From patchwork Mon Mar 25 20:37:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13602921 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2D8A5C60D; Mon, 25 Mar 2024 20:38:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711399087; cv=none; b=juGQtjE5YKn20q84ZYZk78Ct7MQKXD9ilK9Zy3e7OXk1cbFC6cQrFMUJXW6PAM2osjbmKeV9zeCWeZroJOAXHkHX+HBBK65fonlsS2VVUYd8x37kFSW06k2jeyQfmXvsPPhXGnNFXGvp5RlOfvbMzmGT3l1KP+MF6LboIAmwb/M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711399087; c=relaxed/simple; bh=O+nH8ew9YCyT1eBzJVNI7NhlU/W38tr3dfunGVakyyQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=U9+c+v8PGx4tIq0iqRLAi6OC5+yhRGxEqsGC2TBAgpZdLJLiiObxF1sz3qk/sfxZOf7k1Y4vYmSbcAH0WvBV3UvZgSmz2Qmz1tz0sjElhWZykQYflA2SPoQvKykZOQtGwLj4uPWYOikToTvqW6iONckIiw0vu+vCLE2ILg0V96M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BmUixln5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BmUixln5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCE27C433F1; Mon, 25 Mar 2024 20:38:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711399086; bh=O+nH8ew9YCyT1eBzJVNI7NhlU/W38tr3dfunGVakyyQ=; h=From:To:Cc:Subject:Date:From; b=BmUixln5eSjDKD7hwgJRY3Uw7PdEicb7INTOAemawVhpepZKd89Gx+C/t245sF/LW hSfVLAXMXIiJUCVluoAMrrdguBdDR+80rL9R88BzzAhMPF3R+ahSDuHw08z32t3/Ls 4GxNZmDp2XWbzr/GjX4AUbU2qJwb4ECOaWZAtd2Pq0I56+plTiAYnuaK+U+fC1w3k3 O/SFVsEQvyVNHQ5/UXgfIAkSCnqhz5xLvzGEMyB/0A5XV0DtPSSBfQy+/5C0lV/9pJ BJhmrXyPeunFW36qJiLaVtyxu0x3TafJ0dphKd1Pbr7FooQlEK18dyel8qP9+kNC4R j4zTmy4STZE2A== From: Jarkko Sakkinen To: linux-riscv@lists.infradead.org Cc: Jarkko Sakkinen , Masami Hiramatsu , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-kernel@vger.kernel.org, Luis Chamberlain , linux-modules@vger.kernel.org, "Naveen N . Rao" , Anil S Keshavamurthy , "David S . Miller" Subject: [PATCH v3 1/2] kprobes: textmem API Date: Mon, 25 Mar 2024 22:37:54 +0200 Message-ID: <20240325203755.1811-1-jarkko@kernel.org> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Tracing with kprobes while running a monolithic kernel is currently impossible because CONFIG_KPROBES depends on CONFIG_MODULES because it uses the kernel module allocator. Introduce alloc_textmem() and free_textmem() for allocating executable memory. If an arch implements these functions, it can mark this up with the HAVE_ALLOC_EXECMEM kconfig flag. At first this feature will be used for enabling kprobes without modules support for arch/riscv. Link: https://lore.kernel.org/all/20240325115632.04e37297491cadfbbf382767@kernel.org/ Suggested-by: Masami Hiramatsu Signed-off-by: Jarkko Sakkinen --- v3: - A new patch added. - For IS_DEFINED() I need advice as I could not really find that many locations where it would be applicable. --- arch/Kconfig | 16 +++++++++++++++- include/linux/execmem.h | 13 +++++++++++++ kernel/kprobes.c | 17 ++++++++++++++--- kernel/trace/trace_kprobe.c | 18 ++++++++++++++++-- 4 files changed, 58 insertions(+), 6 deletions(-) create mode 100644 include/linux/execmem.h diff --git a/arch/Kconfig b/arch/Kconfig index a5af0edd3eb8..33ba68b7168f 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 ALLOC_EXECMEM select KALLSYMS select TASKS_RCU if PREEMPTION help @@ -215,6 +215,20 @@ config HAVE_OPTPROBES config HAVE_KPROBES_ON_FTRACE bool +config HAVE_ALLOC_EXECMEM + bool + help + Architectures that select this option are capable of allocating executable + memory, which can be used by subsystems but is not dependent of any of its + clients. + +config ALLOC_EXECMEM + bool "Executable (trampoline) memory allocation" + depends on MODULES || HAVE_ALLOC_EXECMEM + help + Select this for executable (trampoline) memory. Can be enabled when either + module allocator or arch-specific allocator is available. + config ARCH_CORRECT_STACKTRACE_ON_KRETPROBE bool help diff --git a/include/linux/execmem.h b/include/linux/execmem.h new file mode 100644 index 000000000000..ae2ff151523a --- /dev/null +++ b/include/linux/execmem.