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dyndbg: gather __dyndbg[] state into struct _ddebug_info

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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>
Link: https://lore.kernel.org/r/20220904214134.408619-12-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jim Cromie 2022-09-04 15:40:48 -06:00 • committed by Greg Kroah-Hartman
parent aa86a15453
commit b7b4eebdba
4 changed files with 50 additions and 25 deletions
Download patch file Download diff file Expand all files Collapse all files

4
kernel/module/internal.h
View file

@ -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;

18
kernel/module/main.c
View file

@ -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: