// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Virtual Processor Dispatch Trace Log
*
* (C) Copyright IBM Corporation 2009
*
* Author: Jeremy Kerr <[email protected]>
*/
#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
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