tracing: Consolidate trace_add/remove_event_call back to the nolock functions

[thirdparty/linux.git] / kernel / trace / trace_uprobe.c

// SPDX-License-Identifier: GPL-2.0
/*
 * uprobes-based tracing events
 *
 * Copyright (C) IBM Corporation, 2010-2012
 * Author:      Srikar Dronamraju <srikar@linux.vnet.ibm.com>
 */
#define pr_fmt(fmt)     "trace_kprobe: " fmt

#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/uprobes.h>
#include <linux/namei.h>
#include <linux/string.h>
#include <linux/rculist.h>

#include "trace_dynevent.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"

#define UPROBE_EVENT_SYSTEM     "uprobes"

struct uprobe_trace_entry_head {
        struct trace_entry      ent;
        unsigned long           vaddr[];
};

#define SIZEOF_TRACE_ENTRY(is_return)                   \
        (sizeof(struct uprobe_trace_entry_head) +       \
         sizeof(unsigned long) * (is_return ? 2 : 1))

#define DATAOF_TRACE_ENTRY(entry, is_return)            \
        ((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))

struct trace_uprobe_filter {
        rwlock_t                rwlock;
        int                     nr_systemwide;
        struct list_head        perf_events;
};

static int trace_uprobe_create(int argc, const char **argv);
static int trace_uprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_uprobe_release(struct dyn_event *ev);
static bool trace_uprobe_is_busy(struct dyn_event *ev);
static bool trace_uprobe_match(const char *system, const char *event,
                               struct dyn_event *ev);

static struct dyn_event_operations trace_uprobe_ops = {
        .create = trace_uprobe_create,
        .show = trace_uprobe_show,
        .is_busy = trace_uprobe_is_busy,
        .free = trace_uprobe_release,
        .match = trace_uprobe_match,
};

/*
 * uprobe event core functions
 */
struct trace_uprobe {
        struct dyn_event                devent;
        struct trace_uprobe_filter      filter;
        struct uprobe_consumer          consumer;
        struct path                     path;
        struct inode                    *inode;
        char                            *filename;
        unsigned long                   offset;
        unsigned long                   ref_ctr_offset;
        unsigned long                   nhit;
        struct trace_probe              tp;
};

static bool is_trace_uprobe(struct dyn_event *ev)
{
        return ev->ops == &trace_uprobe_ops;
}

static struct trace_uprobe *to_trace_uprobe(struct dyn_event *ev)
{
        return container_of(ev, struct trace_uprobe, devent);
}

/**
 * for_each_trace_uprobe - iterate over the trace_uprobe list
 * @pos:        the struct trace_uprobe * for each entry
 * @dpos:       the struct dyn_event * to use as a loop cursor
 */
#define for_each_trace_uprobe(pos, dpos)        \
        for_each_dyn_event(dpos)                \
                if (is_trace_uprobe(dpos) && (pos = to_trace_uprobe(dpos)))

#define SIZEOF_TRACE_UPROBE(n)                          \
        (offsetof(struct trace_uprobe, tp.args) +       \
        (sizeof(struct probe_arg) * (n)))

static int register_uprobe_event(struct trace_uprobe *tu);
static int unregister_uprobe_event(struct trace_uprobe *tu);

struct uprobe_dispatch_data {
        struct trace_uprobe     *tu;
        unsigned long           bp_addr;
};

static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
static int uretprobe_dispatcher(struct uprobe_consumer *con,
                                unsigned long func, struct pt_regs *regs);

#ifdef CONFIG_STACK_GROWSUP
static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
{
        return addr - (n * sizeof(long));
}
#else
static unsigned long adjust_stack_addr(unsigned long addr, unsigned int n)
{
        return addr + (n * sizeof(long));
}
#endif

static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
{
        unsigned long ret;
        unsigned long addr = user_stack_pointer(regs);

        addr = adjust_stack_addr(addr, n);

        if (copy_from_user(&ret, (void __force __user *) addr, sizeof(ret)))
                return 0;

        return ret;
}

/*
 * Uprobes-specific fetch functions
 */
static nokprobe_inline int
probe_mem_read(void *dest, void *src, size_t size)
{
        void __user *vaddr = (void __force __user *)src;

        return copy_from_user(dest, vaddr, size) ? -EFAULT : 0;
}
/*
 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 * length and relative data location.
 */
static nokprobe_inline int
fetch_store_string(unsigned long addr, void *dest, void *base)
{
        long ret;
        u32 loc = *(u32 *)dest;
        int maxlen  = get_loc_len(loc);
        u8 *dst = get_loc_data(dest, base);
        void __user *src = (void __force __user *) addr;

        if (unlikely(!maxlen))
                return -ENOMEM;

        ret = strncpy_from_user(dst, src, maxlen);
        if (ret >= 0) {
                if (ret == maxlen)
                        dst[ret - 1] = '\0';
                *(u32 *)dest = make_data_loc(ret, (void *)dst - base);
        }

        return ret;
}

/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
fetch_store_strlen(unsigned long addr)
{
        int len;
        void __user *vaddr = (void __force __user *) addr;

        len = strnlen_user(vaddr, MAX_STRING_SIZE);

        return (len > MAX_STRING_SIZE) ? 0 : len;
}

static unsigned long translate_user_vaddr(unsigned long file_offset)
{
        unsigned long base_addr;
        struct uprobe_dispatch_data *udd;

        udd = (void *) current->utask->vaddr;

        base_addr = udd->bp_addr - udd->tu->offset;
        return base_addr + file_offset;
}

