* [PATCH v6 18/24] dyndbg: macrofy a 2-index for-loop pattern
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
dynamic-debug currently has 2 __sections (__dyndbg, __dyndb_classes),
struct _ddebug_info keeps track of them both, with 2 members each:
_vec and _vec#_len.
We need to loop over these sections, with index and record pointer,
making ref to both _vec and _vec_len. This is already fiddly and
error-prone, and will get worse as we add a 3rd section.
Lets instead embed/abstract the fiddly-ness in the `for_subvec()`
macro, and avoid repeating it going forward.
This is a for-loop macro expander, so it syntactically expects to
precede either a single statement or a { block } of them, and the
usual typeof or do-while-0 tricks are unavailable to fix the
multiple-expansion warning.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v2: move RvB after SoB
---
lib/dynamic_debug.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 6b699ed23d26..d99c69b9ad12 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -149,6 +149,20 @@ static void v3pr_info_dq(const struct ddebug_query *query, const char *msg)
query->first_lineno, query->last_lineno, query->class_string);
}
+/*
+ * 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
+ * declared in the caller.
+ * @_i: caller provided counter.
+ * @_sp: cursor into _vec, to examine each item.
+ * @_box: ptr to a struct containing @_vec member
+ * @_vec: name of a member in @_box
+ */
+#define for_subvec(_i, _sp, _box, _vec) \
+ for ((_i) = 0, (_sp) = (_box)->_vec; \
+ (_i) < (_box)->num_##_vec; \
+ (_i)++, (_sp)++) /* { block } */
+
static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
const char *class_string,
int *class_id)
@@ -156,7 +170,7 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
struct ddebug_class_map *map;
int i, idx;
- for (map = dt->classes, i = 0; i < dt->num_classes; i++, map++) {
+ for_subvec(i, map, dt, classes) {
idx = match_string(map->class_names, map->length, class_string);
if (idx >= 0) {
*class_id = idx + map->base;
@@ -1167,8 +1181,7 @@ 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 (cm = di->classes, i = 0; i < di->num_classes; i++, cm++) {
-
+ for_subvec(i, cm, di, classes) {
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",
--
2.55.0
^ permalink raw reply related
* [PATCH v6 17/24] dyndbg: replace classmap list with an array-slice
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
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, classmaps 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 of
the classmap structs. The "select-by-modname" condition is reused to
find the start,end of the subrange of classmaps belonging to the module.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v2: RvB after SoB
---
include/linux/dynamic_debug.h | 1 -
lib/dynamic_debug.c | 65 +++++++++++++++++++++++--------------------
2 files changed, 35 insertions(+), 31 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index da9e5c35bc43..d164a24dece1 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -87,7 +87,6 @@ enum ddebug_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 8c3b29904346..6b699ed23d26 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 {
@@ -149,12 +150,13 @@ static void v3pr_info_dq(const struct ddebug_query *query, const char *msg)
}
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,
+ 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;
@@ -165,7 +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
@@ -231,7 +232,7 @@ static int ddebug_change(const struct ddebug_query *query,
unsigned int nfound = 0;
struct flagsbuf fbuf, nbuf;
struct ddebug_class_map *map = NULL;
- int __outvar valid_class;
+ int valid_class;
/* search for matching ddebugs */
mutex_lock(&ddebug_lock);
@@ -1069,9 +1070,10 @@ 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];
@@ -1155,30 +1157,34 @@ 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++;
+ } else if (nc) {
+ /* end of matching classmaps */
+ break;
}
}
- 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);
+ }
}
/*
@@ -1210,10 +1216,9 @@ 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);
@@ -1326,8 +1331,8 @@ 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);
--
2.55.0
^ permalink raw reply related
* [PATCH v6 16/24] dyndbg: tighten fn-sig of ddebug_apply_class_bitmap
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
old_bits arg is currently a pointer to the input bits, but this could
allow inadvertent changes to the input by the fn. Disallow this.
And constify new_bits while here.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v2: move RvB after SoB
---
lib/dynamic_debug.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 0fc9cd14e2d2..8c3b29904346 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -617,7 +617,8 @@ static int ddebug_exec_queries(char *query, const char *modname)
/* apply a new class-param setting */
static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
- unsigned long *new_bits, unsigned long *old_bits,
+ const unsigned long *new_bits,
+ const unsigned long old_bits,
const char *query_modname)
{
#define QUERY_SIZE 128
@@ -626,12 +627,12 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
int matches = 0;
int bi, ct;
- if (*new_bits != *old_bits)
+ if (*new_bits != old_bits)
v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
- *old_bits, query_modname ?: "'*'");
+ old_bits, query_modname ?: "'*'");
for (bi = 0; bi < map->length; bi++) {
- if (test_bit(bi, new_bits) == test_bit(bi, old_bits))
+ if (test_bit(bi, new_bits) == test_bit(bi, &old_bits))
continue;
snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_names[bi],
@@ -643,9 +644,9 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
v2pr_info("bit_%d: %d matches on class: %s -> 0x%lx\n", bi,
ct, map->class_names[bi], *new_bits);
}
- if (*new_bits != *old_bits)
+ if (*new_bits != old_bits)
v2pr_info("applied bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
- *old_bits, query_modname ?: "'*'");
+ old_bits, query_modname ?: "'*'");
return matches;
}
@@ -693,7 +694,7 @@ static int param_set_dyndbg_module_classes(const char *instr,
inrep &= CLASSMAP_BITMASK(map->length);
}
v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp));
- totct += ddebug_apply_class_bitmap(dcp, &inrep, dcp->bits, mod_name);
+ totct += ddebug_apply_class_bitmap(dcp, &inrep, *dcp->bits, mod_name);
*dcp->bits = inrep;
break;
case DD_CLASS_TYPE_LEVEL_NUM:
@@ -706,7 +707,7 @@ static int param_set_dyndbg_module_classes(const char *instr,
old_bits = CLASSMAP_BITMASK(*dcp->lvl);
new_bits = CLASSMAP_BITMASK(inrep);
v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, KP_NAME(kp));
- totct += ddebug_apply_class_bitmap(dcp, &new_bits, &old_bits, mod_name);
+ totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, mod_name);
*dcp->lvl = inrep;
break;
default:
--
2.55.0
^ permalink raw reply related
* [PATCH v6 15/24] dyndbg: refactor param_set_dyndbg_classes and below
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Refactor the callchain below param_set_dyndbg_classes(1) to allow
mod-name specific settings. Split (1) into upper/lower fns, adding
modname param to lower, and passing NULL in from upper. Below that,
add the same param to ddebug_apply_class_bitmap(), and pass it thru to
_ddebug_queries(), replacing NULL with the param.
This allows the callchain to update the classmap in just one module,
vs just all as currently done. While the sysfs param is unlikely to
ever update just one module, the callchain will be used for modprobe
handling, which should update only that just-probed module.
In ddebug_apply_class_bitmap(), also check for actual changes to the
bits before announcing them, to declutter logs.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v2: move RvB after SoB
---
lib/dynamic_debug.c | 51 +++++++++++++++++++++++++++++++++++++++------------
1 file changed, 39 insertions(+), 12 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index ce42e03f1600..0fc9cd14e2d2 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -615,9 +615,10 @@ static int ddebug_exec_queries(char *query, const char *modname)
return nfound;
}
-/* apply a new bitmap to the sys-knob's current bit-state */
+/* apply a new class-param setting */
static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
- unsigned long *new_bits, unsigned long *old_bits)
+ unsigned long *new_bits, unsigned long *old_bits,
+ const char *query_modname)
{
#define QUERY_SIZE 128
char query[QUERY_SIZE];
@@ -625,7 +626,9 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
int matches = 0;
int bi, ct;
- v2pr_info("apply: 0x%lx to: 0x%lx\n", *new_bits, *old_bits);
+ if (*new_bits != *old_bits)
+ v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
+ *old_bits, query_modname ?: "'*'");
for (bi = 0; bi < map->length; bi++) {
if (test_bit(bi, new_bits) == test_bit(bi, old_bits))
@@ -634,12 +637,16 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_names[bi],
test_bit(bi, new_bits) ? '+' : '-', dcp->flags);
- ct = ddebug_exec_queries(query, NULL);
+ ct = ddebug_exec_queries(query, query_modname);
matches += ct;
v2pr_info("bit_%d: %d matches on class: %s -> 0x%lx\n", bi,
ct, map->class_names[bi], *new_bits);
}
+ if (*new_bits != *old_bits)
+ v2pr_info("applied bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
+ *old_bits, query_modname ?: "'*'");
+
return matches;
}
@@ -652,6 +659,7 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
* param_set_dyndbg_classes - class FOO >control
* @instr: string echo>d to sysfs, input depends on map_type
* @kp: kp->arg has state: bits/lvl, map, map_type
+ * @mod_name: module name or null for all modules with the classes
*
* Enable/disable prdbgs by their class, as given in the arguments to
* DECLARE_DYNDBG_CLASSMAP. For LEVEL map-types, enforce relative
@@ -659,7 +667,9 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
*
* Returns: 0 or <0 if error.
*/
-int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
+static int param_set_dyndbg_module_classes(const char *instr,
+ const struct kernel_param *kp,
+ const char *mod_name)
{
const struct ddebug_class_param *dcp = kp->arg;
const struct ddebug_class_map *map = dcp->map;
@@ -682,8 +692,8 @@ int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
KP_NAME(kp), inrep, CLASSMAP_BITMASK(map->length));
inrep &= CLASSMAP_BITMASK(map->length);
}
- v2pr_info("bits:%lx > %s\n", inrep, KP_NAME(kp));
- totct += ddebug_apply_class_bitmap(dcp, &inrep, dcp->bits);
+ v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp));
+ totct += ddebug_apply_class_bitmap(dcp, &inrep, dcp->bits, mod_name);
*dcp->bits = inrep;
break;
case DD_CLASS_TYPE_LEVEL_NUM:
@@ -696,7 +706,7 @@ int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
old_bits = CLASSMAP_BITMASK(*dcp->lvl);
new_bits = CLASSMAP_BITMASK(inrep);
v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, KP_NAME(kp));
- totct += ddebug_apply_class_bitmap(dcp, &new_bits, &old_bits);
+ totct += ddebug_apply_class_bitmap(dcp, &new_bits, &old_bits, mod_name);
*dcp->lvl = inrep;
break;
default:
@@ -706,16 +716,33 @@ int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
vpr_info("%s: total matches: %d\n", KP_NAME(kp), totct);
return 0;
}
+
+/**
+ * param_set_dyndbg_classes - classmap kparam setter
+ * @instr: string echo>d to sysfs, input depends on map_type
+ * @kp: kp->arg has state: bits/lvl, map, map_type
+ *
+ * enable/disable all class'd pr_debugs in the classmap. For LEVEL
+ * map-types, enforce * relative levels by bitpos.
+ *
+ * Returns: 0 or <0 if error.
+ */
+int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
+{
+ return param_set_dyndbg_module_classes(instr, kp, NULL);
+}
EXPORT_SYMBOL(param_set_dyndbg_classes);
/**
- * param_get_dyndbg_classes - classes reader
+ * param_get_dyndbg_classes - classmap kparam getter
* @buffer: string description of controlled bits -> classes
* @kp: kp->arg has state: bits, map
*
- * Reads last written state, underlying prdbg state may have been
- * altered by direct >control. Displays 0x for DISJOINT, 0-N for
- * LEVEL Returns: #chars written or <0 on error
+ * Reads last written state, underlying pr_debug states may have been
+ * altered by direct >control. Displays 0x for DISJOINT classmap
+ * types, 0-N for LEVEL types.
+ *
+ * Returns: ct of chars written or <0 on error
*/
int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
{
--
2.55.0
^ permalink raw reply related
* [PATCH v6 14/24] dyndbg: use KBUILD_MODFILE for unique builtin module names
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Historically dynamic-debug gets its module names from KBUILD_MODNAME.
This works well for loadable modules, as the module loader has always
required them to have unique names, but for builtins it is basically
kbasename(srcfile), which sadly gives us many modules named "main".
IOW, it makes this ambiguous:
bash-5.3# echo module main +m > /proc/dynamic_debug/control
since it would affect all 4 independent modules named main:
bash-5.3# ddgrep =m
init/main.c:1265 [main]initcall_blacklist =m "blacklisting initcall %s\n"
kernel/power/main.c:49 [main]pm_restore_gfp_mask =m "GFP mask restored\n"
kernel/module/main.c:2862 [main]move_module =m "\t0x%lx 0x%.8lx %s\n"
drivers/base/power/main.c:149 [main]device_pm_add =m "Adding info for %s:%s\n"
We can improve this by using KBUILD_MODFILE for dyndbg's modname in
builtins (which is unique), and KBUILD_MODNAME for loadables (which is
already required/guaranteed to be unique by module-loader):
The above control-file entries then become:
init/main.c:1265 [init/main]initcall_blacklist ...
kernel/power/main.c:49 [kernel/power/main]pm_restore_gfp_mask ...
kernel/module/main.c:2862 [kernel/module/main]move_module ...
drivers/base/power/main.c:149 [drivers/base/power/main]device_pm_add ...
While this is a user visible change; [params] becomes [kernel/params]
etc, it is not a behavior change; we now match the query-module
against the subsystem/module name or its kbasename (the
simple-modname), which as before, matches all 4 modules.
This allows queries to be specific when desired: "module init/main",
while preserving the existing meaning of "module main"
The deeper reason for this change is not obvious. If any builtin
"main" module were to add a classmap, it would attach to all "main"
modules. If 2 "main" modules defined separate classmaps, both modules
would inadvertently share both classmaps. Since classmaps map
classnames to 0..62, and independently defined classmaps are most
likely to start at 0 (unless author is planning to share the 0..62
range with other classmaps), we have a setup for later reserved range
conflicts. Having unique names prevents future conflicts.
This solution isn't perfect:
1. it changes displayed [params] to [kernel/params] etc
2. its mostly redundant with "filename */main.*"
3. Ideally, queries like "module power", "module module", "module
base/power" might be better but would break old queries.
