From nobody Mon Feb 9 16:33:35 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E41C814A4FF for ; Wed, 3 Apr 2024 15:02:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712156533; cv=none; b=SyhBU6XooknX3gRuOs07zHRVRzMh7beuuGIVNFGhqr4AGLLjwWgsfYxBrYypDjMoeQYb0qz2IA9MTNCecHKUKhtNn2Xjs0MZRI6/3zXBoQvk4CPurN2jgH0HyktAasXbtv5z5SqXkmne20yUuvU6JYsWNDiWLBjuFkhqOCHscpg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712156533; c=relaxed/simple; bh=3TQz803SJKKWWDXdmpXJtdnVe8cb7gnbBOh1swoHYpo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=YDabxlZjnFFywA5AoD5XMKphluFc0PVraBOvrG0HJx0t3MnqIOuA1OkRyG9UByAThMO4+mVbo9FtG/NSmcNeYM/Q9oFbi/dkJr9wlOzavyDjJPTn+rU1EFSc0ADzbaYscqVKMjFyA3oWtNHum4rroabTRbpmjAoESR+o6YgU/k8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9E98A1595; Wed, 3 Apr 2024 08:02:42 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id F00113F7B4; Wed, 3 Apr 2024 08:02:09 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: anil.s.keshavamurthy@intel.com, aou@eecs.berkeley.edu, catalin.marinas@arm.com, davem@davemloft.net, jarkko@kernel.org, linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, mhiramat@kernel.org, naveen.n.rao@linux.ibm.com, palmer@dabbelt.com, paul.walmsley@sifive.com, will@kernel.org Subject: [PATCH v2 4/4] kprobes: Remove core dependency on modules Date: Wed, 3 Apr 2024 16:01:54 +0100 Message-Id: <20240403150154.667649-5-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240403150154.667649-1-mark.rutland@arm.com> References: <20240403150154.667649-1-mark.rutland@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jarkko Sakkinen Tracing with kprobes while running a monolithic kernel is currently impossible because KPROBES depends on MODULES. While this dependency is necessary when HAVE_KPROBES_ALLOC=3Dn and the core kprobes code allocates memory using module_alloc(), all the other module-specific code only exist to handle the case when MODULES=3Dy, and can be hidden behind ifdeffery. Add the necessary ifdeffery, and remove the dependency on MODULES=3Dy when HAVE_KPROBES_ALLOC=3Dy. As of this patch kprobes can be used when MODULES=3Dn on arm64 and riscv. All other architectures still depend on MODULES, either by virtue of the core dependency on MODULES when HAVE_KPROBES_ALLOC=3Dn, or by virtue of an explciit dependency on MODULES in arch code. Other architectures can enable support by implementing their own kprobes_alloc_insn_page() and kprobes_free_insn_page() which do not depend on MODULES. Signed-off-by: Jarkko Sakkinen Link: https://lore.kernel.org/lkml/20240326134616.7691-1-jarkko@kernel.org/ [Mark: Remove execmem changes, depend on HAVE_KPROBES_ALLOC] Signed-off-by: Mark Rutland Cc: Albert Ou Cc: Anil S Keshavamurthy Cc: Catalin Marinas Cc: David S. Miller Cc: Jarkko Sakkinen Cc: Masami Hiramatsu Cc: Naveen N. Rao Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Will Deacon Tested-by: Jarkko Sakkinen # arch/riscv --- arch/Kconfig | 2 +- kernel/kprobes.c | 46 ++++++++++++++++++++++--------------- kernel/trace/trace_kprobe.c | 15 ++++++++++-- 3 files changed, 41 insertions(+), 22 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 85bb59f7b8c07..0df2c88547b3c 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -52,7 +52,7 @@ config GENERIC_ENTRY =20 config KPROBES bool "Kprobes" - depends on MODULES + depends on MODULES || HAVE_KPROBES_ALLOC depends on HAVE_KPROBES select KALLSYMS select TASKS_RCU if PREEMPTION diff --git a/kernel/kprobes.c b/kernel/kprobes.c index fa2ee4e59eca2..ec4493a41b505 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1594,6 +1594,7 @@ static int check_kprobe_address_safe(struct kprobe *p, goto out; } =20 +#ifdef CONFIG_MODULES /* * If the module freed '.init.text', we couldn't insert * kprobes in there. @@ -1604,7 +1605,9 @@ static int check_kprobe_address_safe(struct kprobe *p, *probed_mod =3D NULL; ret =3D -ENOENT; } +#endif /* CONFIG_MODULES */ } + out: preempt_enable(); jump_label_unlock(); @@ -2484,24 +2487,6 @@ int kprobe_add_area_blacklist(unsigned long start, u= nsigned long end) return 0; } =20 -/* Remove all symbols in given area from kprobe blacklist */ -static void kprobe_remove_area_blacklist(unsigned long start, unsigned lon= g 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 >=3D 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 *va= lue, char *type, char *sym) { @@ -2566,6 +2551,25 @@ static int __init populate_kprobe_blacklist(unsigned= long *start, return ret ? : arch_populate_kprobe_blacklist(); } =20 +#ifdef CONFIG_MODULES +/* Remove all symbols in given area from kprobe blacklist */ +static void kprobe_remove_area_blacklist(unsigned long start, unsigned lon= g 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 >=3D 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; @@ -2662,6 +2666,9 @@ static int kprobes_module_callback(struct notifier_bl= ock *nb, mutex_unlock(&kprobe_mutex); return NOTIFY_DONE; } +#else +#define kprobes_module_callback (NULL) +#endif /* CONFIG_MODULES */ =20 static struct notifier_block kprobe_module_nb =3D { .notifier_call =3D kprobes_module_callback, @@ -2726,7 +2733,8 @@ static int __init init_kprobes(void) err =3D arch_init_kprobes(); if (!err) err =3D register_die_notifier(&kprobe_exceptions_nb); - if (!err) + + if (!err && IS_ENABLED(CONFIG_MODULES)) err =3D register_module_notifier(&kprobe_module_nb); =20 kprobes_initialized =3D (err =3D=3D 0); diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 14099cc17fc9e..c509ba776e679 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) =3D=3D 0 && name[len] =3D=3D = ':'; } =20 +#ifdef CONFIG_MODULES static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe = *tk) { char *p; @@ -129,6 +130,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(s= truct trace_kprobe *tk) =20 return ret; } +#else +#define trace_kprobe_module_exist(tk) false /* aka a module never exists */ +#endif /* CONFIG_MODULES */ =20 static bool trace_kprobe_is_busy(struct dyn_event *ev) { @@ -670,6 +674,7 @@ static int register_trace_kprobe(struct trace_kprobe *t= k) return ret; } =20 +#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) @@ -699,6 +704,9 @@ static int trace_kprobe_module_callback(struct notifier= _block *nb, =20 return NOTIFY_DONE; } +#else +#define trace_kprobe_module_callback (NULL) +#endif /* CONFIG_MODULES */ =20 static struct notifier_block trace_kprobe_module_nb =3D { .notifier_call =3D trace_kprobe_module_callback, @@ -1933,8 +1941,11 @@ static __init int init_kprobe_trace_early(void) if (ret) return ret; =20 - if (register_module_notifier(&trace_kprobe_module_nb)) - return -EINVAL; + if (IS_ENABLED(CONFIG_MODULES)) { + ret =3D register_module_notifier(&trace_kprobe_module_nb); + if (ret) + return -EINVAL; + } =20 return 0; } --=20 2.30.2