[PATCH v2 12/59] dyndbg, module: make proper substructs in _ddebug_info
Louis Chauvet
louis.chauvet at bootlin.com
Mon Mar 24 15:10:54 UTC 2025
Le 20/03/2025 à 19:51, Jim Cromie a écrit :
> recompose struct _ddebug_info, inserting proper sub-structs.
>
> The struct currently has 2 pairs of fields: descs, num_descs and
> classes, num_classes. Several for-loops operate on these field pairs,
> soon many more will be added.
>
> Looping over these blocks by respective field-pairs is repetitive and
> fiddly, differing only by the field-names. Before adding a 3rd
> section and compounding the fiddly details problem, make proper
> substructs of each section, with the same named fields.
>
> So this patch does:
>
> Adds 3 "vector<T>" structs, each with { <T> *start, int len; }
> components, for _ddebug_descriptors, _ddebug_class_maps, and
> _ddebug_class_users respectively.
>
> Invariant: These vectors ref a contiguous subrange of __section memory
> in builtin/DATA or in loadable modules via mod->dyndbg_info; with
> guaranteed life-time for us.
>
> Bundles these 3 vectors (subrange-refs) struct (reformed) _ddebug_info,
> where they're __packed to close the paholes introduced otherwise.
>
> The common fields allow improving the for_subvec() macro by dropping
> the ugly num_##<T> paste-up.
>
> Also recompose struct ddebug_table to contain a _ddebug_info. This
> reinforces its use as a cursor into relevant data for a builtin
> module, and access to the full _ddebug state for modules.
>
> NOTES:
>
> Fixup names: section names improved, struct names normalized to
> _ddebug_*
Maybe this should be in a separate patch?
> struct module contains a _ddebug_info field and module/main.c sets it
> up, so that gets adjusted.
>
> The __packed attribute on _ddebug_info and the 3 contained structs
> closes the holes otherwise created by the structification (which was
> my excuse for not doing it originally).
>
> Signed-off-by: Jim Cromie <jim.cromie at gmail.com>
> ---
> -v2 rework towards front of series
> ---
> include/asm-generic/vmlinux.lds.h | 4 +-
> include/linux/dynamic_debug.h | 28 +++++++---
> kernel/module/main.c | 12 ++--
> lib/dynamic_debug.c | 91 ++++++++++++++++---------------
> 4 files changed, 74 insertions(+), 61 deletions(-)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index c9c66089ea2f..f834ad1fb8c4 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -366,8 +366,8 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
> *(__tracepoints) \
> /* implement dynamic printk debug */ \
> . = ALIGN(8); \
> - BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) \
> - BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
> + BOUNDED_SECTION_BY(__dyndbg_class_maps, ___dyndbg_class_maps) \
> + BOUNDED_SECTION_BY(__dyndbg_descriptors, ___dyndbg_descs) \
> CODETAG_SECTIONS() \
> LIKELY_PROFILE() \
> BRANCH_PROFILE() \
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index e458d4b838ac..c388ab05a6e1 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -110,13 +110,23 @@ struct ddebug_class_map {
> .class_names = _var##_classnames, \
> }
>
> -/* encapsulate linker provided built-in (or module) dyndbg data */
> +/*
> + * @_ddebug_info: gathers module/builtin dyndbg_* __sections together.
> + * For builtins, it is used as a cursor, with the inner structs
> + * marking sub-vectors of the builtin __sections in DATA.
> + */
> +struct _ddebug_descs {
> + struct _ddebug *start;
> + int len;
> +} __packed;
> +struct _ddebug_class_maps {
> + struct ddebug_class_map *start;
> + int len;
> +} __packed;
> struct _ddebug_info {
> - struct _ddebug *descs;
> - struct ddebug_class_map *classes;
> - unsigned int num_descs;
> - unsigned int num_classes;
> -};
> + struct _ddebug_descs descs;
> + struct _ddebug_class_maps maps;
> +} __packed;
>
> struct ddebug_class_param {
> union {
> @@ -159,7 +169,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
>
> #define DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, cls, fmt) \
> static struct _ddebug __aligned(8) \
> - __section("__dyndbg") name = { \
> + __section("__dyndbg_descriptors") name = { \
> .modname = KBUILD_MODNAME, \
> .function = __func__, \
> .filename = __FILE__, \
> @@ -242,7 +252,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
> * macro.