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_EXECMEM_H +#define _LINUX_EXECMEM_H + +#ifdef CONFIG_HAVE_ALLOC_EXECMEM +void *alloc_execmem(unsigned long size, gfp_t gfp); +void free_execmem(void *region); +#else +#define alloc_execmem(size, gfp) module_alloc(size) +#define free_execmem(region) module_memfree(region) +#endif + +#endif /* _LINUX_EXECMEM_H */ diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9d9095e81792..a1a547723c3c 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -44,6 +44,7 @@ #include #include #include +#include #define KPROBE_HASH_BITS 6 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) @@ -113,17 +114,17 @@ enum kprobe_slot_state { void __weak *alloc_insn_page(void) { /* - * Use module_alloc() so this page is within +/- 2GB of where the + * Use alloc_execmem() so this page is within +/- 2GB of where the * kernel image and loaded module images reside. This is required * for most of the architectures. * (e.g. x86-64 needs this to handle the %rip-relative fixups.) */ - return module_alloc(PAGE_SIZE); + return alloc_execmem(PAGE_SIZE); } static void free_insn_page(void *page) { - module_memfree(page); + free_execmem(page); } struct kprobe_insn_cache kprobe_insn_slots = { @@ -1580,6 +1581,7 @@ 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 +1605,8 @@ static int check_kprobe_address_safe(struct kprobe *p, ret = -ENOENT; } } +#endif + out: preempt_enable(); jump_label_unlock(); @@ -2482,6 +2486,7 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end) return 0; } +#ifdef 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 +2504,7 @@ static void kprobe_remove_ksym_blacklist(unsigned long entry) { kprobe_remove_area_blacklist(entry, entry + 1); } +#endif /* CONFIG_MODULES */ int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, char *type, char *sym) @@ -2564,6 +2570,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start, return ret ? : arch_populate_kprobe_blacklist(); } +#ifdef CONFIG_MODULES static void add_module_kprobe_blacklist(struct module *mod) { unsigned long start, end; @@ -2665,6 +2672,7 @@ static struct notifier_block kprobe_module_nb = { .notifier_call = kprobes_module_callback, .priority = 0 }; +#endif /* CONFIG_MODULES */ void kprobe_free_init_mem(void) { @@ -2724,8 +2732,11 @@ 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 c4c6e0e0068b..f8fbd5e76dda 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 +130,7 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) return ret; } +#endif /* CONFIG_MODULES */ static bool trace_kprobe_is_busy(struct dyn_event *ev) { @@ -608,7 +610,11 @@ static int append_trace_kprobe(struct trace_kprobe *tk, struct trace_kprobe *to) /* Register k*probe */ ret = __register_trace_kprobe(tk); - if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) { +#ifdef CONFIG_MODULES + if (ret == -ENOENT && trace_kprobe_module_exist(tk)) + ret = 0; +#endif /* CONFIG_MODULES */ + if (ret == -ENOENT) { pr_warn("This probe might be able to register after target module is loaded. Continue.\n"); ret = 0; } @@ -655,7 +661,11 @@ static int register_trace_kprobe(struct trace_kprobe *tk) /* Register k*probe */ ret = __register_trace_kprobe(tk); - if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) { +#ifdef CONFIG_MODULES + if (ret == -ENOENT && trace_kprobe_module_exist(tk)) + ret = 0; +#endif /* CONFIG_MODULES */ + if (ret == -ENOENT) { pr_warn("This probe might be able to register after target module is loaded. Continue.\n"); ret = 0; } @@ -670,6 +680,7 @@ 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 +715,7 @@ static struct notifier_block trace_kprobe_module_nb = { .notifier_call = trace_kprobe_module_callback, .priority = 1 /* Invoked after kprobe module callback */ }; +#endif /* CONFIG_MODULES */ static int count_symbols(void *data, unsigned long unused) { @@ -1897,8 +1909,10 @@ 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 /* CONFIG_MODULES */ return 0; }