| Message ID | 20230113143303.867580-2-jolsa@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kallsyms: Optimize the search for module symbols by livepatch and bpf | expand |
On Fri, Jan 13, 2023 at 6:43 AM Jiri Olsa <jolsa@kernel.org> wrote: > > From: Zhen Lei <thunder.leizhen@huawei.com> > > Currently we traverse all symbols of all modules to find the specified > function for the specified module. But in reality, we just need to find > the given module and then traverse all the symbols in it. > > Let's add a new parameter 'const char *modname' to function > module_kallsyms_on_each_symbol(), then we can compare the module names > directly in this function and call hook 'fn' after matching. If 'modname' > is NULL, the symbols of all modules are still traversed for compatibility > with other usage cases. > > Phase1: mod1-->mod2..(subsequent modules do not need to be compared) > | > Phase2: -->f1-->f2-->f3 > > Assuming that there are m modules, each module has n symbols on average, > then the time complexity is reduced from O(m * n) to O(m) + O(n). > > Reviewed-by: Petr Mladek <pmladek@suse.com> > Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <song@kernel.org> > --- > include/linux/module.h | 6 ++++-- > kernel/livepatch/core.c | 10 +--------- > kernel/module/kallsyms.c | 13 ++++++++++++- > kernel/trace/bpf_trace.c | 2 +- > kernel/trace/ftrace.c | 2 +- > 5 files changed, 19 insertions(+), 14 deletions(-) > > diff --git a/include/linux/module.h b/include/linux/module.h > index 8c5909c0076c..514bc81568c5 100644 > --- a/include/linux/module.h > +++ b/include/linux/module.h > @@ -879,11 +879,13 @@ static inline bool module_sig_ok(struct module *module) > #endif /* CONFIG_MODULE_SIG */ > > #if defined(CONFIG_MODULES) && defined(CONFIG_KALLSYMS) > -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, > +int module_kallsyms_on_each_symbol(const char *modname, > + int (*fn)(void *, const char *, > struct module *, unsigned long), > void *data); > #else > -static inline int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, > +static inline int module_kallsyms_on_each_symbol(const char *modname, > + int (*fn)(void *, const char *, > struct module *, unsigned long), > void *data) > { > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > index 201f0c0482fb..c973ed9e42f8 100644 > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -118,7 +118,6 @@ static struct klp_object *klp_find_object(struct klp_patch *patch, > } > > struct klp_find_arg { > - const char *objname; > const char *name; > unsigned long addr; > unsigned long count; > @@ -148,15 +147,9 @@ static int klp_find_callback(void *data, const char *name, > { > struct klp_find_arg *args = data; > > - if ((mod && !args->objname) || (!mod && args->objname)) > - return 0; > - > if (strcmp(args->name, name)) > return 0; > > - if (args->objname && strcmp(args->objname, mod->name)) > - return 0; > - > return klp_match_callback(data, addr); > } > > @@ -164,7 +157,6 @@ static int klp_find_object_symbol(const char *objname, const char *name, > unsigned long sympos, unsigned long *addr) > { > struct klp_find_arg args = { > - .objname = objname, > .name = name, > .addr = 0, > .count = 0, > @@ -172,7 +164,7 @@ static int klp_find_object_symbol(const char *objname, const char *name, > }; > > if (objname) > - module_kallsyms_on_each_symbol(klp_find_callback, &args); > + module_kallsyms_on_each_symbol(objname, klp_find_callback, &args); > else > kallsyms_on_each_match_symbol(klp_match_callback, name, &args); > > diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c > index 4523f99b0358..ab2376a1be88 100644 > --- a/kernel/module/kallsyms.c > +++ b/kernel/module/kallsyms.c > @@ -494,7 +494,8 @@ unsigned long module_kallsyms_lookup_name(const char *name) > return ret; > } > > -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, > +int module_kallsyms_on_each_symbol(const char *modname, > + int (*fn)(void *, const char *, > struct module *, unsigned long), > void *data) > { > @@ -509,6 +510,9 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, > if (mod->state == MODULE_STATE_UNFORMED) > continue; > > + if (modname && strcmp(modname, mod->name)) > + continue; > + > /* Use rcu_dereference_sched() to remain compliant with the sparse tool */ > preempt_disable(); > kallsyms = rcu_dereference_sched(mod->kallsyms); > @@ -525,6 +529,13 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, > if (ret != 0) > goto out; > } > + > + /* > + * The given module is found, the subsequent modules do not > + * need to be compared. > + */ > + if (modname) > + break; > } > out: > mutex_unlock(&module_mutex); > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 23ce498bca97..095f7f8d34a1 