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![Wu Fengguang](/assets/img/avatar_default.png)
Add marker_synchronize_unregister() before module unloading. This prevents possible trace calls into unloaded module text. Signed-off-by: Wu Fengguang <wfg@linux.intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
285 lines
6.2 KiB
C
285 lines
6.2 KiB
C
/*
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* kvm trace
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*
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* It is designed to allow debugging traces of kvm to be generated
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* on UP / SMP machines. Each trace entry can be timestamped so that
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* it's possible to reconstruct a chronological record of trace events.
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* The implementation refers to blktrace kernel support.
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*
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* Copyright (c) 2008 Intel Corporation
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* Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
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*
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* Authors: Feng(Eric) Liu, eric.e.liu@intel.com
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*
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* Date: Feb 2008
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*/
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#include <linux/module.h>
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#include <linux/relay.h>
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#include <linux/debugfs.h>
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#include <linux/ktime.h>
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#include <linux/kvm_host.h>
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#define KVM_TRACE_STATE_RUNNING (1 << 0)
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#define KVM_TRACE_STATE_PAUSE (1 << 1)
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#define KVM_TRACE_STATE_CLEARUP (1 << 2)
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struct kvm_trace {
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int trace_state;
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struct rchan *rchan;
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struct dentry *lost_file;
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atomic_t lost_records;
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};
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static struct kvm_trace *kvm_trace;
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struct kvm_trace_probe {
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const char *name;
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const char *format;
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u32 timestamp_in;
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marker_probe_func *probe_func;
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};
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static inline int calc_rec_size(int timestamp, int extra)
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{
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int rec_size = KVM_TRC_HEAD_SIZE;
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rec_size += extra;
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return timestamp ? rec_size += KVM_TRC_CYCLE_SIZE : rec_size;
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}
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static void kvm_add_trace(void *probe_private, void *call_data,
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const char *format, va_list *args)
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{
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struct kvm_trace_probe *p = probe_private;
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struct kvm_trace *kt = kvm_trace;
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struct kvm_trace_rec rec;
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struct kvm_vcpu *vcpu;
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int i, size;
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u32 extra;
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if (unlikely(kt->trace_state != KVM_TRACE_STATE_RUNNING))
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return;
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rec.rec_val = TRACE_REC_EVENT_ID(va_arg(*args, u32));
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vcpu = va_arg(*args, struct kvm_vcpu *);
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rec.pid = current->tgid;
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rec.vcpu_id = vcpu->vcpu_id;
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extra = va_arg(*args, u32);
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WARN_ON(!(extra <= KVM_TRC_EXTRA_MAX));
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extra = min_t(u32, extra, KVM_TRC_EXTRA_MAX);
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rec.rec_val |= TRACE_REC_TCS(p->timestamp_in)
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| TRACE_REC_NUM_DATA_ARGS(extra);
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if (p->timestamp_in) {
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rec.u.timestamp.timestamp = ktime_to_ns(ktime_get());
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for (i = 0; i < extra; i++)
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rec.u.timestamp.extra_u32[i] = va_arg(*args, u32);
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} else {
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for (i = 0; i < extra; i++)
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rec.u.notimestamp.extra_u32[i] = va_arg(*args, u32);
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}
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size = calc_rec_size(p->timestamp_in, extra * sizeof(u32));
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relay_write(kt->rchan, &rec, size);
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}
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static struct kvm_trace_probe kvm_trace_probes[] = {
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{ "kvm_trace_entryexit", "%u %p %u %u %u %u %u %u", 1, kvm_add_trace },
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{ "kvm_trace_handler", "%u %p %u %u %u %u %u %u", 0, kvm_add_trace },
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};
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static int lost_records_get(void *data, u64 *val)
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{
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struct kvm_trace *kt = data;
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*val = atomic_read(&kt->lost_records);
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(kvm_trace_lost_ops, lost_records_get, NULL, "%llu\n");
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/*
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* The relay channel is used in "no-overwrite" mode, it keeps trace of how
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* many times we encountered a full subbuffer, to tell user space app the
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* lost records there were.
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*/
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static int kvm_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
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void *prev_subbuf, size_t prev_padding)
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{
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struct kvm_trace *kt;
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if (!relay_buf_full(buf)) {
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if (!prev_subbuf) {
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/*
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* executed only once when the channel is opened
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* save metadata as first record
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*/
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subbuf_start_reserve(buf, sizeof(u32));
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*(u32 *)subbuf = 0x12345678;
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}
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return 1;
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}
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kt = buf->chan->private_data;
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atomic_inc(&kt->lost_records);
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return 0;
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}
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static struct dentry *kvm_create_buf_file_callack(const char *filename,
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struct dentry *parent,
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int mode,
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struct rchan_buf *buf,
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int *is_global)
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{
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return debugfs_create_file(filename, mode, parent, buf,
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&relay_file_operations);
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}
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static int kvm_remove_buf_file_callback(struct dentry *dentry)
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{
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debugfs_remove(dentry);
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return 0;
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}
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static struct rchan_callbacks kvm_relay_callbacks = {
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.subbuf_start = kvm_subbuf_start_callback,
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.create_buf_file = kvm_create_buf_file_callack,
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.remove_buf_file = kvm_remove_buf_file_callback,
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};
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static int do_kvm_trace_enable(struct kvm_user_trace_setup *kuts)
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{
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struct kvm_trace *kt;
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int i, r = -ENOMEM;
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if (!kuts->buf_size || !kuts->buf_nr)
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return -EINVAL;
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kt = kzalloc(sizeof(*kt), GFP_KERNEL);
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if (!kt)
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goto err;
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r = -EIO;
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atomic_set(&kt->lost_records, 0);
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kt->lost_file = debugfs_create_file("lost_records", 0444, kvm_debugfs_dir,
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kt, &kvm_trace_lost_ops);
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if (!kt->lost_file)
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goto err;
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kt->rchan = relay_open("trace", kvm_debugfs_dir, kuts->buf_size,
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kuts->buf_nr, &kvm_relay_callbacks, kt);
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if (!kt->rchan)
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goto err;
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kvm_trace = kt;
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for (i = 0; i < ARRAY_SIZE(kvm_trace_probes); i++) {
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struct kvm_trace_probe *p = &kvm_trace_probes[i];
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r = marker_probe_register(p->name, p->format, p->probe_func, p);
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if (r)
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printk(KERN_INFO "Unable to register probe %s\n",
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p->name);
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}
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kvm_trace->trace_state = KVM_TRACE_STATE_RUNNING;
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return 0;
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err:
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if (kt) {
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if (kt->lost_file)
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debugfs_remove(kt->lost_file);
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if (kt->rchan)
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relay_close(kt->rchan);
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kfree(kt);
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}
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return r;
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}
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static int kvm_trace_enable(char __user *arg)
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{
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struct kvm_user_trace_setup kuts;
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int ret;
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ret = copy_from_user(&kuts, arg, sizeof(kuts));
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if (ret)
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return -EFAULT;
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ret = do_kvm_trace_enable(&kuts);
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if (ret)
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return ret;
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return 0;
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}
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static int kvm_trace_pause(void)
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{
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struct kvm_trace *kt = kvm_trace;
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int r = -EINVAL;
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if (kt == NULL)
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return r;
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if (kt->trace_state == KVM_TRACE_STATE_RUNNING) {
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kt->trace_state = KVM_TRACE_STATE_PAUSE;
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relay_flush(kt->rchan);
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r = 0;
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}
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return r;
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}
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void kvm_trace_cleanup(void)
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{
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struct kvm_trace *kt = kvm_trace;
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int i;
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if (kt == NULL)
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return;
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if (kt->trace_state == KVM_TRACE_STATE_RUNNING ||
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kt->trace_state == KVM_TRACE_STATE_PAUSE) {
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kt->trace_state = KVM_TRACE_STATE_CLEARUP;
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for (i = 0; i < ARRAY_SIZE(kvm_trace_probes); i++) {
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struct kvm_trace_probe *p = &kvm_trace_probes[i];
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marker_probe_unregister(p->name, p->probe_func, p);
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}
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marker_synchronize_unregister();
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relay_close(kt->rchan);
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debugfs_remove(kt->lost_file);
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kfree(kt);
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}
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}
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int kvm_trace_ioctl(unsigned int ioctl, unsigned long arg)
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{
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void __user *argp = (void __user *)arg;
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long r = -EINVAL;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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switch (ioctl) {
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case KVM_TRACE_ENABLE:
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r = kvm_trace_enable(argp);
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break;
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case KVM_TRACE_PAUSE:
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r = kvm_trace_pause();
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break;
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case KVM_TRACE_DISABLE:
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r = 0;
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kvm_trace_cleanup();
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break;
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}
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return r;
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}
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