diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c index 432ad2e80ce3..80c052e93f9e 100644 --- a/drivers/perf/riscv_pmu.c +++ b/drivers/perf/riscv_pmu.c @@ -38,7 +38,15 @@ void arch_perf_update_userpage(struct perf_event *event, userpg->cap_user_time_short = 0; userpg->cap_user_rdpmc = riscv_perf_user_access(event); - userpg->pmc_width = 64; +#ifdef CONFIG_RISCV_PMU + /* + * The counters are 64-bit but the priv spec doesn't mandate all the + * bits to be implemented: that's why, counter width can vary based on + * the cpu vendor. + */ + if (userpg->cap_user_rdpmc) + userpg->pmc_width = to_riscv_pmu(event->pmu)->ctr_get_width(event->hw.idx) + 1; +#endif do { rd = sched_clock_read_begin(&seq); diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c index 760eb2afcf82..9a51053b1f99 100644 --- a/drivers/perf/riscv_pmu_sbi.c +++ b/drivers/perf/riscv_pmu_sbi.c @@ -24,6 +24,14 @@ #include #include +#define SYSCTL_NO_USER_ACCESS 0 +#define SYSCTL_USER_ACCESS 1 +#define SYSCTL_LEGACY 2 + +#define PERF_EVENT_FLAG_NO_USER_ACCESS BIT(SYSCTL_NO_USER_ACCESS) +#define PERF_EVENT_FLAG_USER_ACCESS BIT(SYSCTL_USER_ACCESS) +#define PERF_EVENT_FLAG_LEGACY BIT(SYSCTL_LEGACY) + PMU_FORMAT_ATTR(event, "config:0-47"); PMU_FORMAT_ATTR(firmware, "config:63"); @@ -43,6 +51,9 @@ static const struct attribute_group *riscv_pmu_attr_groups[] = { NULL, }; +/* Allow user mode access by default */ +static int sysctl_perf_user_access __read_mostly = SYSCTL_USER_ACCESS; + /* * RISC-V doesn't have heterogeneous harts yet. This need to be part of * per_cpu in case of harts with different pmu counters @@ -301,6 +312,11 @@ int riscv_pmu_get_hpm_info(u32 *hw_ctr_width, u32 *num_hw_ctr) } EXPORT_SYMBOL_GPL(riscv_pmu_get_hpm_info); +static uint8_t pmu_sbi_csr_index(struct perf_event *event) +{ + return pmu_ctr_list[event->hw.idx].csr - CSR_CYCLE; +} + static unsigned long pmu_sbi_get_filter_flags(struct perf_event *event) { unsigned long cflags = 0; @@ -329,18 +345,34 @@ static int pmu_sbi_ctr_get_idx(struct perf_event *event) struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events); struct sbiret ret; int idx; - uint64_t cbase = 0; + uint64_t cbase = 0, cmask = rvpmu->cmask; unsigned long cflags = 0; cflags = pmu_sbi_get_filter_flags(event); + + /* + * In legacy mode, we have to force the fixed counters for those events + * but not in the user access mode as we want to use the other counters + * that support sampling/filtering. + */ + if (hwc->flags & PERF_EVENT_FLAG_LEGACY) { + if (event->attr.config == PERF_COUNT_HW_CPU_CYCLES) { + cflags |= SBI_PMU_CFG_FLAG_SKIP_MATCH; + cmask = 1; + } else if (event->attr.config == PERF_COUNT_HW_INSTRUCTIONS) { + cflags |= SBI_PMU_CFG_FLAG_SKIP_MATCH; + cmask = 1UL << (CSR_INSTRET - CSR_CYCLE); + } + } + /* retrieve the available counter index */ #if defined(CONFIG_32BIT) ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, - rvpmu->cmask, cflags, hwc->event_base, hwc->config, + cmask, cflags, hwc->event_base, hwc->config, hwc->config >> 32); #else ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, - rvpmu->cmask, cflags, hwc->event_base, hwc->config, 0); + cmask, cflags, hwc->event_base, hwc->config, 0); #endif if (ret.error) { pr_debug("Not able to find a counter for event %lx config %llx\n", @@ -474,6 +506,22 @@ static u64 pmu_sbi_ctr_read(struct perf_event *event) return val; } +static void pmu_sbi_set_scounteren(void *arg) +{ + struct perf_event *event = (struct perf_event *)arg; + + csr_write(CSR_SCOUNTEREN, + csr_read(CSR_SCOUNTEREN) | (1 << pmu_sbi_csr_index(event))); +} + +static void pmu_sbi_reset_scounteren(void *arg) +{ + struct perf_event *event = (struct perf_event *)arg; + + csr_write(CSR_SCOUNTEREN, + csr_read(CSR_SCOUNTEREN) & ~(1 << pmu_sbi_csr_index(event))); +} + static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival) { struct sbiret ret; @@ -490,6 +538,10 @@ static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival) if (ret.error && (ret.error != SBI_ERR_ALREADY_STARTED)) pr_err("Starting counter idx %d failed with error %d\n", hwc->idx, sbi_err_map_linux_errno(ret.error)); + + if ((hwc->flags & PERF_EVENT_FLAG_USER_ACCESS) && + (hwc->flags & PERF_EVENT_FLAG_USER_READ_CNT)) + pmu_sbi_set_scounteren((void *)event); } static void pmu_sbi_ctr_stop(struct perf_event *event, unsigned long flag) @@ -497,6 +549,10 @@ static void pmu_sbi_ctr_stop(struct perf_event *event, unsigned long flag) struct sbiret ret; struct hw_perf_event *hwc = &event->hw; + if ((hwc->flags & PERF_EVENT_FLAG_USER_ACCESS) && + (hwc->flags & PERF_EVENT_FLAG_USER_READ_CNT)) + pmu_sbi_reset_scounteren((void *)event); + ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0); if (ret.error && (ret.error != SBI_ERR_ALREADY_STOPPED) && flag != SBI_PMU_STOP_FLAG_RESET) @@ -704,10 +760,13 @@ static int pmu_sbi_starting_cpu(unsigned int cpu, struct hlist_node *node) struct cpu_hw_events *cpu_hw_evt = this_cpu_ptr(pmu->hw_events); /* - * Enable the access for CYCLE, TIME, and INSTRET CSRs from userspace, - * as is necessary to maintain uABI compatibility. + * We keep enabling userspace access to CYCLE, TIME and INSTRET via the + * legacy option but that will be removed in the future. */ - csr_write(CSR_SCOUNTEREN, 0x7); + if (sysctl_perf_user_access == SYSCTL_LEGACY) + csr_write(CSR_SCOUNTEREN, 0x7); + else + csr_write(CSR_SCOUNTEREN, 0x2); /* Stop all the counters so that they can be enabled from perf */ pmu_sbi_stop_all(pmu); @@ -838,6 +897,121 @@ static void riscv_pmu_destroy(struct riscv_pmu *pmu) cpuhp_state_remove_instance(CPUHP_AP_PERF_RISCV_STARTING, &pmu->node); } +static void pmu_sbi_event_init(struct perf_event *event) +{ + /* + * The permissions are set at event_init so that we do not depend + * on the sysctl value that can change. + */ + if (sysctl_perf_user_access == SYSCTL_NO_USER_ACCESS) + event->hw.flags |= PERF_EVENT_FLAG_NO_USER_ACCESS; + else if (sysctl_perf_user_access == SYSCTL_USER_ACCESS) + event->hw.flags |= PERF_EVENT_FLAG_USER_ACCESS; + else + event->hw.flags |= PERF_EVENT_FLAG_LEGACY; +} + +static void pmu_sbi_event_mapped(struct perf_event *event, struct mm_struct *mm) +{ + if (event->hw.flags & PERF_EVENT_FLAG_NO_USER_ACCESS) + return; + + if (event->hw.flags & PERF_EVENT_FLAG_LEGACY) { + if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES && + event->attr.config != PERF_COUNT_HW_INSTRUCTIONS) { + return; + } + } + + /* + * The user mmapped the event to directly access it: this is where + * we determine based on sysctl_perf_user_access if we grant userspace + * the direct access to this