[Intel-gfx] [PATCH v6 11/57] dyndbg: gather __dyndbg[] state into struct _ddebug_info

Jim Cromie
2022-09-04T21:44:42Z

This new struct composes the linker provided (vector,len) section,
and provides a place to add other __dyndbg[] state-data later:

descs - the vector of descriptors in __dyndbg section.
num_descs - length of the data/section.

Use it, in several different ways, as follows:

In lib/dynamic_debug.c:

ddebug_add_module(): Alter params-list, replacing 2 args (array,index)
with a struct _ddebug_info * containing them both, with room for
expansion. This helps future-proof the function prototype against the
looming addition of class-map info into the dyndbg-state, by providing
a place to add more member fields later.

NB: later add static struct _ddebug_info builtins_state declaration,
not needed yet.

ddebug_add_module() is called in 2 contexts:

In dynamic_debug_init(), declare, init a struct _ddebug_info di
auto-var to use as a cursor. Then iterate over the prdbg blocks of
the builtin modules, and update the di cursor before calling
_add_module for each.

Its called from kernel/module/main.c:load_info() for each loaded
module:

In internal.h, alter struct load_info, replacing the dyndbg array,len
fields with an embedded _ddebug_info containing them both; and
populate its members in find_module_sections().

The 2 calling contexts differ in that _init deals with contiguous
subranges of __dyndbgs[] section, packed together, while loadable
modules are added one at a time.

So rename ddebug_add_module() into outer/__inner fns, call __inner
from _init, and provide the offset into the builtin __dyndbgs[] where
the module's prdbgs reside. The cursor provides start, len of the
subrange for each. The offset will be used later to pack the results
of builtin __dyndbg_sites[] de-duplication, and is 0 and unneeded for
loadable modules,

Note:

kernel/module/main.c includes <dynamic_debug.h> for struct
_ddeubg_info. This might be prone to include loops, since its also
included by printk.h. Nothing has broken in robot-land on this.

cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/linux/dynamic_debug.h | 13 +++++++-----
kernel/module/internal.h | 4 ++--
kernel/module/main.c | 18 ++++++++--------
lib/dynamic_debug.c | 40 +++++++++++++++++++++++++++--------
4 files changed, 50 insertions(+), 25 deletions(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 8d9eec5f6d8b..6a2001250da1 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -51,12 +51,16 @@ struct _ddebug {
#endif
} __attribute__((aligned(8)));

-
+/* encapsulate linker provided built-in (or module) dyndbg data */
+struct _ddebug_info {
+ struct _ddebug *descs;
+ unsigned int num_descs;
+};

#if defined(CONFIG_DYNAMIC_DEBUG_CORE)

-int ddebug_add_module(struct _ddebug *tab, unsigned int n,
- const char *modname);
+int ddebug_add_module(struct _ddebug_info *dyndbg, const char *modname);
+
extern int ddebug_remove_module(const char *mod_name);
extern __printf(2, 3)
void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...);
@@ -184,8 +188,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
#include <linux/errno.h>
#include <linux/printk.h>

-static inline int ddebug_add_module(struct _ddebug *tab, unsigned int n,
- const char *modname)
+static inline int ddebug_add_module(struct _ddebug_info *dinfo, const char *modname)
{
return 0;
}
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 680d980a4fb2..2e2bf236f558 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -53,6 +53,7 @@ extern const struct kernel_symbol __stop___ksymtab_gpl[];
extern const s32 __start___kcrctab[];
extern const s32 __start___kcrctab_gpl[];

+#include <linux/dynamic_debug.h>
struct load_info {
const char *name;
/* pointer to module in temporary copy, freed at end of load_module() */
@@ -62,8 +63,7 @@ struct load_info {
Elf_Shdr *sechdrs;
char *secstrings, *strtab;
unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs;
- struct _ddebug *debug;
- unsigned int num_debug;
+ struct _ddebug_info dyndbg;
bool sig_ok;
#ifdef CONFIG_KALLSYMS
unsigned long mod_kallsyms_init_off;
diff --git a/kernel/module/main.c b/kernel/module/main.c
index a4e4d84b6f4e..4c20bc3ff203 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1598,16 +1598,16 @@ static void free_modinfo(struct module *mod)
}
}

-static void dynamic_debug_setup(struct module *mod, struct _ddebug *debug, unsigned int num)
+static void dynamic_debug_setup(struct module *mod, struct _ddebug_info *dyndbg)
{
- if (!debug)
+ if (!dyndbg->num_descs)
return;
- ddebug_add_module(debug, num, mod->name);
+ ddebug_add_module(dyndbg, mod->name);
}