/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
                   void *base)
{
        unsigned long val;

        /* 1st stage: get value from context */
        switch (code->op) {
        case FETCH_OP_REG:
                val = regs_get_register(regs, code->param);
                break;
        case FETCH_OP_STACK:
                val = get_user_stack_nth(regs, code->param);
                break;
        case FETCH_OP_STACKP:
                val = user_stack_pointer(regs);
                break;
        case FETCH_OP_RETVAL:
                val = regs_return_value(regs);
                break;
        case FETCH_OP_IMM:
                val = code->immediate;
                break;
        case FETCH_OP_FOFFS:
                val = translate_user_vaddr(code->immediate);
                break;
        default:
                return -EILSEQ;
        }
        code++;

        return process_fetch_insn_bottom(code, val, dest, base);
}
NOKPROBE_SYMBOL(process_fetch_insn)

static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
{
        rwlock_init(&filter->rwlock);
        filter->nr_systemwide = 0;
        INIT_LIST_HEAD(&filter->perf_events);
}

static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
{
        return !filter->nr_systemwide && list_empty(&filter->perf_events);
}

static inline bool is_ret_probe(struct trace_uprobe *tu)
{
        return tu->consumer.ret_handler != NULL;
}

static bool trace_uprobe_is_busy(struct dyn_event *ev)
{
        struct trace_uprobe *tu = to_trace_uprobe(ev);

        return trace_probe_is_enabled(&tu->tp);
}

static bool trace_uprobe_match(const char *system, const char *event,
                               struct dyn_event *ev)
{
        struct trace_uprobe *tu = to_trace_uprobe(ev);

        return strcmp(trace_event_name(&tu->tp.call), event) == 0 &&
                (!system || strcmp(tu->tp.call.class->system, system) == 0);
}

/*
 * Allocate new trace_uprobe and initialize it (including uprobes).
 */
static struct trace_uprobe *
alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
{
        struct trace_uprobe *tu;

        if (!event || !is_good_name(event))
                return ERR_PTR(-EINVAL);

        if (!group || !is_good_name(group))
                return ERR_PTR(-EINVAL);

        tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
        if (!tu)
                return ERR_PTR(-ENOMEM);

        tu->tp.call.class = &tu->tp.class;
        tu->tp.call.name = kstrdup(event, GFP_KERNEL);
        if (!tu->tp.call.name)
                goto error;

        tu->tp.class.system = kstrdup(group, GFP_KERNEL);
        if (!tu->tp.class.system)
                goto error;

        dyn_event_init(&tu->devent, &trace_uprobe_ops);
        INIT_LIST_HEAD(&tu->tp.files);
        tu->consumer.handler = uprobe_dispatcher;
        if (is_ret)
                tu->consumer.ret_handler = uretprobe_dispatcher;
        init_trace_uprobe_filter(&tu->filter);
        return tu;

error:
        kfree(tu->tp.call.name);
        kfree(tu);

        return ERR_PTR(-ENOMEM);
}

static void free_trace_uprobe(struct trace_uprobe *tu)
{
        int i;

        if (!tu)
                return;

        for (i = 0; i < tu->tp.nr_args; i++)
                traceprobe_free_probe_arg(&tu->tp.args[i]);

        path_put(&tu->path);
        kfree(tu->tp.call.class->system);
        kfree(tu->tp.call.name);
        kfree(tu->filename);
        kfree(tu);
}

static struct trace_uprobe *find_probe_event(const char *event, const char *group)
{
        struct dyn_event *pos;
        struct trace_uprobe *tu;

        for_each_trace_uprobe(tu, pos)
                if (strcmp(trace_event_name(&tu->tp.call), event) == 0 &&
                    strcmp(tu->tp.call.class->system, group) == 0)
                        return tu;

        return NULL;
}

/* Unregister a trace_uprobe and probe_event */
static int unregister_trace_uprobe(struct trace_uprobe *tu)
{
        int ret;

        ret = unregister_uprobe_event(tu);
        if (ret)
                return ret;

        dyn_event_remove(&tu->devent);
        free_trace_uprobe(tu);
        return 0;
}

/*
 * Uprobe with multiple reference counter is not allowed. i.e.
 * If inode and offset matches, reference counter offset *must*
 * match as well. Though, there is one exception: If user is
 * replacing old trace_uprobe with new one(same group/event),
 * then we allow same uprobe with new reference counter as far
 * as the new one does not conflict with any other existing
 * ones.
 */
static struct trace_uprobe *find_old_trace_uprobe(struct trace_uprobe *new)
{
        struct dyn_event *pos;
        struct trace_uprobe *tmp, *old = NULL;
        struct inode *new_inode = d_real_inode(new->path.dentry);

        old = find_probe_event(trace_event_name(&new->tp.call),
                                new->tp.call.class->system);

        for_each_trace_uprobe(tmp, pos) {
                if ((old ? old != tmp : true) &&
                    new_inode == d_real_inode(tmp->path.dentry) &&
                    new->offset == tmp->offset &&
                    new->ref_ctr_offset != tmp->ref_ctr_offset) {
                        pr_warn("Reference counter offset mismatch.");
                        return ERR_PTR(-EINVAL);
                }
        }
        return old;
}

/* Register a trace_uprobe and probe_event */
static int register_trace_uprobe(struct trace_uprobe *tu)
{
        struct trace_uprobe *old_tu;
        int ret;

        mutex_lock(&event_mutex);

        /* register as an event */
        old_tu = find_old_trace_uprobe(tu);
        if (IS_ERR(old_tu)) {
                ret = PTR_ERR(old_tu);
                goto end;
        }

        if (old_tu) {
                /* delete old event */
                ret = unregister_trace_uprobe(old_tu);
                if (ret)
                        goto end;
        }

        ret = register_uprobe_event(tu);
        if (ret) {
                pr_warn("Failed to register probe event(%d)\n", ret);
                goto end;
        }

        dyn_event_add(&tu->devent);

end:
        mutex_unlock(&event_mutex);

        return ret;
}

/*
 * Argument syntax:
 *  - Add uprobe: p|r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS]
 *
 *  - Remove uprobe: -:[GRP/]EVENT
 */
static int trace_uprobe_create(int argc, const char **argv)
{
        struct trace_uprobe *tu;
        const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
        char *arg, *filename, *rctr, *rctr_end, *tmp;
        char buf[MAX_EVENT_NAME_LEN];
        struct path path;
        unsigned long offset, ref_ctr_offset;
        bool is_return = false;
        int i, ret;

        ret = 0;
        ref_ctr_offset = 0;

        /* argc must be >= 1 */
        if (argv[0][0] == 'r')
                is_return = true;
        else if (argv[0][0] != 'p' || argc < 2)
                return -ECANCELED;

        if (argv[0][1] == ':')
                event = &argv[0][2];

        if (!strchr(argv[1], '/'))
                return -ECANCELED;

        filename = kstrdup(argv[1], GFP_KERNEL);
        if (!filename)
                return -ENOMEM;

        /* Find the last occurrence, in case the path contains ':' too. */
        arg = strrchr(filename, ':');
        if (!arg || !isdigit(arg[1])) {
                kfree(filename);
                return -ECANCELED;
        }

        *arg++ = '\0';
        ret = kern_path(filename, LOOKUP_FOLLOW, &path);
        if (ret) {
                kfree(filename);
                return ret;
        }
        if (!d_is_reg(path.dentry)) {
                ret = -EINVAL;
                goto fail_address_parse;
        }

        /* Parse reference counter offset if specified. */
        rctr = strchr(arg, '(');
        if (rctr) {
                rctr_end = strchr(rctr, ')');
                if (rctr > rctr_end || *(rctr_end + 1) != 0) {
                        ret = -EINVAL;
                        pr_info("Invalid reference counter offset.\n");
                        goto fail_address_parse;
                }

                *rctr++ = '\0';
                *rctr_end = '\0';
                ret = kstrtoul(rctr, 0, &ref_ctr_offset);
                if (ret) {
                        pr_info("Invalid reference counter offset.\n");
                        goto fail_address_parse;
                }
        }

        /* Parse uprobe offset. */
        ret = kstrtoul(arg, 0, &offset);
        if (ret)
                goto fail_address_parse;

        argc -= 2;
        argv += 2;

        /* setup a probe */
        if (event) {
                ret = traceprobe_parse_event_name(&event, &group, buf);
                if (ret)
                        goto fail_address_parse;
        } else {
                char *tail;
                char *ptr;

                tail = kstrdup(kbasename(filename), GFP_KERNEL);
                if (!tail) {
                        ret = -ENOMEM;
                        goto fail_address_parse;
                }

                ptr = strpbrk(tail, ".-_");
                if (ptr)
                        *ptr = '\0';

                snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
                event = buf;
                kfree(tail);
        }

        tu = alloc_trace_uprobe(group, event, argc, is_return);
        if (IS_ERR(tu)) {
                pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
                ret = PTR_ERR(tu);
                goto fail_address_parse;
        }
        tu->offset = offset;
        tu->ref_ctr_offset = ref_ctr_offset;
        tu->path = path;
        tu->filename = filename;