Adding classmaps to the builtins named "[main]" is unlikely, so this
change isn't absolutely necessary, but it seemed proper to at least
address the latent problem.
Adjust Documentation with "simple modname" and "subsystem modname".
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v5: move ahead of array-slice patch to silence sashiko complaint about it
v4: call match_wildcard_hyphen() to allow dash vs underscore modname equivalence
v3: use KBUILD_MODFILE to give unique modnames for builtins
---
Documentation/admin-guide/dynamic-debug-howto.rst | 42 +++++++++++++----------
include/linux/dynamic_debug.h | 15 ++++++--
lib/dynamic_debug.c | 3 +-
3 files changed, 38 insertions(+), 22 deletions(-)
diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 9c2f096ed1d8..99bbae37d34e 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -38,12 +38,12 @@ You can view the currently configured behaviour in the *prdbg* catalog::
:#> head -n7 /proc/dynamic_debug/control
# filename:lineno [module]function flags format
- init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\n"
- init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\n"
- init/main.c:1424 [main]run_init_process =_ " with arguments:\n"
- init/main.c:1426 [main]run_init_process =_ " %s\n"
- init/main.c:1427 [main]run_init_process =_ " with environment:\n"
- init/main.c:1429 [main]run_init_process =_ " %s\n"
+ init/main.c:1179 [init/main]initcall_blacklist =_ "blacklisting initcall %s\n"
+ init/main.c:1218 [init/main]initcall_blacklisted =_ "initcall %s blacklisted\n"
+ init/main.c:1424 [init/main]run_init_process =_ " with arguments:\n"
+ init/main.c:1426 [init/main]run_init_process =_ " %s\n"
+ init/main.c:1427 [init/main]run_init_process =_ " with environment:\n"
+ init/main.c:1429 [init/main]run_init_process =_ " %s\n"
The 3rd space-delimited column shows the current flags, preceded by
a ``=`` for easy use with grep/cut. ``=p`` shows enabled callsites.
@@ -59,10 +59,10 @@ query/commands to the control file. Example::
:#> ddcmd '-p; module main func run* +p'
:#> grep =p /proc/dynamic_debug/control
- init/main.c:1424 [main]run_init_process =p " with arguments:\n"
- init/main.c:1426 [main]run_init_process =p " %s\n"
- init/main.c:1427 [main]run_init_process =p " with environment:\n"
- init/main.c:1429 [main]run_init_process =p " %s\n"
+ init/main.c:1424 [init/main]run_init_process =p " with arguments:\n"
+ init/main.c:1426 [init/main]run_init_process =p " %s\n"
+ init/main.c:1427 [init/main]run_init_process =p " with environment:\n"
+ init/main.c:1429 [init/main]run_init_process =p " %s\n"
Error messages go to console/syslog::
@@ -161,17 +161,21 @@ file
file kernel/freezer.c # ie column 1 of control file
file drivers/usb/* # all callsites under it
file inode.c:start_* # parse :tail as a func (above)
- file inode.c:1-100 # parse :tail as a line-range (above)
+ file inode.c:1-100 # parse :tail as a line-range (below)
module
- The given string is compared against the module name
- of each callsite. The module name is the string as
- seen in ``lsmod``, i.e. without the directory or the ``.ko``
- suffix and with ``-`` changed to ``_``. Examples::
-
- module sunrpc
- module nfsd
- module drm* # both drm, drm_kms_helper
+ The query string is compared against the subsystem module name of
+ each callsite, as shown in the control file, or its simple name.
+ The simple module name is the string as seen in ``lsmod``,
+ i.e. without the directory or the ``.ko`` suffix and with ``-``
+ changed to ``_``.
+ Examples::
+
+ module nfsd # simple modname (as from lsmod)
+ module init/main # subsystem modname (as in control file)
+ module */main # any subsystem ending in main
+ module main # simple modname, selects same as above
+ module drm* # both drm, drm_kms_helper
format
The given string is searched for in the dynamic debug format
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 9ae1accb9bf6..da9e5c35bc43 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -10,6 +10,17 @@
#define __DDEBUG_ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+/*
+ * Pick the best name for the module:
+ * KBUILD_MODFILE includes the path (e.g., drivers/usb/core/usbcore) for built-ins.
+ * Fall back to KBUILD_MODNAME for modules (loader requires unique names).
+ */
+#ifdef KBUILD_MODFILE
+# define DDEBUG_MODNAME KBUILD_MODFILE
+#else
+# define DDEBUG_MODNAME KBUILD_MODNAME
+#endif
+
/*
* An instance of this structure is created in a special
* ELF section at every dynamic debug callsite. At runtime,
@@ -121,7 +132,7 @@ struct ddebug_class_param {
static struct ddebug_class_map __aligned(8) __used \
__section("__dyndbg_classes") _var = { \
.mod = THIS_MODULE, \
- .mod_name = KBUILD_MODNAME, \
+ .mod_name = DDEBUG_MODNAME, \
.base = _base, \
.map_type = _maptype, \
.length = (sizeof(_var##_classnames) / sizeof(_var##_classnames[0])), \
@@ -160,7 +171,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
#define DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, cls, fmt) \
static struct _ddebug __aligned(8) \
__section("__dyndbg") name = { \
- .modname = KBUILD_MODNAME, \
+ .modname = DDEBUG_MODNAME, \
.function = __func__, \
.filename = __FILE__, \
.format = (fmt), \
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 2e321b7eb957..ce42e03f1600 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -239,7 +239,8 @@ static int ddebug_change(const struct ddebug_query *query,
/* match against the module name */
if (query->module &&
- !match_wildcard(query->module, dt->mod_name))
+ !match_wildcard_hyphen(query->module, dt->mod_name) &&
+ !match_wildcard_hyphen(query->module, kbasename(dt->mod_name)))
continue;
if (query->class_string) {
--
2.55.0
^ permalink raw reply related
* [PATCH v6 13/24] lib/parser: add match_wildcard_hyphen() for agnostic matching
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
This commit introduces match_wildcard_hyphen() as a variant of the
existing match_wildcard() function. It treats hyphens and underscores
as identical characters during the matching process.
This is necessary for subsystems like dynamic_debug that need to match
module names provided by users (who often use underscores) against
names stored in the kernel (which may use hyphens, especially when
using KBUILD_MODFILE for built-ins).
To avoid code duplication, the core logic is refactored into a private
__match_wildcard() function marked as __always_inline. This allows the
compiler to generate optimized versions for both the strict and agnostic
callsites with zero runtime overhead.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v5: move ahead of array-slice patch to silence sashiko complaint about it
v4: initial version
---
include/linux/parser.h | 1 +
lib/parser.c | 58 +++++++++++++++++++++++++++++++++++++-------------
2 files changed, 44 insertions(+), 15 deletions(-)
diff --git a/include/linux/parser.h b/include/linux/parser.h
index dd79f45a37b8..a3cc7bc5fb93 100644
--- a/include/linux/parser.h
+++ b/include/linux/parser.h
@@ -34,6 +34,7 @@ int match_u64(substring_t *, u64 *result);
int match_octal(substring_t *, int *result);
int match_hex(substring_t *, int *result);
bool match_wildcard(const char *pattern, const char *str);
+bool match_wildcard_hyphen(const char *pattern, const char *str);
size_t match_strlcpy(char *, const substring_t *, size_t);
char *match_strdup(const substring_t *);
diff --git a/lib/parser.c b/lib/parser.c
index 62da0ac0d438..d5be01fa9adf 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -268,20 +268,13 @@ int match_hex(substring_t *s, int *result)
}
EXPORT_SYMBOL(match_hex);
-/**
- * match_wildcard - parse if a string matches given wildcard pattern
- * @pattern: wildcard pattern
- * @str: the string to be parsed
- *
- * Description: Parse the string @str to check if matches wildcard
- * pattern @pattern. The pattern may contain two types of wildcards:
- *
- * * '*' - matches zero or more characters
- * * '?' - matches one character
- *
- * Return: If the @str matches the @pattern, return true, else return false.
- */
-bool match_wildcard(const char *pattern, const char *str)
+static inline char dash2underscore(char c)
+{
+ return (c == '-') ? '_' : c;
+}
+
+static __always_inline bool __match_wildcard(const char *pattern, const char *str,
+ bool hyphen_agnostic)
{
const char *s = str;
const char *p = pattern;
@@ -301,7 +294,9 @@ bool match_wildcard(const char *pattern, const char *str)
pattern = p;
break;
default:
- if (*s == *p) {
+ if (hyphen_agnostic ?
+ (dash2underscore(*s) == dash2underscore(*p)) :
+ (*s == *p)) {
s++;
p++;
} else {
@@ -319,8 +314,41 @@ bool match_wildcard(const char *pattern, const char *str)
++p;
return !*p;
}
+
+/**
+ * match_wildcard - parse if a string matches given wildcard pattern
+ * @pattern: wildcard pattern
+ * @str: the string to be parsed
+ *
+ * Description: Parse the string @str to check if matches wildcard
+ * pattern @pattern. The pattern may contain two types of wildcards:
+ *
+ * * '*' - matches zero or more characters
+ * * '?' - matches one character
+ *
+ * Return: If the @str matches the @pattern, return true, else return false.
+ */
+bool match_wildcard(const char *pattern, const char *str)
+{
+ return __match_wildcard(pattern, str, false);
+}
EXPORT_SYMBOL(match_wildcard);
+/**
+ * match_wildcard_hyphen - parse if a string matches given wildcard pattern
+ * @pattern: wildcard pattern
+ * @str: the string to be parsed
+ *
+ * Description: Same as match_wildcard, but treats '-' and '_' as identical.
+ *
+ * Return: If the @str matches the @pattern, return true, else return false.
+ */
+bool match_wildcard_hyphen(const char *pattern, const char *str)
+{
+ return __match_wildcard(pattern, str, true);
+}
+EXPORT_SYMBOL(match_wildcard_hyphen);
+
/**
* match_strlcpy - Copy the characters from a substring_t to a sized buffer
* @dest: where to copy to
--
2.55.0
^ permalink raw reply related
* [PATCH v6 12/24] dyndbg: reduce verbose/debug clutter
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
currently, for verbose=3, these are logged (blank lines for clarity):
dyndbg: query 0: "class DRM_UT_CORE +p" mod:*
dyndbg: split into words: "class" "DRM_UT_CORE" "+p"
dyndbg: op='+'
dyndbg: flags=0x1
dyndbg: *flagsp=0x1 *maskp=0xffffffff
dyndbg: parsed: func="" file="" module="" format="" lineno=0-0 class=...
dyndbg: no matches for query
dyndbg: no-match: func="" file="" module="" format="" lineno=0-0 class=...
dyndbg: processed 1 queries, with 0 matches, 0 errs
That is excessive, so this patch:
- shrinks 3 lines of 2nd stanza to single line
- drops 1st 2 lines of 3rd stanza
3rd line is like 1st, with result, not procedure.
2nd line is just status, retold in 4th, with more info.
New output:
dyndbg: query 0: "class DRM_UT_CORE +p"
dyndbg: split into words: "class" "DRM_UT_CORE" "+p"
dyndbg: op='+' flags=0x1 maskp=0xffffffff
dyndbg: processed 1 queries, with 0 matches, 0 errs
Also drop several verbose=3 messages in ddebug_add_module. When
modprobing a module, dyndbg currently logs/says "add-module", and then
"skipping" if the module has no prdbgs. Instead just check 1st and
return quietly.
Unmatched query diagnostics are intentionally restricted to verbose
level 3 (v3pr_info_dq) to reduce dmesg output clutter on standard
verbose levels (verbose=1 and verbose=2), aligning with the overall
de-cluttering of dynamic debug logging.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v4: rename vpr_dq_info to v3pr_dq_info to tell its active logging level
adjust some vX levels per doc'd intentions
v2: RvB after SoB
trivial change to verbose-debug output line to output the actual
"module" keyword rather than "mod:", and do so only when the module is
constrained by the callchain (ie as part of a modprobe).
was: query X: "(keyword value)* [+-=]flags" mod:*
now: query X: "(keyword value)* [+-=]flags"
or query X: module FOO "keyword value)* [+-=]flags"
IOW, adjust output to reflect the input grammar more closely.
