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[24.9.77.57]) by smtp.googlemail.com with ESMTPSA id w13sm10583057ilg.48.2021.03.16.23.54.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Mar 2021 23:54:32 -0700 (PDT) From: Jim Cromie To: jbaron@akamai.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org Cc: Jim Cromie Subject: [RFC PATCH v4 13/19] dyndbg+module: expose ddebug_sites to modules Date: Wed, 17 Mar 2021 00:54:06 -0600 Message-Id: <20210317065412.2890414-14-jim.cromie@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210317065412.2890414-1-jim.cromie@gmail.com> References: <20210317065412.2890414-1-jim.cromie@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- include/linux/dynamic_debug.h | 4 ++-- kernel/module-internal.h | 1 + kernel/module.c | 9 ++++++--- lib/dynamic_debug.c | 20 ++++++++++++-------- 4 files changed, 21 insertions(+), 13 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..be2e97ae2da9 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 { @@ -1014,14 +1015,14 @@ 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; 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; } /* @@ -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