[PATCH v4 18/25] dyndbg: Upgrade class param storage to u64 for 64-bit classmaps
From: Jim Cromie
Date: Tue Jun 02 2026 - 18:55:40 EST
Currently, `struct ddebug_class_param` uses `unsigned long` pointers
to store the state of `bits` and `lvl`. On 32-bit architectures, this
limits the bit-vector to 32 bits, which truncates 64-bit classmaps
(such as the one needed by `__drm_debug`).
To guarantee support for 64-bit debug categories across all
architectures, upgrade the internal storage types in `struct
_ddebug_class_param` to `u64`. This inherently makes both union
members the same size while safely avoiding truncation.
This includes:
- Changing union members `bits` and `lvl` to `u64 *`.
- Using `kstrtou64()` for sysfs input parsing.
- Replacing array-based `test_bit()` operations with safe `u64` scalar
bitwise logic (`!!(val & (1ULL << bi))`).
- adjusting lib/test_dynamic_debug.c too
- Updating `drm_print`'s `__drm_debug` refs to `u64`
further changes to drm later, when BROKEN is fixed.
Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
v4: undo change struct ddebug_class_param to _ddebug_class_param
this is better done in next patch, with other normalization on _ddebug
v3:
fix undefd behavior when classmaps is all 64 bits.
change module_param_named( type-arg from ulong to ullong)
change struct ddebug_class_param to _ddebug_class_param
in drivers/gpu/drm/drm_print.{c,h}
api change later
v2:
patch was "make bits & lvl same size"
but that size was unsigned long, only 32 bits on i386 etc
use u64 for all bits, and %llu %llx
u64-fix
u64-drm-dbg
_ddebug-cl-parm-drm
---
drivers/gpu/drm/drm_print.c | 4 ++--
include/drm/drm_print.h | 2 +-
include/linux/dynamic_debug.h | 4 ++--
lib/dynamic_debug.c | 34 ++++++++++++++++++----------------
lib/test_dynamic_debug.c | 2 +-
5 files changed, 24 insertions(+), 22 deletions(-)
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index ded9461df5f2..3a470e808e39 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -40,7 +40,7 @@
* __drm_debug: Enable debug output.
* Bitmask of DRM_UT_x. See include/drm/drm_print.h for details.
*/
-unsigned long __drm_debug;
+u64 __drm_debug;
EXPORT_SYMBOL(__drm_debug);
MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
@@ -54,7 +54,7 @@ MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug cat
"\t\tBit 8 (0x100) will enable DP messages (displayport code)");
#if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
-module_param_named(debug, __drm_debug, ulong, 0600);
+module_param_named(debug, __drm_debug, ullong, 0600);
#else
/* classnames must match vals of enum drm_debug_category */
DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index ab017b05e175..21a0ced0b2f2 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -39,7 +39,7 @@ struct drm_device;
struct seq_file;
/* Do *not* use outside of drm_print.[ch]! */
-extern unsigned long __drm_debug;
+extern u64 __drm_debug;
/**
* DOC: print
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 0443781ed95b..91546a99014b 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -91,8 +91,8 @@ struct _ddebug_info {
struct ddebug_class_param {
union {
- unsigned long *bits;
- unsigned int *lvl;
+ u64 *bits;
+ u64 *lvl;
};
char flags[8];
const struct ddebug_class_map *map;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index a593e040d1ae..f164e11c1853 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -627,8 +627,7 @@ 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,
- const unsigned long *new_bits,
- const unsigned long old_bits,
+ const u64 *new_bits, const u64 old_bits,
const char *query_modname)
{
#define QUERY_SIZE 128
