From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f74.google.com (mail-ej1-f74.google.com [209.85.218.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CEDE71F560D for ; Thu, 6 Feb 2025 18:18:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738865905; cv=none; b=n9R6H4xHzEtmIKuhDiIrF1JjUW80VD9hafB8PX1tJFBcE9/J7oGexWQrfdOvTn1YMfCMQUWP06dcK7G9X4AkUDvA67ZjIywANSYP8jB5ZGLgtUfa9teePZKmzkt2iDpW6kkGhiHAtt/LS32sQ+9w+coUqLRAprBxYpu7XJRTyzM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738865905; c=relaxed/simple; bh=NUEXWlEAE92KV/GEdPakz1UqBNLjHONT9ssvsb3eGUA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=axSS+AEXoHJLu46maoxQS0LNLZ9oOn/DIurO1tAdcyslOEx+rs3dUC3+JHrOXXxlUBnPwiP5nXHPmcN2bzlRjZpGDFISWvrmORgJYYx7l4KnGJGCXZSnkr7pjP5zf7gd3896bj+sxU83tZIZqxIzeetGUucScORx7ngy+7YMaVQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--elver.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=M/LiMICe; arc=none smtp.client-ip=209.85.218.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--elver.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="M/LiMICe" Received: by mail-ej1-f74.google.com with SMTP id a640c23a62f3a-ab2b300e5daso124379166b.1 for ; Thu, 06 Feb 2025 10:18:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1738865901; x=1739470701; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=wzjNorLMqe8QUgEHsGwtuhtrhRqTVkmGkehlX/wsBpI=; b=M/LiMICeoG+CQ1ynKHv1E9cwRCvcdq0OHOJXSp8UqwzRNCJTbbU0xrclZfDkck3Ff9 fSD6R7gtc22vQMoogEzmQ4VOt52hNsWMO426mIKKQTmjlK22VDdCEH+uvaBiE0Z4new4 PTXoxG+Pwu4tH6TbJwrFdPkuAlRKbAxpQ6KwFRw97+6b2HD9ZkyCpKKV3lBL1S2/5TTV dgKlN3bwk1A1REScmeDJVOH3nOogBlLcKv6O8ASRv3gKw1ps747DUKVr8NF5fhzcJq6T Fk0dlaIdufOZzcKQmVKYXCR8hpn7CERY6pvyAwremUzSOqgqQLVE6XdlX+AhjBZdusEn Y8Ow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738865901; x=1739470701; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=wzjNorLMqe8QUgEHsGwtuhtrhRqTVkmGkehlX/wsBpI=; b=o6/wWfq2rybJz3CwkCGrmDroAsaWn/2SRf+1aw9pdmquHOGoxP16JGvWf+s3WhHQov j+NLS2tavkbkNIdwnlC9YQiHLQlRJEBxIbfeCECbIVgTsK9pSsfhAwCiE6ITTvNFgb4r SimbsjWRydHAdMb6FIBch3zrZB5Afr83aIZjCsgBp2W5fIgFDxCRoqwqSviMZfQZxLk4 xBaEmP8Ot5l4ntjRAMteIJoztc70f42OeSYF8tIXPqcmA2/8Piobw4rbFQdXVRZ5Zjdg X1WzmTmFv8U74mEBnO1Ff8TK7+0GsnDHzD0MoytamvRysErnN2pfCqyTuxKlX8PX8+dk hGIg== X-Forwarded-Encrypted: i=1; AJvYcCXBqZuwfEFWEJi7fdj62IUgg4I5ih8lT0B9c4a4hE9cFkJGxoqFJjmp6X+jZi6t7LIm+2cZ@lists.linux.dev X-Gm-Message-State: AOJu0YwWFD7gk7iQPmgffB3g1KsOSNXQeawxGznO/6wFiJH9GWhlbtiG jTHzQqAUsZVOvgguqhVAypcZtnx0eqJaNXMpbuMIqb4XB7yjt4S4pYkzPOfezOkFzMw1aisy6g= = X-Google-Smtp-Source: AGHT+IFsRC9lsbg4c4TRqzZ93jQ5joCg0R4FF8MgHcqadtERExxxGFc9QGo4Fx50fBZiM7U81D6CptTy4g== X-Received: from edag33.prod.google.com ([2002:a05:6402:3221:b0:5dc:74ee:c4dd]) (user=elver job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:3903:b0:5dc:da2f:9cda with SMTP id 4fb4d7f45d1cf-5de450e1eccmr537344a12.27.1738865901391; Thu, 06 Feb 2025 10:18:21 -0800 (PST) Date: Thu, 6 Feb 2025 19:10:08 +0100 In-Reply-To: <20250206181711.1902989-1-elver@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250206181711.1902989-1-elver@google.com> X-Mailer: git-send-email 2.48.1.502.g6dc24dfdaf-goog Message-ID: <20250206181711.1902989-15-elver@google.com> Subject: [PATCH RFC 14/24] bit_spinlock: Support Clang's capability analysis From: Marco Elver To: elver@google.com Cc: "Paul E. McKenney" , Alexander Potapenko , Bart Van Assche , Bill Wendling , Boqun Feng , Dmitry Vyukov , Frederic Weisbecker , Greg Kroah-Hartman , Ingo Molnar , Jann Horn , Joel Fernandes , Jonathan Corbet , Josh Triplett , Justin Stitt , Kees Cook , Mark Rutland , Mathieu Desnoyers , Miguel Ojeda , Nathan Chancellor , Neeraj Upadhyay , Nick Desaulniers , Peter Zijlstra , Steven Rostedt , Thomas Gleixner , Uladzislau Rezki , Waiman Long , Will Deacon , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, rcu@vger.kernel.org, linux-crypto@vger.kernel.org Content-Type: text/plain; charset="UTF-8" The annotations for bit_spinlock.h have simply been using "bitlock" as the token. For Sparse, that was likely sufficient in most cases. But Clang's capability analysis is more precise, and we need to ensure we can distinguish different bitlocks. To do so, add a token capability, and a macro __bitlock(bitnum, addr) that is used to construct unique per-bitlock tokens. Add the appropriate test. is implicitly included through other includes, and requires 2 annotations to indicate that acquisition (without release) and release (without prior acquisition) of its bitlock is intended. Signed-off-by: Marco Elver --- .../dev-tools/capability-analysis.rst | 3 ++- include/linux/bit_spinlock.h | 22 +++++++++++++--- include/linux/list_bl.h | 2 ++ lib/test_capability-analysis.c | 26 +++++++++++++++++++ 4 files changed, 48 insertions(+), 5 deletions(-) diff --git a/Documentation/dev-tools/capability-analysis.rst b/Documentation/dev-tools/capability-analysis.rst index 8d9336e91ce2..a34dfe7b0b09 100644 --- a/Documentation/dev-tools/capability-analysis.rst +++ b/Documentation/dev-tools/capability-analysis.rst @@ -85,7 +85,8 @@ Supported Kernel Primitives ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Currently the following synchronization primitives are supported: -`raw_spinlock_t`, `spinlock_t`, `rwlock_t`, `mutex`, `seqlock_t`. +`raw_spinlock_t`, `spinlock_t`, `rwlock_t`, `mutex`, `seqlock_t`, +`bit_spinlock`. For capabilities with an initialization function (e.g., `spin_lock_init()`), calling this function on the capability instance before initializing any diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h index f1174a2fcc4d..57114b44ce5d 100644 --- a/include/linux/bit_spinlock.h +++ b/include/linux/bit_spinlock.h @@ -9,6 +9,16 @@ #include /* for cpu_relax() */ +/* + * For static capability analysis, we need a unique token for each possible bit + * that can be used as a bit_spinlock. The easiest way to do that is to create a + * fake capability that we can cast to with the __bitlock(bitnum, addr) macro + * below, which will give us unique instances for each (bit, addr) pair that the + * static analysis can use. + */ +struct_with_capability(__capability_bitlock) { }; +#define __bitlock(bitnum, addr) (struct __capability_bitlock *)(bitnum + (addr)) + /* * bit-based spin_lock() * @@ -16,6 +26,7 @@ * are significantly faster. */ static inline void bit_spin_lock(int bitnum, unsigned long *addr) + __acquires(__bitlock(bitnum, addr)) { /* * Assuming the lock is