Commit b7b4eebd authored by Jim Cromie's avatar Jim Cromie Committed by Greg Kroah-Hartman
Browse files

dyndbg: gather __dyndbg[] state into struct _ddebug_info 



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: default avatarJim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-12-jim.cromie@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent aa86a154

include/linux/dynamic_debug.h

+8 −5
Original line number Diff line number Diff line
@@ -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;

}

kernel/module/internal.h

+2 −2
Original line number Diff line number Diff line
@@ -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;

kernel/module/main.c

+9 −9
Original line number Diff line number Diff line
@@ -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:

lib/dynamic_debug.c

+31 −9
Original line number Diff line number Diff line
@@ -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;