1 files changed, 756 insertions, 0 deletions

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
new file mode 100644
index 000000000000..9e123ae326bc
--- /dev/null
+++ b/lib/dynamic_debug.c
@@ -0,0 +1,756 @@
+/*
+ * lib/dynamic_debug.c
+ *
+ * make pr_debug()/dev_dbg() calls runtime configurable based upon their
+ * source module.
+ *
+ * Copyright (C) 2008 Jason Baron <jbaron@redhat.com>
+ * By Greg Banks <gnb@melbourne.sgi.com>
+ * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kallsyms.h>
+#include <linux/version.h>
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/list.h>
+#include <linux/sysctl.h>
+#include <linux/ctype.h>
+#include <linux/uaccess.h>
+#include <linux/dynamic_debug.h>
+#include <linux/debugfs.h>
+
+extern struct _ddebug __start___verbose[];
+extern struct _ddebug __stop___verbose[];
+
+/* dynamic_debug_enabled, and dynamic_debug_enabled2 are bitmasks in which
+ * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
+ * use independent hash functions, to reduce the chance of false positives.
+ */
+long long dynamic_debug_enabled;
+EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
+long long dynamic_debug_enabled2;
+EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);
+
+struct ddebug_table {
+        struct list_head link;
+        char *mod_name;
+        unsigned int num_ddebugs;
+        unsigned int num_enabled;
+        struct _ddebug *ddebugs;
+};
+
+struct ddebug_query {
+        const char *filename;
+        const char *module;
+        const char *function;
+        const char *format;
+        unsigned int first_lineno, last_lineno;
+};
+
+struct ddebug_iter {
+        struct ddebug_table *table;
+        unsigned int idx;
+};
+
+static DEFINE_MUTEX(ddebug_lock);
+static LIST_HEAD(ddebug_tables);
+static int verbose = 0;
+
+/* Return the last part of a pathname */
+static inline const char *basename(const char *path)
+{
+        const char *tail = strrchr(path, '/');
+        return tail ? tail+1 : path;
+}
+
+/* format a string into buf[] which describes the _ddebug's flags */
+static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
+                                    size_t maxlen)
+{
+        char *p = buf;
+
+        BUG_ON(maxlen < 4);
+        if (dp->flags & _DPRINTK_FLAGS_PRINT)
+                *p++ = 'p';
+        if (p == buf)
+                *p++ = '-';
+        *p = '\0';
+
+        return buf;
+}
+
+/*
+ * must be called with ddebug_lock held
+ */
+
+static int disabled_hash(char hash, bool first_table)
+{
+        struct ddebug_table *dt;
+        char table_hash_value;
+
+        list_for_each_entry(dt, &ddebug_tables, link) {
+                if (first_table)
+                        table_hash_value = dt->ddebugs->primary_hash;
+                else
+                        table_hash_value = dt->ddebugs->secondary_hash;
+                if (dt->num_enabled && (hash == table_hash_value))
+                        return 0;
+        }
+        return 1;
+}
+
+/*
+ * Search the tables for _ddebug's which match the given
+ * `query' and apply the `flags' and `mask' to them.  Tells
+ * the user which ddebug's were changed, or whether none
+ * were matched.