drop-info-parsed
vinfo-applied-nomatch
dyndbg: tweak verbose-levels per doc
---
lib/dynamic_debug.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index efe12fac6363..2e321b7eb957 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -128,7 +128,7 @@ do { \
#define v3pr_info(fmt, ...) vnpr_info(3, fmt, ##__VA_ARGS__)
#define v4pr_info(fmt, ...) vnpr_info(4, fmt, ##__VA_ARGS__)
-static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
+static void v3pr_info_dq(const struct ddebug_query *query, const char *msg)
{
/* trim any trailing newlines */
int fmtlen = 0;
@@ -280,9 +280,6 @@ static int ddebug_change(const struct ddebug_query *query,
}
mutex_unlock(&ddebug_lock);
- if (!nfound && verbose)
- pr_info("no matches for query\n");
-
return nfound;
}
@@ -491,7 +488,6 @@ static int ddebug_parse_query(char *words[], int nwords,
*/
query->module = modname;
- vpr_info_dq(query, "parsed");
return 0;
}
@@ -515,7 +511,6 @@ static int ddebug_parse_flags(const char *str, struct flag_settings *modifiers)
pr_err("bad flag-op %c, at start of %s\n", *str, str);
return -EINVAL;
}
- v3pr_info("op='%c'\n", op);
for (; *str ; ++str) {
for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
@@ -529,7 +524,6 @@ static int ddebug_parse_flags(const char *str, struct flag_settings *modifiers)
return -EINVAL;
}
}
- v3pr_info("flags=0x%x\n", modifiers->flags);
/* calculate final flags, mask based upon op */
switch (op) {
@@ -545,7 +539,7 @@ static int ddebug_parse_flags(const char *str, struct flag_settings *modifiers)
modifiers->flags = 0;
break;
}
- v3pr_info("*flagsp=0x%x *maskp=0x%x\n", modifiers->flags, modifiers->mask);
+ v3pr_info("op='%c' flags=0x%x maskp=0x%x\n", op, modifiers->flags, modifiers->mask);
return 0;
}
@@ -574,7 +568,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
}
/* actually go and implement the change */
nfound = ddebug_change(&query, &modifiers);
- vpr_info_dq(&query, nfound ? "applied" : "no-match");
+ v3pr_info_dq(&query, nfound ? "applied" : "no-match");
return nfound;
}
@@ -597,7 +591,10 @@ static int ddebug_exec_queries(char *query, const char *modname)
if (!query || !*query || *query == '#')
continue;
- vpr_info("query %d: \"%s\" mod:%s\n", i, query, modname ?: "*");
+ if (modname)
+ v2pr_info("query %d: module %s \"%s\"\n", i, modname, query);
+ else
+ v2pr_info("query %d: \"%s\"\n", i, query);
rc = ddebug_exec_query(query, modname);
if (rc < 0) {
@@ -1163,11 +1160,10 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
{
struct ddebug_table *dt;
- v3pr_info("add-module: %s.%d sites\n", modname, di->num_descs);
- if (!di->num_descs) {
- v3pr_info(" skip %s\n", modname);
+ if (!di->num_descs)
return 0;
- }
+
+ v3pr_info("add-module: %s %d sites\n", modname, di->num_descs);
dt = kzalloc_obj(*dt);
if (dt == NULL) {
--
2.55.0
^ permalink raw reply related
* [PATCH v6 11/24] dyndbg: bump num-tokens in a query-cmd from 9 to 15
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Current MAXWORDS in ddebug_exec_query() is too small to accept a legal
query-command using all 6 keywords. We *need* 13, but this adds a few
extra to allow certain errors to fail on subsequent, more meaningful
grammar checks.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index cd6b6c710ee2..efe12fac6363 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -554,7 +554,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
{
struct flag_settings modifiers = {};
struct ddebug_query query = {};
-#define MAXWORDS 9
+#define MAXWORDS 15
int nwords, nfound;
char *words[MAXWORDS];
--
2.55.0
^ permalink raw reply related
* [PATCH v6 10/24] dyndbg: drop NUM_TYPE_ARGS
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
ARRAY_SIZE almost works here, since array decl is complete.
But define it locally, named __DDEBUG_ARRAY_SIZE, to avoid
include conflicts with boot/<something> on some arch.
no functional change
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v5: drop include, it causes redefined probs in /boot/* for some arch.
v2: include linux/array_size.h, correct commit subject, review after sob
---
include/linux/dynamic_debug.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 9607121c3072..9ae1accb9bf6 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -8,6 +8,8 @@
#include <linux/build_bug.h>
+#define __DDEBUG_ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
/*
* An instance of this structure is created in a special
* ELF section at every dynamic debug callsite. At runtime,
@@ -122,11 +124,9 @@ struct ddebug_class_param {
.mod_name = KBUILD_MODNAME, \
.base = _base, \
.map_type = _maptype, \
- .length = NUM_TYPE_ARGS(char*, __VA_ARGS__), \
+ .length = (sizeof(_var##_classnames) / sizeof(_var##_classnames[0])), \
.class_names = _var##_classnames, \
}
-#define NUM_TYPE_ARGS(eltype, ...) \
- (sizeof((eltype[]) {__VA_ARGS__}) / sizeof(eltype))
extern __printf(2, 3)
void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...);
--
2.55.0
^ permalink raw reply related
* [PATCH v6 09/24] dyndbg-API: remove DD_CLASS_TYPE_(DISJOINT|LEVEL)_NAMES and code
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Remove the DD_CLASS_TYPE_*_NAMES classmap types and code.
These 2 classmap types accept class names at the PARAM interface, for
example:
echo +DRM_UT_CORE,-DRM_UT_KMS > /sys/module/drm/parameters/debug_names
The code works, but its only used by test-dynamic-debug, and wasn't
asked for by anyone else, so reduce LOC & test-surface; simplify things.
Also rename enum class_map_type to enum ddebug_class_map_type.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v3:
fix name of enum in kdoc
also change name of struct (to future name)
v2:
move RvB after SoB
respect const instr in param_set_dyndbg_module_classes, return -EINVAL on classtype err.
---
include/linux/dynamic_debug.h | 28 ++++--------
lib/dynamic_debug.c | 99 +++----------------------------------------
lib/test_dynamic_debug.c | 26 ------------
3 files changed, 15 insertions(+), 138 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index a10adac8e8f0..9607121c3072 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -59,27 +59,17 @@ struct _ddebug {
#endif
} __attribute__((aligned(8)));
-enum class_map_type {
+enum ddebug_class_map_type {
DD_CLASS_TYPE_DISJOINT_BITS,
/**
- * DD_CLASS_TYPE_DISJOINT_BITS: classes are independent, one per bit.
- * expecting hex input. Built for drm.debug, basis for other types.
+ * DD_CLASS_TYPE_DISJOINT_BITS: classes are independent,
+ * mapped to bits[0..N]. Expects hex input. Built for
+ * drm.debug, basis for other types.
*/
DD_CLASS_TYPE_LEVEL_NUM,
/**
- * DD_CLASS_TYPE_LEVEL_NUM: input is numeric level, 0-N.
- * N turns on just bits N-1 .. 0, so N=0 turns all bits off.
- */
- DD_CLASS_TYPE_DISJOINT_NAMES,
- /**
- * DD_CLASS_TYPE_DISJOINT_NAMES: input is a CSV of [+-]CLASS_NAMES,
- * classes are independent, like _DISJOINT_BITS.
- */
- DD_CLASS_TYPE_LEVEL_NAMES,
- /**
- * DD_CLASS_TYPE_LEVEL_NAMES: input is a CSV of [+-]CLASS_NAMES,
- * intended for names like: INFO,DEBUG,TRACE, with a module prefix
- * avoid EMERG,ALERT,CRIT,ERR,WARNING: they're not debug
+ * DD_CLASS_TYPE_LEVEL_NUM: input is numeric level, 0..N.
+ * Input N turns on bits 0..N-1
*/
};
@@ -90,7 +80,7 @@ struct ddebug_class_map {
const char **class_names;
const int length;
const int base; /* index of 1st .class_id, allows split/shared space */
- enum class_map_type map_type;
+ enum ddebug_class_map_type map_type;
};
/* encapsulate linker provided built-in (or module) dyndbg data */
@@ -119,8 +109,8 @@ struct ddebug_class_param {
/**
* DECLARE_DYNDBG_CLASSMAP - declare classnames known by a module
- * @_var: a struct ddebug_class_map, passed to module_param_cb
- * @_type: enum class_map_type, chooses bits/verbose, numeric/symbolic
+ * @_var: a struct _ddebug_class_map, passed to module_param_cb
+ * @_maptype: enum ddebug_class_map_type, chooses bits/verbose
* @_base: offset of 1st class-name. splits .class_id space
* @classes: class-names used to control class'd prdbgs
*/
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index a86e1d5845e6..cd6b6c710ee2 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -650,76 +650,6 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
#define CLASSMAP_BITMASK(width) ((1UL << (width)) - 1)
-/* accept comma-separated-list of [+-] classnames */
-static int param_set_dyndbg_classnames(const char *instr, const struct kernel_param *kp)
-{
- const struct ddebug_class_param *dcp = kp->arg;
- const struct ddebug_class_map *map = dcp->map;
- unsigned long curr_bits, old_bits;
- char *cl_str, *p, *tmp;
- int cls_id, totct = 0;
- bool wanted;
-
- cl_str = tmp = kstrdup_and_replace(instr, '\n', '\0', GFP_KERNEL);
- if (!tmp)
- return -ENOMEM;
-
- /* start with previously set state-bits, then modify */
- curr_bits = old_bits = *dcp->bits;
- vpr_info("\"%s\" > %s:0x%lx\n", cl_str, KP_NAME(kp), curr_bits);
-
- for (; cl_str; cl_str = p) {
- p = strchr(cl_str, ',');
- if (p)
- *p++ = '\0';
-
- if (*cl_str == '-') {
- wanted = false;
- cl_str++;
- } else {
- wanted = true;
- if (*cl_str == '+')
- cl_str++;
- }
- cls_id = match_string(map->class_names, map->length, cl_str);
- if (cls_id < 0) {
- pr_err("%s unknown to %s\n", cl_str, KP_NAME(kp));
- continue;
- }
-
- /* have one or more valid class_ids of one *_NAMES type */
- switch (map->map_type) {
- case DD_CLASS_TYPE_DISJOINT_NAMES:
- /* the +/- pertains to a single bit */
- if (test_bit(cls_id, &curr_bits) == wanted) {
- v3pr_info("no change on %s\n", cl_str);
- continue;
- }
- curr_bits ^= BIT(cls_id);
- totct += ddebug_apply_class_bitmap(dcp, &curr_bits, dcp->bits);
- *dcp->bits = curr_bits;
- v2pr_info("%s: changed bit %d:%s\n", KP_NAME(kp), cls_id,
- map->class_names[cls_id]);
- break;
- case DD_CLASS_TYPE_LEVEL_NAMES:
- /* cls_id = N in 0..max. wanted +/- determines N or N-1 */
- old_bits = CLASSMAP_BITMASK(*dcp->lvl);
- curr_bits = CLASSMAP_BITMASK(cls_id + (wanted ? 1 : 0 ));
-
- totct += ddebug_apply_class_bitmap(dcp, &curr_bits, &old_bits);
- *dcp->lvl = (cls_id + (wanted ? 1 : 0));
- v2pr_info("%s: changed bit-%d: \"%s\" %lx->%lx\n", KP_NAME(kp), cls_id,
- map->class_names[cls_id], old_bits, curr_bits);
- break;
- default:
- pr_err("illegal map-type value %d\n", map->map_type);
- }
- }
- kfree(tmp);
- vpr_info("total matches: %d\n", totct);
- return 0;
-}
-
/**
* param_set_dyndbg_classes - class FOO >control
* @instr: string echo>d to sysfs, input depends on map_type
@@ -738,28 +668,14 @@ int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
unsigned long inrep, new_bits, old_bits;
int rc, totct = 0;
- switch (map->map_type) {
-
- case DD_CLASS_TYPE_DISJOINT_NAMES:
- case DD_CLASS_TYPE_LEVEL_NAMES:
- /* handle [+-]classnames list separately, we are done here */
- return param_set_dyndbg_classnames(instr, kp);
-
- case DD_CLASS_TYPE_DISJOINT_BITS:
- case DD_CLASS_TYPE_LEVEL_NUM:
- /* numeric input, accept and fall-thru */
- rc = kstrtoul(instr, 0, &inrep);
- if (rc) {
- pr_err("expecting numeric input: %s > %s\n", instr, KP_NAME(kp));
- return -EINVAL;
- }
- break;
- default:
- pr_err("%s: bad map type: %d\n", KP_NAME(kp), map->map_type);
+ rc = kstrtoul(instr, 0, &inrep);
+ if (rc) {
+ int len = strcspn(instr, "\n");
+ pr_err("expecting numeric input, not: %.*s > %s\n",
+ len, instr, KP_NAME(kp));
return -EINVAL;
}
- /* only _BITS,_NUM (numeric) map-types get here */
switch (map->map_type) {
case DD_CLASS_TYPE_DISJOINT_BITS:
/* expect bits. mask and warn if too many */
@@ -787,6 +703,7 @@ int param_set_dyndbg_classes(const char *instr, const struct kernel_param *kp)
break;
default:
pr_warn("%s: bad map type: %d\n", KP_NAME(kp), map->map_type);
+ return -EINVAL;
}
vpr_info("%s: total matches: %d\n", KP_NAME(kp), totct);
return 0;
@@ -808,12 +725,8 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
const struct ddebug_class_map *map = dcp->map;
switch (map->map_type) {
-
- case DD_CLASS_TYPE_DISJOINT_NAMES:
case DD_CLASS_TYPE_DISJOINT_BITS:
return scnprintf(buffer, PAGE_SIZE, "0x%lx\n", *dcp->bits);
-
- case DD_CLASS_TYPE_LEVEL_NAMES:
case DD_CLASS_TYPE_LEVEL_NUM:
return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl);
default:
diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
index 77c2a669b6af..74d183ebf3e0 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c
@@ -74,13 +74,6 @@ DECLARE_DYNDBG_CLASSMAP(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS, 0,
DD_SYS_WRAP(disjoint_bits, p);
DD_SYS_WRAP(disjoint_bits, T);
-/* symbolic input, independent bits */
-enum cat_disjoint_names { LOW = 11, MID, HI };
-DECLARE_DYNDBG_CLASSMAP(map_disjoint_names, DD_CLASS_TYPE_DISJOINT_NAMES, 10,
- "LOW", "MID", "HI");
-DD_SYS_WRAP(disjoint_names, p);
-DD_SYS_WRAP(disjoint_names, T);
-
/* numeric verbosity, V2 > V1 related */
enum cat_level_num { V0 = 14, V1, V2, V3, V4, V5, V6, V7 };
DECLARE_DYNDBG_CLASSMAP(map_level_num, DD_CLASS_TYPE_LEVEL_NUM, 14,
@@ -88,13 +81,6 @@ DECLARE_DYNDBG_CLASSMAP(map_level_num, DD_CLASS_TYPE_LEVEL_NUM, 14,
DD_SYS_WRAP(level_num, p);
DD_SYS_WRAP(level_num, T);
-/* symbolic verbosity */
-enum cat_level_names { L0 = 22, L1, L2, L3, L4, L5, L6, L7 };
-DECLARE_DYNDBG_CLASSMAP(map_level_names, DD_CLASS_TYPE_LEVEL_NAMES, 22,
- "L0", "L1", "L2", "L3", "L4", "L5", "L6", "L7");
-DD_SYS_WRAP(level_names, p);
-DD_SYS_WRAP(level_names, T);
-
/* stand-in for all pr_debug etc */
#define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n")
@@ -102,10 +88,6 @@ static void do_cats(void)
{
pr_debug("doing categories\n");
- prdbg(LOW);
- prdbg(MID);
- prdbg(HI);
-
prdbg(D2_CORE);
prdbg(D2_DRIVER);
prdbg(D2_KMS);
@@ -129,14 +111,6 @@ static void do_levels(void)
prdbg(V5);
prdbg(V6);
prdbg(V7);
-
- prdbg(L1);
- prdbg(L2);
- prdbg(L3);
- prdbg(L4);
- prdbg(L5);
- prdbg(L6);
- prdbg(L7);
}
static void do_prints(void)
--
2.55.0
^ permalink raw reply related
* [PATCH v6 08/24] dyndbg: reword "class unknown," to "class:_UNKNOWN_"
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
When a dyndbg classname is unknown to a kernel module, the callsite is
un-addressable via >control queries, and therefore uncontrollable.
