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Fri, 08 Mar 2024 12:57:04 -0800 (PST) Received: from gmail.com ([192.184.166.229]) by smtp.gmail.com with ESMTPSA id o11-20020a17090323cb00b001dcc0d06959sm69529plh.245.2024.03.08.12.57.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Mar 2024 12:57:04 -0800 (PST) Date: Fri, 8 Mar 2024 12:57:02 -0800 From: Calvin Owens To: Masami Hiramatsu Cc: Luis Chamberlain , Andrew Morton , Alexei Starovoitov , Steven Rostedt , Daniel Borkmann , Andrii Nakryiko , Naveen N Rao , Anil S Keshavamurthy , David S Miller , Thomas Gleixner , bpf@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH 3/4] kprobes: Allow kprobes with CONFIG_MODULES=n Message-ID: References: <2af01251ca21d79fa29092505d192f1f1b746cff.1709676663.git.jcalvinowens@gmail.com> <20240308114603.289720cf17ed75ba7bce8779@kernel.org> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240308114603.289720cf17ed75ba7bce8779@kernel.org> On Friday 03/08 at 11:46 +0900, Masami Hiramatsu wrote: > On Wed, 6 Mar 2024 12:05:10 -0800 > Calvin Owens wrote: > > > If something like this is merged down the road, it can go in at leisure > > once the module_alloc change is in: it's a one-way dependency. > > > > Signed-off-by: Calvin Owens > > --- > > arch/Kconfig | 2 +- > > kernel/kprobes.c | 22 ++++++++++++++++++++++ > > kernel/trace/trace_kprobe.c | 11 +++++++++++ > > 3 files changed, 34 insertions(+), 1 deletion(-) > > > > diff --git a/arch/Kconfig b/arch/Kconfig > > index cfc24ced16dd..e60ce984d095 100644 > > --- a/arch/Kconfig > > +++ b/arch/Kconfig > > @@ -52,8 +52,8 @@ config GENERIC_ENTRY > > > > config KPROBES > > bool "Kprobes" > > - depends on MODULES > > depends on HAVE_KPROBES > > + select MODULE_ALLOC > > OK, if we use EXEC_ALLOC, > > config EXEC_ALLOC > depends on HAVE_EXEC_ALLOC > > And > > config KPROBES > bool "Kprobes" > depends on MODULES || EXEC_ALLOC > select EXEC_ALLOC if HAVE_EXEC_ALLOC > > then kprobes can be enabled either modules supported or exec_alloc is supported. > (new arch does not need to implement exec_alloc) > > Maybe we also need something like > > #ifdef CONFIG_EXEC_ALLOC > #define module_alloc(size) exec_alloc(size) > #endif > > in kprobes.h, or just add `replacing module_alloc with exec_alloc` patch. > > Thank you, The example was helpful, thanks. I see what you mean with HAVE_EXEC_ALLOC, I'll implement it like that in the next verison. > > select KALLSYMS > > select TASKS_RCU if PREEMPTION > > help > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > index 9d9095e81792..194270e17d57 100644 > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -1556,8 +1556,12 @@ static bool is_cfi_preamble_symbol(unsigned long addr) > > str_has_prefix("__pfx_", symbuf); > > } > > > > +#if IS_ENABLED(CONFIG_MODULES) > > static int check_kprobe_address_safe(struct kprobe *p, > > struct module **probed_mod) > > +#else > > +static int check_kprobe_address_safe(struct kprobe *p) > > +#endif > > { > > int ret; > > > > @@ -1580,6 +1584,7 @@ static int check_kprobe_address_safe(struct kprobe *p, > > goto out; > > } > > > > +#if IS_ENABLED(CONFIG_MODULES) > > /* Check if 'p' is probing a module. */ > > *probed_mod = __module_text_address((unsigned long) p->addr); > > if (*probed_mod) { > > @@ -1603,6 +1608,8 @@ static int check_kprobe_address_safe(struct kprobe *p, > > ret = -ENOENT; > > } > > } > > +#endif > > + > > out: > > preempt_enable(); > > jump_label_unlock(); > > @@ -1614,7 +1621,9 @@ int register_kprobe(struct kprobe *p) > > { > > int ret; > > struct kprobe *old_p; > > +#if IS_ENABLED(CONFIG_MODULES) > > struct module *probed_mod; > > +#endif > > kprobe_opcode_t *addr; > > bool