-static void dynamic_debug_remove(struct module *mod, struct _ddebug *debug)
+static void dynamic_debug_remove(struct module *mod, struct _ddebug_info *dyndbg)
{
- if (debug)
+ if (dyndbg->num_descs)
ddebug_remove_module(mod->name);
}

@@ -2111,8 +2111,8 @@ static int find_module_sections(struct module *mod, struct load_info *info)
if (section_addr(info, "__obsparm"))
pr_warn("%s: Ignoring obsolete parameters\n", mod->name);

- info->debug = section_objs(info, "__dyndbg",
- sizeof(*info->debug), &info->num_debug);
+ info->dyndbg.descs = section_objs(info, "__dyndbg",
+ sizeof(*info->dyndbg.descs), &info->dyndbg.num_descs);

return 0;
}
@@ -2807,7 +2807,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
}

init_build_id(mod, info);
- dynamic_debug_setup(mod, info->debug, info->num_debug);
+ dynamic_debug_setup(mod, &info->dyndbg);

/* Ftrace init must be called in the MODULE_STATE_UNFORMED state */
ftrace_module_init(mod);
@@ -2871,7 +2871,7 @@ static int load_module(struct load_info *info, const char __user *uargs,

ddebug_cleanup:
ftrace_release_mod(mod);
- dynamic_debug_remove(mod, info->debug);
+ dynamic_debug_remove(mod, &info->dyndbg);
synchronize_rcu();
kfree(mod->args);
free_arch_cleanup:
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 2e8ebef3bd0d..c358ccdf4a39 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -923,14 +923,20 @@ static const struct proc_ops proc_fops = {
* Allocate a new ddebug_table for the given module
* and add it to the global list.
*/
-int ddebug_add_module(struct _ddebug *tab, unsigned int n,
- const char *name)
+static int __ddebug_add_module(struct _ddebug_info *di, unsigned int base,
+ const char *modname)
{
struct ddebug_table *dt;

+ v3pr_info("add-module: %s.%d sites\n", modname, di->num_descs);
+ if (!di->num_descs) {
+ v3pr_info(" skip %s\n", modname);
+ return 0;
+ }
+
dt = kzalloc(sizeof(*dt), GFP_KERNEL);
if (dt == NULL) {
- pr_err("error adding module: %s\n", name);
+ pr_err("error adding module: %s\n", modname);
return -ENOMEM;
}
/*
@@ -939,18 +945,25 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
* member of struct module, which lives at least as long as
* this struct ddebug_table.
*/
- dt->mod_name = name;
- dt->num_ddebugs = n;
- dt->ddebugs = tab;
+ dt->mod_name = modname;
+ dt->ddebugs = di->descs;
+ dt->num_ddebugs = di->num_descs;
+
+ INIT_LIST_HEAD(&dt->link);

mutex_lock(&ddebug_lock);
list_add_tail(&dt->link, &ddebug_tables);
mutex_unlock(&ddebug_lock);

- vpr_info("%3u debug prints in module %s\n", n, dt->mod_name);
+ vpr_info("%3u debug prints in module %s\n", di->num_descs, modname);
return 0;
}

+int ddebug_add_module(struct _ddebug_info *di, const char *modname)
+{
+ return __ddebug_add_module(di, 0, modname);
+}
+
/* helper for ddebug_dyndbg_(boot|module)_param_cb */
static int ddebug_dyndbg_param_cb(char *param, char *val,
const char *modname, int on_err)
@@ -1064,6 +1077,11 @@ static int __init dynamic_debug_init(void)
const char *modname;
char *cmdline;

+ struct _ddebug_info di = {
+ .descs = __start___dyndbg,
+ .num_descs = __stop___dyndbg - __start___dyndbg,
+ };
+
if (&__start___dyndbg == &__stop___dyndbg) {
if (IS_ENABLED(CONFIG_DYNAMIC_DEBUG)) {
pr_warn("_ddebug table is empty in a CONFIG_DYNAMIC_DEBUG build\n");
@@ -1082,7 +1100,9 @@ static int __init dynamic_debug_init(void)

if (strcmp(modname, iter->modname)) {
mod_ct++;
- ret = ddebug_add_module(iter_mod_start, mod_sites, modname);
+ di.num_descs = mod_sites;
+ di.descs = iter_mod_start;
+ ret = __ddebug_add_module(&di, i - mod_sites, modname);
if (ret)
goto out_err;

@@ -1091,7 +1111,9 @@ static int __init dynamic_debug_init(void)
iter_mod_start = iter;
}
}
- ret = ddebug_add_module(iter_mod_start, mod_sites, modname);
+ di.num_descs = mod_sites;
+ di.descs = iter_mod_start;
+ ret = __ddebug_add_module(&di, i - mod_sites, modname);
if (ret)
goto out_err;

--
2.37.2