[2/5] kprobes: Use guard() for external locks

Message ID	173371208663.480397.7535769878667655223.stgit@devnote2 (mailing list archive)
State	New
Headers	show 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 8A1BA433BC; Mon, 9 Dec 2024 02:41:33 +0000 (UTC) From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org> To: Steven Rostedt <rostedt@goodmis.org>, Peter Zijlstra <peterz@infradead.org> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>, Masami Hiramatsu <mhiramat@kernel.org>, "David S . Miller" <davem@davemloft.net>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Oleg Nesterov <oleg@redhat.com>, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>, Naveen N Rao <naveen@kernel.org>, Josh Poimboeuf <jpoimboe@kernel.org>, Jason Baron <jbaron@akamai.com>, Ard Biesheuvel <ardb@kernel.org>, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH 2/5] kprobes: Use guard() for external locks Date: Mon, 9 Dec 2024 11:41:26 +0900 Message-ID: <173371208663.480397.7535769878667655223.stgit@devnote2> In-Reply-To: <173371205755.480397.7893311565254712194.stgit@devnote2> References: <173371205755.480397.7893311565254712194.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit
Series	kprobes: jump label: Cleanup with guard and __free \| expand [0/5] kprobes: jump label: Cleanup with guard and __free [1/5] jump_label: Define guard() for jump_label_lock [2/5] kprobes: Use guard() for external locks [3/5] kprobes: Use guard for rcu_read_lock [4/5] kprobes: Remove unneeded goto [5/5] kprobes: Remove remaining gotos

diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 62b5b08d809d..004eb8326520 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -596,41 +596,38 @@ static void kick_kprobe_optimizer(void) /* Kprobe jump optimizer */ static void kprobe_optimizer(struct work_struct *work) { - mutex_lock(&kprobe_mutex); - cpus_read_lock(); - mutex_lock(&text_mutex); + guard(mutex)(&kprobe_mutex); - /* - * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) - * kprobes before waiting for quiesence period. - */ - do_unoptimize_kprobes(); + scoped_guard(cpus_read_lock) { + guard(mutex)(&text_mutex); - /* - * Step 2: Wait for quiesence period to ensure all potentially - * preempted tasks to have normally scheduled. Because optprobe - * may modify multiple instructions, there is a chance that Nth - * instruction is preempted. In that case, such tasks can return - * to 2nd-Nth byte of jump instruction. This wait is for avoiding it. - * Note that on non-preemptive kernel, this is transparently converted - * to synchronoze_sched() to wait for all interrupts to have completed. - */ - synchronize_rcu_tasks(); + /* + * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) + * kprobes before waiting for quiesence period. + */ + do_unoptimize_kprobes(); - /* Step 3: Optimize kprobes after quiesence period */ - do_optimize_kprobes(); + /* + * Step 2: Wait for quiesence period to ensure all potentially + * preempted tasks to have normally scheduled. Because optprobe + * may modify multiple instructions, there is a chance that Nth + * instruction is preempted. In that case, such tasks can return + * to 2nd-Nth byte of jump instruction. This wait is for avoiding it. + * Note that on non-preemptive kernel, this is transparently converted + * to synchronoze_sched() to wait for all interrupts to have completed. + */ + synchronize_rcu_tasks(); - /* Step 4: Free cleaned kprobes after quiesence period */ - do_free_cleaned_kprobes(); + /* Step 3: Optimize