> */
> #define _dynamic_func_call_cls(cls, fmt, func, ...) \
> - __dynamic_func_call_cls(__UNIQUE_ID(ddebug), cls, fmt, func, ##__VA_ARGS__)
> + __dynamic_func_call_cls(__UNIQUE_ID(_ddebug), cls, fmt, func, ##__VA_ARGS__)
> #define _dynamic_func_call(fmt, func, ...) \
> _dynamic_func_call_cls(_DPRINTK_CLASS_DFLT, fmt, func, ##__VA_ARGS__)
>
> @@ -252,7 +262,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
> * with precisely the macro's varargs.
> */
> #define _dynamic_func_call_cls_no_desc(cls, fmt, func, ...) \
> - __dynamic_func_call_cls_no_desc(__UNIQUE_ID(ddebug), cls, fmt, \
> + __dynamic_func_call_cls_no_desc(__UNIQUE_ID(_ddebug), cls, fmt, \
> func, ##__VA_ARGS__)
> #define _dynamic_func_call_no_desc(fmt, func, ...) \
> _dynamic_func_call_cls_no_desc(_DPRINTK_CLASS_DFLT, fmt, \
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 1fb9ad289a6f..b60f728e36ac 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2621,12 +2621,12 @@ static int find_module_sections(struct module *mod, struct load_info *info)
> pr_warn("%s: Ignoring obsolete parameters\n", mod->name);
>
> #ifdef CONFIG_DYNAMIC_DEBUG_CORE
> - mod->dyndbg_info.descs = section_objs(info, "__dyndbg",
> - sizeof(*mod->dyndbg_info.descs),
> - &mod->dyndbg_info.num_descs);
> - mod->dyndbg_info.classes = section_objs(info, "__dyndbg_classes",
> - sizeof(*mod->dyndbg_info.classes),
> - &mod->dyndbg_info.num_classes);
> + mod->dyndbg_info.descs.start = section_objs(info, "__dyndbg_descriptors",
> + sizeof(*mod->dyndbg_info.descs.start),
> + &mod->dyndbg_info.descs.len);
> + mod->dyndbg_info.maps.start = section_objs(info, "__dyndbg_class_maps",
> + sizeof(*mod->dyndbg_info.maps.start),
> + &mod->dyndbg_info.maps.len);
> #endif
>
> return 0;
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 94f6c8fd787b..663c125006d0 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -39,17 +39,15 @@
>
> #include <rdma/ib_verbs.h>
>
> -extern struct _ddebug __start___dyndbg[];
> -extern struct _ddebug __stop___dyndbg[];
> -extern struct ddebug_class_map __start___dyndbg_classes[];
> -extern struct ddebug_class_map __stop___dyndbg_classes[];
> +extern struct _ddebug __start___dyndbg_descs[];
> +extern struct _ddebug __stop___dyndbg_descs[];
> +extern struct ddebug_class_map __start___dyndbg_class_maps[];
> +extern struct ddebug_class_map __stop___dyndbg_class_maps[];
>
> struct ddebug_table {
> struct list_head link;
> const char *mod_name;
> - struct _ddebug *ddebugs;
> - struct ddebug_class_map *classes;
> - unsigned int num_ddebugs, num_classes;
> + struct _ddebug_info info;
> };
>
> struct ddebug_query {
> @@ -128,7 +126,6 @@ do { \
> #define v3pr_info(fmt, ...) vnpr_info(3, fmt, ##__VA_ARGS__)
> #define v4pr_info(fmt, ...) vnpr_info(4, fmt, ##__VA_ARGS__)
>
> -
> /*
> * simplify a repeated for-loop pattern walking N steps in a T _vec
> * member inside a struct _box. It expects int i and T *_sp to be
> @@ -139,8 +136,8 @@ do { \
> * @_vec: name of a sub-struct member in _box, with array-ref and length
> */
> #define for_subvec(_i, _sp, _box, _vec) \
> - for ((_i) = 0, (_sp) = (_box)->_vec; \
> - (_i) < (_box)->num_##_vec; \
> + for ((_i) = 0, (_sp) = (_box)->_vec.start; \
> + (_i) < (_box)->_vec.len; \
> (_i)++, (_sp)++)
>
> static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> @@ -163,6 +160,13 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> query->first_lineno, query->last_lineno, query->class_string);
> }
>
> +#define vpr_dt_info(dt_p, msg_p, ...) ({ \
> + struct ddebug_table const *_dt = dt_p; \
> + v2pr_info(msg_p " module:%s nd:%d nc:%d nu:%d\n", ##__VA_ARGS__, \
> + _dt->mod_name, _dt->info.descs.len, _dt->info.maps.len, \
> + _dt->info.users.len); \
> + })
> +
This macro is not used before PATCH 17/59, maybe move it there?