+ */
+static void ddebug_change(const struct ddebug_query *query,
+                           unsigned int flags, unsigned int mask)
+{
+        int i;
+        struct ddebug_table *dt;
+        unsigned int newflags;
+        unsigned int nfound = 0;
+        char flagbuf[8];
+
+        /* search for matching ddebugs */
+        mutex_lock(&ddebug_lock);
+        list_for_each_entry(dt, &ddebug_tables, link) {
+
+                /* match against the module name */
+                if (query->module != NULL &&
+                    strcmp(query->module, dt->mod_name))
+                        continue;
+
+                for (i = 0 ; i < dt->num_ddebugs ; i++) {
+                        struct _ddebug *dp = &dt->ddebugs[i];
+
+                        /* match against the source filename */
+                        if (query->filename != NULL &&
+                            strcmp(query->filename, dp->filename) &&
+                            strcmp(query->filename, basename(dp->filename)))
+                                continue;
+
+                        /* match against the function */
+                        if (query->function != NULL &&
+                            strcmp(query->function, dp->function))
+                                continue;
+
+                        /* match against the format */
+                        if (query->format != NULL &&
+                            strstr(dp->format, query->format) == NULL)
+                                continue;
+
+                        /* match against the line number range */
+                        if (query->first_lineno &&
+                            dp->lineno < query->first_lineno)
+                                continue;
+                        if (query->last_lineno &&
+                            dp->lineno > query->last_lineno)
+                                continue;
+
+                        nfound++;
+
+                        newflags = (dp->flags & mask) | flags;
+                        if (newflags == dp->flags)
+                                continue;
+
+                        if (!newflags)
+                                dt->num_enabled--;
+                        else if (!dp-flags)
+                                dt->num_enabled++;
+                        dp->flags = newflags;
+                        if (newflags) {
+                                dynamic_debug_enabled |=
+                                                (1LL << dp->primary_hash);
+                                dynamic_debug_enabled2 |=
+                                                (1LL << dp->secondary_hash);
+                        } else {
+                                if (disabled_hash(dp->primary_hash, true))
+                                        dynamic_debug_enabled &=
+                                                ~(1LL << dp->primary_hash);
+                                if (disabled_hash(dp->secondary_hash, false))
+                                        dynamic_debug_enabled2 &=
+                                                ~(1LL << dp->secondary_hash);
+                        }
+                        if (verbose)
+                                printk(KERN_INFO
+                                        "ddebug: changed %s:%d [%s]%s %s\n",
+                                        dp->filename, dp->lineno,
+                                        dt->mod_name, dp->function,
+                                        ddebug_describe_flags(dp, flagbuf,
+                                                        sizeof(flagbuf)));
+                }
+        }
+        mutex_unlock(&ddebug_lock);
+
+        if (!nfound && verbose)
+                printk(KERN_INFO "ddebug: no matches for query\n");
+}
+
+/*
+ * Wrapper around strsep() to collapse the multiple empty tokens
+ * that it returns when fed sequences of separator characters.
+ * Now, if we had strtok_r()...
+ */
+static inline char *nearly_strtok_r(char **p, const char *sep)
+{
+        char *r;
+
+        while ((r = strsep(p, sep)) != NULL && *r == '\0')
+                ;
+        return r;
+}
+
+/*
+ * Split the buffer `buf' into space-separated words.
+ * Return the number of such words or <0 on error.
+ */
+static int ddebug_tokenize(char *buf, char *words[], int maxwords)
+{
+        int nwords = 0;
+
+        while (nwords < maxwords &&
+               (words[nwords] = nearly_strtok_r(&buf, " \t\r\n")) != NULL)
+                nwords++;
+        if (buf)
+                return -EINVAL; /* ran out of words[] before bytes */
+
+        if (verbose) {
+                int i;
+                printk(KERN_INFO "%s: split into words:", __func__);
+                for (i = 0 ; i < nwords ; i++)
+                        printk(" \"%s\"", words[i]);
+                printk("\n");
+        }
+
+        return nwords;
+}
+
+/*
+ * Parse a single line number.  Note that the empty string ""
+ * is treated as a special case and converted to zero, which
+ * is later treated as a "don't care" value.
+ */
+static inline int parse_lineno(const char *str, unsigned int *val)
+{
+        char *end = NULL;
+        BUG_ON(str == NULL);
+        if (*str == '\0') {
+                *val = 0;
+                return 0;
+        }
+        *val = simple_strtoul(str, &end, 10);
+        return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
+}
+
+/*
+ * Undo octal escaping in a string, inplace.  This is useful to
+ * allow the user to express a query which matches a format
+ * containing embedded spaces.