The control-file displays this condition as "class unknown, _id:N"
currently. That spelling is sub-optimal/too-generic, so change it to
"class:_UNKNOWN_ _id:N" to loudly announce the erroneous situation,
and to make it uniquely greppable.
NB: while this might be seen as a user-visible change, this shouldn't
disqualify the change:
a- it reports a classmap coding error condition, which should be
detected in (or before) review.
b- SHOUTING the error makes it more visible, uniquely greppable.
c- the classmap feature is marked BROKEN for its only current user.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
lib/dynamic_debug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 577a07916072..a86e1d5845e6 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1170,7 +1170,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
if (class)
seq_printf(m, " class:%s", class);
else
- seq_printf(m, " class unknown, _id:%d", dp->class_id);
+ seq_printf(m, " class:_UNKNOWN_ _id:%d", dp->class_id);
}
seq_putc(m, '\n');
--
2.55.0
^ permalink raw reply related
* [PATCH v6 07/24] dyndbg: add stub macro for DECLARE_DYNDBG_CLASSMAP
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Add the stub macro for !DYNAMIC_DEBUG builds, after moving the
original macro-defn down under the big ifdef. Do it now so future
changes have a cleaner starting point.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/linux/dynamic_debug.h | 43 ++++++++++++++++++++++---------------------
1 file changed, 22 insertions(+), 21 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 05743900a116..a10adac8e8f0 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -93,27 +93,6 @@ struct ddebug_class_map {
enum class_map_type map_type;
};
-/**
- * DECLARE_DYNDBG_CLASSMAP - declare classnames known by a module
- * @_var: a struct ddebug_class_map, passed to module_param_cb
- * @_type: enum class_map_type, chooses bits/verbose, numeric/symbolic
- * @_base: offset of 1st class-name. splits .class_id space
- * @classes: class-names used to control class'd prdbgs
- */
-#define DECLARE_DYNDBG_CLASSMAP(_var, _maptype, _base, ...) \
- static const char *_var##_classnames[] = { __VA_ARGS__ }; \
- static struct ddebug_class_map __aligned(8) __used \
- __section("__dyndbg_classes") _var = { \
- .mod = THIS_MODULE, \
- .mod_name = KBUILD_MODNAME, \
- .base = _base, \
- .map_type = _maptype, \
- .length = NUM_TYPE_ARGS(char*, __VA_ARGS__), \
- .class_names = _var##_classnames, \
- }
-#define NUM_TYPE_ARGS(eltype, ...) \
- (sizeof((eltype[]){__VA_ARGS__}) / sizeof(eltype))
-
/* encapsulate linker provided built-in (or module) dyndbg data */
struct _ddebug_info {
struct _ddebug *descs;
@@ -138,6 +117,27 @@ struct ddebug_class_param {
#if defined(CONFIG_DYNAMIC_DEBUG) || \
(defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
+/**
+ * DECLARE_DYNDBG_CLASSMAP - declare classnames known by a module
+ * @_var: a struct ddebug_class_map, passed to module_param_cb
+ * @_type: enum class_map_type, chooses bits/verbose, numeric/symbolic
+ * @_base: offset of 1st class-name. splits .class_id space
+ * @classes: class-names used to control class'd prdbgs
+ */
+#define DECLARE_DYNDBG_CLASSMAP(_var, _maptype, _base, ...) \
+ static const char *_var##_classnames[] = { __VA_ARGS__ }; \
+ static struct ddebug_class_map __aligned(8) __used \
+ __section("__dyndbg_classes") _var = { \
+ .mod = THIS_MODULE, \
+ .mod_name = KBUILD_MODNAME, \
+ .base = _base, \
+ .map_type = _maptype, \
+ .length = NUM_TYPE_ARGS(char*, __VA_ARGS__), \
+ .class_names = _var##_classnames, \
+ }
+#define NUM_TYPE_ARGS(eltype, ...) \
+ (sizeof((eltype[]) {__VA_ARGS__}) / sizeof(eltype))
+
extern __printf(2, 3)
void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...);
@@ -314,6 +314,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)
#define DYNAMIC_DEBUG_BRANCH(descriptor) false
+#define DECLARE_DYNDBG_CLASSMAP(...)
#define dynamic_pr_debug(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
--
2.55.0
^ permalink raw reply related
* [PATCH v6 06/24] dyndbg: factor ddebug_match_desc out from ddebug_change
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
ddebug_change() is a big (~100 lines) function with a nested for loop.
The outer loop walks the per-module ddebug_tables list, and does
module stuff: it filters on a query's "module FOO*" and "class BAR",
failures here skip the entire inner loop.
The inner loop (60 lines) scans a module's descriptors. It starts
with a long block of filters on function, line, format, and the
validated "BAR" class (or the legacy/_DPRINTK_CLASS_DFLT).
These filters "continue" past pr_debugs that don't match the query
criteria, before it falls through the code below that counts matches,
then adjusts the flags and static-keys. This is unnecessarily hard to
think about.
So move the per-descriptor filter-block into a boolean function:
ddebug_match_desc(desc), and change each "continue" to "return false".
This puts a clear interface in place, so any future changes are either
inside, outside, or across this interface.
also fix checkpatch complaints about spaces and braces.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
v5: check for null format in callsite. shouldnt happen, but pr_debug() isnt illegal
---
lib/dynamic_debug.c | 87 +++++++++++++++++++++++++++++++----------------------
1 file changed, 51 insertions(+), 36 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 18a71a9108d3..577a07916072 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -172,6 +172,56 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
* callsites, normally the same as number of changes. If verbose,
* logs the changes. Takes ddebug_lock.
*/
+static bool ddebug_match_desc(const struct ddebug_query *query,
+ struct _ddebug *dp,
+ int valid_class)
+{
+ /* match site against query-class */
+ if (dp->class_id != valid_class)
+ return false;
+
+ /* match against the source filename */
+ if (query->filename &&
+ !match_wildcard(query->filename, dp->filename) &&
+ !match_wildcard(query->filename,
+ kbasename(dp->filename)) &&
+ !match_wildcard(query->filename,
+ trim_prefix(dp->filename)))
+ return false;
+
+ /* match against the function */
+ if (query->function &&
+ !match_wildcard(query->function, dp->function))
+ return false;
+
+ /* match against the format */
+ if (query->format) {
+ if (!dp->format) {
+ pr_info("encountered a NULL format\n");
+ return false;
+ }
+ if (*query->format == '^') {
+ char *p;
+ /* anchored search. match must be at beginning */
+ p = strstr(dp->format, query->format + 1);
+ if (p != dp->format)
+ return false;
+ } else if (!strstr(dp->format, query->format)) {
+ return false;
+ }
+ }
+
+ /* match against the line number range */
+ if (query->first_lineno &&
+ dp->lineno < query->first_lineno)
+ return false;
+ if (query->last_lineno &&
+ dp->lineno > query->last_lineno)
+ return false;
+
+ return true;
+}
+
static int ddebug_change(const struct ddebug_query *query,
struct flag_settings *modifiers)
{
@@ -204,42 +254,7 @@ static int ddebug_change(const struct ddebug_query *query,
for (i = 0; i < dt->num_ddebugs; i++) {
struct _ddebug *dp = &dt->ddebugs[i];
- /* match site against query-class */
- if (dp->class_id != valid_class)
- continue;
-
- /* match against the source filename */
- if (query->filename &&
- !match_wildcard(query->filename, dp->filename) &&
- !match_wildcard(query->filename,
- kbasename(dp->filename)) &&
- !match_wildcard(query->filename,
- trim_prefix(dp->filename)))
- continue;
-
- /* match against the function */
- if (query->function &&
- !match_wildcard(query->function, dp->function))
- continue;
-
- /* match against the format */
- if (query->format) {
- if (*query->format == '^') {
- char *p;
- /* anchored search. match must be at beginning */
- p = strstr(dp->format, query->format+1);
- if (p != dp->format)
- continue;
- } else if (!strstr(dp->format, query->format))
- 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)
+ if (!ddebug_match_desc(query, dp, valid_class))
continue;
nfound++;
--
2.55.0
^ permalink raw reply related
* [PATCH v6 05/24] dyndbg.lds.S: fix lost dyndbg sections in modules
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
With CONFIG_DRM_USE_DYNAMIC_DEBUG=y, several build configs had
problems with __dyndbg* sections getting lost in drm drivers. Fix
this by following the model demonstrated in codetag.lds.h.
Introduce include/asm-generic/dyndbg.lds.h, to bundle dynamic-debug's
multiple sections together, into 2 macros:
vmlinux.lds.h DATA_DATA: move the 2 BOUNDED_SECTION_BY(__dyndbg*)
calls into dyndbg.lds.h DYNDBG_SECTIONS(). vmlinux.lds.h now includes
the new file and calls the new macro.
MOD_DYNDBG_SECTIONS keeps the 2 sections by name, aligns them and sets
the output address to 0 when the sections are empty.
dyndbg.lds.h includes (reuses) bounded-section.lds.h
scripts/module.lds.S: now calls MOD_DYNDBG_SECTIONS right before the
CODETAG macro (consistent with their placements in vmlinux.lds.h), and
also includes dyndbg.lds.h
This isolates vmlinux.lds.h from further __dyndbg section additions.
CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
---
v3: move #includes to top, drop extra ALIGN(8) in DYNDBG_SECTIONS, add RvBy
v2: Address linker script review feedback for relocatable modules.
MOD_DYNDBG_SECTIONS() used the BOUNDED_SECTION_BY() macro, which
proved problematic for kernel modules for two reasons:
1. Unwanted Empty Sections:
BOUNDED_SECTION_BY() automatically generates `__start` and `__stop`
symbols. When applied to `MOD_DYNDBG_SECTIONS()`, the linker assumes
the sections are populated due to the symbol definitions, forcing an
empty `__dyndbg` and `__dyndbg_classes` output section in every
compiled module, even those without dynamic debug configuration.
Since the module loader uses `section_objs()` to locate data via
ELF headers instead of relying on `__start`/`__stop` symbols, these
assignments are completely unnecessary.
2. Non-zero Output Addresses:
During relocatable linking (e.g., `ld.bfd -r`), omitting an explicit
base address causes the section to inherit the current location
counter. This results in non-zero sh_addr values in `.ko` files,
which is confusing, degrades compressibility, and can cause issues
with external tools parsing the ELF.
Fix both issues by dropping `BOUNDED_SECTION_BY()` in favor of a simple
`KEEP(*(...))` constraint and explicitly defining the sections with a `0`
base address: `__dyndbg 0 : ALIGN(8) { ... }`.
fixup-inc-vml
---
MAINTAINERS | 1 +
include/asm-generic/dyndbg.lds.h | 18 ++++++++++++++++++
include/asm-generic/vmlinux.lds.h | 6 ++----
scripts/module.lds.S | 2 ++
4 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index 4a8b0fd665ce..25400fee9f32 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9178,6 +9178,7 @@ DYNAMIC DEBUG
M: Jason Baron <jbaron@akamai.com>
M: Jim Cromie <jim.cromie@gmail.com>
S: Maintained
+F: include/asm-generic/dyndbg.lds.h
F: include/linux/dynamic_debug.h
F: lib/dynamic_debug.c
F: lib/test_dynamic_debug.c
diff --git a/include/asm-generic/dyndbg.lds.h b/include/asm-generic/dyndbg.lds.h
new file mode 100644
index 000000000000..9d8951bef688
--- /dev/null
+++ b/include/asm-generic/dyndbg.lds.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_GENERIC_DYNDBG_LDS_H
+#define __ASM_GENERIC_DYNDBG_LDS_H
+
+#include <asm-generic/bounded_sections.lds.h>
+#define DYNDBG_SECTIONS() \
+ BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
+ BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes)
+
+#define MOD_DYNDBG_SECTIONS() \
+ __dyndbg 0 : ALIGN(8) { \
+ KEEP(*(__dyndbg)) \
+ } \
+ __dyndbg_classes 0 : ALIGN(8) { \
+ KEEP(*(__dyndbg_classes)) \
+ }
+
+#endif /* __ASM_GENERIC_DYNDBG_LDS_H */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 3758a79d0430..bd60f278f762 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -52,6 +52,7 @@
#include <asm-generic/bounded_sections.lds.h>
#include <asm-generic/codetag.lds.h>
+#include <asm-generic/dyndbg.lds.h>
#ifndef LOAD_OFFSET
#define LOAD_OFFSET 0
@@ -344,10 +345,7 @@
*(.data..do_once) \
STRUCT_ALIGN(); \
*(__tracepoints) \
- /* implement dynamic printk debug */ \
- . = ALIGN(8); \
- BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) \
- BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
+ DYNDBG_SECTIONS() \
CODETAG_SECTIONS() \
LIKELY_PROFILE() \
BRANCH_PROFILE() \
diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index b62683061d79..2e62dc5bd5d4 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -10,6 +10,7 @@
#endif
#include <asm-generic/codetag.lds.h>
+#include <asm-generic/dyndbg.lds.h>
SECTIONS {
/DISCARD/ : {
@@ -61,6 +62,7 @@ SECTIONS {
*(.rodata..L*)
}
+ MOD_DYNDBG_SECTIONS()
MOD_SEPARATE_CODETAG_SECTIONS()
}
--
2.55.0
^ permalink raw reply related
* [PATCH v6 04/24] vmlinux.lds.h: remove redundant ALIGN(8) directives
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
The BOUNDED_SECTION_PRE_LABEL and BOUNDED_SECTION_POST_LABEL macros
were recently updated to inherently enforce an 8-byte alignment. This
makes the explicit '. = ALIGN(8);' statements preceding 'naked' macro
calls in vmlinux.lds.h redundant.