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -2735,7 +2735,7 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3 > int err; > > /* We return either err < 0 in case of error, ... */ > - err = module_kallsyms_on_each_symbol(module_callback, &args); > + err = module_kallsyms_on_each_symbol(NULL, module_callback, &args); > if (err) { > kprobe_multi_put_modules(args.mods, args.mods_cnt); > kfree(args.mods); > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 442438b93fe9..d249a55d9005 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -8324,7 +8324,7 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a > found_all = kallsyms_on_each_symbol(kallsyms_callback, &args); > if (found_all) > return 0; > - found_all = module_kallsyms_on_each_symbol(kallsyms_callback, &args); > + found_all = module_kallsyms_on_each_symbol(NULL, kallsyms_callback, &args); > return found_all ? 0 : -ESRCH; > } > > -- > 2.39.0 >
diff --git a/include/linux/module.h b/include/linux/module.h index 8c5909c0076c..514bc81568c5 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -879,11 +879,13 @@ static inline bool module_sig_ok(struct module *module) #endif /* CONFIG_MODULE_SIG */ #if defined(CONFIG_MODULES) && defined(CONFIG_KALLSYMS) -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, +int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, struct module *, unsigned long), void *data); #else -static inline int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, +static inline int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, struct module *, unsigned long), void *data) { diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 201f0c0482fb..c973ed9e42f8 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -118,7 +118,6 @@ static struct klp_object *klp_find_object(struct klp_patch *patch, } struct klp_find_arg { - const char *objname; const char *name; unsigned long addr; unsigned long count; @@ -148,15 +147,9 @@ static int klp_find_callback(void *data, const char *name, { struct klp_find_arg *args = data; - if ((mod && !args->objname) || (!mod && args->objname)) - return 0; - if (strcmp(args->name, name)) return 0; - if (args->objname && strcmp(args->objname, mod->name)) - return 0; - return klp_match_callback(data, addr); } @@ -164,7 +157,6 @@ static int klp_find_object_symbol(const char *objname, const char *name, unsigned long sympos, unsigned long *addr) { struct klp_find_arg args = { - .objname = objname, .name = name, .addr = 0, .count = 0, @@ -172,7 +164,7 @@ static int klp_find_object_symbol(const char *objname, const char *name, }; if (objname) - module_kallsyms_on_each_symbol(klp_find_callback, &args); + module_kallsyms_on_each_symbol(objname, klp_find_callback, &args); else kallsyms_on_each_match_symbol(klp_match_callback, name, &args); diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index 4523f99b0358..ab2376a1be88 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -494,7 +494,8 @@ unsigned long module_kallsyms_lookup_name(const char *name) return ret; } -int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, +int module_kallsyms_on_each_symbol(const char *modname, + int (*fn)(void *, const char *, struct module *, unsigned long), void *data) { @@ -509,6 +510,9 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, if (mod->state == MODULE_STATE_UNFORMED) continue; + if (modname && strcmp(modname, mod->name)) + continue; + /* Use rcu_dereference_sched() to remain compliant with the sparse tool */ preempt_disable(); kallsyms = rcu_dereference_sched(mod->kallsyms); @@ -525,6 +529,13 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, if (ret != 0) goto out; } + + /* + * The given module is found, the subsequent modules do not + * need to be compared. + */ + if (modname) + break; } out: mutex_unlock(&module_mutex); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 23ce498bca97..095f7f8d34a1 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2735,7 +2735,7 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3 int err; /* We return either err < 0 in case of error, ... */ - err = module_kallsyms_on_each_symbol(module_callback, &args); + err = module_kallsyms_on_each_symbol(NULL, module_callback, &args); if (err) { kprobe_multi_put_modules(args.mods, args.mods_cnt); kfree(args.mods); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 442438b93fe9..d249a55d9005 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -8324,7 +8324,7 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a found_all = kallsyms_on_each_symbol(kallsyms_callback, &args); if (found_all) return 0; - found_all = module_kallsyms_on_each_symbol(kallsyms_callback, &args); + found_all = module_kallsyms_on_each_symbol(NULL, kallsyms_callback, &args); return found_all ? 0 : -ESRCH; }