[PATCH v8 23/43] dyndbg: reduce class param storage to u32

[Jim Cromie via B4 Relay <devnull+jim.cromie.gmail.com@kernel.org>]

From: Jim Cromie <jim.cromie@gmail.com>

Currently, `struct ddebug_class_param` uses pointers to `unsigned
long` values which store the state of `bits` and `lvl`, so it changes
sizes depending upon the architecture.  Make it always u32 for
consistency.

The bits field references __drm_debug, which was unsigned int, before
commit f158936b60a7 ("drm: POC drm on dyndbg - use in core, 2 helpers, 3 drivers.")
changed it to unsigned long.  This patch changes it back.

That enlargement was a thinko; although modules can have up to 63
classes, and *could* have put all those classes in a single classmap,
the reason for it is to support multiple classmaps (with
non-overlapping class-id ranges).

32 bits is a practical limit for a class-param's usability since all
classes are set together with a single write of a hex value; 16 would
be a realistic limit, drm.debug has ~12 classes.

  #> echo 0x0fff > /sys/module/drm/parameters/debug

Several followon patches add a number of compile-time validations,
including a num-classes <=32 check.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
v8: add a <32 limit to prevent undefined shifts on 32 bit number
v5: u32 for all arches
v4: undo change struct ddebug_class_param to _ddebug_class_param

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
---
 drivers/gpu/drm/drm_print.c   |  4 ++--
 include/drm/drm_print.h       |  2 +-
 include/linux/dynamic_debug.h |  4 ++--
 lib/dynamic_debug.c           | 37 ++++++++++++++++++++-----------------
 lib/test_dynamic_debug.c      |  2 +-
 5 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index e5b900640300..68671d93b986 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;
+u32 __drm_debug;
 EXPORT_SYMBOL(__drm_debug);
 
 MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n"
@@ -56,7 +56,7 @@ MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug cat
 "\t\tBit 9 (0x200) will enable DRMRES messages (managed resources code)");
 
 #if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
-module_param_named(debug, __drm_debug, ulong, 0600);
+module_param_named(debug, __drm_debug, uint, 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 2adc5ac688e1..50b3ba0ae76d 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 u32 __drm_debug;
 
 /**
  * DOC: print
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index bc20dc640b22..9e5668b5c644 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -107,8 +107,8 @@ struct _ddebug_info {
 
 struct ddebug_class_param {
 	union {
-		unsigned long *bits;
-		unsigned int *lvl;
+		u32 *bits;
+		u32 *lvl;
 	};
 	char flags[8];
 	const struct ddebug_class_map *map;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 2cbac60569c7..1196667f95e1 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -585,6 +585,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
 		pr_err("query parse failed\n");
 		return -EINVAL;
 	}
+
 	/* actually go and implement the change */
 	nfound = ddebug_change(&query, &modifiers);
 	v3pr_info_dq(&query, nfound ? "applied" : "no-match");
@@ -635,8 +636,7 @@ 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 u32 *new_bits, const u32 old_bits,
 				     const char *query_modname)
 {
 #define QUERY_SIZE 128
@@ -646,24 +646,27 @@ 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%x to: 0x%x 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))
+	for (bi = 0; bi < map->length && bi < 32; bi++) {
+		bool new_b = !!(*new_bits & BIT(bi));
+		bool old_b = !!(old_bits & BIT(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%x\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%x to: 0x%x for %s\n", *new_bits,
 			  old_bits, query_modname ?: "'*'");
 
 	return matches;
@@ -672,7 +675,7 @@ 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) >= 32 ? ~0U : (1U << (width)) - 1)
 
 /*
  * param-setter helper to validate numeric input, clamp its value by
@@ -684,10 +687,10 @@ 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, old_val;
+	u32 inrep, new_bits, old_bits, old_val;
 	int rc, totct = 0;
 
-	rc = kstrtoul(instr, 0, &inrep);
+	rc = kstrtou32(instr, 0, &inrep);
 	if (rc) {
 		int len = strcspn(instr, "\n");
 
@@ -700,26 +703,26 @@ 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%x exceeds mask: 0x%x, masking\n",
 				KP_NAME(kp), inrep, CLASSMAP_BITMASK(map->length));
 			inrep &= CLASSMAP_BITMASK(map->length);
 		}
 		old_val = READ_ONCE(*dcp->bits);
-		v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp));
+		v2pr_info("bits:0x%x > %s.%s\n", inrep, mod_name ?: "*", KP_NAME(kp));
 		totct += ddebug_apply_class_bitmap(dcp, &inrep, old_val, mod_name);
 		WRITE_ONCE(*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:%u exceeds max:%d, clamping\n",
 				KP_NAME(kp), inrep, map->length);
 			inrep = map->length;
 		}
 		old_val = READ_ONCE(*dcp->lvl);
 		old_bits = CLASSMAP_BITMASK(old_val);
 		new_bits = CLASSMAP_BITMASK(inrep);
-		v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, KP_NAME(kp));
+		v2pr_info("lvl:%u bits:0x%x > %s\n", inrep, new_bits, KP_NAME(kp));
 		totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, mod_name);
 		WRITE_ONCE(*dcp->lvl, inrep);
 		break;
@@ -765,9 +768,9 @@ 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%x\n", *dcp->bits);
 	case DD_CLASS_TYPE_LEVEL_NUM:
-		return scnprintf(buffer, PAGE_SIZE, "%d\n", *dcp->lvl);
+		return scnprintf(buffer, PAGE_SIZE, "%u\n", *dcp->lvl);
 	default:
 		return -1;
 	}
diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
index 74d183ebf3e0..9e8e028461ad 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c
@@ -40,7 +40,7 @@ module_param_cb(do_prints, &param_ops_do_prints, NULL, 0600);
  * - tie together sysname, mapname, bitsname, flagsname
  */
 #define DD_SYS_WRAP(_model, _flags)					\
-	static unsigned long bits_##_model;				\
+	static u32 bits_##_model;					\
 	static struct ddebug_class_param _flags##_model = {		\
 		.bits = &bits_##_model,					\
 		.flags = #_flags,					\

-- 
2.55.0