        /* parse arguments */
        for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
                tmp = kstrdup(argv[i], GFP_KERNEL);
                if (!tmp) {
                        ret = -ENOMEM;
                        goto error;
                }

                ret = traceprobe_parse_probe_arg(&tu->tp, i, tmp,
                                        is_return ? TPARG_FL_RETURN : 0);
                kfree(tmp);
                if (ret)
                        goto error;
        }

        ret = register_trace_uprobe(tu);
        if (ret)
                goto error;
        return 0;

error:
        free_trace_uprobe(tu);
        return ret;

fail_address_parse:
        path_put(&path);
        kfree(filename);

        pr_info("Failed to parse address or file.\n");

        return ret;
}

static int create_or_delete_trace_uprobe(int argc, char **argv)
{
        int ret;

        if (argv[0][0] == '-')
                return dyn_event_release(argc, argv, &trace_uprobe_ops);

        ret = trace_uprobe_create(argc, (const char **)argv);
        return ret == -ECANCELED ? -EINVAL : ret;
}

static int trace_uprobe_release(struct dyn_event *ev)
{
        struct trace_uprobe *tu = to_trace_uprobe(ev);

        return unregister_trace_uprobe(tu);
}

/* Probes listing interfaces */
static int trace_uprobe_show(struct seq_file *m, struct dyn_event *ev)
{
        struct trace_uprobe *tu = to_trace_uprobe(ev);
        char c = is_ret_probe(tu) ? 'r' : 'p';
        int i;

        seq_printf(m, "%c:%s/%s %s:0x%0*lx", c, tu->tp.call.class->system,
                        trace_event_name(&tu->tp.call), tu->filename,
                        (int)(sizeof(void *) * 2), tu->offset);

        if (tu->ref_ctr_offset)
                seq_printf(m, "(0x%lx)", tu->ref_ctr_offset);

        for (i = 0; i < tu->tp.nr_args; i++)
                seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm);

        seq_putc(m, '\n');
        return 0;
}

static int probes_seq_show(struct seq_file *m, void *v)
{
        struct dyn_event *ev = v;

        if (!is_trace_uprobe(ev))
                return 0;

        return trace_uprobe_show(m, ev);
}

static const struct seq_operations probes_seq_op = {
        .start  = dyn_event_seq_start,
        .next   = dyn_event_seq_next,
        .stop   = dyn_event_seq_stop,
        .show   = probes_seq_show
};

static int probes_open(struct inode *inode, struct file *file)
{
        int ret;

        if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
                ret = dyn_events_release_all(&trace_uprobe_ops);
                if (ret)
                        return ret;
        }

        return seq_open(file, &probes_seq_op);
}

static ssize_t probes_write(struct file *file, const char __user *buffer,
                            size_t count, loff_t *ppos)
{
        return trace_parse_run_command(file, buffer, count, ppos,
                                        create_or_delete_trace_uprobe);
}

static const struct file_operations uprobe_events_ops = {
        .owner          = THIS_MODULE,
        .open           = probes_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
        .write          = probes_write,
};

/* Probes profiling interfaces */
static int probes_profile_seq_show(struct seq_file *m, void *v)
{
        struct dyn_event *ev = v;
        struct trace_uprobe *tu;

        if (!is_trace_uprobe(ev))
                return 0;

        tu = to_trace_uprobe(ev);
        seq_printf(m, "  %s %-44s %15lu\n", tu->filename,
                        trace_event_name(&tu->tp.call), tu->nhit);
        return 0;
}

static const struct seq_operations profile_seq_op = {
        .start  = dyn_event_seq_start,
        .next   = dyn_event_seq_next,
        .stop   = dyn_event_seq_stop,
        .show   = probes_profile_seq_show
};

static int profile_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &profile_seq_op);
}

static const struct file_operations uprobe_profile_ops = {
        .owner          = THIS_MODULE,
        .open           = profile_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

struct uprobe_cpu_buffer {
        struct mutex mutex;
        void *buf;
};
static struct uprobe_cpu_buffer __percpu *uprobe_cpu_buffer;
static int uprobe_buffer_refcnt;

static int uprobe_buffer_init(void)
{
        int cpu, err_cpu;

        uprobe_cpu_buffer = alloc_percpu(struct uprobe_cpu_buffer);
        if (uprobe_cpu_buffer == NULL)
                return -ENOMEM;

        for_each_possible_cpu(cpu) {
                struct page *p = alloc_pages_node(cpu_to_node(cpu),
                                                  GFP_KERNEL, 0);
                if (p == NULL) {
                        err_cpu = cpu;
                        goto err;
                }
                per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf = page_address(p);
                mutex_init(&per_cpu_ptr(uprobe_cpu_buffer, cpu)->mutex);
        }

        return 0;

err:
        for_each_possible_cpu(cpu) {
                if (cpu == err_cpu)
                        break;
                free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer, cpu)->buf);
        }

        free_percpu(uprobe_cpu_buffer);
        return -ENOMEM;
}

static int uprobe_buffer_enable(void)
{
        int ret = 0;