uncontended, this never enters @@ -34,13 +45,14 @@ static inline void bit_spin_lock(int bitnum, unsigned long *addr) preempt_disable(); } #endif - __acquire(bitlock); + __acquire(__bitlock(bitnum, addr)); } /* * Return true if it was acquired */ static inline int bit_spin_trylock(int bitnum, unsigned long *addr) + __cond_acquires(1, __bitlock(bitnum, addr)) { preempt_disable(); #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) @@ -49,7 +61,7 @@ static inline int bit_spin_trylock(int bitnum, unsigned long *addr) return 0; } #endif - __acquire(bitlock); + __acquire(__bitlock(bitnum, addr)); return 1; } @@ -57,6 +69,7 @@ static inline int bit_spin_trylock(int bitnum, unsigned long *addr) * bit-based spin_unlock() */ static inline void bit_spin_unlock(int bitnum, unsigned long *addr) + __releases(__bitlock(bitnum, addr)) { #ifdef CONFIG_DEBUG_SPINLOCK BUG_ON(!test_bit(bitnum, addr)); @@ -65,7 +78,7 @@ static inline void bit_spin_unlock(int bitnum, unsigned long *addr) clear_bit_unlock(bitnum, addr); #endif preempt_enable(); - __release(bitlock); + __release(__bitlock(bitnum, addr)); } /* @@ -74,6 +87,7 @@ static inline void bit_spin_unlock(int bitnum, unsigned long *addr) * protecting the rest of the flags in the word. */ static inline void __bit_spin_unlock(int bitnum, unsigned long *addr) + __releases(__bitlock(bitnum, addr)) { #ifdef CONFIG_DEBUG_SPINLOCK BUG_ON(!test_bit(bitnum, addr)); @@ -82,7 +96,7 @@ static inline void __bit_spin_unlock(int bitnum, unsigned long *addr) __clear_bit_unlock(bitnum, addr); #endif preempt_enable(); - __release(bitlock); + __release(__bitlock(bitnum, addr)); } /* diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h index ae1b541446c9..df9eebe6afca 100644 --- a/include/linux/list_bl.h +++ b/include/linux/list_bl.h @@ -144,11 +144,13 @@ static inline void hlist_bl_del_init(struct hlist_bl_node *n) } static inline void hlist_bl_lock(struct hlist_bl_head *b) + __acquires(__bitlock(0, b)) { bit_spin_lock(0, (unsigned long *)b); } static inline void hlist_bl_unlock(struct hlist_bl_head *b) + __releases(__bitlock(0, b)) { __bit_spin_unlock(0, (unsigned long *)b); } diff --git a/lib/test_capability-analysis.c b/lib/test_capability-analysis.c index 1e4b90f76420..fc8dcad2a994 100644 --- a/lib/test_capability-analysis.c +++ b/lib/test_capability-analysis.c @@ -4,6 +4,7 @@ * positive errors when compiled with Clang's capability analysis. */ +#include #include #include #include @@ -251,3 +252,28 @@ static void __used test_seqlock_writer(struct test_seqlock_data *d) d->counter++; write_sequnlock_irqrestore(&d->sl, flags); } + +struct test_bit_spinlock_data { + unsigned long bits; + int counter __var_guarded_by(__bitlock(3, &bits)); +}; + +static void __used test_bit_spin_lock(struct test_bit_spinlock_data *d) +{ + /* + * Note, the analysis seems to have false negatives, because it won't + * precisely recognize the bit of the fake __bitlock() token. + */ + bit_spin_lock(3, &d->bits); + d->counter++; + bit_spin_unlock(3, &d->bits); + + bit_spin_lock(3, &d->bits); + d->counter++; + __bit_spin_unlock(3, &d->bits); + + if (bit_spin_trylock(3, &d->bits)) { + d->counter++; + bit_spin_unlock(3, &d->bits); + } +} -- 2.48.1.502.g6dc24dfdaf-goog