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Date: Mon, 15 Mar 2021 23:07:56 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: jbaron@...mai.com, gregkh@...uxfoundation.org,
linux-kernel@...r.kernel.org
Cc: Jim Cromie <jim.cromie@...il.com>
Subject: [RFC PATCH v3 13/18] dyndbg+module: expose ddebug_sites to modules
In order to drop the pointer connecting _ddebug's to _ddebug_sites,
we need to elevate the latter; we need to track it in (internal)
ddebug_tables, and set it in ddebug_add_module. That last part
exposes it by interface to module.c, so we add a field to load_info,
and adjust load_module to initialize it from the elf section.
Its possible that this closes a "hole" created when __dyndbg_sites
section was added, in that the section wasn't "managed" directly, and
could conceivably get lost later. I never saw any misbehavior loading
i915.ko into a vm, but still..
TBD/RFC:
these 2 vectors should be in a single struct. if this struct can have
ddebugs[], ie a flex-array, then container_of can get us to the
sites*, yielding &ddebug_sites[N], and allowing to drop _ddebug.site
The trouble with this is that ddebugs* now points to someone elses
memory, and we cant just steal it and stomp on the memory just in
front of it (for the sites ptr).
rename n to numdbgs
Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
include/linux/dynamic_debug.h | 4 ++--
kernel/module-internal.h | 1 +
kernel/module.c | 9 ++++++---
lib/dynamic_debug.c | 18 +++++++++++-------
4 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index d811273c8484..7d33475d226a 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -70,8 +70,8 @@ struct _ddebug {
/* exported for module authors to exercise >control */
int dynamic_debug_exec_queries(const char *query, const char *modname);
-int ddebug_add_module(struct _ddebug *tab, unsigned int n,
- const char *modname);
+int ddebug_add_module(struct _ddebug *tab, struct _ddebug_site *sites,
+ unsigned int numdbgs, 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, ...);
diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 33783abc377b..fb61eb2f8032 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h
@@ -18,6 +18,7 @@ struct load_info {
char *secstrings, *strtab;
unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs;
struct _ddebug *debug;
+ struct _ddebug_site *sites;
unsigned int num_debug;
bool sig_ok;
#ifdef CONFIG_KALLSYMS
diff --git a/kernel/module.c b/kernel/module.c
index 30479355ab85..792903230acd 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2780,11 +2780,12 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
}
#endif /* CONFIG_KALLSYMS */
-static void dynamic_debug_setup(struct module *mod, struct _ddebug *debug, unsigned int num)
+static void dynamic_debug_setup(struct module *mod, struct _ddebug *debug,
+ struct _ddebug_site *sites, unsigned int num)
{
if (!debug)
return;
- ddebug_add_module(debug, num, mod->name);
+ ddebug_add_module(debug, sites, num, mod->name);
}
static void dynamic_debug_remove(struct module *mod, struct _ddebug *debug)
@@ -3333,6 +3334,8 @@ static int find_module_sections(struct module *mod, struct load_info *info)
info->debug = section_objs(info, "__dyndbg",
sizeof(*info->debug), &info->num_debug);
+ info->sites = section_objs(info, "__dyndbg_sites",
+ sizeof(*info->sites), &info->num_debug);
return 0;
}
@@ -4004,7 +4007,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
goto free_arch_cleanup;
}
- dynamic_debug_setup(mod, info->debug, info->num_debug);
+ dynamic_debug_setup(mod, info->debug, info->sites, info->num_debug);
/* Ftrace init must be called in the MODULE_STATE_UNFORMED state */
ftrace_module_init(mod);
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index fdc2d0e15731..5529b17461ae 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -49,6 +49,7 @@ struct ddebug_table {
const char *mod_name;
unsigned int num_ddebugs;
struct _ddebug *ddebugs;
+ struct _ddebug_site *sites;
};
struct ddebug_query {
@@ -1014,8 +1015,8 @@ 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)
+int ddebug_add_module(struct _ddebug *tab, struct _ddebug_site *sites,
+ unsigned int numdbgs, const char *modname)
{
struct ddebug_table *dt;
@@ -1030,15 +1031,16 @@ 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->mod_name = modname;
+ dt->num_ddebugs = numdbgs;
dt->ddebugs = tab;
+ dt->sites = sites;
mutex_lock(&ddebug_lock);
list_add(&dt->link, &ddebug_tables);
mutex_unlock(&ddebug_lock);
- v2pr_info("%3u debug prints in module %s\n", n, dt->mod_name);
+ v2pr_info("%3u debug prints in module %s\n", numdbgs, modname);
return 0;
}
@@ -1178,7 +1180,9 @@ static int __init dynamic_debug_init(void)
if (strcmp(modname, site->modname)) {
modct++;
- ret = ddebug_add_module(iter_mod_start, site_ct, modname);
+
+ ret = ddebug_add_module(iter_mod_start, site_mod_start,
+ site_ct, modname);
if (ret)
goto out_err;
site_ct = 0;
@@ -1188,7 +1192,7 @@ static int __init dynamic_debug_init(void)
}
site_ct++;
}
- ret = ddebug_add_module(iter_mod_start, site_ct, modname);
+ ret = ddebug_add_module(iter_mod_start, site_mod_start, site_ct, modname);
if (ret)
goto out_err;
--
2.29.2
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