Remove these redundant alignment directives to clean up the file and
clarify that the macros handle their own alignment padding.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/asm-generic/vmlinux.lds.h | 13 -------------
1 file changed, 13 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f29fc079e37e..3758a79d0430 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -228,7 +228,6 @@
#ifdef CONFIG_KPROBES
#define KPROBE_BLACKLIST() \
- . = ALIGN(8); \
BOUNDED_SECTION(_kprobe_blacklist)
#else
#define KPROBE_BLACKLIST()
@@ -244,7 +243,6 @@
#ifdef CONFIG_EVENT_TRACING
#define FTRACE_EVENTS() \
- . = ALIGN(8); \
BOUNDED_SECTION(_ftrace_events) \
BOUNDED_SECTION_BY(_ftrace_eval_map, _ftrace_eval_maps)
#else
@@ -261,7 +259,6 @@
#ifdef CONFIG_FTRACE_SYSCALLS
#define TRACE_SYSCALLS() \
- . = ALIGN(8); \
BOUNDED_SECTION_BY(__syscalls_metadata, _syscalls_metadata)
#else
#define TRACE_SYSCALLS()
@@ -276,7 +273,6 @@
#ifdef CONFIG_SERIAL_EARLYCON
#define EARLYCON_TABLE() \
- . = ALIGN(8); \
BOUNDED_SECTION_POST_LABEL(__earlycon_table, __earlycon_table, , _end)
#else
#define EARLYCON_TABLE()
@@ -284,11 +280,9 @@
#ifdef CONFIG_SECURITY
#define LSM_TABLE() \
- . = ALIGN(8); \
BOUNDED_SECTION_PRE_LABEL(.lsm_info.init, _lsm_info, __start, __end)
#define EARLY_LSM_TABLE() \
- . = ALIGN(8); \
BOUNDED_SECTION_PRE_LABEL(.early_lsm_info.init, _early_lsm_info, __start, __end)
#else
#define LSM_TABLE()
@@ -314,7 +308,6 @@
#ifdef CONFIG_ACPI
#define ACPI_PROBE_TABLE(name) \
- . = ALIGN(8); \
BOUNDED_SECTION_POST_LABEL(__##name##_acpi_probe_table, \
__##name##_acpi_probe_table,, _end)
#else
@@ -323,7 +316,6 @@
#ifdef CONFIG_THERMAL
#define THERMAL_TABLE(name) \
- . = ALIGN(8); \
BOUNDED_SECTION_POST_LABEL(__##name##_thermal_table, \
__##name##_thermal_table,, _end)
#else
@@ -403,12 +395,10 @@
__end_init_stack = .;
#define JUMP_TABLE_DATA \
- . = ALIGN(8); \
BOUNDED_SECTION_BY(__jump_table, ___jump_table)
#ifdef CONFIG_HAVE_STATIC_CALL_INLINE
#define STATIC_CALL_DATA \
- . = ALIGN(8); \
BOUNDED_SECTION_BY(.static_call_sites, _static_call_sites) \
BOUNDED_SECTION_BY(.static_call_tramp_key, _static_call_tramp_key)
#else
@@ -453,7 +443,6 @@
*(.rodata) *(.rodata.*) *(.data.rel.ro*) \
SCHED_DATA \
RO_AFTER_INIT_DATA /* Read only after init */ \
- . = ALIGN(8); \
BOUNDED_SECTION_BY(__tracepoints_ptrs, ___tracepoints_ptrs) \
*(__tracepoints_strings)/* Tracepoints: strings */ \
} \
@@ -947,12 +936,10 @@
/* Alignment must be consistent with (kunit_suite *) in include/kunit/test.h */
#define KUNIT_TABLE() \
- . = ALIGN(8); \
BOUNDED_SECTION_POST_LABEL(.kunit_test_suites, __kunit_suites, _start, _end)
/* Alignment must be consistent with (kunit_suite *) in include/kunit/test.h */
#define KUNIT_INIT_TABLE() \
- . = ALIGN(8); \
BOUNDED_SECTION_POST_LABEL(.kunit_init_test_suites, \
__kunit_init_suites, _start, _end)
--
2.55.0
^ permalink raw reply related
* [PATCH v6 03/24] vmlinux.lds.h: Fix ALIGN(8) omission causing NULL ptr on i386
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Louis Chauvet, Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Almost all uses of the BOUNDED_SECTION macros are ALIGN(8), either
explicitly, or by being below an aligned section containing x*8 byte
objects. The noteworthy exception is BOUNDED_SECTION(__dyndbg), which
immediately follows BOUNDED_SECTION(__dyndbg_classes).
On i386, struct _ddebug_classmap is 28 bytes, so without an explicit
ALIGN(8) in the macro, the following __dyndbg section gets misaligned,
causing a NULL ptr deref in dynamic_debug_init().
So fix this with an explicit ALIGN(8) in the existing BOUNDED_SECTION
macros, and introduce _ALIGNED variants to handle the cases with an
explicit . = ALIGN(x)
Also add explicit alignments for: EXCEPTION_TABLE, ORC_UNWIND_TABLE,
TRACEDATA, INIT_SETUP, and NOTES.
update BOUNDED_SECTION uses inside . = ALIGN(x) stanzas to use
_ALIGNED variants, but keep the outer ALIGNs so the symbols between
them are not "re-aligned".
In particular, scripts/sorttable.c does not tolerate sloppy padding.
At the top of ORC_UNWIND_TABLE, add . = ALIGN(4) to match the struct
orc_header __align() call in the code:
commit b9f174c811e3 ("x86/unwind/orc: Add ELF section with ORC version identifier")
Suggested-by: Louis Chauvet <louis.chauvet@bootlin.com> # _ALIGNED variants.
Link: https://lore.kernel.org/lkml/177402491426.6181.12855763650074831089.b4-review@b4/
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v3:
sashiko complained about NOTES and .BTF_ids.
gemini asserts that NOTES are natively 4-byte aligned, add comment repeating it.
.BTF_ids doesnt use BOUNDED_BY, since start/end isnt needed;
sashiko evidently got confused by immediately preceding usage.
v2:
sashiko picked up 2 cases, added to the explicit list above
https://sashiko.dev/#/patchset/20260515-asm-generic-1-v3-0-680b273666d4%40gmail.com
---
include/asm-generic/bounded_sections.lds.h | 17 ++++++++++++++---
include/asm-generic/vmlinux.lds.h | 18 ++++++++++--------
2 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/include/asm-generic/bounded_sections.lds.h b/include/asm-generic/bounded_sections.lds.h
index 268cdc34389b..8ff3e3420f60 100644
--- a/include/asm-generic/bounded_sections.lds.h
+++ b/include/asm-generic/bounded_sections.lds.h
@@ -3,19 +3,30 @@
#ifndef _ASM_GENERIC_BOUNDED_SECTIONS_H
#define _ASM_GENERIC_BOUNDED_SECTIONS_H
-#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+#define BOUNDED_SECTION_PRE_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, _ALIGNED_) \
+ . = ALIGN(_ALIGNED_); \
_BEGIN_##_label_ = .; \
KEEP(*(_sec_)) \
_END_##_label_ = .;
-#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+ BOUNDED_SECTION_PRE_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, 8)
+
+#define BOUNDED_SECTION_POST_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, _ALIGNED_) \
+ . = ALIGN(_ALIGNED_); \
_label_##_BEGIN_ = .; \
KEEP(*(_sec_)) \
_label_##_END_ = .;
+#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+ BOUNDED_SECTION_POST_LABEL_ALIGNED(_sec_, _label_, _BEGIN_, _END_, 8)
+
#define BOUNDED_SECTION_BY(_sec_, _label_) \
BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
-#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec)
+#define BOUNDED_SECTION_BY_ALIGNED(_sec_, _label_, _ALIGNED_) \
+ BOUNDED_SECTION_PRE_LABEL_ALIGNED(_sec_, _label_, __start, __stop, _ALIGNED_)
+
+#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec)
#endif /* _ASM_GENERIC_BOUNDED_SECTIONS_H */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f5ddf31b7f26..f29fc079e37e 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -640,7 +640,7 @@
#define EXCEPTION_TABLE(align) \
. = ALIGN(align); \
__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(__ex_table, ___ex_table) \
+ BOUNDED_SECTION_BY_ALIGNED(__ex_table, ___ex_table, align) \
}
/*
@@ -650,7 +650,7 @@
#define BTF \
. = ALIGN(PAGE_SIZE); \
.BTF : AT(ADDR(.BTF) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.BTF, _BTF) \
+ BOUNDED_SECTION_BY_ALIGNED(.BTF, _BTF, PAGE_SIZE) \
} \
. = ALIGN(PAGE_SIZE); \
.BTF_ids : AT(ADDR(.BTF_ids) - LOAD_OFFSET) { \
@@ -832,16 +832,17 @@
#ifdef CONFIG_UNWINDER_ORC
#define ORC_UNWIND_TABLE \
+ . = ALIGN(4); \
.orc_header : AT(ADDR(.orc_header) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.orc_header, _orc_header) \
+ BOUNDED_SECTION_BY_ALIGNED(.orc_header, _orc_header, 4) \
} \
. = ALIGN(4); \
.orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.orc_unwind_ip, _orc_unwind_ip) \
+ BOUNDED_SECTION_BY_ALIGNED(.orc_unwind_ip, _orc_unwind_ip, 4)\
} \
. = ALIGN(2); \
.orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.orc_unwind, _orc_unwind) \
+ BOUNDED_SECTION_BY_ALIGNED(.orc_unwind, _orc_unwind, 2) \
} \
text_size = _etext - _stext; \
. = ALIGN(4); \
@@ -869,7 +870,7 @@
#define TRACEDATA \
. = ALIGN(4); \
.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) { \
- BOUNDED_SECTION_POST_LABEL(.tracedata, __tracedata, _start, _end) \
+ BOUNDED_SECTION_POST_LABEL_ALIGNED(.tracedata, __tracedata, _start, _end, 4) \
}
#else
#define TRACEDATA
@@ -898,13 +899,14 @@
*(.note.gnu.property) \
} \
.notes : AT(ADDR(.notes) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.note.*, _notes) \
+ /* *(.note.*) are natively 4-byte aligned */ \
+ BOUNDED_SECTION_BY_ALIGNED(.note.*, _notes, 4) \
} NOTES_HEADERS \
NOTES_HEADERS_RESTORE
#define INIT_SETUP(initsetup_align) \
. = ALIGN(initsetup_align); \
- BOUNDED_SECTION_POST_LABEL(.init.setup, __setup, _start, _end)
+ BOUNDED_SECTION_POST_LABEL_ALIGNED(.init.setup, __setup, _start, _end, initsetup_align)
#define INIT_CALLS_LEVEL(level) \
__initcall##level##_start = .; \
--
2.55.0
^ permalink raw reply related
* [PATCH v6 02/24] vmlinux.lds.h: drop unused HEADERED_SECTION* macros
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
These macros are unused, no point in carrying them any more.
NB: these macros were just moved to bounded_sections.lds.h, from
vmlinux.lds.h, which is the known entity, and therefore more
meaningful in the 1-line summary, so thats what I used as the topic.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/asm-generic/bounded_sections.lds.h | 15 ---------------
1 file changed, 15 deletions(-)
diff --git a/include/asm-generic/bounded_sections.lds.h b/include/asm-generic/bounded_sections.lds.h
index 8c29293ca7fb..268cdc34389b 100644
--- a/include/asm-generic/bounded_sections.lds.h
+++ b/include/asm-generic/bounded_sections.lds.h
@@ -18,19 +18,4 @@
#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec)
-#define HEADERED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_, _HDR_) \
- _HDR_##_label_ = .; \
- KEEP(*(.gnu.linkonce.##_sec_)) \
- BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_)
-
-#define HEADERED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_, _HDR_) \
- _label_##_HDR_ = .; \
- KEEP(*(.gnu.linkonce.##_sec_)) \
- BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_)
-
-#define HEADERED_SECTION_BY(_sec_, _label_) \
- HEADERED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
-
-#define HEADERED_SECTION(_sec) HEADERED_SECTION_BY(_sec, _sec)
-
#endif /* _ASM_GENERIC_BOUNDED_SECTIONS_H */
--
2.55.0
^ permalink raw reply related
* [PATCH v6 01/24] vmlinux.lds.h: refactor BOUNDED_SECTION_* macros into bounded_sections.lds.h
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie
In-Reply-To: <20260707-dd-maint-2-v6-0-381f3edb0045@gmail.com>
Move BOUNDED_SECTION_* macros to a new helper file:
include/asm-generic/bounded_sections.lds.h and include it back into
vmlinux.lds.h. This allows its reuse later to fix a failure to keep
dyndbg sections in some circumstances.
NOTES:
These macros are only for use in vmlinux.lds.h, where the _start &
_end symbols are needed. Modules keep sections separate in ELF
sections, with their boundaries known, so the _start and _end are not
useful, and may confuse tools not expecting them.