        BUG_ON(!mutex_is_locked(&event_mutex));

        if (uprobe_buffer_refcnt++ == 0) {
                ret = uprobe_buffer_init();
                if (ret < 0)
                        uprobe_buffer_refcnt--;
        }

        return ret;
}

static void uprobe_buffer_disable(void)
{
        int cpu;

        BUG_ON(!mutex_is_locked(&event_mutex));

        if (--uprobe_buffer_refcnt == 0) {
                for_each_possible_cpu(cpu)
                        free_page((unsigned long)per_cpu_ptr(uprobe_cpu_buffer,
                                                             cpu)->buf);

                free_percpu(uprobe_cpu_buffer);
                uprobe_cpu_buffer = NULL;
        }
}

static struct uprobe_cpu_buffer *uprobe_buffer_get(void)
{
        struct uprobe_cpu_buffer *ucb;
        int cpu;

        cpu = raw_smp_processor_id();
        ucb = per_cpu_ptr(uprobe_cpu_buffer, cpu);

        /*
         * Use per-cpu buffers for fastest access, but we might migrate
         * so the mutex makes sure we have sole access to it.
         */
        mutex_lock(&ucb->mutex);

        return ucb;
}

static void uprobe_buffer_put(struct uprobe_cpu_buffer *ucb)
{
        mutex_unlock(&ucb->mutex);
}

static void __uprobe_trace_func(struct trace_uprobe *tu,
                                unsigned long func, struct pt_regs *regs,
                                struct uprobe_cpu_buffer *ucb, int dsize,
                                struct trace_event_file *trace_file)
{
        struct uprobe_trace_entry_head *entry;
        struct ring_buffer_event *event;
        struct ring_buffer *buffer;
        void *data;
        int size, esize;
        struct trace_event_call *call = &tu->tp.call;

        WARN_ON(call != trace_file->event_call);

        if (WARN_ON_ONCE(tu->tp.size + dsize > PAGE_SIZE))
                return;

        if (trace_trigger_soft_disabled(trace_file))
                return;

        esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
        size = esize + tu->tp.size + dsize;
        event = trace_event_buffer_lock_reserve(&buffer, trace_file,
                                                call->event.type, size, 0, 0);
        if (!event)
                return;

        entry = ring_buffer_event_data(event);
        if (is_ret_probe(tu)) {
                entry->vaddr[0] = func;
                entry->vaddr[1] = instruction_pointer(regs);
                data = DATAOF_TRACE_ENTRY(entry, true);
        } else {
                entry->vaddr[0] = instruction_pointer(regs);
                data = DATAOF_TRACE_ENTRY(entry, false);
        }

        memcpy(data, ucb->buf, tu->tp.size + dsize);

        event_trigger_unlock_commit(trace_file, buffer, event, entry, 0, 0);
}

/* uprobe handler */
static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs,
                             struct uprobe_cpu_buffer *ucb, int dsize)
{
        struct event_file_link *link;

        if (is_ret_probe(tu))
                return 0;

        rcu_read_lock();
        list_for_each_entry_rcu(link, &tu->tp.files, list)
                __uprobe_trace_func(tu, 0, regs, ucb, dsize, link->file);
        rcu_read_unlock();

        return 0;
}

static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
                                 struct pt_regs *regs,
                                 struct uprobe_cpu_buffer *ucb, int dsize)
{
        struct event_file_link *link;

        rcu_read_lock();
        list_for_each_entry_rcu(link, &tu->tp.files, list)
                __uprobe_trace_func(tu, func, regs, ucb, dsize, link->file);
        rcu_read_unlock();
}

/* Event entry printers */
static enum print_line_t
print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
{
        struct uprobe_trace_entry_head *entry;
        struct trace_seq *s = &iter->seq;
        struct trace_uprobe *tu;
        u8 *data;

        entry = (struct uprobe_trace_entry_head *)iter->ent;
        tu = container_of(event, struct trace_uprobe, tp.call.event);

        if (is_ret_probe(tu)) {
                trace_seq_printf(s, "%s: (0x%lx <- 0x%lx)",
                                 trace_event_name(&tu->tp.call),
                                 entry->vaddr[1], entry->vaddr[0]);
                data = DATAOF_TRACE_ENTRY(entry, true);
        } else {
                trace_seq_printf(s, "%s: (0x%lx)",
                                 trace_event_name(&tu->tp.call),
                                 entry->vaddr[0]);
                data = DATAOF_TRACE_ENTRY(entry, false);
        }

        if (print_probe_args(s, tu->tp.args, tu->tp.nr_args, data, entry) < 0)
                goto out;

        trace_seq_putc(s, '\n');

 out:
        return trace_handle_return(s);
}

typedef bool (*filter_func_t)(struct uprobe_consumer *self,
                                enum uprobe_filter_ctx ctx,
                                struct mm_struct *mm);

static int
probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file,
                   filter_func_t filter)
{
        bool enabled = trace_probe_is_enabled(&tu->tp);
        struct event_file_link *link = NULL;
        int ret;

        if (file) {
                if (tu->tp.flags & TP_FLAG_PROFILE)
                        return -EINTR;

