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Message-ID: <20231012194711.3288031-3-jim.cromie@gmail.com>
Date: Thu, 12 Oct 2023 13:47:03 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: linux-kernel@...r.kernel.org
Cc: david@...hat.com, Liam.Howlett@...cle.com, linux-mm@...ck.org,
Jim Cromie <jim.cromie@...il.com>
Subject: [RFC PATCH 02/10] dyndbg: split __dyndbg_sites section out from __dyndbg
split struct _ddebug_site out from struct _ddebug (adding a site ptr),
and add new __dyndbg_sites section placement to vmlinux.lds.h
This is an implementation detail to isolate the redundant columns into
a separate section, so it specifically excludes lineno.
This allows (later) to copy and compress the info into a better (more
compact) representation thats still fast enough. Then we can just
reclaim the whole __dyndbg_sites section.
Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
include/asm-generic/vmlinux.lds.h | 1 +
include/linux/dynamic_debug.h | 40 ++++++++++++++++++-------------
kernel/module/main.c | 3 +++
lib/dynamic_debug.c | 6 +++++
4 files changed, 33 insertions(+), 17 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 5451f926a753..1d128259e373 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -368,6 +368,7 @@
BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) \
BOUNDED_SECTION_BY(__dyndbg_class_users, ___dyndbg_class_users) \
BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
+ BOUNDED_SECTION_BY(__dyndbg_sites, ___dyndbg_sites) \
LIKELY_PROFILE() \
BRANCH_PROFILE() \
TRACE_PRINTKS() \
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index aacfafc466c0..5206a2cfdb37 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -9,21 +9,25 @@
#include <linux/build_bug.h>
/*
- * An instance of this structure is created in a special
- * ELF section at every dynamic debug callsite. At runtime,
- * the special section is treated as an array of these.
+ * A pair of these structs are created into 2 special ELF sections for
+ * each pr_debug callsite. At runtime, the special sections are
+ * treated as arrays.
*/
-
-struct _ddebug {
+struct _ddebug;
+struct _ddebug_site {
/*
- * These fields are used to drive the user interface
- * for selecting and displaying debug callsites.
+ * These fields are used to:
+ * - display callsites in the control file
+ * - query/select callsites by the code's organization
+ * - prefix/decorate pr_debug messages per user choices
*/
- struct /* _ddebug_site */ {
- const char *_modname;
- const char *_function;
- const char *_filename;
- };
+ const char *_modname;
+ const char *_function;
+ const char *_filename;
+};
+
+struct _ddebug {
+ struct _ddebug_site *site;
const char *format;
unsigned int lineno:18;
#define CLS_BITS 6
@@ -64,10 +68,6 @@ struct _ddebug {
#endif
} __attribute__((aligned(8)));
-#define desc_modname(d) (d)->modname
-#define desc_filename(d) (d)->filename
-#define desc_function(d) (d)->function
-
enum ddebug_class_map_type {
DD_CLASS_TYPE_DISJOINT_BITS,
/**
@@ -139,9 +139,11 @@ struct ddebug_class_user {
/* encapsulate linker provided built-in (or module) dyndbg data */
struct _ddebug_info {
struct _ddebug *descs;
+ struct _ddebug_site *sites;
struct ddebug_class_map *classes;
struct ddebug_class_user *class_users;
unsigned int num_descs;
+ unsigned int num_sites;
unsigned int num_classes;
unsigned int num_class_users;
};
@@ -226,9 +228,13 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
._filename = __FILE__
#define DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, cls, fmt) \
+ static struct _ddebug_site __aligned(8) \
+ __section("__dyndbg_sites") name ##_site = { \
+ DYNAMIC_DEBUG_SITE_INIT(), \
+ }; \
static struct _ddebug __aligned(8) \
__section("__dyndbg") name = { \
- DYNAMIC_DEBUG_SITE_INIT(), \
+ .site = &(name ##_site), \
.format = (fmt), \
.lineno = __LINE__, \
.flags = _DPRINTK_FLAGS_DEFAULT, \
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 6b0b0d82b5ab..43458184744d 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2211,6 +2211,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
mod->dyndbg_info.descs = section_objs(info, "__dyndbg",
sizeof(*mod->dyndbg_info.descs),
&mod->dyndbg_info.num_descs);
+ mod->dyndbg_info.sites = section_objs(info, "__dyndbg_sites",
+ sizeof(*mod->dyndbg_info.sites),
+ &mod->dyndbg_info.num_sites);
mod->dyndbg_info.classes = section_objs(info, "__dyndbg_classes",
sizeof(*mod->dyndbg_info.classes),
&mod->dyndbg_info.num_classes);
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c0e595483cb9..0ad9f1bc00f0 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -41,6 +41,8 @@
extern struct _ddebug __start___dyndbg[];
extern struct _ddebug __stop___dyndbg[];
+extern struct _ddebug_site __start___dyndbg_sites[];
+extern struct _ddebug_site __stop___dyndbg_sites[];
extern struct ddebug_class_map __start___dyndbg_classes[];
extern struct ddebug_class_map __stop___dyndbg_classes[];
extern struct ddebug_class_user __start___dyndbg_class_users[];
@@ -191,6 +193,10 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
return NULL;
}
+#define desc_modname(d) (d)->site->_modname
+#define desc_filename(d) (d)->site->_filename
+#define desc_function(d) (d)->site->_function
+
/*
* Search the tables for _ddebug's which match the given `query' and
* apply the `flags' and `mask' to them. Returns number of matching
--
2.41.0
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