By curiosity, do you know why the `verbose` parameter was introduced? It
is not possible to use dyndbg on dyndbg?
> #define __outvar /* filled by callee */
> static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
> const char *class_string,
> @@ -171,7 +175,7 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
> struct ddebug_class_map *map;
> int i, idx;
>
> - for_subvec(i, map, dt, classes) {
> + for_subvec(i, map, &dt->info, maps) {
> idx = match_string(map->class_names, map->length, class_string);
> if (idx >= 0) {
> *class_id = idx + map->base;
> @@ -217,8 +221,8 @@ static int ddebug_change(const struct ddebug_query *query,
> valid_class = _DPRINTK_CLASS_DFLT;
> }
>
> - for (i = 0; i < dt->num_ddebugs; i++) {
> - struct _ddebug *dp = &dt->ddebugs[i];
> + for (i = 0; i < dt->info.descs.len; i++) {
> + struct _ddebug *dp = &dt->info.descs.start[i];
>
> /* match site against query-class */
> if (dp->class_id != valid_class)
> @@ -1065,8 +1069,8 @@ static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
> }
> iter->table = list_entry(ddebug_tables.next,
> struct ddebug_table, link);
> - iter->idx = iter->table->num_ddebugs;
> - return &iter->table->ddebugs[--iter->idx];
> + iter->idx = iter->table->info.descs.len;
> + return &iter->table->info.descs.start[--iter->idx];
> }
>
> /*
> @@ -1087,10 +1091,10 @@ static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
> }
> iter->table = list_entry(iter->table->link.next,
> struct ddebug_table, link);
> - iter->idx = iter->table->num_ddebugs;
> + iter->idx = iter->table->info.descs.len;
> --iter->idx;
> }
> - return &iter->table->ddebugs[iter->idx];
> + return &iter->table->info.descs.start[iter->idx];
> }
>
> /*
> @@ -1137,12 +1141,12 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
> #define class_in_range(class_id, map) \
> (class_id >= map->base && class_id < map->base + map->length)
>
> -static const char *ddebug_class_name(struct ddebug_iter *iter, struct _ddebug *dp)
> +static const char *ddebug_class_name(struct ddebug_table *dt, struct _ddebug *dp)
> {
> - struct ddebug_class_map *map = iter->table->classes;
> - int i, nc = iter->table->num_classes;
> + struct ddebug_class_map *map;
> + int i;
>
> - for (i = 0; i < nc; i++, map++)
> + for_subvec(i, map, &dt->info, maps)
This change can't be done in 11/59? (perhaps with classes and not maps).
> if (class_in_range(dp->class_id, map))
> return map->class_names[dp->class_id - map->base];
>
> @@ -1176,7 +1180,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
> seq_putc(m, '"');
>
> if (dp->class_id != _DPRINTK_CLASS_DFLT) {
> - class = ddebug_class_name(iter, dp);
> + class = ddebug_class_name(iter->table, dp);
> if (class)
> seq_printf(m, " class:%s", class);
> else
> @@ -1236,18 +1240,18 @@ static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug
> * the builtin/modular classmap vector/section. Save the start
> * and length of the subrange at its edges.
