Received-SPF: pass (google.com: domain of linux-kernel+bounces-141268-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Mike Rapoport <rppt@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	=?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= <bjorn@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	"David S. Miller" <davem@davemloft.net>,
	Dinh Nguyen <dinguyen@kernel.org>,
	Donald Dutile <ddutile@redhat.com>,
	Eric Chanudet <echanude@redhat.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Helge Deller <deller@gmx.de>,
	Huacai Chen <chenhuacai@kernel.org>,
	Kent Overstreet <kent.overstreet@linux.dev>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Mike Rapoport <rppt@kernel.org>,
	Nadav Amit <nadav.amit@gmail.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Puranjay Mohan <puranjay12@gmail.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Russell King <linux@armlinux.org.uk>,
	Song Liu <song@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	bpf@vger.kernel.org,
	linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mips@vger.kernel.org,
	linux-mm@kvack.org,
	linux-modules@vger.kernel.org,
	linux-parisc@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org,
	loongarch@lists.linux.dev,
	netdev@vger.kernel.org,
	sparclinux@vger.kernel.org,
	x86@kernel.org
Subject: [PATCH v4 14/15] kprobes: remove dependency on CONFIG_MODULES
Date: Thu, 11 Apr 2024 19:00:50 +0300
Message-ID: <20240411160051.2093261-15-rppt@kernel.org>
In-Reply-To: <20240411160051.2093261-1-rppt@kernel.org>
References: <20240411160051.2093261-1-rppt@kernel.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

From: "Mike Rapoport (IBM)" <rppt@kernel.org>

kprobes depended on CONFIG_MODULES because it has to allocate memory for
code.

Since code allocations are now implemented with execmem, kprobes can be
enabled in non-modular kernels.

Add #ifdef CONFIG_MODULE guards for the code dealing with kprobes inside
modules, make CONFIG_KPROBES select CONFIG_EXECMEM and drop the
dependency of CONFIG_KPROBES on CONFIG_MODULES.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
 arch/Kconfig                |  2 +-
 kernel/kprobes.c            | 43 +++++++++++++++++++++----------------
 kernel/trace/trace_kprobe.c | 11 ++++++++++
 3 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index bc9e8e5dccd5..68177adf61a0 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -52,9 +52,9 @@ config GENERIC_ENTRY
 
 config KPROBES
 	bool "Kprobes"
-	depends on MODULES
 	depends on HAVE_KPROBES
 	select KALLSYMS
+	select EXECMEM
 	select TASKS_RCU if PREEMPTION
 	help
 	  Kprobes allows you to trap at almost any kernel address and
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 047ca629ce49..90c056853e6f 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1580,6 +1580,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
 		goto out;
 	}
 
+#ifdef CONFIG_MODULES
 	/* Check if 'p' is probing a module. */
 	*probed_mod = __module_text_address((unsigned long) p->addr);
 	if (*probed_mod) {
@@ -1603,6 +1604,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
 			ret = -ENOENT;
 		}
 	}
+#endif
+
 out:
 	preempt_enable();
 	jump_label_unlock();
@@ -2482,24 +2485,6 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
 	return 0;
 }
 
-/* Remove all symbols in given area from kprobe blacklist */
-static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
-{
-	struct kprobe_blacklist_entry *ent, *n;
-
-	list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
-		if (ent->start_addr < start || ent->start_addr >= end)
-			continue;
-		list_del(&ent->list);
-		kfree(ent);
-	}
-}
-
-static void kprobe_remove_ksym_blacklist(unsigned long entry)
-{
-	kprobe_remove_area_blacklist(entry, entry + 1);
-}
-
 int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
 				   char *type, char *sym)
 {
@@ -2564,6 +2549,25 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
 	return ret ? : arch_populate_kprobe_blacklist();
 }
 
+#ifdef CONFIG_MODULES
+/* Remove all symbols in given area from kprobe blacklist */
+static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
+{
+	struct kprobe_blacklist_entry *ent, *n;
+
+	list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
+		if (ent->start_addr < start || ent->start_addr >= end)
+			continue;
+		list_del(&ent->list);
+		kfree(ent);
+	}
+}
+
+static void kprobe_remove_ksym_blacklist(unsigned long entry)
+{
+	kprobe_remove_area_blacklist(entry, entry + 1);
+}
+
 static void add_module_kprobe_blacklist(struct module *mod)
 {
 	unsigned long start, end;
@@ -2665,6 +2669,7 @@ static struct notifier_block kprobe_module_nb = {
 	.notifier_call = kprobes_module_callback,
 	.priority = 0
 };
+#endif
 
 void kprobe_free_init_mem(void)
 {
@@ -2724,8 +2729,10 @@ static int __init init_kprobes(void)
 	err = arch_init_kprobes();
 	if (!err)
 		err = register_die_notifier(&kprobe_exceptions_nb);
+#ifdef 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 14099cc17fc9..f0610137d6a3 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -111,6 +111,7 @@ static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
 	return strncmp(module_name(mod), name, len) == 0 && name[len] == ':';
 }
 
+#ifdef CONFIG_MODULES
 static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 {
 	char *p;
@@ -129,6 +130,12 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 
 	return ret;
 }
+#else
+static inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
+{
+	return false;
+}
+#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;
 }
 
+#ifdef 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
 
 static int count_symbols(void *data, unsigned long unused)
 {
@@ -1933,8 +1942,10 @@ static __init int init_kprobe_trace_early(void)
 	if (ret)
 		return ret;
 
+#ifdef CONFIG_MODULES
 	if (register_module_notifier(&trace_kprobe_module_nb))
 		return -EINVAL;
+#endif
 
 	return 0;
 }
-- 
2.43.0