This patch ignores a checkpatch warning, because new file is covered
by "GENERIC INCLUDE/ASM HEADER FILES" in MAINTAINERS
CC: Arnd Bergmann <arnd@arndb.de>
CC: linux-arch@vger.kernel.org
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v3: move include to top
---
include/asm-generic/bounded_sections.lds.h | 36 ++++++++++++++++++++++++++++++
include/asm-generic/vmlinux.lds.h | 31 +------------------------
2 files changed, 37 insertions(+), 30 deletions(-)
diff --git a/include/asm-generic/bounded_sections.lds.h b/include/asm-generic/bounded_sections.lds.h
new file mode 100644
index 000000000000..8c29293ca7fb
--- /dev/null
+++ b/include/asm-generic/bounded_sections.lds.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _ASM_GENERIC_BOUNDED_SECTIONS_H
+#define _ASM_GENERIC_BOUNDED_SECTIONS_H
+
+#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+ _BEGIN_##_label_ = .; \
+ KEEP(*(_sec_)) \
+ _END_##_label_ = .;
+
+#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+ _label_##_BEGIN_ = .; \
+ KEEP(*(_sec_)) \
+ _label_##_END_ = .;
+
+#define BOUNDED_SECTION_BY(_sec_, _label_) \
+ BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
+
+#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec)
+
+#define HEADERED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_, _HDR_) \
+ _HDR_##_label_ = .; \
+ KEEP(*(.gnu.linkonce.##_sec_)) \
+ BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_)
+
+#define HEADERED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_, _HDR_) \
+ _label_##_HDR_ = .; \
+ KEEP(*(.gnu.linkonce.##_sec_)) \
+ BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_)
+
+#define HEADERED_SECTION_BY(_sec_, _label_) \
+ HEADERED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
+
+#define HEADERED_SECTION(_sec) HEADERED_SECTION_BY(_sec, _sec)
+
+#endif /* _ASM_GENERIC_BOUNDED_SECTIONS_H */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 5659f4b5a125..f5ddf31b7f26 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -50,6 +50,7 @@
* [__nosave_begin, __nosave_end] for the nosave data
*/
+#include <asm-generic/bounded_sections.lds.h>
#include <asm-generic/codetag.lds.h>
#ifndef LOAD_OFFSET
@@ -211,36 +212,6 @@
# endif
#endif
-#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \
- _BEGIN_##_label_ = .; \
- KEEP(*(_sec_)) \
- _END_##_label_ = .;
-
-#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \
- _label_##_BEGIN_ = .; \
- KEEP(*(_sec_)) \
- _label_##_END_ = .;
-
-#define BOUNDED_SECTION_BY(_sec_, _label_) \
- BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
-
-#define BOUNDED_SECTION(_sec) BOUNDED_SECTION_BY(_sec, _sec)
-
-#define HEADERED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_, _HDR_) \
- _HDR_##_label_ = .; \
- KEEP(*(.gnu.linkonce.##_sec_)) \
- BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_)
-
-#define HEADERED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_, _HDR_) \
- _label_##_HDR_ = .; \
- KEEP(*(.gnu.linkonce.##_sec_)) \
- BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_)
-
-#define HEADERED_SECTION_BY(_sec_, _label_) \
- HEADERED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
-
-#define HEADERED_SECTION(_sec) HEADERED_SECTION_BY(_sec, _sec)
-
#ifdef CONFIG_TRACE_BRANCH_PROFILING
#define LIKELY_PROFILE() \
BOUNDED_SECTION_BY(_ftrace_annotated_branch, _annotated_branch_profile)
--
2.55.0
^ permalink raw reply related
* [PATCH v6 00/24] fix dynamic-debug classmaps API for DRM
From: Jim Cromie @ 2026-07-08 2:18 UTC (permalink / raw)
To: Andrew Morton, Jason Baron, Greg Kroah-Hartman, Jonathan Corbet,
Shuah Khan, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
David Airlie, Simona Vetter, Arnd Bergmann, Luis Chamberlain,
Petr Pavlu
Cc: linux-kernel, linux-doc, dri-devel, linux-arch, linux-modules,
Jim Cromie, Louis Chauvet
This series fixes problems which broke CONFIG_DRM_USE_DYNAMIC_DEBUG=Y.
1st chunk fixes a section misalignement on i386, when CONFIG_DRM=y and
CONFIG_DRM_USE_DYNAMIC_DEBUG=Y. It also repairs a linkage failure
where the dyndbg sections got dropped from loadable modules in some
arches. This chunk was reviewed by Petr Pavlu (thx).
2nd chunk is a set of cleanups, callchain refactors, struct refactors,
and internal reorgs in preparation for the API change needed to fix
the regression seen in DRM where boot-time drm.debug settings (in
core) did not propagate to drivers.
3rd is the API change itself; replacing DECLARE_DYNDBG_CLASSMAP (used
in both core and drivers, a K&R define-once-use-thereafter violation,
which caused the regression) with DYNAMIC_DEBUG_CLASSMAP_DEFINE in
core, and $1_USE in drivers and helpers.
There are 2 user-visible changes:
1. change an ERROR condition displayed in dynamic_debug/control,
from "class:unknown, _id:1" to "class:_UNKNOWN_ id:1"
This only happens if a classmap is incorrectly defined, so it should
not pass review, and should be SHOUTED about. And since classmaps are
BROKEN for DRM (its only user), this affects no users.
2. change builtin module names, displayed in dynamic_debug/control,
from simple "[main]" to subsystem "[init/main]" etc. This corrects an
existing naming ambiguity, which is disallowed for loadable modules by
the module loader. To preserve legacy query behavior, "module main"
will select all of "[*/main]".
NB: the current ambiguity prevents cleanly adding classmaps to
builtins named "[main]". Such an addition is quite unlikely, so this
change could be dropped, but it seemed proper to correct it and point
it out.
3. revert a change in classmaps-v1 (2022) which enlarged __drm_debug
from (unsigned) int to long int. 64 categories of drm-debug is well
past reasonable, the param is now a u32, for clarity.
---
this is based on v7.2-rc2
Ive trimmed the cc-list to stay under gmail's 500msgs/day
Changes in v6:
previous versions split the 1st chunk into a separate submission, in
an attempt to get past gmail's 500 msgs/day limit, and to ease review.
This complicated application; although the 2nd chunk had the b4
dependency on the 1st, this fact was missed by sashiko, which
therefore couldnt apply it.
A followon series adds compile-time and runtime checks to fail-fast if
classmaps are used incorrectly.
Changes in v5:
move KBUILD_MODFILE ahead of array-slice, to address sashiko
complaints which were fixed by later patches in V4.
Changes in v4:
Dyndbg previously used KBUILD_MODNAME to provide module-name, this
works well for loadable modules (module loader requires unique module
names), but for builtin modules, is effectively kbasename, and is not
guaranteed unique.
So we get 4 modules named "main": init/main, kernel/power/main,
kernel/base/power/main. This ambiguity is visible in user-space since
the beginning of dyndbg.
Now suppose kernel/{,base}/power/main want to define classmaps to
categorize the various pr-debugs they have. The current code finds a
module's classmaps by strcmp on modname, so init/main will match
against classmaps defined by both kernel/{,base}/power/main.
The current code will also map "main" classes to kernel/*/power/main,
so they will probably work at first, but 2 independent classmaps can
both use class-ids 0-N, but will conflict if they're both used by a
module. Then we have classmap overlaps and unpredictable results.
v3:
- move #includes to top of files,
- drop redundant ALIGN(8) in dydnbg.lds.S: DYNDBG_SECTIONS macro
- add Reviewed-by tag (thx Petr)
v2:
- avoid BOUNDED_SECTION in modules, dont need _start & _end symbols.
- sets 0 address to the sections, not just whatever current is.
---
Jim Cromie (24):
vmlinux.lds.h: refactor BOUNDED_SECTION_* macros into bounded_sections.lds.h
vmlinux.lds.h: drop unused HEADERED_SECTION* macros
vmlinux.lds.h: Fix ALIGN(8) omission causing NULL ptr on i386
vmlinux.lds.h: remove redundant ALIGN(8) directives
dyndbg.lds.S: fix lost dyndbg sections in modules
dyndbg: factor ddebug_match_desc out from ddebug_change
dyndbg: add stub macro for DECLARE_DYNDBG_CLASSMAP
dyndbg: reword "class unknown," to "class:_UNKNOWN_"
dyndbg-API: remove DD_CLASS_TYPE_(DISJOINT|LEVEL)_NAMES and code
dyndbg: drop NUM_TYPE_ARGS
dyndbg: bump num-tokens in a query-cmd from 9 to 15
dyndbg: reduce verbose/debug clutter
lib/parser: add match_wildcard_hyphen() for agnostic matching
dyndbg: use KBUILD_MODFILE for unique builtin module names
dyndbg: refactor param_set_dyndbg_classes and below
dyndbg: tighten fn-sig of ddebug_apply_class_bitmap
dyndbg: replace classmap list with an array-slice
dyndbg: macrofy a 2-index for-loop pattern
dyndbg: pin class param storage to u32
dyndbg,module: make proper substructs in _ddebug_info
dyndbg: move mod_name down from struct ddebug_table to _ddebug_info
dyndbg: hoist classmap-filter-by-modname up to ddebug_add_module
dyndbg: change __dynamic_func_call_cls* macros into expressions
dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP
Documentation/admin-guide/dynamic-debug-howto.rst | 42 +-
MAINTAINERS | 1 +
drivers/gpu/drm/drm_print.c | 6 +-
include/asm-generic/bounded_sections.lds.h | 32 ++
include/asm-generic/dyndbg.lds.h | 22 +
include/asm-generic/vmlinux.lds.h | 68 +--
include/drm/drm_print.h | 2 +-
include/linux/dynamic_debug.h | 275 +++++++---
include/linux/parser.h | 1 +
kernel/module/main.c | 15 +-
lib/Kconfig.debug | 24 +-
lib/Makefile | 3 +
lib/dynamic_debug.c | 608 +++++++++++++---------
lib/parser.c | 58 ++-
lib/test_dynamic_debug.c | 145 ++++--
lib/test_dynamic_debug_submod.c | 14 +
scripts/module.lds.S | 2 +
17 files changed, 846 insertions(+), 472 deletions(-)
---
base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
change-id: 20260521-dd-maint-2-76c542079420
prerequisite-change-id: 20260630-fix-align-589738662161:v4
prerequisite-patch-id: d6b2b7d254c7e8bbc0aea891d49b15dc1e71eaa4
prerequisite-patch-id: 3dffaa165e78dc58e443469755eddb07972d0ddf
prerequisite-patch-id: 2c4827d84b4159e71df89cca2a03938a534ecdb5
prerequisite-patch-id: 4599f9be1eb06c0d7f2a7c657d4940411635e94b
prerequisite-patch-id: aea9e121b30e3c7f3d76921b49f81ad421b7af51
Best regards,
--
Jim Cromie <jim.cromie@gmail.com>
^ permalink raw reply
* [PATCH v4] module: Extend module_blacklist parameter to built-in modules
From: Aaron Tomlin @ 2026-07-08 2:00 UTC (permalink / raw)
To: arnd, mcgrof, petr.pavlu, da.gomez, samitolvanen, peterz
Cc: akpm, mhiramat, atomlin, neelx, da.anzani, sean, chjohnst, steve,
mproche, nick.lane, linux-arch, linux-modules, linux-kernel
Currently, the "module_blacklist=" command-line parameter only applies
to loadable modules. If a module is built-in, the parameter is silently
ignored. This patch extends the blacklisting functionality to built-in
modules by intercepting their initialisation routines during early boot.
To preserve the existing user-space ABI, "module_blacklist=" is kept
as a legacy alias pointing to the same module_denylist variable.
To achieve this, we introduce a new ".initcall.modnames" memory section.
For each built-in module, we use a standard C structure (i.e., struct
initcall_modname) to map its initcall function pointer to its associated
KBUILD_MODNAME string.
During boot, do_one_initcall() cross-references the initcall function
pointer against this table. If a match is found and the module is
present in the denylist, the initcall is skipped.
To make the denylist functional on monolithic kernels, the command-line
parameter parsing and the module_is_denylisted() lookup function are
decoupled from the loadable module subsystem and moved to init/main.c.
This enables "module_denylist=" and "module_blacklist=" to intercept
built-in modules even on kernels built with CONFIG_MODULES=n.
Design Considerations and Trade-offs:
1. LTO and CFI Compatibility vs. PREL32
Previous iterations of this patch attempted to use top-level
inline assembly to generate 32-bit relative offsets (PREL32) to
save memory. However, raw inline assembly operates blindly
outside of the C compiler's visibility. When compiled with
CONFIG_LTO_CLANG or CONFIG_CFI_CLANG, the compiler applies
symbol renaming and generates Control Flow Integrity stubs.
The raw assembly string-matching fails to track these changes,
resulting in undefined references or runtime address mismatches.
To resolve this, we strictly use standard C structures to hold
the function pointers. This natively allows the compiler to
resolve LTO renaming and map CFI stubs correctly. We trade the
minor spatial optimisation of PREL32 (using absolute 64-bit
pointers instead) to guarantee architectural safety under modern
compiler protections. Because this metadata is placed in an
".init" section and freed entirely after boot, the temporary
memory overhead is negligible.
2. Prevention of UAF (Use-After-Free) via temporal and spatial
boundaries:
Because do_one_initcall() is a shared path invoked by both the
early boot process and runtime module loading (i.e.,
do_init_module()), we must prevent loadable modules from
attempting to scan the ".initcall.modnames" section after it has
been reclaimed by free_initmem().
To ensure safety, we employ a two-fold validation check:
- A temporal check using 'system_state >= SYSTEM_FREEING_INITMEM'
to immediately return NULL once init memory is freed.
- A spatial check using 'is_kernel_text()' and
'is_kernel_inittext()' to confirm the function resides in core
kernel text.
Since dynamically loaded modules reside in separately allocated
module memory outside these ranges, they bypass the table lookup
entirely. This makes the lookup lockless, race-free, and safe
from UAF vulnerabilities.