> */
> - for_subvec(i, cm, di, classes) {
> + for_subvec(i, cm, di, maps) {
> if (!strcmp(cm->mod_name, dt->mod_name)) {
> 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;
> + dt->info.maps.start = cm;
> }
> nc++;
> }
> }
> if (nc) {
> - dt->num_classes = nc;
> + dt->info.maps.len = nc;
> vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
> }
> }
> @@ -1260,10 +1264,10 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> {
> struct ddebug_table *dt;
>
> - if (!di->num_descs)
> + if (!di->descs.len)
> return 0;
>
> - v3pr_info("add-module: %s %d sites\n", modname, di->num_descs);
> + v3pr_info("add-module: %s %d sites\n", modname, di->descs.len);
>
> dt = kzalloc(sizeof(*dt), GFP_KERNEL);
> if (dt == NULL) {
> @@ -1277,19 +1281,18 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> * this struct ddebug_table.
> */
> dt->mod_name = modname;
> - dt->ddebugs = di->descs;
> - dt->num_ddebugs = di->num_descs;
> + dt->info = *di;
>
> INIT_LIST_HEAD(&dt->link);
>
> - if (di->classes && di->num_classes)
> + if (di->maps.len)
> ddebug_attach_module_classes(dt, di);
>
> mutex_lock(&ddebug_lock);
> list_add_tail(&dt->link, &ddebug_tables);
> mutex_unlock(&ddebug_lock);
>
> - vpr_info("%3u debug prints in module %s\n", di->num_descs, modname);
> + vpr_info("%3u debug prints in module %s\n", di->descs.len, modname);
> return 0;
> }
>
> @@ -1436,10 +1439,10 @@ static int __init dynamic_debug_init(void)
> char *cmdline;
>
> struct _ddebug_info di = {
> - .descs = __start___dyndbg,
> - .classes = __start___dyndbg_classes,
> - .num_descs = __stop___dyndbg - __start___dyndbg,
> - .num_classes = __stop___dyndbg_classes - __start___dyndbg_classes,
> + .descs.start = __start___dyndbg_descs,
> + .maps.start = __start___dyndbg_class_maps,
> + .descs.len = __stop___dyndbg_descs - __start___dyndbg_descs,
> + .maps.len = __stop___dyndbg_class_maps - __start___dyndbg_class_maps,
> };
>
> #ifdef CONFIG_MODULES
> @@ -1450,7 +1453,7 @@ static int __init dynamic_debug_init(void)
> }
> #endif /* CONFIG_MODULES */
>
> - if (&__start___dyndbg == &__stop___dyndbg) {
> + if (&__start___dyndbg_descs == &__stop___dyndbg_descs) {
> if (IS_ENABLED(CONFIG_DYNAMIC_DEBUG)) {
> pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
> return 1;
> @@ -1460,16 +1463,16 @@ static int __init dynamic_debug_init(void)
> return 0;
> }
>
> - iter = iter_mod_start = __start___dyndbg;
> + iter = iter_mod_start = __start___dyndbg_descs;
> modname = iter->modname;
> i = mod_sites = mod_ct = 0;
>
> - for (; iter < __stop___dyndbg; iter++, i++, mod_sites++) {
> + for (; iter < __stop___dyndbg_descs; iter++, i++, mod_sites++) {
>
> if (strcmp(modname, iter->modname)) {
> mod_ct++;
> - di.num_descs = mod_sites;
> - di.descs = iter_mod_start;
> + di.descs.len = mod_sites;
> + di.descs.start = iter_mod_start;
> ret = ddebug_add_module(&di, modname);
> if (ret)
> goto out_err;
> @@ -1479,8 +1482,8 @@ static int __init dynamic_debug_init(void)
> iter_mod_start = iter;
> }
> }
> - di.num_descs = mod_sites;
> - di.descs = iter_mod_start;
> + di.descs.len = mod_sites;
> + di.descs.start = iter_mod_start;
> ret = ddebug_add_module(&di, modname);
> if (ret)
> goto out_err;
> @@ -1490,8 +1493,8 @@ static int __init dynamic_debug_init(void)
> i, mod_ct, (int)((mod_ct * sizeof(struct ddebug_table)) >> 10),
> (int)((i * sizeof(struct _ddebug)) >> 10));
>
> - if (di.num_classes)
> - v2pr_info(" %d builtin ddebug class-maps\n", di.num_classes);
> + if (di.maps.len)
> + v2pr_info(" %d builtin ddebug class-maps\n", di.maps.len);
>
> /* now that ddebug tables are loaded, process all boot args
> * again to find and activate queries given in dyndbg params.
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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