kprobes after quiesence period */ + do_optimize_kprobes(); - mutex_unlock(&text_mutex); - cpus_read_unlock(); + /* Step 4: Free cleaned kprobes after quiesence period */ + do_free_cleaned_kprobes(); + } /* Step 5: Kick optimizer again if needed */ if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) kick_kprobe_optimizer(); - - mutex_unlock(&kprobe_mutex); } static void wait_for_kprobe_optimizer_locked(void) @@ -853,29 +850,24 @@ static void try_to_optimize_kprobe(struct kprobe *p) return; /* For preparing optimization, jump_label_text_reserved() is called. */ - cpus_read_lock(); - jump_label_lock(); - mutex_lock(&text_mutex); + guard(cpus_read_lock)(); + guard(jump_label_lock)(); + guard(mutex)(&text_mutex); ap = alloc_aggr_kprobe(p); if (!ap) - goto out; + return; op = container_of(ap, struct optimized_kprobe, kp); if (!arch_prepared_optinsn(&op->optinsn)) { /* If failed to setup optimizing, fallback to kprobe. */ arch_remove_optimized_kprobe(op); kfree(op); - goto out; + return; } init_aggr_kprobe(ap, p); optimize_kprobe(ap); /* This just kicks optimizer thread. */ - -out: - mutex_unlock(&text_mutex); - jump_label_unlock(); - cpus_read_unlock(); } static void optimize_all_kprobes(void) @@ -1158,12 +1150,9 @@ static int arm_kprobe(struct kprobe *kp) if (unlikely(kprobe_ftrace(kp))) return arm_kprobe_ftrace(kp); - cpus_read_lock(); - mutex_lock(&text_mutex); + guard(cpus_read_lock)(); + guard(mutex)(&text_mutex); __arm_kprobe(kp); - mutex_unlock(&text_mutex); - cpus_read_unlock(); - return 0; } @@ -1172,12 +1161,9 @@ static int disarm_kprobe(struct kprobe *kp, bool reopt) if (unlikely(kprobe_ftrace(kp))) return disarm_kprobe_ftrace(kp); - cpus_read_lock(); - mutex_lock(&text_mutex); + guard(cpus_read_lock)(); + guard(mutex)(&text_mutex); __disarm_kprobe(kp, reopt); - mutex_unlock(&text_mutex); - cpus_read_unlock(); - return 0; } @@ -1294,62 +1280,55 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p) int ret = 0; struct kprobe *ap = orig_p; - cpus_read_lock(); - - /* For preparing optimization, jump_label_text_reserved() is called */ - jump_label_lock(); - mutex_lock(&text_mutex); - - if (!kprobe_aggrprobe(orig_p)) { - /* If 'orig_p' is not an 'aggr_kprobe', create new one. */ - ap = alloc_aggr_kprobe(orig_p); - if (!ap) { - ret = -ENOMEM; - goto out; + scoped_guard(cpus_read_lock) { + /* For preparing optimization, jump_label_text_reserved() is called */ + guard(jump_label_lock)(); + guard(mutex)(&text_mutex); + + if (!kprobe_aggrprobe(orig_p)) { + /* If 'orig_p' is not an 'aggr_kprobe', create new one. */ + ap = alloc_aggr_kprobe(orig_p); + if (!ap) + return -ENOMEM; + init_aggr_kprobe(ap, orig_p); + } else if (kprobe_unused(ap)) { + /* This probe is going to die. Rescue it */ + ret = reuse_unused_kprobe(ap); + if (ret) + return ret; } - init_aggr_kprobe(ap, orig_p); - } else if (kprobe_unused(ap)) { - /* This probe is going to die. Rescue it */ - ret = reuse_unused_kprobe(ap); - if (ret) - goto out; - } - if (kprobe_gone(ap)) { - /* - * Attempting to insert new probe at the same location that - * had a probe in the module vaddr area which already - * freed. So, the instruction slot has already been - * released. We need a new slot for the new probe. - */ - ret = arch_prepare_kprobe(ap); - if (ret) + if (kprobe_gone(ap)) { /* - * Even if fail to allocate new slot, don't need to - * free the 'ap'. It will be used next time, or - * freed by unregister_kprobe(). + * Attempting to insert new probe at the same location that + * had