Re: [PATCH v8-RESEND 05/33] dyndbg: replace classmap list with a vector

[Łukasz Bartosik]

On Thu, May 16, 2024 at 7:44 PM Jim Cromie <jim.cromie@xxxxxxxxx> wrote:
>
> Classmaps are stored in an elf section/array, but are individually
> list-linked onto dyndbg's per-module ddebug_table for operation.
>
> This is unnecessary; even when ddebug_attach_classmap() is handling
> the builtin section (with classmaps for multiple builtin modules), its
> contents are ordered, so a module's possibly multiple classmaps will
> be consecutive in the section, and could be treated as a vector/block,
> since both start-addy and subrange length are in the ddebug_info arg.

Should it be start-addr instead of start-addy ?

>
> IOW, this treats classmaps similarly to _ddebugs, which are already
> kept as vector-refs (address+len).
>
> So this changes:
>
> struct ddebug_class_map drops list-head link.
>
> struct ddebug_table drops the list-head maps, and gets: classes &
> num_classes for the start-addy and num_classes, placed to improve

The same here. Should it be start-addr instead of start-addy ?

> struct packing.
>
> The loading: in ddebug_attach_module_classes(), replace the
> for-the-modname list-add loop, with a forloop that finds the module's

Please add space forloop -> for loop

> subrange (start,length) of matching classmaps within the possibly
> builtin classmaps vector, and saves those to the ddebug_table.
>
> The reading/using: change list-foreach loops in ddebug_class_name() &
> ddebug_find_valid_class() to walk the array from start to length.
>
> Also:
> Move #define __outvar up, above an added use in a fn-prototype.
> Simplify ddebug_attach_module_classes args, ref has both addy,len.

addy,len -> addr,len ?


>
> no functional changes
>
> Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
> ---
>  include/linux/dynamic_debug.h |  1 -
>  lib/dynamic_debug.c           | 61 ++++++++++++++++++-----------------
>  2 files changed, 32 insertions(+), 30 deletions(-)
>
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index 5231aaf361c4..b53217e4b711 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -83,7 +83,6 @@ enum class_map_type {
>  };
>
>  struct ddebug_class_map {
> -       struct list_head link;
>         struct module *mod;
>         const char *mod_name;   /* needed for builtins */
>         const char **class_names;
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 152b04c05981..46e4cdd8e6be 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -45,10 +45,11 @@ extern struct ddebug_class_map __start___dyndbg_classes[];
>  extern struct ddebug_class_map __stop___dyndbg_classes[];
>
>  struct ddebug_table {
> -       struct list_head link, maps;
> +       struct list_head link;
>         const char *mod_name;
> -       unsigned int num_ddebugs;
>         struct _ddebug *ddebugs;
> +       struct ddebug_class_map *classes;
> +       unsigned int num_ddebugs, num_classes;
>  };
>
>  struct ddebug_query {
> @@ -147,13 +148,15 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>                   query->first_lineno, query->last_lineno, query->class_string);
>  }
>
> +#define __outvar /* filled by callee */
>  static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
> -                                                         const char *class_string, int *class_id)
> +                                                       const char *class_string,
> +                                                       __outvar int *class_id)
>  {
>         struct ddebug_class_map *map;
> -       int idx;
> +       int i, idx;
>
> -       list_for_each_entry(map, &dt->maps, link) {
> +       for (map = dt->classes, i = 0; i < dt->num_classes; i++, map++) {
>                 idx = match_string(map->class_names, map->length, class_string);
>                 if (idx >= 0) {
>                         *class_id = idx + map->base;
> @@ -164,7 +167,6 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
>         return NULL;
>  }
>
> -#define __outvar /* filled by callee */
>  /*
>   * Search the tables for _ddebug's which match the given `query' and
>   * apply the `flags' and `mask' to them.  Returns number of matching
> @@ -1114,9 +1116,10 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
>
>  static const char *ddebug_class_name(struct ddebug_iter *iter, struct _ddebug *dp)
>  {
> -       struct ddebug_class_map *map;
> +       struct ddebug_class_map *map = iter->table->classes;
> +       int i, nc = iter->table->num_classes;
>
> -       list_for_each_entry(map, &iter->table->maps, link)
> +       for (i = 0; i < nc; i++, map++)
>                 if (class_in_range(dp->class_id, map))
>                         return map->class_names[dp->class_id - map->base];
>
> @@ -1200,30 +1203,31 @@ static const struct proc_ops proc_fops = {
>         .proc_write = ddebug_proc_write
>  };
>
> -static void ddebug_attach_module_classes(struct ddebug_table *dt,
> -                                        struct ddebug_class_map *classes,
> -                                        int num_classes)
> +static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug_info *di)
>  {
>         struct ddebug_class_map *cm;
> -       int i, j, ct = 0;
> +       int i, nc = 0;
>
> -       for (cm = classes, i = 0; i < num_classes; i++, cm++) {
> +       /*
> +        * Find this module's classmaps in a subrange/wholerange of
> +        * the builtin/modular classmap vector/section.  Save the start
> +        * and length of the subrange at its edges.
> +        */
> +       for (cm = di->classes, i = 0; i < di->num_classes; i++, cm++) {
>
>                 if (!strcmp(cm->mod_name, dt->mod_name)) {
> -
> -                       v2pr_info("class[%d]: module:%s base:%d len:%d ty:%d\n", i,
> -                                 cm->mod_name, cm->base, cm->length, cm->map_type);
> -
> -                       for (j = 0; j < cm->length; j++)
> -                               v3pr_info(" %d: %d %s\n", j + cm->base, j,
> -                                         cm->class_names[j]);
> -
> -                       list_add(&cm->link, &dt->maps);
> -                       ct++;
> +                       if (!nc) {
> +                               v2pr_info("start subrange, class[%d]: module:%s base:%d len:%d ty:%d\n",
> +                                         i, cm->mod_name, cm->base, cm->length, cm->map_type);
> +                               dt->classes = cm;
> +                       }
> +                       nc++;
>                 }
>         }
> -       if (ct)
> -               vpr_info("module:%s attached %d classes\n", dt->mod_name, ct);
> +       if (nc) {
> +               dt->num_classes = nc;
> +               vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
> +       }
>  }
>
>  /*
> @@ -1256,10 +1260,9 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
>         dt->num_ddebugs = di->num_descs;
>
>         INIT_LIST_HEAD(&dt->link);
> -       INIT_LIST_HEAD(&dt->maps);
>
>         if (di->classes && di->num_classes)
> -               ddebug_attach_module_classes(dt, di->classes, di->num_classes);
> +               ddebug_attach_module_classes(dt, di);
>
>         mutex_lock(&ddebug_lock);
>         list_add_tail(&dt->link, &ddebug_tables);
> @@ -1372,8 +1375,8 @@ 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);
> +                                                    struct ddebug_table,
> +                                                    link);
>                 ddebug_table_free(dt);
>         }
>         mutex_unlock(&ddebug_lock);
> --
> 2.45.0
>