                link = kmalloc(sizeof(*link), GFP_KERNEL);
                if (!link)
                        return -ENOMEM;

                link->file = file;
                list_add_tail_rcu(&link->list, &tu->tp.files);

                tu->tp.flags |= TP_FLAG_TRACE;
        } else {
                if (tu->tp.flags & TP_FLAG_TRACE)
                        return -EINTR;

                tu->tp.flags |= TP_FLAG_PROFILE;
        }

        WARN_ON(!uprobe_filter_is_empty(&tu->filter));

        if (enabled)
                return 0;

        ret = uprobe_buffer_enable();
        if (ret)
                goto err_flags;

        tu->consumer.filter = filter;
        tu->inode = d_real_inode(tu->path.dentry);
        if (tu->ref_ctr_offset) {
                ret = uprobe_register_refctr(tu->inode, tu->offset,
                                tu->ref_ctr_offset, &tu->consumer);
        } else {
                ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
        }

        if (ret)
                goto err_buffer;

        return 0;

 err_buffer:
        uprobe_buffer_disable();

 err_flags:
        if (file) {
                list_del(&link->list);
                kfree(link);
                tu->tp.flags &= ~TP_FLAG_TRACE;
        } else {
                tu->tp.flags &= ~TP_FLAG_PROFILE;
        }
        return ret;
}

static void
probe_event_disable(struct trace_uprobe *tu, struct trace_event_file *file)
{
        if (!trace_probe_is_enabled(&tu->tp))
                return;

        if (file) {
                struct event_file_link *link;

                link = find_event_file_link(&tu->tp, file);
                if (!link)
                        return;

                list_del_rcu(&link->list);
                /* synchronize with u{,ret}probe_trace_func */
                synchronize_rcu();
                kfree(link);

                if (!list_empty(&tu->tp.files))
                        return;
        }

        WARN_ON(!uprobe_filter_is_empty(&tu->filter));

        uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
        tu->inode = NULL;
        tu->tp.flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;

        uprobe_buffer_disable();
}

static int uprobe_event_define_fields(struct trace_event_call *event_call)
{
        int ret, size;
        struct uprobe_trace_entry_head field;
        struct trace_uprobe *tu = event_call->data;

        if (is_ret_probe(tu)) {
                DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_FUNC, 0);
                DEFINE_FIELD(unsigned long, vaddr[1], FIELD_STRING_RETIP, 0);
                size = SIZEOF_TRACE_ENTRY(true);
        } else {
                DEFINE_FIELD(unsigned long, vaddr[0], FIELD_STRING_IP, 0);
                size = SIZEOF_TRACE_ENTRY(false);
        }

        return traceprobe_define_arg_fields(event_call, size, &tu->tp);
}

#ifdef CONFIG_PERF_EVENTS
static bool
__uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
{
        struct perf_event *event;

        if (filter->nr_systemwide)
                return true;

        list_for_each_entry(event, &filter->perf_events, hw.tp_list) {
                if (event->hw.target->mm == mm)
                        return true;
        }

        return false;
}

static inline bool
uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
{
        return __uprobe_perf_filter(&tu->filter, event->hw.target->mm);
}

static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
{
        bool done;

        write_lock(&tu->filter.rwlock);
        if (event->hw.target) {
                list_del(&event->hw.tp_list);
                done = tu->filter.nr_systemwide ||
                        (event->hw.target->flags & PF_EXITING) ||
                        uprobe_filter_event(tu, event);
        } else {
                tu->filter.nr_systemwide--;
                done = tu->filter.nr_systemwide;
        }
        write_unlock(&tu->filter.rwlock);

        if (!done)
                return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);

        return 0;
}

static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
{
        bool done;
        int err;

        write_lock(&tu->filter.rwlock);
        if (event->hw.target) {
                /*
                 * event->parent != NULL means copy_process(), we can avoid
                 * uprobe_apply(). current->mm must be probed and we can rely
                 * on dup_mmap() which preserves the already installed bp's.
                 *
                 * attr.enable_on_exec means that exec/mmap will install the
                 * breakpoints we need.
                 */
                done = tu->filter.nr_systemwide ||
                        event->parent || event->attr.enable_on_exec ||
                        uprobe_filter_event(tu, event);
                list_add(&event->hw.tp_list, &tu->filter.perf_events);
        } else {
                done = tu->filter.nr_systemwide;
                tu->filter.nr_systemwide++;
        }
        write_unlock(&tu->filter.rwlock);

        err = 0;
        if (!done) {
                err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
                if (err)
                        uprobe_perf_close(tu, event);
        }
        return err;
}

static bool uprobe_perf_filter(struct uprobe_consumer *uc,
                                enum uprobe_filter_ctx ctx, struct mm_struct *mm)
{
        struct trace_uprobe *tu;
        int ret;

        tu = container_of(uc, struct trace_uprobe, consumer);
        read_lock(&tu->filter.rwlock);
        ret = __uprobe_perf_filter(&tu->filter, mm);
        read_unlock(&tu->filter.rwlock);

        return ret;
}

static void __uprobe_perf_func(struct trace_uprobe *tu,
                               unsigned long func, struct pt_regs *regs,
                               struct uprobe_cpu_buffer *ucb, int dsize)
{
        struct trace_event_call *call = &tu->tp.call;
        struct uprobe_trace_entry_head *entry;
        struct hlist_head *head;
        void *data;
        int size, esize;
        int rctx;

        if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
                return;

        esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));

        size = esize + tu->tp.size + dsize;
        size = ALIGN(size + sizeof(u32), sizeof(u64)) - sizeof(u32);
        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
                return;

        preempt_disable();
        head = this_cpu_ptr(call->perf_events);
        if (hlist_empty(head))
                goto out;

        entry = perf_trace_buf_alloc(size, NULL, &rctx);
        if (!entry)
                goto out;

        if (is_ret_probe(tu)) {
                entry->vaddr[0] = func;
                entry->vaddr[1] = instruction_pointer(regs);
                data = DATAOF_TRACE_ENTRY(entry, true);
        } else {
                entry->vaddr[0] = instruction_pointer(regs);
                data = DATAOF_TRACE_ENTRY(entry, false);
        }

        memcpy(data, ucb->buf, tu->tp.size + dsize);

        if (size - esize > tu->tp.size + dsize) {
                int len = tu->tp.size + dsize;

                memset(data + len, 0, size - esize - len);
        }

        perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
                              head, NULL);
 out:
        preempt_enable();
}

/* uprobe profile handler */
static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs,
                            struct uprobe_cpu_buffer *ucb, int dsize)
{
        if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
                return UPROBE_HANDLER_REMOVE;

        if (!is_ret_probe(tu))
                __uprobe_perf_func(tu, 0, regs, ucb, dsize);
        return 0;
}

static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
                                struct pt_regs *regs,
                                struct uprobe_cpu_buffer *ucb, int dsize)
{
        __uprobe_perf_func(tu, func, regs, ucb, dsize);
}

int bpf_get_uprobe_info(const struct perf_event *event, u32 *fd_type,
                        const char **filename, u64 *probe_offset,
                        bool perf_type_tracepoint)
{
        const char *pevent = trace_event_name(event->tp_event);
        const char *group = event->tp_event->class->system;
        struct trace_uprobe *tu;

        if (perf_type_tracepoint)
                tu = find_probe_event(pevent, group);
        else
                tu = event->tp_event->data;
        if (!tu)
                return -EINVAL;

        *fd_type = is_ret_probe(tu) ? BPF_FD_TYPE_URETPROBE
                                    : BPF_FD_TYPE_UPROBE;
        *filename = tu->filename;
        *probe_offset = tu->offset;
        return 0;
}
#endif  /* CONFIG_PERF_EVENTS */

static int
trace_uprobe_register(struct trace_event_call *event, enum trace_reg type,
                      void *data)
{
        struct trace_uprobe *tu = event->data;
        struct trace_event_file *file = data;

        switch (type) {
        case TRACE_REG_REGISTER:
                return probe_event_enable(tu, file, NULL);

        case TRACE_REG_UNREGISTER:
                probe_event_disable(tu, file);
                return 0;

#ifdef CONFIG_PERF_EVENTS
        case TRACE_REG_PERF_REGISTER:
                return probe_event_enable(tu, NULL, uprobe_perf_filter);

        case TRACE_REG_PERF_UNREGISTER:
                probe_event_disable(tu, NULL);
                return 0;

        case TRACE_REG_PERF_OPEN:
                return uprobe_perf_open(tu, data);

        case TRACE_REG_PERF_CLOSE:
                return uprobe_perf_close(tu, data);

#endif
        default:
                return 0;
        }
        return 0;
}

static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
{
        struct trace_uprobe *tu;
        struct uprobe_dispatch_data udd;
        struct uprobe_cpu_buffer *ucb;
        int dsize, esize;
        int ret = 0;


        tu = container_of(con, struct trace_uprobe, consumer);
        tu->nhit++;

        udd.tu = tu;
        udd.bp_addr = instruction_pointer(regs);

        current->utask->vaddr = (unsigned long) &udd;

        if (WARN_ON_ONCE(!uprobe_cpu_buffer))
                return 0;

        dsize = __get_data_size(&tu->tp, regs);
        esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));

        ucb = uprobe_buffer_get();
        store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);

        if (tu->tp.flags & TP_FLAG_TRACE)
                ret |= uprobe_trace_func(tu, regs, ucb, dsize);