a probe in the module vaddr area which already + * freed. So, the instruction slot has already been + * released. We need a new slot for the new probe. */ - goto out; + ret = arch_prepare_kprobe(ap); + if (ret) + /* + * Even if fail to allocate new slot, don't need to + * free the 'ap'. It will be used next time, or + * freed by unregister_kprobe(). + */ + return ret; - /* Prepare optimized instructions if possible. */ - prepare_optimized_kprobe(ap); + /* Prepare optimized instructions if possible. */ + prepare_optimized_kprobe(ap); - /* - * Clear gone flag to prevent allocating new slot again, and - * set disabled flag because it is not armed yet. - */ - ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) - | KPROBE_FLAG_DISABLED; - } - - /* Copy the insn slot of 'p' to 'ap'. */ - copy_kprobe(ap, p); - ret = add_new_kprobe(ap, p); + /* + * Clear gone flag to prevent allocating new slot again, and + * set disabled flag because it is not armed yet. + */ + ap->flags = (ap->flags & ~KPROBE_FLAG_GONE) + | KPROBE_FLAG_DISABLED; + } -out: - mutex_unlock(&text_mutex); - jump_label_unlock(); - cpus_read_unlock(); + /* Copy the insn slot of 'p' to 'ap'. */ + copy_kprobe(ap, p); + ret = add_new_kprobe(ap, p); + } if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) { ap->flags &= ~KPROBE_FLAG_DISABLED; @@ -1559,26 +1538,23 @@ static int check_kprobe_address_safe(struct kprobe *p, ret = check_ftrace_location(p); if (ret) return ret; - jump_label_lock(); + + guard(jump_label_lock)(); /* Ensure the address is in a text area, and find a module if exists. */ *probed_mod = NULL; if (!core_kernel_text((unsigned long) p->addr)) { guard(preempt)(); *probed_mod = __module_text_address((unsigned long) p->addr); - if (!(*probed_mod)) { - ret = -EINVAL; - goto out; - } + if (!(*probed_mod)) + return -EINVAL; /* * We must hold a refcount of the probed module while updating * its code to prohibit unexpected unloading. */ - if (unlikely(!try_module_get(*probed_mod))) { - ret = -ENOENT; - goto out; - } + if (unlikely(!try_module_get(*probed_mod))) + return -ENOENT; } /* Ensure it is not in reserved area. */ if (in_gate_area_no_mm((unsigned long) p->addr) || @@ -1588,8 +1564,7 @@ static int check_kprobe_address_safe(struct kprobe *p, find_bug((unsigned long)p->addr) || is_cfi_preamble_symbol((unsigned long)p->addr)) { module_put(*probed_mod); - ret = -EINVAL; - goto out; + return -EINVAL; } /* Get module refcount and reject __init functions for loaded modules. */ @@ -1601,14 +1576,11 @@ static int check_kprobe_address_safe(struct kprobe *p, if (within_module_init((unsigned long)p->addr, *probed_mod) && !module_is_coming(*probed_mod)) { module_put(*probed_mod); - ret = -ENOENT; + return -ENOENT; } } -out: - jump_label_unlock(); - - return ret; + return 0; } static int __register_kprobe(struct kprobe *p) @@ -1623,14 +1595,13 @@ static int __register_kprobe(struct kprobe *p) /* Since this may unoptimize 'old_p', locking 'text_mutex'. */ return register_aggr_kprobe(old_p, p); - cpus_read_lock(); - /* Prevent text modification */ - mutex_lock(&text_mutex); - ret = prepare_kprobe(p); - mutex_unlock(&text_mutex); - cpus_read_unlock(); - if (ret) - return ret; + scoped_guard(cpus_read_lock) { + /* Prevent text modification */ + guard(mutex)(&text_mutex); + ret = prepare_kprobe(p); + if (ret) + return ret; + } INIT_HLIST_NODE(&p->hlist); hlist_add_head_rcu(&p->hlist,

[2/5] kprobes: Use guard() for external locks

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