diff options
Diffstat (limited to 'arch/powerpc/platforms/pseries/dtl.c')
-rw-r--r-- | arch/powerpc/platforms/pseries/dtl.c | 445 |
1 files changed, 445 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c new file mode 100644 index 0000000000..3f1cdccebc --- /dev/null +++ b/arch/powerpc/platforms/pseries/dtl.c @@ -0,0 +1,445 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Virtual Processor Dispatch Trace Log + * + * (C) Copyright IBM Corporation 2009 + * + * Author: Jeremy Kerr <jk@ozlabs.org> + */ + +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <asm/smp.h> +#include <linux/uaccess.h> +#include <linux/debugfs.h> +#include <asm/firmware.h> +#include <asm/dtl.h> +#include <asm/lppaca.h> +#include <asm/plpar_wrappers.h> +#include <asm/machdep.h> + +#ifdef CONFIG_DTL +struct dtl { + struct dtl_entry *buf; + int cpu; + int buf_entries; + u64 last_idx; + spinlock_t lock; +}; +static DEFINE_PER_CPU(struct dtl, cpu_dtl); + +static u8 dtl_event_mask = DTL_LOG_ALL; + + +/* + * Size of per-cpu log buffers. Firmware requires that the buffer does + * not cross a 4k boundary. + */ +static int dtl_buf_entries = N_DISPATCH_LOG; + +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE + +/* + * When CONFIG_VIRT_CPU_ACCOUNTING_NATIVE = y, the cpu accounting code controls + * reading from the dispatch trace log. If other code wants to consume + * DTL entries, it can set this pointer to a function that will get + * called once for each DTL entry that gets processed. + */ +static void (*dtl_consumer)(struct dtl_entry *entry, u64 index); + +struct dtl_ring { + u64 write_index; + struct dtl_entry *write_ptr; + struct dtl_entry *buf; + struct dtl_entry *buf_end; +}; + +static DEFINE_PER_CPU(struct dtl_ring, dtl_rings); + +static atomic_t dtl_count; + +/* + * The cpu accounting code controls the DTL ring buffer, and we get + * given entries as they are processed. + */ +static void consume_dtle(struct dtl_entry *dtle, u64 index) +{ + struct dtl_ring *dtlr = this_cpu_ptr(&dtl_rings); + struct dtl_entry *wp = dtlr->write_ptr; + struct lppaca *vpa = local_paca->lppaca_ptr; + + if (!wp) + return; + + *wp = *dtle; + barrier(); + + /* check for hypervisor ring buffer overflow, ignore this entry if so */ + if (index + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) + return; + + ++wp; + if (wp == dtlr->buf_end) + wp = dtlr->buf; + dtlr->write_ptr = wp; + + /* incrementing write_index makes the new entry visible */ + smp_wmb(); + ++dtlr->write_index; +} + +static int dtl_start(struct dtl *dtl) +{ + struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu); + + dtlr->buf = dtl->buf; + dtlr->buf_end = dtl->buf + dtl->buf_entries; + dtlr->write_index = 0; + + /* setting write_ptr enables logging into our buffer */ + smp_wmb(); + dtlr->write_ptr = dtl->buf; + + /* enable event logging */ + lppaca_of(dtl->cpu).dtl_enable_mask |= dtl_event_mask; + + dtl_consumer = consume_dtle; + atomic_inc(&dtl_count); + return 0; +} + +static void dtl_stop(struct dtl *dtl) +{ + struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu); + + dtlr->write_ptr = NULL; + smp_wmb(); + + dtlr->buf = NULL; + + /* restore dtl_enable_mask */ + lppaca_of(dtl->cpu).dtl_enable_mask = DTL_LOG_PREEMPT; + + if (atomic_dec_and_test(&dtl_count)) + dtl_consumer = NULL; +} + +static u64 dtl_current_index(struct dtl *dtl) +{ + return per_cpu(dtl_rings, dtl->cpu).write_index; +} + +#else /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ + +static int dtl_start(struct dtl *dtl) +{ + unsigned long addr; + int ret, hwcpu; + + /* Register our dtl buffer with the hypervisor. The HV expects the + * buffer size to be passed in the second word of the buffer */ + ((u32 *)dtl->buf)[1] = cpu_to_be32(DISPATCH_LOG_BYTES); + + hwcpu = get_hard_smp_processor_id(dtl->cpu); + addr = __pa(dtl->buf); + ret = register_dtl(hwcpu, addr); + if (ret) { + printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) " + "failed with %d\n", __func__, dtl->cpu, hwcpu, ret); + return -EIO; + } + + /* set our initial buffer indices */ + lppaca_of(dtl->cpu).dtl_idx = 0; + + /* ensure that our updates to the lppaca fields have occurred before + * we actually enable the logging */ + smp_wmb(); + + /* enable event logging */ + lppaca_of(dtl->cpu).dtl_enable_mask = dtl_event_mask; + + return 0; +} + +static void dtl_stop(struct dtl *dtl) +{ + int hwcpu = get_hard_smp_processor_id(dtl->cpu); + + lppaca_of(dtl->cpu).dtl_enable_mask = 0x0; + + unregister_dtl(hwcpu); +} + +static u64 dtl_current_index(struct dtl *dtl) +{ + return be64_to_cpu(lppaca_of(dtl->cpu).dtl_idx); +} +#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ + +static int dtl_enable(struct dtl *dtl) +{ + long int n_entries; + long int rc; + struct dtl_entry *buf = NULL; + + if (!dtl_cache) + return -ENOMEM; + + /* only allow one reader */ + if (dtl->buf) + return -EBUSY; + + /* ensure there are no other conflicting dtl users */ + if (!read_trylock(&dtl_access_lock)) + return -EBUSY; + + n_entries = dtl_buf_entries; + buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu)); + if (!buf) { + printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n", + __func__, dtl->cpu); + read_unlock(&dtl_access_lock); + return -ENOMEM; + } + + spin_lock(&dtl->lock); + rc = -EBUSY; + if (!dtl->buf) { + /* store the original allocation size for use during read */ + dtl->buf_entries = n_entries; + dtl->buf = buf; + dtl->last_idx = 0; + rc = dtl_start(dtl); + if (rc) + dtl->buf = NULL; + } + spin_unlock(&dtl->lock); + + if (rc) { + read_unlock(&dtl_access_lock); + kmem_cache_free(dtl_cache, buf); + } + + return rc; +} + +static void dtl_disable(struct dtl *dtl) +{ + spin_lock(&dtl->lock); + dtl_stop(dtl); + kmem_cache_free(dtl_cache, dtl->buf); + dtl->buf = NULL; + dtl->buf_entries = 0; + spin_unlock(&dtl->lock); + read_unlock(&dtl_access_lock); +} + +/* file interface */ + +static int dtl_file_open(struct inode *inode, struct file *filp) +{ + struct dtl *dtl = inode->i_private; + int rc; + + rc = dtl_enable(dtl); + if (rc) + return rc; + + filp->private_data = dtl; + return 0; +} + +static int dtl_file_release(struct inode *inode, struct file *filp) +{ + struct dtl *dtl = inode->i_private; + dtl_disable(dtl); + return 0; +} + +static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len, + loff_t *pos) +{ + long int rc, n_read, n_req, read_size; + struct dtl *dtl; + u64 cur_idx, last_idx, i; + + if ((len % sizeof(struct dtl_entry)) != 0) + return -EINVAL; + + dtl = filp->private_data; + + /* requested number of entries to read */ + n_req = len / sizeof(struct dtl_entry); + + /* actual number of entries read */ + n_read = 0; + + spin_lock(&dtl->lock); + + cur_idx = dtl_current_index(dtl); + last_idx = dtl->last_idx; + + if (last_idx + dtl->buf_entries <= cur_idx) + last_idx = cur_idx - dtl->buf_entries + 1; + + if (last_idx + n_req > cur_idx) + n_req = cur_idx - last_idx; + + if (n_req > 0) + dtl->last_idx = last_idx + n_req; + + spin_unlock(&dtl->lock); + + if (n_req <= 