[PATCH v7c 11/24] dyndbg: tighten fn-sig of ddebug_apply_class_bitmap

Jim Cromie
2023-10-18T17:07:04Z

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>
---
lib/dynamic_debug.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8158943b350d..8beb98a831f5 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -593,7 +593,8 @@ 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
@@ -602,12 +603,12 @@ 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],
@@ -619,9 +620,9 @@ 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;
}
@@ -678,7 +679,7 @@ static int param_set_dyndbg_classnames(const char *instr, const struct kernel_pa
continue;
}
curr_bits ^= BIT(cls_id);
- totct += ddebug_apply_class_bitmap(dcp, &curr_bits, dcp->bits, NULL);
+ totct += ddebug_apply_class_bitmap(dcp, &curr_bits, *dcp->bits, NULL);
*dcp->bits = curr_bits;
v2pr_info("%s: changed bit %d:%s\n", KP_NAME(kp), cls_id,
map->class_names[cls_id]);
@@ -688,7 +689,7 @@ static int param_set_dyndbg_classnames(const char *instr, const struct kernel_pa
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, NULL);
+ totct += ddebug_apply_class_bitmap(dcp, &curr_bits, old_bits, NULL);
*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);
@@ -742,7 +743,7 @@ static int param_set_dyndbg_module_classes(const char *instr,
inrep &= CLASSMAP_BITMASK(map->length);
}
v2pr_info("bits:0x%lx > %s.%s\n", inrep, modnm ?: "*", KP_NAME(kp));
- totct += ddebug_apply_class_bitmap(dcp, &inrep, dcp->bits, modnm);
+ totct += ddebug_apply_class_bitmap(dcp, &inrep, *dcp->bits, modnm);
*dcp->bits = inrep;
break;
case DD_CLASS_TYPE_LEVEL_NUM:
@@ -755,7 +756,7 @@ 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, modnm);
+ totct += ddebug_apply_class_bitmap(dcp, &new_bits, old_bits, modnm);
*dcp->lvl = inrep;
break;
default:
--
2.41.0