@@ -638,24 +637,27 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
int bi, ct;
if (*new_bits != old_bits)
- v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_bits,
+ v2pr_info("apply bitmap: 0x%llx to: 0x%llx 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))
+ bool new_b = !!(*new_bits & (1ULL << bi));
+ bool old_b = !!(old_bits & (1ULL << bi));
+
+ if (new_b == old_b)
continue;
snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_names[bi],
- test_bit(bi, new_bits) ? '+' : '-', dcp->flags);
+ new_b ? '+' : '-', dcp->flags);
ct = ddebug_exec_queries(query, query_modname);
matches += ct;
- v2pr_info("bit_%d: %d matches on class: %s -> 0x%lx\n", bi,
+ v2pr_info("bit_%d: %d matches on class: %s -> 0x%llx\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,
+ v2pr_info("applied bitmap: 0x%llx to: 0x%llx for %s\n", *new_bits,
old_bits, query_modname ?: "'*'");
return matches;
@@ -664,7 +666,7 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
/* stub to later conditionally add "$module." prefix where not already done */
#define KP_NAME(kp) kp->name
-#define CLASSMAP_BITMASK(width) ((1UL << (width)) - 1)
+#define CLASSMAP_BITMASK(width) ((width) == 64 ? ~0ULL : (1ULL << (width)) - 1)
/**
* param_set_dyndbg_classes - class FOO >control
@@ -684,10 +686,10 @@ static int param_set_dyndbg_module_classes(const char *instr,
{
const struct ddebug_class_param *dcp = kp->arg;
const struct ddebug_class_map *map = dcp->map;
- unsigned long inrep, new_bits, old_bits;
+ u64 inrep, new_bits, old_bits;
int rc, totct = 0;
- rc = kstrtoul(instr, 0, &inrep);
+ rc = kstrtou64(instr, 0, &inrep);
if (rc) {
int len = strcspn(instr, "\n");
pr_err("expecting numeric input, not: %.*s > %s\n",
@@ -699,24 +701,24 @@ static int param_set_dyndbg_module_classes(const char *instr,
case DD_CLASS_TYPE_DISJOINT_BITS:
/* expect bits. mask and warn if too many */
if (inrep & ~CLASSMAP_BITMASK(map->length)) {
- pr_warn("%s: input: 0x%lx exceeds mask: 0x%lx, masking\n",
+ pr_warn("%s: input: 0x%llx exceeds mask: 0x%llx, masking\n",
KP_NAME(kp), inrep, CLASSMAP_BITMASK(map->length));
inrep &= CLASSMAP_BITMASK(map->length);
}
- v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp));
+ v2pr_info("bits:0x%llx > %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:
/* input is bitpos, of highest verbosity to be enabled */
if (inrep > map->length) {
- pr_warn("%s: level:%ld exceeds max:%d, clamping\n",
+ pr_warn("%s: level:%llu exceeds max:%d, clamping\n",
KP_NAME(kp), inrep, map->length);
inrep = map->length;
}
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));
+ v2pr_info("lvl:%llu bits:0x%llx > %s\n", inrep, new_bits, KP_NAME(kp));
totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, mod_name);
*dcp->lvl = inrep;
break;
@@ -762,9 +764,9 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
switch (map->map_type) {
case DD_CLASS_TYPE_DISJOINT_BITS:
- return scnprintf(buffer, PAGE_SIZE, "0x%lx\n", *dcp->bits);
+ return scnprintf(buffer, PAGE_SIZE, "0x%llx\n", *dcp->bits);
case DD_CLASS_TYPE_LEVEL_NUM:
- return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl);
+ return scnprintf(buffer, PAGE_SIZE, "%llu\n", *dcp->lvl);
default:
return -1;
}
diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
index 74d183ebf3e0..c049580d2152 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c
@@ -40,7 +40,7 @@ module_param_cb(do_prints, ¶m_ops_do_prints, NULL, 0600);
* - tie together sysname, mapname, bitsname, flagsname
*/
#define DD_SYS_WRAP(_model, _flags) \
- static unsigned long bits_##_model; \
+ static u64 bits_##_model; \
static struct ddebug_class_param _flags##_model = { \
.bits = &bits_##_model, \
.flags = #_flags, \
--
2.54.0