Le 20/03/2025 à 19:51, Jim Cromie a écrit :
Classmaps are stored in an elf section/array, but currently are
individually list-linked onto dyndbg's per-module ddebug_table for
operation. This is unnecessary.
Just like dyndbg's descriptors, classes are packed in compile order;
so even with many builtin modules employing multiple classmaps, each
modules' maps are packed contiguously, and can be treated as a
array-start-address & array-length.
So this drops the whole list building operation done in
ddebug_attach_module_classes(), and removes the list-head members.
The "select-by-modname" condition is reused to find the start,end of
the subrange.
NOTE: This "filter-by-modname" on classmaps should really be done in
ddebug_add_module(1); ie at least one step closer to ddebug_init(2),
which already splits up pr-debug descriptors into subranges by
modname, then calls (1) on each. (2) knows nothing of classmaps
currently, and doesn't need to. For now, just add comment.
Signed-off-by: Jim Cromie <jim.cro...@gmail.com>
---
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 ac199293d203..e458d4b838ac 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 dd7320b9616d..d5572712ce55 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)
Thanks for your explanation of __outvar! It makes sense. I never seen
this pattern anywhere in the kernel, maybe a simple doc comment is
enough to carry the information:
/**
* ddebug_find_valid_class - Find a valid class for a
* given string
* @dt: debug table to inspect
* @class_string: string to match on
* @class_id: output pointer for the class_id value
*
* Returns: Pointer to the ddebug_class_map instance, if found.
* @class_id will be set to the id of this class. If no class
* matching @class_string is found, returns NULL and class_id is
* set to -ENOENT.
*/
Or at maybe change the documentation of __outvar to be a bit more
explicit about how it works (I had difficulties to understand because a
lot of "magic macro" exist in the kernel and sometimes carry information
to the compiler, but this one is always empty):
/**
* __outvar - Denotes that an argument is used as an output
* value
* This macro does nothing apart clarify for the reader that
* the parameter will be filled by the callee
*/
With any of the modifications (feel free to reword them as you want):
Reviewed-by: Louis Chauvet <louis.chau...@bootlin.com>
{
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
@@ -1122,9 +1124,10 @@ 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];
@@ -1208,30 +1211,31 @@ 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);
+ }
}
/*
@@ -1263,10 +1267,9 @@ 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);
@@ -1379,8 +1382,8 @@ 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);
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