0) + return 0; + + i = last_idx % dtl->buf_entries; + + /* read the tail of the buffer if we've wrapped */ + if (i + n_req > dtl->buf_entries) { + read_size = dtl->buf_entries - i; + + rc = copy_to_user(buf, &dtl->buf[i], + read_size * sizeof(struct dtl_entry)); + if (rc) + return -EFAULT; + + i = 0; + n_req -= read_size; + n_read += read_size; + buf += read_size * sizeof(struct dtl_entry); + } + + /* .. and now the head */ + rc = copy_to_user(buf, &dtl->buf[i], n_req * sizeof(struct dtl_entry)); + if (rc) + return -EFAULT; + + n_read += n_req; + + return n_read * sizeof(struct dtl_entry); +} + +static const struct file_operations dtl_fops = { + .open = dtl_file_open, + .release = dtl_file_release, + .read = dtl_file_read, + .llseek = no_llseek, +}; + +static struct dentry *dtl_dir; + +static void dtl_setup_file(struct dtl *dtl) +{ + char name[10]; + + sprintf(name, "cpu-%d", dtl->cpu); + + debugfs_create_file(name, 0400, dtl_dir, dtl, &dtl_fops); +} + +static int dtl_init(void) +{ + int i; + + if (!firmware_has_feature(FW_FEATURE_SPLPAR)) + return -ENODEV; + + /* set up common debugfs structure */ + + dtl_dir = debugfs_create_dir("dtl", arch_debugfs_dir); + + debugfs_create_x8("dtl_event_mask", 0600, dtl_dir, &dtl_event_mask); + debugfs_create_u32("dtl_buf_entries", 0400, dtl_dir, &dtl_buf_entries); + + /* set up the per-cpu log structures */ + for_each_possible_cpu(i) { + struct dtl *dtl = &per_cpu(cpu_dtl, i); + spin_lock_init(&dtl->lock); + dtl->cpu = i; + + dtl_setup_file(dtl); + } + + return 0; +} +machine_arch_initcall(pseries, dtl_init); +#endif /* CONFIG_DTL */ + +#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE +/* + * Scan the dispatch trace log and count up the stolen time. + * Should be called with interrupts disabled. + */ +static notrace u64 scan_dispatch_log(u64 stop_tb) +{ + u64 i = local_paca->dtl_ridx; + struct dtl_entry *dtl = local_paca->dtl_curr; + struct dtl_entry *dtl_end = local_paca->dispatch_log_end; + struct lppaca *vpa = local_paca->lppaca_ptr; + u64 tb_delta; + u64 stolen = 0; + u64 dtb; + + if (!dtl) + return 0; + + if (i == be64_to_cpu(vpa->dtl_idx)) + return 0; + while (i < be64_to_cpu(vpa->dtl_idx)) { + dtb = be64_to_cpu(dtl->timebase); + tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) + + be32_to_cpu(dtl->ready_to_enqueue_time); + barrier(); + if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) { + /* buffer has overflowed */ + i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG; + dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG); + continue; + } + if (dtb > stop_tb) + break; +#ifdef CONFIG_DTL + if (dtl_consumer) + dtl_consumer(dtl, i); +#endif + stolen += tb_delta; + ++i; + ++dtl; + if (dtl == dtl_end) + dtl = local_paca->dispatch_log; + } + local_paca->dtl_ridx = i; + local_paca->dtl_curr = dtl; + return stolen; +} + +/* + * Accumulate stolen time by scanning the dispatch trace log. + * Called on entry from user mode. + */ +void notrace pseries_accumulate_stolen_time(void) +{ + u64 sst, ust; + struct cpu_accounting_data *acct = &local_paca->accounting; + + sst = scan_dispatch_log(acct->starttime_user); + ust = scan_dispatch_log(acct->starttime); + acct->stime -= sst; + acct->utime -= ust; + acct->steal_time += ust + sst; +} + +u64 pseries_calculate_stolen_time(u64 stop_tb) +{ + if (!firmware_has_feature(FW_FEATURE_SPLPAR)) + return 0; + + if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx)) + return scan_dispatch_log(stop_tb); + + return 0; +} + +#endif |