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-rw-r--r--arch/powerpc/platforms/pseries/dtl.c357
1 files changed, 357 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
new file mode 100644
index 000000000..982f069e4
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -0,0 +1,357 @@
+// 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 <asm/firmware.h>
+#include <asm/dtl.h>
+#include <asm/lppaca.h>
+#include <asm/debugfs.h>
+#include <asm/plpar_wrappers.h>
+#include <asm/machdep.h>
+
+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
+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", powerpc_debugfs_root);
+
+ 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);