+ */
+#define isodigit(c)             ((c) >= '0' && (c) <= '7')
+static char *unescape(char *str)
+{
+        char *in = str;
+        char *out = str;
+
+        while (*in) {
+                if (*in == '\\') {
+                        if (in[1] == '\\') {
+                                *out++ = '\\';
+                                in += 2;
+                                continue;
+                        } else if (in[1] == 't') {
+                                *out++ = '\t';
+                                in += 2;
+                                continue;
+                        } else if (in[1] == 'n') {
+                                *out++ = '\n';
+                                in += 2;
+                                continue;
+                        } else if (isodigit(in[1]) &&
+                                 isodigit(in[2]) &&
+                                 isodigit(in[3])) {
+                                *out++ = ((in[1] - '0')<<6) |
+                                          ((in[2] - '0')<<3) |
+                                          (in[3] - '0');
+                                in += 4;
+                                continue;
+                        }
+                }
+                *out++ = *in++;
+        }
+        *out = '\0';
+
+        return str;
+}
+
+/*
+ * Parse words[] as a ddebug query specification, which is a series
+ * of (keyword, value) pairs chosen from these possibilities:
+ *
+ * func <function-name>
+ * file <full-pathname>
+ * file <base-filename>
+ * module <module-name>
+ * format <escaped-string-to-find-in-format>
+ * line <lineno>
+ * line <first-lineno>-<last-lineno> // where either may be empty
+ */
+static int ddebug_parse_query(char *words[], int nwords,
+                               struct ddebug_query *query)
+{
+        unsigned int i;
+
+        /* check we have an even number of words */
+        if (nwords % 2 != 0)
+                return -EINVAL;
+        memset(query, 0, sizeof(*query));
+
+        for (i = 0 ; i < nwords ; i += 2) {
+                if (!strcmp(words[i], "func"))
+                        query->function = words[i+1];
+                else if (!strcmp(words[i], "file"))
+                        query->filename = words[i+1];
+                else if (!strcmp(words[i], "module"))
+                        query->module = words[i+1];
+                else if (!strcmp(words[i], "format"))
+                        query->format = unescape(words[i+1]);
+                else if (!strcmp(words[i], "line")) {
+                        char *first = words[i+1];
+                        char *last = strchr(first, '-');
+                        if (last)
+                                *last++ = '\0';
+                        if (parse_lineno(first, &query->first_lineno) < 0)
+                                return -EINVAL;
+                        if (last != NULL) {
+                                /* range <first>-<last> */
+                                if (parse_lineno(last, &query->last_lineno) < 0)
+                                        return -EINVAL;
+                        } else {
+                                query->last_lineno = query->first_lineno;
+                        }
+                } else {
+                        if (verbose)
+                                printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
+                                        __func__, words[i]);
+                        return -EINVAL;
+                }
+        }
+
+        if (verbose)
+                printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
+                       "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
+                        __func__, query->function, query->filename,
+                        query->module, query->format, query->first_lineno,
+                        query->last_lineno);
+
+        return 0;
+}
+
+/*
+ * Parse `str' as a flags specification, format [-+=][p]+.
+ * Sets up *maskp and *flagsp to be used when changing the
+ * flags fields of matched _ddebug's.  Returns 0 on success
+ * or <0 on error.
+ */
+static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
+                               unsigned int *maskp)
+{
+        unsigned flags = 0;
+        int op = '=';
+
+        switch (*str) {
+        case '+':
+        case '-':
+        case '=':
+                op = *str++;
+                break;
+        default:
+                return -EINVAL;
+        }
+        if (verbose)
+                printk(KERN_INFO "%s: op='%c'\n", __func__, op);
+
+        for ( ; *str ; ++str) {
+                switch (*str) {
+                case 'p':
+                        flags |= _DPRINTK_FLAGS_PRINT;
+                        break;
+                default:
+                        return -EINVAL;
+                }
+        }
+        if (flags == 0)
+                return -EINVAL;
+        if (verbose)
+                printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);
+
+        /* calculate final *flagsp, *maskp according to mask and op */
+        switch (op) {
+        case '=':
+                *maskp = 0;
+                *flagsp = flags;
+                break;
+        case '+':
+                *maskp = ~0U;
+                *flagsp = flags;
+                break;
+        case '-':
+                *maskp = ~flags;
+                *flagsp = 0;
+                break;
+        }
+        if (verbose)
+                printk(KERN_INFO "%s: *flagsp=0x%x *maskp=0x%x\n",
+                        __func__, *flagsp, *maskp);
+        return 0;
+}
+
+/*
+ * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
+ * command text from userspace, parses and executes it.
+ */
+static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
+                                  size_t len, loff_t *offp)
+{
+        unsigned int flags = 0, mask = 0;
+        struct ddebug_query query;
+#define MAXWORDS 9
+        int nwords;
+        char *words[MAXWORDS];
+        char tmpbuf[256];
+
+        if (len == 0)
+                return 0;
+        /* we don't check *offp -- multiple writes() are allowed */
+        if (len > sizeof(tmpbuf)-1)
+                return -E2BIG;
+        if (copy_from_user(tmpbuf, ubuf, len))
+                return -EFAULT;
+        tmpbuf[len] = '\0';
+        if (verbose)
+                printk(KERN_INFO "%s: read %d bytes from userspace\n",
+                        __func__, (int)len);
+
+        nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS);
+        if (nwords < 0)
+                return -EINVAL;
+        if (ddebug_parse_query(words, nwords-1, &query))
+                return -EINVAL;
+        if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
+                return -EINVAL;
+
+        /* actually go and implement the change */
+        ddebug_change(&query, flags, mask);
+
+        *offp += len;
+        return len;
+}
+
+/*
+ * Set the iterator to point to the first _ddebug object
+ * and return a pointer to that first object.  Returns
+ * NULL if there are no _ddebugs at all.
