpuhw->state; -} - -/* - * Stop and cancel a group events scheduling tranctions. - * Assumes cpumf_pmu_del() is called for each successful added - * cpumf_pmu_add() during the transaction. - */ -static void cpumf_pmu_cancel_txn(struct pmu *pmu) -{ - unsigned int txn_flags; - struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); - - WARN_ON_ONCE(!cpuhw->txn_flags); /* no txn in flight */ - - txn_flags = cpuhw->txn_flags; - cpuhw->txn_flags = 0; - if (txn_flags & ~PERF_PMU_TXN_ADD) - return; - - WARN_ON(cpuhw->tx_state != cpuhw->state); - - perf_pmu_enable(pmu); -} - -/* - * Commit the group events scheduling transaction. On success, the - * transaction is closed. On error, the transaction is kept open - * until cpumf_pmu_cancel_txn() is called. - */ -static int cpumf_pmu_commit_txn(struct pmu *pmu) -{ - struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events); - u64 state; - - WARN_ON_ONCE(!cpuhw->txn_flags); /* no txn in flight */ - - if (cpuhw->txn_flags & ~PERF_PMU_TXN_ADD) { - cpuhw->txn_flags = 0; - return 0; - } - - /* check if the updated state can be scheduled */ - state = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1); - state >>= CPUMF_LCCTL_ENABLE_SHIFT; - if ((state & cpuhw->info.auth_ctl) != state) - return -ENOENT; - - cpuhw->txn_flags = 0; - perf_pmu_enable(pmu); - return 0; -} - /* Performance monitoring unit for s390x */ static struct pmu cpumf_pmu = { .task_ctx_nr = perf_sw_context, @@ -533,9 +452,6 @@ static struct pmu cpumf_pmu = { .start = cpumf_pmu_start, .stop = cpumf_pmu_stop, .read = cpumf_pmu_read, - .start_txn = cpumf_pmu_start_txn, - .commit_txn = cpumf_pmu_commit_txn, - .cancel_txn = cpumf_pmu_cancel_txn, }; static int __init cpumf_pmu_init(void) diff --git a/arch/s390/kernel/perf_cpum_cf_common.c b/arch/s390/kernel/perf_cpum_cf_common.c index 6d53215c8484b..2300fbaac556a 100644 --- a/arch/s390/kernel/perf_cpum_cf_common.c +++ b/arch/s390/kernel/perf_cpum_cf_common.c @@ -30,7 +30,6 @@ DEFINE_PER_CPU(struct cpu_cf_events, cpu_cf_events) = { .alert = ATOMIC64_INIT(0), .state = 0, .flags = 0, - .txn_flags = 0, }; /* Indicator whether the CPU-Measurement Counter Facility Support is ready */ static bool cpum_cf_initalized;