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
---
Changes since v3:
- Renamed the external function prototype and internal helper to
module_is_denylisted(), while updating the backing variable in
main.c to module_denylist. To preserve user-space compatibility
while adopting modern terminology, separate core_param entries have
been introduced, allowing both the preferred module_denylist=
parameter and the legacy module_blacklist= parameter to resolve to
the same underlying variable (Andrew Morton)
- I introduced the __initcall_fn_ptr() macro helper to dynamically
resolve the initcall pointer configuration:
- For architectures with relative 32-bit relocations
(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS=y), it resolves to the
relocation stub pointer __initcall_stub(fn, __iid, id)
- For architectures without PREL32 relocations, it resolves
directly to the function pointer fn
- Decoupled the module_denylist parameter parsing and the
module_is_denylisted() function from CONFIG_MODULES, moving the
logic to init/main.c. This ensures the denylist works for built-in
modules even on monolithic kernels built without loadable module
support (CONFIG_MODULES=n)
- Removed the conditional stub implementation of
module_is_denylisted() in module.h and replaced it with a single,
unconditional declaration outside of the #ifdef CONFIG_MODULES block.
This prevents compiler warnings about missing prototypes and ensures
visibility under a monolithic configuration
- Replaced the initmem_freed state variable and its synchronisation
logic in kernel_init() with race-free spatial boundary checks using
is_kernel_text() and is_kernel_inittext() in initcall_get_modname()
- Aligned the .initcall_modnames table with relocations by assigning
.initcall_fn using the __initcall_stub() helper in
___define_initcall(). This ensures the lookup matches the actual stub
pointer passed to do_one_initcall() when
CONFIG_HAVE_ARCH_PREL32_RELOCATIONS is enabled. Passed the preprocessor
__iid argument to ____define_initcall_modname once to avoid double
evaluation of __COUNTER__ (which caused build failures with LTO)
- Updated initcall_get_modname() in main.c to resolve the function
pointer fn using dereference_function_descriptor(fn) prior to
checking the .text and .init.text boundaries, and dereference both
fn and p->initcall_fn in the comparison loop to support descriptor-based
architectures (e.g., PPC64)
- Linked to v3: https://lore.kernel.org/lkml/20260706050337.7613-1-atomlin@atomlin.com/
Changes since v2:
- Avoided relative 32-bit offsets (PREL32) with inline assembly, opting
instead for standard C structures with absolute pointers. This fixes LTO
and CFI compatibility issues (e.g., under Clang) where raw inline assembly
fails to track compiler-generated symbols and CFI stubs
- Placed module name strings into the ".init.rodata" section via a dedicated
static array to ensure they are freed from memory after boot
- Avoided Use-After-Free (UAF) bugs post-boot when loading dynamic modules:
- Added an 'initmem_freed' flag, marked as '__ro_after_init', set after
free_initmem() to skip table lookups for dynamically loaded modules
- Added a blacklist check in do_init_module() for dynamic modules
- Simplified the linker script using the BOUNDED_SECTION_PRE_LABEL() macro
to define the ".initcall.modnames" section boundary
- Added a dummy/stub implementation of module_is_blacklisted() when
CONFIG_MODULES is disabled to avoid build errors
- Linked to v2: https://lore.kernel.org/lkml/20260622140259.2974-1-atomlin@atomlin.com/
Changes since v1:
- Pivoted entirely from exposing built-in initcalls and their blacklist
status via a debugfs interface to directly extending the existing
"module_blacklist=" and new "module_blacklist=" to intercept built-in
modules at boot (Petr Pavlu)
- Implemented 32-bit relative offsets (CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)
to store the mappings, preventing binary bloat and preserving KASLR
efficacy
- Linked to v1: https://lore.kernel.org/lkml/20260510061301.41341-1-atomlin@atomlin.com/
---
include/asm-generic/vmlinux.lds.h | 4 ++-
include/linux/init.h | 26 +++++++++++++--
include/linux/module.h | 2 ++
init/main.c | 53 +++++++++++++++++++++++++++++++
kernel/module/main.c | 24 ++------------
5 files changed, 84 insertions(+), 25 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 5659f4b5a125..fc863595743e 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -734,7 +734,9 @@
EARLYCON_TABLE() \
LSM_TABLE() \
EARLY_LSM_TABLE() \
- KUNIT_INIT_TABLE()
+ KUNIT_INIT_TABLE() \
+ . = ALIGN(8); \
+ BOUNDED_SECTION_PRE_LABEL(.initcall.modnames, initcall_modnames, __start_, __stop_)
#define INIT_TEXT \
*(.init.text .init.text.*) \
diff --git a/include/linux/init.h b/include/linux/init.h
index 40331923b9f4..9c78b6c30361 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -271,8 +271,30 @@ extern struct module __this_module;
__initcall_name(initcall, __iid, id), \
__initcall_section(__sec, __iid))
-#define ___define_initcall(fn, id, __sec) \
- __unique_initcall(fn, id, __sec, __initcall_id(fn))
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define __initcall_fn_ptr(fn, __iid, id) __initcall_stub(fn, __iid, id)
+#else
+#define __initcall_fn_ptr(fn, __iid, id) fn
+#endif
+
+struct initcall_modname {
+ initcall_t initcall_fn;
+ const char *modname;
+};
+
+#define ____define_initcall_modname(fn, id, __sec, __iid) \
+ __unique_initcall(fn, id, __sec, __iid) \
+ static const char __initstr_##fn[] __used __aligned(1) \
+ __section(".init.rodata") = KBUILD_MODNAME; \
+ static const struct initcall_modname __modname_##fn __used \
+ __section(".initcall.modnames") = { \
+ .initcall_fn = __initcall_fn_ptr(fn, __iid, id), \
+ .modname = __initstr_##fn \
+ };
+
+#define ___define_initcall(fn, id, __sec) \
+ ____define_initcall_modname(fn, id, __sec, __initcall_id(fn))
+
#define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
diff --git a/include/linux/module.h b/include/linux/module.h
index 7566815fabbe..bc2968c225e1 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -883,6 +883,8 @@ static inline void module_for_each_mod(int(*func)(struct module *mod, void *data
}
#endif /* CONFIG_MODULES */
+extern bool module_is_denylisted(const char *module_name);
+
#ifdef CONFIG_SYSFS
extern struct kset *module_kset;
extern const struct kobj_type module_ktype;
diff --git a/init/main.c b/init/main.c
index e363232b428b..af71811d24e3 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1334,12 +1334,65 @@ static inline void do_trace_initcall_level(const char *level)
}
#endif /* !TRACEPOINTS_ENABLED */
+extern struct initcall_modname __start_initcall_modnames[];
+extern struct initcall_modname __stop_initcall_modnames[];
+
+/* module_denylist is a comma-separated list of module names */
+static char *module_denylist;
+bool module_is_denylisted(const char *module_name)
+{
+ const char *p;
+ size_t len;
+
+ if (!module_denylist)
+ return false;
+
+ for (p = module_denylist; *p; p += len) {
+ len = strcspn(p, ",");
+ if (strlen(module_name) == len && !memcmp(module_name, p, len))
+ return true;
+ if (p[len] == ',')
+ len++;
+ }
+ return false;
+}
+core_param(module_denylist, module_denylist, charp, 0400);
+core_param(module_blacklist, module_denylist, charp, 0400);
+
+static const char *initcall_get_modname(initcall_t fn)
+{
+ struct initcall_modname *p;
+ unsigned long addr = (unsigned long)dereference_function_descriptor(fn);
+
+ if (system_state >= SYSTEM_FREEING_INITMEM)
+ return NULL;
+
+ if (!is_kernel_text(addr) &&
+ !is_kernel_inittext(addr))
+ return NULL;
+
+ for (p = __start_initcall_modnames; p < __stop_initcall_modnames; p++) {
+ if (dereference_function_descriptor(p->initcall_fn) ==
+ dereference_function_descriptor(fn))
+ return p->modname;
+ }
+ return NULL;
+}
+
int __init_or_module do_one_initcall(initcall_t fn)
{
int count = preempt_count();
char msgbuf[64];
+ const char *modname;
int ret;
+ modname = initcall_get_modname(fn);
+ if (modname && module_is_denylisted(modname)) {
+ pr_info("Skipping initcall for blacklisted built-in module %s\n",
+ modname);
+ return 0;
+ }
+
if (initcall_blacklisted(fn))
return -EPERM;
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 46dd8d25a605..e6d9c52b9786 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2919,26 +2919,6 @@ int __weak module_frob_arch_sections(Elf_Ehdr *hdr,
return 0;
}
-/* module_blacklist is a comma-separated list of module names */
-static char *module_blacklist;
-static bool blacklisted(const char *module_name)
-{
- const char *p;
- size_t len;
-
- if (!module_blacklist)
- return false;
-
- for (p = module_blacklist; *p; p += len) {
- len = strcspn(p, ",");
- if (strlen(module_name) == len && !memcmp(module_name, p, len))
- return true;
- if (p[len] == ',')
- len++;
- }
- return false;
-}
-core_param(module_blacklist, module_blacklist, charp, 0400);
static struct module *layout_and_allocate(struct load_info *info, int flags)
{
@@ -3389,9 +3369,9 @@ static int early_mod_check(struct load_info *info, int flags)
/*
* Now that we know we have the correct module name, check
- * if it's blacklisted.
+ * if it's denylisted.
*/
- if (blacklisted(info->name)) {
+ if (module_is_denylisted(info->name)) {
pr_err("Module %s is blacklisted\n", info->name);
return -EPERM;
}
--
2.54.0
^ permalink raw reply related
* Re: [PATCH] module: validate string table section types
From: sashiko-bot @ 2026-07-08 1:33 UTC (permalink / raw)
To: Thiébaud Weksteen; +Cc: linux-modules
In-Reply-To: <20260708012107.1621513-1-tweek@google.com>
Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
Pre-existing issues:
- [High] The patch fixes an out-of-bounds read vulnerability for string tables by ensuring they are of type SHT_STRTAB, but fails to address the exact same vulnerability class for several other ELF sections (e.g., .modinfo, .gnu.linkonce.this_module, __version_ext_names, __ksymtab).
- [High] Iterating over sections in lookup functions triggers an out-of-bounds string read for SHT_NULL sections due to missing sh_name bounds checking.
- [High] Validation logic for section headers accesses sechdrs[0] out of bounds if e_shnum is 0 and e_shoff is near the end of the file.
--
--- Patch [1]: [PATCH] module: validate string table section types ---
commit e8e815fedf365febe70f5870d807616d37946281
Author: Thiébaud Weksteen <tweek@google.com>
module: validate string table section types
In elf_validity_cache_sechdrs, section sizes and offsets are validated,
unless the section type is SHT_NULL or SHT_NOBITS.
Later, elf_validity_cache_secstrings and elf_validity_cache_index_str
access the section name table (.shstrtab) and symbol string table
(.strtab) headers without first ensuring that their types are
SHT_STRTAB. If a section type is SHT_NULL or SHT_NOBITS, sh_offset has
not been validated and may reference out-of-bounds memory when
dereferenced in elf_validity_cache_secstrings or
elf_validity_cache_strtab.
Validate that both string section headers are of type SHT_STRTAB before
caching them.
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 46dd8d25a6058..7cbc8f0e28c61 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2011,6 +2011,7 @@ static int elf_validity_cache_sechdrs(struct load_info *info)
[Severity: High]
This is a pre-existing issue, but does the validation logic in
elf_validity_cache_sechdrs() access sechdrs out of bounds if e_shnum is 0
and e_shoff is near the end of the file?
The overflow check evaluates to 0 > positive if e_shnum is 0 and e_shoff is
less than info->len, allowing the check to incorrectly pass:
elf_validity_cache_sechdrs() {
...
if (info->hdr->e_shoff >= info->len
|| (info->hdr->e_shnum * sizeof(Elf_Shdr) >
info->len - info->hdr->e_shoff)) {
...
}
The code then sets sechdrs and blindly accesses sechdrs[0], reading past the
end of the user-provided module buffer:
elf_validity_cache_sechdrs() {
...
if (sechdrs[0].sh_type != SHT_NULL
|| sechdrs[0].sh_size != 0
|| sechdrs[0].sh_addr != 0) {
...
}
> * Specifically checks:
> *
> * * Section name table index is inbounds of section headers
> + * * Section name table type is SHT_STRTAB
> * * Section name table is not empty
> * * Section name table is NUL terminated
[ ... ]
> @@ -2038,6 +2039,11 @@ static int elf_validity_cache_secstrings(struct load_info *info)
>
> strhdr = &info->sechdrs[info->hdr->e_shstrndx];
>
> + if (strhdr->sh_type != SHT_STRTAB) {
> + pr_err("Invalid ELF section name table type: %u\n", strhdr->sh_type);
> + return -ENOEXEC;
> + }
> +
[Severity: High]
This is a pre-existing issue, but does iterating over sections in lookup
functions trigger an out-of-bounds string read for SHT_NULL sections due to
missing sh_name bounds checking?
In elf_validity_cache_secstrings(), bounds validation of sh_name against the
string table size is explicitly skipped for SHT_NULL sections:
elf_validity_cache_secstrings() {
...
if (shdr->sh_type == SHT_NULL)
continue;
...
}
Later, section lookup functions like find_any_unique_sec() iterate over all
sections and blindly pass the unvalidated info->secstrings pointer to strcmp():
find_any_unique_sec() {
...
if (strcmp(info->secstrings + info->sechdrs[i].sh_name,
name) == 0) {
...
}
Could this cause an immediate out-of-bounds memory read when strcmp()
executes if an attacker sets a huge sh_name on a SHT_NULL section?
[ ... ]
> @@ -2218,6 +2224,12 @@ static int elf_validity_cache_index_str(struct load_info *info)
> return -ENOEXEC;
> }
>
> + if (info->sechdrs[str_idx].sh_type != SHT_STRTAB) {
> + pr_err("Invalid ELF symbol string table type: %u\n",
> + info->sechdrs[str_idx].sh_type);
> + return -ENOEXEC;
> + }
> +
[Severity: High]
This is a pre-existing issue, but while this patch fixes an out-of-bounds
read vulnerability for string tables by ensuring they are of type SHT_STRTAB,
does the same vulnerability class exist for other ELF sections?