+ */
+static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
+{
+        if (list_empty(&ddebug_tables)) {
+                iter->table = NULL;
+                iter->idx = 0;
+                return NULL;
+        }
+        iter->table = list_entry(ddebug_tables.next,
+                                 struct ddebug_table, link);
+        iter->idx = 0;
+        return &iter->table->ddebugs[iter->idx];
+}
+
+/*
+ * Advance the iterator to point to the next _ddebug
+ * object from the one the iterator currently points at,
+ * and returns a pointer to the new _ddebug.  Returns
+ * NULL if the iterator has seen all the _ddebugs.
+ */
+static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
+{
+        if (iter->table == NULL)
+                return NULL;
+        if (++iter->idx == iter->table->num_ddebugs) {
+                /* iterate to next table */
+                iter->idx = 0;
+                if (list_is_last(&iter->table->link, &ddebug_tables)) {
+                        iter->table = NULL;
+                        return NULL;
+                }
+                iter->table = list_entry(iter->table->link.next,
+                                         struct ddebug_table, link);
+        }
+        return &iter->table->ddebugs[iter->idx];
+}
+
+/*
+ * Seq_ops start method.  Called at the start of every
+ * read() call from userspace.  Takes the ddebug_lock and
+ * seeks the seq_file's iterator to the given position.
+ */
+static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
+{
+        struct ddebug_iter *iter = m->private;
+        struct _ddebug *dp;
+        int n = *pos;
+
+        if (verbose)
+                printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
+                        __func__, m, (unsigned long long)*pos);
+
+        mutex_lock(&ddebug_lock);
+
+        if (!n)
+                return SEQ_START_TOKEN;
+        if (n < 0)
+                return NULL;
+        dp = ddebug_iter_first(iter);
+        while (dp != NULL && --n > 0)
+                dp = ddebug_iter_next(iter);
+        return dp;
+}
+
+/*
+ * Seq_ops next method.  Called several times within a read()
+ * call from userspace, with ddebug_lock held.  Walks to the
+ * next _ddebug object with a special case for the header line.
+ */
+static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
+{
+        struct ddebug_iter *iter = m->private;
+        struct _ddebug *dp;
+
+        if (verbose)
+                printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
+                        __func__, m, p, (unsigned long long)*pos);
+
+        if (p == SEQ_START_TOKEN)
+                dp = ddebug_iter_first(iter);
+        else
+                dp = ddebug_iter_next(iter);
+        ++*pos;
+        return dp;
+}
+
+/*
+ * Seq_ops show method.  Called several times within a read()
+ * call from userspace, with ddebug_lock held.  Formats the
+ * current _ddebug as a single human-readable line, with a
+ * special case for the header line.
+ */
+static int ddebug_proc_show(struct seq_file *m, void *p)
+{
+        struct ddebug_iter *iter = m->private;
+        struct _ddebug *dp = p;
+        char flagsbuf[8];
+
+        if (verbose)
+                printk(KERN_INFO "%s: called m=%p p=%p\n",
+                        __func__, m, p);
+
+        if (p == SEQ_START_TOKEN) {
+                seq_puts(m,
+                        "# filename:lineno [module]function flags format\n");
+                return 0;
+        }
+
+        seq_printf(m, "%s:%u [%s]%s %s \"",
+                   dp->filename, dp->lineno,
+                   iter->table->mod_name, dp->function,
+                   ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
+        seq_escape(m, dp->format, "\t\r\n\"");
+        seq_puts(m, "\"\n");
+
+        return 0;
+}
+
+/*
+ * Seq_ops stop method.  Called at the end of each read()
+ * call from userspace.  Drops ddebug_lock.
+ */
+static void ddebug_proc_stop(struct seq_file *m, void *p)
+{
+        if (verbose)
+                printk(KERN_INFO "%s: called m=%p p=%p\n",
+                        __func__, m, p);
+        mutex_unlock(&ddebug_lock);
+}
+
+static const struct seq_operations ddebug_proc_seqops = {
+        .start = ddebug_proc_start,
+        .next = ddebug_proc_next,
+        .show = ddebug_proc_show,
+        .stop = ddebug_proc_stop
+};
+
+/*
+ * File_ops->open method for <debugfs>/dynamic_debug/control.  Does the seq_file
+ * setup dance, and also creates an iterator to walk the _ddebugs.