event. That means that within the same + * task, some events may be directly accessible and some other may not, + * if the user changes the value of sysctl_perf_user_accesss in the + * meantime. + */ + + event->hw.flags |= PERF_EVENT_FLAG_USER_READ_CNT; + + /* + * We must enable userspace access *before* advertising in the user page + * that it is possible to do so to avoid any race. + * And we must notify all cpus here because threads that currently run + * on other cpus will try to directly access the counter too without + * calling pmu_sbi_ctr_start. + */ + if (event->hw.flags & PERF_EVENT_FLAG_USER_ACCESS) + on_each_cpu_mask(mm_cpumask(mm), + pmu_sbi_set_scounteren, (void *)event, 1); +} + +static void pmu_sbi_event_unmapped(struct perf_event *event, struct mm_struct *mm) +{ + if (event->hw.flags & PERF_EVENT_FLAG_NO_USER_ACCESS) + return; + + if (event->hw.flags & PERF_EVENT_FLAG_LEGACY) { + if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES && + event->attr.config != PERF_COUNT_HW_INSTRUCTIONS) { + return; + } + } + + /* + * Here we can directly remove user access since the user does not have + * access to the user page anymore so we avoid the racy window where the + * user could have read cap_user_rdpmc to true right before we disable + * it. + */ + event->hw.flags &= ~PERF_EVENT_FLAG_USER_READ_CNT; + + if (event->hw.flags & PERF_EVENT_FLAG_USER_ACCESS) + on_each_cpu_mask(mm_cpumask(mm), + pmu_sbi_reset_scounteren, (void *)event, 1); +} + +static void riscv_pmu_update_counter_access(void *info) +{ + if (sysctl_perf_user_access == SYSCTL_LEGACY) + csr_write(CSR_SCOUNTEREN, 0x7); + else + csr_write(CSR_SCOUNTEREN, 0x2); +} + +static int riscv_pmu_proc_user_access_handler(struct ctl_table *table, + int write, void *buffer, + size_t *lenp, loff_t *ppos) +{ + int prev = sysctl_perf_user_access; + int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + + /* + * Test against the previous value since we clear SCOUNTEREN when + * sysctl_perf_user_access is set to SYSCTL_USER_ACCESS, but we should + * not do that if that was already the case. + */ + if (ret || !write || prev == sysctl_perf_user_access) + return ret; + + on_each_cpu(riscv_pmu_update_counter_access, NULL, 1); + + return 0; +} + +static struct ctl_table sbi_pmu_sysctl_table[] = { + { + .procname = "perf_user_access", + .data = &sysctl_perf_user_access, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = riscv_pmu_proc_user_access_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_TWO, + }, + { } +}; + static int pmu_sbi_device_probe(struct platform_device *pdev) { struct riscv_pmu *pmu = NULL; @@ -881,6 +1055,10 @@ static int pmu_sbi_device_probe(struct platform_device *pdev) pmu->ctr_get_width = pmu_sbi_ctr_get_width; pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx; pmu->ctr_read = pmu_sbi_ctr_read; + pmu->event_init = pmu_sbi_event_init; + pmu->event_mapped = pmu_sbi_event_mapped; + pmu->event_unmapped = pmu_sbi_event_unmapped; + pmu->csr_index = pmu_sbi_csr_index; ret = cpuhp_state_add_instance(CPUHP_AP_PERF_RISCV_STARTING, &pmu->node); if (ret) @@ -894,6 +1072,8 @@ static int pmu_sbi_device_probe(struct platform_device *pdev) if (ret) goto out_unregister; + register_sysctl("kernel", sbi_pmu_sysctl_table); + return 0; out_unregister: