[v6,44/57] dyndbg: extend __ddebug_add_module proto to allow packing sites

Commit Message

Jim Cromie Sept. 4, 2022, 9:41 p.m. UTC

In order to actually reclaim useful blocks of memory, we need to
repack the vector of redundant site recs, not just detect the
duplicates.  To allow this, extend __ddebug_add_module()s prototype by
adding:

   struct _ddebug_site *packed_sites - address of empty "stack"
   unsigned int *packed_base - index of Top-of-Stack

This allows dynamic_debug_init() to tell __ddebug_add_module() where
to push the unique site recs it finds while de-duplicating, and to
communicate the new TOS back for the next iteration.

Since we know we are shrinking data, we can overwrite _ddebug_sites[],
for both builtins, and loadable modules, via ddebug_add_module().

For ddebug_add_module(), which is called from kernel/module/main, the
2 args: reuse the module.sites vector, with a 0 offset.  This will
allow de-duplication of the local vector.

No de-duplication is done yet, so no use of the stack.

Signed-off-by: Jim Cromie <[e-mail]>
---
 lib/dynamic_debug.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

Patch

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 506a7e2e59d6..1b57e43e9c31 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -1341,7 +1341,8 @@  static void ddebug_attach_module_classes(struct ddebug_table *dt,
  * and add it to the global list.
  */
 static int __ddebug_add_module(struct _ddebug_info *di, unsigned int base,
-			       const char *modname)
+			       const char *modname, struct _ddebug_site *packed_sites,
+			       unsigned int *packed_base)
 {
 	struct ddebug_table *dt;
 	int i;
@@ -1390,7 +1391,8 @@  static int __ddebug_add_module(struct _ddebug_info *di, unsigned int base,
 
 int ddebug_add_module(struct _ddebug_info *di, const char *modname)
 {
-	return __ddebug_add_module(di, 0, modname);
+	unsigned int packed_base = 0;
+	return __ddebug_add_module(di, 0, modname, di->sites, &packed_base);
 }
 
 /* helper for ddebug_dyndbg_(boot|module)_param_cb */
@@ -1506,7 +1508,7 @@  static int __init dynamic_debug_init(void)
 {
 	struct _ddebug *iter, *iter_mod_start;
 	struct _ddebug_site *site, *site_mod_start;
-	int ret, i, mod_sites, mod_ct;
+	int ret, i, mod_sites, mod_ct, site_base;
 	const char *modname;
 	char *cmdline;
 
@@ -1550,7 +1552,8 @@  static int __init dynamic_debug_init(void)
 			di.num_descs = mod_sites;
 			di.descs = iter_mod_start;
 			di.sites = site_mod_start;
-			ret = __ddebug_add_module(&di, i - mod_sites, modname);
+			ret = __ddebug_add_module(&di, i - mod_sites, modname,
+						  __start___dyndbg_sites, &site_base);
 			if (ret)
 				goto out_err;
 
@@ -1563,11 +1566,13 @@  static int __init dynamic_debug_init(void)
 	di.num_descs = mod_sites;
 	di.descs = iter_mod_start;
 	di.sites = site_mod_start;
-	ret = __ddebug_add_module(&di, i - mod_sites, modname);
+	ret = __ddebug_add_module(&di, i - mod_sites, modname,
+				  __start___dyndbg_sites, &site_base);
 	if (ret)
 		goto out_err;
 
 	ddebug_init_success = 1;
+
 	vpr_info("%d prdebugs in %d modules, %d KiB in ddebug tables, %d kiB in __dyndbg section\n",
 		 i, mod_ct, (int)((mod_ct * sizeof(struct ddebug_table)) >> 10),
 		 (int)((i * sizeof(struct _ddebug)) >> 10));