+ * Note that we create a seq_file always, even for O_WRONLY files
+ * where it's not needed, as doing so simplifies the ->release method.
+ */
+static int ddebug_proc_open(struct inode *inode, struct file *file)
+{
+        struct ddebug_iter *iter;
+        int err;
+
+        if (verbose)
+                printk(KERN_INFO "%s: called\n", __func__);
+
+        iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+        if (iter == NULL)
+                return -ENOMEM;
+
+        err = seq_open(file, &ddebug_proc_seqops);
+        if (err) {
+                kfree(iter);
+                return err;
+        }
+        ((struct seq_file *) file->private_data)->private = iter;
+        return 0;
+}
+
+static const struct file_operations ddebug_proc_fops = {
+        .owner = THIS_MODULE,
+        .open = ddebug_proc_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = seq_release_private,
+        .write = ddebug_proc_write
+};
+
+/*
+ * Allocate a new ddebug_table for the given module
+ * and add it to the global list.
+ */
+int ddebug_add_module(struct _ddebug *tab, unsigned int n,
+                             const char *name)
+{
+        struct ddebug_table *dt;
+        char *new_name;
+
+        dt = kzalloc(sizeof(*dt), GFP_KERNEL);
+        if (dt == NULL)
+                return -ENOMEM;
+        new_name = kstrdup(name, GFP_KERNEL);
+        if (new_name == NULL) {
+                kfree(dt);
+                return -ENOMEM;
+        }
+        dt->mod_name = new_name;
+        dt->num_ddebugs = n;
+        dt->num_enabled = 0;
+        dt->ddebugs = tab;
+
+        mutex_lock(&ddebug_lock);
+        list_add_tail(&dt->link, &ddebug_tables);
+        mutex_unlock(&ddebug_lock);
+
+        if (verbose)
+                printk(KERN_INFO "%u debug prints in module %s\n",
+                                 n, dt->mod_name);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(ddebug_add_module);
+
+static void ddebug_table_free(struct ddebug_table *dt)
+{
+        list_del_init(&dt->link);
+        kfree(dt->mod_name);
+        kfree(dt);
+}
+
+/*
+ * Called in response to a module being unloaded.  Removes
+ * any ddebug_table's which point at the module.
+ */
+int ddebug_remove_module(char *mod_name)
+{
+        struct ddebug_table *dt, *nextdt;
+        int ret = -ENOENT;
+
+        if (verbose)
+                printk(KERN_INFO "%s: removing module \"%s\"\n",
+                                __func__, mod_name);
+
+        mutex_lock(&ddebug_lock);
+        list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
+                if (!strcmp(dt->mod_name, mod_name)) {
+                        ddebug_table_free(dt);
+                        ret = 0;
+                }
+        }
+        mutex_unlock(&ddebug_lock);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(ddebug_remove_module);
+
+static void ddebug_remove_all_tables(void)
+{
+        mutex_lock(&ddebug_lock);
+        while (!list_empty(&ddebug_tables)) {
+                struct ddebug_table *dt = list_entry(ddebug_tables.next,
+                                                      struct ddebug_table,
+                                                      link);
+                ddebug_table_free(dt);
+        }
+        mutex_unlock(&ddebug_lock);
+}
+
+static int __init dynamic_debug_init(void)
+{
+        struct dentry *dir, *file;
+        struct _ddebug *iter, *iter_start;
+        const char *modname = NULL;
+        int ret = 0;
+        int n = 0;
+
+        dir = debugfs_create_dir("dynamic_debug", NULL);
+        if (!dir)
+                return -ENOMEM;
+        file = debugfs_create_file("control", 0644, dir, NULL,
+                                        &ddebug_proc_fops);
+        if (!file) {
+                debugfs_remove(dir);
+                return -ENOMEM;
+        }
+        if (__start___verbose != __stop___verbose) {
+                iter = __start___verbose;
+                modname = iter->modname;
+                iter_start = iter;
+                for (; iter < __stop___verbose; iter++) {
+                        if (strcmp(modname, iter->modname)) {
+                                ret = ddebug_add_module(iter_start, n, modname);
+                                if (ret)
+                                        goto out_free;
+                                n = 0;
+                                modname = iter->modname;
+                                iter_start = iter;
+                        }
+                        n++;
+                }
+                ret = ddebug_add_module(iter_start, n, modname);
+        }
+out_free:
+        if (ret) {
+                ddebug_remove_all_tables();
+                debugfs_remove(dir);
+                debugfs_remove(file);
+        }
+        return 0;
+}
+module_init(dynamic_debug_init);