on_func_entry; > > > > @@ -1633,7 +1642,11 @@ int register_kprobe(struct kprobe *p) > > p->nmissed = 0; > > INIT_LIST_HEAD(&p->list); > > > > +#if IS_ENABLED(CONFIG_MODULES) > > ret = check_kprobe_address_safe(p, &probed_mod); > > +#else > > + ret = check_kprobe_address_safe(p); > > +#endif > > if (ret) > > return ret; > > > > @@ -1676,8 +1689,10 @@ int register_kprobe(struct kprobe *p) > > out: > > mutex_unlock(&kprobe_mutex); > > > > +#if IS_ENABLED(CONFIG_MODULES) > > if (probed_mod) > > module_put(probed_mod); > > +#endif > > > > return ret; > > } > > @@ -2482,6 +2497,7 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end) > > return 0; > > } > > > > +#if IS_ENABLED(CONFIG_MODULES) > > /* Remove all symbols in given area from kprobe blacklist */ > > static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) > > { > > @@ -2499,6 +2515,7 @@ static void kprobe_remove_ksym_blacklist(unsigned long entry) > > { > > kprobe_remove_area_blacklist(entry, entry + 1); > > } > > +#endif > > > > int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, > > char *type, char *sym) > > @@ -2564,6 +2581,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start, > > return ret ? : arch_populate_kprobe_blacklist(); > > } > > > > +#if IS_ENABLED(CONFIG_MODULES) > > static void add_module_kprobe_blacklist(struct module *mod) > > { > > unsigned long start, end; > > @@ -2665,6 +2683,7 @@ static struct notifier_block kprobe_module_nb = { > > .notifier_call = kprobes_module_callback, > > .priority = 0 > > }; > > +#endif /* IS_ENABLED(CONFIG_MODULES) */ > > > > void kprobe_free_init_mem(void) > > { > > @@ -2724,8 +2743,11 @@ static int __init init_kprobes(void) > > err = arch_init_kprobes(); > > if (!err) > > err = register_die_notifier(&kprobe_exceptions_nb); > > + > > +#if IS_ENABLED(CONFIG_MODULES) > > if (!err) > > err = register_module_notifier(&kprobe_module_nb); > > +#endif > > > > kprobes_initialized = (err == 0); > > kprobe_sysctls_init(); > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > > index c4c6e0e0068b..dd4598f775b9 100644 > > --- a/kernel/trace/trace_kprobe.c > > +++ b/kernel/trace/trace_kprobe.c > > @@ -102,6 +102,7 @@ static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk) > > return kprobe_gone(&tk->rp.kp); > > } > > > > +#if IS_ENABLED(CONFIG_MODULES) > > static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk, > > struct module *mod) > > { > > @@ -129,6 +130,12 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) > > > > return ret; > > } > > +#else > > +static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) > > +{ > > + return true; > > +} > > +#endif > > > > static bool trace_kprobe_is_busy(struct dyn_event *ev) > > { > > @@ -670,6 +677,7 @@ static int register_trace_kprobe(struct trace_kprobe *tk) > > return ret; > > } > > > > +#if IS_ENABLED(CONFIG_MODULES) > > /* Module notifier call back, checking event on the module */ > > static int trace_kprobe_module_callback(struct notifier_block *nb, > > unsigned long val, void *data) > > @@ -704,6 +712,7 @@ static struct notifier_block trace_kprobe_module_nb = { > > .notifier_call = trace_kprobe_module_callback, > > .priority = 1 /* Invoked after kprobe module callback */ > > }; > > +#endif /* IS_ENABLED(CONFIG_MODULES) */ > > > > static int count_symbols(void *data, unsigned long unused) > > { > > @@ -1897,8 +1906,10 @@ static __init int init_kprobe_trace_early(void) > > if (ret) > > return ret; > > > > +#if IS_ENABLED(CONFIG_MODULES) > > if (register_module_notifier(&trace_kprobe_module_nb)) > > return -EINVAL; > > +#endif > > > > return 0; > > } > > -- > > 2.43.0 > > > > > -- > Masami Hiramatsu (Google)