#ifdef CONFIG_PERF_EVENTS
        if (tu->tp.flags & TP_FLAG_PROFILE)
                ret |= uprobe_perf_func(tu, regs, ucb, dsize);
#endif
        uprobe_buffer_put(ucb);
        return ret;
}

static int uretprobe_dispatcher(struct uprobe_consumer *con,
                                unsigned long func, struct pt_regs *regs)
{
        struct trace_uprobe *tu;
        struct uprobe_dispatch_data udd;
        struct uprobe_cpu_buffer *ucb;
        int dsize, esize;

        tu = container_of(con, struct trace_uprobe, consumer);

        udd.tu = tu;
        udd.bp_addr = func;

        current->utask->vaddr = (unsigned long) &udd;

        if (WARN_ON_ONCE(!uprobe_cpu_buffer))
                return 0;

        dsize = __get_data_size(&tu->tp, regs);
        esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));

        ucb = uprobe_buffer_get();
        store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);

        if (tu->tp.flags & TP_FLAG_TRACE)
                uretprobe_trace_func(tu, func, regs, ucb, dsize);

#ifdef CONFIG_PERF_EVENTS
        if (tu->tp.flags & TP_FLAG_PROFILE)
                uretprobe_perf_func(tu, func, regs, ucb, dsize);
#endif
        uprobe_buffer_put(ucb);
        return 0;
}

static struct trace_event_functions uprobe_funcs = {
        .trace          = print_uprobe_event
};

static inline void init_trace_event_call(struct trace_uprobe *tu,
                                         struct trace_event_call *call)
{
        INIT_LIST_HEAD(&call->class->fields);
        call->event.funcs = &uprobe_funcs;
        call->class->define_fields = uprobe_event_define_fields;

        call->flags = TRACE_EVENT_FL_UPROBE;
        call->class->reg = trace_uprobe_register;
        call->data = tu;
}

static int register_uprobe_event(struct trace_uprobe *tu)
{
        struct trace_event_call *call = &tu->tp.call;
        int ret = 0;

        init_trace_event_call(tu, call);

        if (traceprobe_set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
                return -ENOMEM;

        ret = register_trace_event(&call->event);
        if (!ret) {
                kfree(call->print_fmt);
                return -ENODEV;
        }

        ret = trace_add_event_call(call);

        if (ret) {
                pr_info("Failed to register uprobe event: %s\n",
                        trace_event_name(call));
                kfree(call->print_fmt);
                unregister_trace_event(&call->event);
        }

        return ret;
}

static int unregister_uprobe_event(struct trace_uprobe *tu)
{
        int ret;

        /* tu->event is unregistered in trace_remove_event_call() */
        ret = trace_remove_event_call(&tu->tp.call);
        if (ret)
                return ret;
        kfree(tu->tp.call.print_fmt);
        tu->tp.call.print_fmt = NULL;
        return 0;
}

#ifdef CONFIG_PERF_EVENTS
struct trace_event_call *
create_local_trace_uprobe(char *name, unsigned long offs,
                          unsigned long ref_ctr_offset, bool is_return)
{
        struct trace_uprobe *tu;
        struct path path;
        int ret;

        ret = kern_path(name, LOOKUP_FOLLOW, &path);
        if (ret)
                return ERR_PTR(ret);

        if (!d_is_reg(path.dentry)) {
                path_put(&path);
                return ERR_PTR(-EINVAL);
        }

        /*
         * local trace_kprobes are not added to dyn_event, so they are never
         * searched in find_trace_kprobe(). Therefore, there is no concern of
         * duplicated name "DUMMY_EVENT" here.
         */
        tu = alloc_trace_uprobe(UPROBE_EVENT_SYSTEM, "DUMMY_EVENT", 0,
                                is_return);

        if (IS_ERR(tu)) {
                pr_info("Failed to allocate trace_uprobe.(%d)\n",
                        (int)PTR_ERR(tu));
                path_put(&path);
                return ERR_CAST(tu);
        }

        tu->offset = offs;
        tu->path = path;
        tu->ref_ctr_offset = ref_ctr_offset;
        tu->filename = kstrdup(name, GFP_KERNEL);
        init_trace_event_call(tu, &tu->tp.call);

        if (traceprobe_set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0) {
                ret = -ENOMEM;
                goto error;
        }

        return &tu->tp.call;
error:
        free_trace_uprobe(tu);
        return ERR_PTR(ret);
}

void destroy_local_trace_uprobe(struct trace_event_call *event_call)
{
        struct trace_uprobe *tu;

        tu = container_of(event_call, struct trace_uprobe, tp.call);

        kfree(tu->tp.call.print_fmt);
        tu->tp.call.print_fmt = NULL;

        free_trace_uprobe(tu);
}
#endif /* CONFIG_PERF_EVENTS */

/* Make a trace interface for controling probe points */
static __init int init_uprobe_trace(void)
{
        struct dentry *d_tracer;
        int ret;

        ret = dyn_event_register(&trace_uprobe_ops);
        if (ret)
                return ret;

        d_tracer = tracing_init_dentry();
        if (IS_ERR(d_tracer))
                return 0;

        trace_create_file("uprobe_events", 0644, d_tracer,
                                    NULL, &uprobe_events_ops);
        /* Profile interface */
        trace_create_file("uprobe_profile", 0444, d_tracer,
                                    NULL, &uprobe_profile_ops);
        return 0;
}

fs_initcall(init_uprobe_trace);