Since elf_validity_cache_sechdrs() skips bounds checking of sh_offset and
sh_size for SHT_NULL and SHT_NOBITS sections, lookup functions can match
sections by name while ignoring sh_type.
For example, elf_validity_cache_index_info() looks up .modinfo by name and
caches it without validating its sh_type:
elf_validity_cache_index_info() {
...
info_idx = find_any_unique_sec(info, ".modinfo");
...
}
Similarly, in elf_validity_cache_index_mod(), the .gnu.linkonce.this_module
section rejects SHT_NOBITS but fails to reject SHT_NULL:
elf_validity_cache_index_mod() {
...
if (shdr->sh_type == SHT_NOBITS) {
...
}
And in move_module(), the loop skips SHT_NOBITS but calls memcpy for
SHT_NULL:
move_module() {
...
memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
...
}
Could a malicious module supply these sections with type SHT_NULL and an
arbitrary, unvalidated sh_offset, leading to out-of-bounds reads or copies?
> info->index.str = str_idx;
> return 0;
> }
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260708012107.1621513-1-tweek@google.com?part=1
^ permalink raw reply
* [PATCH] module: validate string table section types
From: Thiébaud Weksteen @ 2026-07-08 1:21 UTC (permalink / raw)
To: Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen
Cc: Thiébaud Weksteen, Aaron Tomlin, Siddharth Nayyar,
linux-modules, linux-kernel
In elf_validity_cache_sechdrs, section sizes and offsets are validated,
unless the section type is SHT_NULL or SHT_NOBITS.
Later, elf_validity_cache_secstrings and elf_validity_cache_index_str
access the section name table (.shstrtab) and symbol string table
(.strtab) headers without first ensuring that their types are
SHT_STRTAB. If a section type is SHT_NULL or SHT_NOBITS, sh_offset has
not been validated and may reference out-of-bounds memory when
dereferenced in elf_validity_cache_secstrings or
elf_validity_cache_strtab.
Validate that both string section headers are of type SHT_STRTAB before
caching them.
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
---
kernel/module/main.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 46dd8d25a605..7cbc8f0e28c6 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2011,6 +2011,7 @@ static int elf_validity_cache_sechdrs(struct load_info *info)
* Specifically checks:
*
* * Section name table index is inbounds of section headers
+ * * Section name table type is SHT_STRTAB
* * Section name table is not empty
* * Section name table is NUL terminated
* * All section name offsets are inbounds of the section
@@ -2038,6 +2039,11 @@ static int elf_validity_cache_secstrings(struct load_info *info)
strhdr = &info->sechdrs[info->hdr->e_shstrndx];
+ if (strhdr->sh_type != SHT_STRTAB) {
+ pr_err("Invalid ELF section name table type: %u\n", strhdr->sh_type);
+ return -ENOEXEC;
+ }
+
/*
* The section name table must be NUL-terminated, as required
* by the spec. This makes strcmp and pr_* calls that access
@@ -2204,7 +2210,7 @@ static int elf_validity_cache_index_sym(struct load_info *info)
* Must have &load_info->index.sym populated.
*
* Looks at the symbol table's associated string table, makes sure it is
- * in-bounds, and caches it.
+ * in-bounds and of type SHT_STRTAB, and caches it.
*
* Return: %0 if valid, %-ENOEXEC on failure.
*/
@@ -2218,6 +2224,12 @@ static int elf_validity_cache_index_str(struct load_info *info)
return -ENOEXEC;
}
+ if (info->sechdrs[str_idx].sh_type != SHT_STRTAB) {
+ pr_err("Invalid ELF symbol string table type: %u\n",
+ info->sechdrs[str_idx].sh_type);
+ return -ENOEXEC;
+ }
+
info->index.str = str_idx;
return 0;
}
--
2.55.0.795.g602f6c329a-goog
^ permalink raw reply related
* Re: [PATCH v3] module: Extend module_blacklist parameter to built-in modules
From: Aaron Tomlin @ 2026-07-07 19:38 UTC (permalink / raw)
To: arnd, mcgrof, petr.pavlu, da.gomez, samitolvanen, peterz
Cc: akpm, mhiramat, neelx, da.anzani, sean, chjohnst, steve, mproche,
nick.lane, linux-arch, linux-modules, linux-kernel
In-Reply-To: <20260706050337.7613-1-atomlin@atomlin.com>
On Mon, Jul 06, 2026 at 01:03:37AM -0400, Aaron Tomlin wrote:
> Currently, the "module_blacklist=" command-line parameter only applies to
> loadable modules. If a module is built-in, the parameter is silently
> ignored. This patch extends the blacklisting functionality to built-in
> modules by intercepting their initialization routines during early boot.
>
> To achieve this, we introduce a new ".initcall.modnames" memory section.
> For each built-in module, we use a standard C structure (i.e., struct
> initcall_modname) to map its initcall function pointer to its associated
> KBUILD_MODNAME string.
>
> During boot, do_one_initcall() cross-references the initcall function
> pointer against this table. If a match is found and the module is
> present in the blacklist, the initcall is skipped.
Hi Arnd, Luis, Petr, Daniel, Sami,
Please ignore. I will send a v4.
Sashiko [1] correctly reported further issues (e.g., CONFIG_MODULES=n)
which have been addressed as follows:
- Decoupled the module_blacklist parameter parsing and the
module_is_blacklisted() function from CONFIG_MODULES, moving the
logic to init/main.c. This ensures the blacklist works for built-in
modules even on monolithic kernels built without loadable module
support (CONFIG_MODULES=n)
- Removed the conditional stub implementation of
module_is_blacklisted() in module.h and replaced it with a single,
unconditional declaration outside of the #ifdef CONFIG_MODULES block.
This prevents compiler warnings about missing prototypes and ensures
visibility under a monolithic configuration
- Replaced the initmem_freed state variable and its synchronisation
logic in kernel_init() with race-free spatial boundary checks using
is_kernel_text() and is_kernel_inittext() in initcall_get_modname() .
- Aligned the .initcall_modnames table with relocations by assigning
.initcall_fn using the __initcall_stub() helper in
___define_initcall(). This ensures the lookup matches the actual stub
pointer passed to do_one_initcall() when
CONFIG_HAVE_ARCH_PREL32_RELOCATIONS is enabled
- Updated initcall_get_modname() in main.c to resolve the function
pointer fn using dereference_function_descriptor(fn) prior to
checking the .text and .init.text boundaries
[1]: https://sashiko.dev/#/patchset/20260706050337.7613-1-atomlin%40atomlin.com
--
Aaron Tomlin
^ permalink raw reply
* Re: [PATCH net v2] ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF
From: Paul E. McKenney @ 2026-07-07 16:39 UTC (permalink / raw)
To: Petr Pavlu
Cc: Sebastian Andrzej Siewior, Qingfang Deng, Breno Leitao,
Norbert Szetei, Andrew Lunn, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Taegu Ha, Kees Cook, linux-ppp,
linux-kernel, Guillaume Nault, netdev, Luis Chamberlain,
Daniel Gomez, Sami Tolvanen, Aaron Tomlin, linux-modules
In-Reply-To: <0dfe59c2-bf60-40fe-90e6-d6e1003709d0@suse.com>
On Tue, Jul 07, 2026 at 05:32:10PM +0200, Petr Pavlu wrote:
> On 7/6/26 11:29 AM, Sebastian Andrzej Siewior wrote:
> > + MODULE maintainer
>
> + Paul E. McKenney
>
> >
> > On 2026-07-05 10:57:44 [+0800], Qingfang Deng wrote:
> >> On 7/4/2026 at 12:32 AM, Breno Leitao wrote:
> >>> On Fri, Jul 03, 2026 at 03:27:00PM +0800, Qingfang Deng wrote:
> >>>> AI-review found an issue: https://sashiko.dev/#/patchset/D9C0245B-608B-4884-8A09-F55BA4A9F948%40doyensec.com
> >>>>
> >>>> An rcu_barrier() call is needed at the end of ppp_cleanup().
> >>>
> >>> I was initially unclear why rcu_barrier() would be necessary on a kfree path,
> >>> but it appears to be required during module unload to ensure that
> >>> ppp_release_channel_free() completes before the module's struct rcu_head is
> >>> destroyed. Is that the correct understanding?
> >>
> >> It's required to ensure that all ppp_release_channel_free() callback
> >> complete before the text segment of the module is unloaded.
> >
> > So either a rcu_barrier() in ppp's module_exit() callback or a
> > synchronize_rcu() instead of the call_rcu(). And all this because the
> > module RCU callbacks pending which can be invoked after the module has
> > been removed. There is a synchronize_rcu() during module exit but this
> > is after the module code is gone.
> >
> > I'm curious how many modules have a call_rcu() within their code but
> > don't have anything to enforce its completion before module removal is
> > complete? Wouldn't something like
> >
> >
> > diff --git a/kernel/module/main.c b/kernel/module/main.c
> > index 46dd8d25a6058..8eae1ea2d6eb4 100644
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -858,6 +858,9 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
> > goto out;
> >
> > mutex_unlock(&module_mutex);
> > +
> > + /* Ensure all rcu callbacks issued by the module have completed */
> > + rcu_barrier();
> > /* Final destruction now no one is using it. */
> > if (mod->exit != NULL)
> > mod->exit();
> >
> > make sense?
There was some discussion of doing exactly this back in the day, but
at that time there were many modules that didn't do call_rcu() at all,
let alone call_rcu() with a function defined in that module. And yes,
there were performance concerns.
Now rcu_barrier() has seen some performance work in the meantime, but
careful benchmarking would be required to justify the above patch.
That said, some automation would be very good, given that this sort of
bug happens from time to time.
> This is discussed in Documentation/RCU/rcubarrier.rst and
> Documentation/RCU/Design/Requirements/Requirements.rst. The latter
> contains:
>
> | Loadable Modules
> | ~~~~~~~~~~~~~~~~
> |
> | The Linux kernel has loadable modules, and these modules can also be
> | unloaded. After a given module has been unloaded, any attempt to call
> | one of its functions results in a segmentation fault. The module-unload
> | functions must therefore cancel any delayed calls to loadable-module
> | functions, for example, any outstanding mod_timer() must be dealt
> | with via timer_shutdown_sync() or similar.
> |
> | Unfortunately, there is no way to cancel an RCU callback; once you
> | invoke call_rcu(), the callback function is eventually going to be
> | invoked, unless the system goes down first. Because it is normally
> | considered socially irresponsible to crash the system in response to a
> | module unload request, we need some other way to deal with in-flight RCU
> | callbacks.
> |
> | RCU therefore provides rcu_barrier(), which waits until all
> | in-flight RCU callbacks have been invoked. If a module uses
> | call_rcu(), its exit function should therefore prevent any future
> | invocation of call_rcu(), then invoke rcu_barrier(). In theory,
> | the underlying module-unload code could invoke rcu_barrier()
> | unconditionally, but in practice this would incur unacceptable
> | latencies.
>
> I don't know if the last part about unacceptable latencies is still
> relevant. I haven't done any measurements myself.
Actual measurements would most definitely be needed!
Alternatives include:
o Provide a patch like that above, but only execute the
rcu_barrier() in some debug mode. If your code works when
that debug is enabled but does not otherwise, you add the
rcu_barrier().
o If debug is enabled, make rcu_do_batch() check the function
before invoking it. If the function is not mapped, issue a
diagnostic, and don't try to invoke the function. (But is
there a sufficiently cheap way to check for the function not
being mapped?)
o Make the page-fault code check this possibility. (But it would
need to know that rcu_do_batch() was involved, which could no
doubt be arranged.)
o Make call_rcu() keep track of the fact that it was passed a
function defined in a module, and set a flag that caused the
module-exit code for that module to do rcu_barrier(). The
trick here would be doing this without unacceptable increases
to call_rcu() overheads.
o Some sort of static analysis that determines that call_rcu()
was passed a function defined in a module and either issues
needed diagnostics or (somehow) letting the module-unload
code know that rcu_barrier() is needed.
o One challenge for many of these alternatives is that the module is
already gone. Maybe a KASAN-like trick that tracks the module's
old memory for some time afterwards? Or maybe the user usually
knows which module was just now unloaded? (Except for modules
being dependent on each other...)
o Your ideas here!!!
Thanx, Paul
^ permalink raw reply
* Re: [PATCH 3/4] tpm_crb_ffa: Include linux/slab.h for kzalloc_obj() and kfree()
From: sashiko-bot @ 2026-07-07 15:43 UTC (permalink / raw)
To: Petr Pavlu
Cc: kvm, Heiko Carstens, linux-modules, Alexander Gordeev, linux-s390,
Vasily Gorbik
In-Reply-To: <20260707153819.4172541-4-petr.pavlu@suse.com>
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The commit message incorrectly claims that the file uses `kzalloc_obj()` instead of `kzalloc()`.
--
--- Patch [3]: [PATCH 3/4] tpm_crb_ffa: Include linux/slab.h for kzalloc_obj() and kfree() ---
commit a56e4cf89267d12126bd70f7981a05c846959016
Author: Petr Pavlu <petr.pavlu@suse.com>
tpm_crb_ffa: Include linux/slab.h for kzalloc_obj() and kfree()
This commit adds the missing linux/slab.h inclusion to tpm_crb_ffa.c.
It removes the reliance on indirect inclusion through linux/module.h.
This prepares for the eventual removal of linux/elf.h from linux/module.h.
> tpm_crb_ffa: Include linux/slab.h for kzalloc_obj() and kfree()
[Severity: Low]
This isn't a bug, but there appears to be a typo in the commit subject.
Did you mean kzalloc() instead of kzalloc_obj()? Looking at
tpm_crb_ffa_probe() in the driver, it correctly calls kzalloc().
> The drivers/char/tpm/tpm_crb_ffa.c file uses kzalloc_obj() and kfree(),
[Severity: Low]
This isn't a bug, but the same typo is also present here in the commit
description.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260707153819.4172541-1-petr.pavlu@suse.com?part=3
^ permalink raw reply
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