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);