From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (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 E7C883CF1E5; Wed, 14 Oct 2026 09:53:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791971604; cv=none; b=r+cP2CxiuoIWnTogwKCi8EMKXoMlX/qx6Bk8/Leev0/j+HH0L0gd7I2xtt4DvMggZ+YGg7oUajZAl/SMguneDUP2SBdxMfFFOAcmNih0rIiQCkVd7c6rSqNnsvfhrIhut3U7WLL0eN31Ec7k4MNBmT0MIXFzcNdyBwfiMyvvRBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791971604; c=relaxed/simple; bh=biPtmC0wOFMGfWl9M/PsEX6DOpe2VvgmQEmZJgJUhrU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=NMCFkZcGEAdRRJwDWAGKcafQF4C6ctNv6zhyoGAPBgu1Kulqfhh4OrKONl8Xs3t3SfbLCdUiX8OhQfXXZ8ZIA7F98UfMrIEdwBjk9xPKay5kgyC85KOIB8WrArqoMPBelRQzLV1g9GLJGinaqObsBspO2sbrsUWzjN4dd64bSOc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=j/iRy6Hg; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="j/iRy6Hg" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=nj il1zqbwsx3R7+HXKM6YsB1392h9RcOPNgYxsO1yKc=; b=j/iRy6HgRoWPCvfRRV g0u3x5Y4FnZbesFrH3r7CNz1szgPhvuZx2bVI8ots++53TKgNpTRGkreDrO3satZ QWzMSmxfLV14iIwULyHks3N5uBrt5qmvOKEFPGr8BpeX6+Tor8PpgN1rbqVytH9c glC1f/KUaPkVik5/OJmFMDBng= Received: from localhost (unknown []) by gzga-smtp-mtada-g0-2 (Coremail) with SMTP id _____wAnTvTnUM9q6kpbEQ--.10126S2; Wed, 14 Oct 2026 17:52:40 +0800 (CST) From: Hui Su To: elver@google.com, dvyukov@google.com Cc: kasan-dev@googlegroups.com, corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 1/4] kcsan: add targeted watchpoint matching Date: Wed, 14 Oct 2026 18:52:35 +0900 Message-ID: <20261014095238.2132580-2-sh_def@163.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wAnTvTnUM9q6kpbEQ--.10126S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxCw15XF4fCry5tFWxJr4xZwb_yoW5ZFyDpF yDKryrJ398XFWavF43A3WDZr1rGw1kGry7tFWxC39293W5Kr9ag34kWr9rtF4jgrZF9F15 GFZ8ArZ5CrWUJ3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jb8n5UUUUU= X-CM-SenderInfo: xvkbvvri6rljoofrz/xtbC6QjcPGrPUOjT4QAA3u Add target state and a static key to KCSAN. When a target is set, only non-atomic instrumented accesses containing that address are eligible for watchpoint setup. Other accesses do not consume the skip interval. Keep report filtering independent from target matching. Signed-off-by: Hui Su --- kernel/kcsan/core.c | 37 +++++++++++++++++++++++++++++++++++++ kernel/kcsan/kcsan.h | 10 ++++++++++ 2 files changed, 47 insertions(+) diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index 2db82661cd60..2a58a3a53adb 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -12,10 +12,12 @@ #include #include #include +#include #include #include #include #include +#include #include #include #include @@ -108,9 +110,40 @@ static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS-1]; */ static DEFINE_PER_CPU(long, kcsan_skip); +static DEFINE_STATIC_KEY_FALSE(kcsan_target_key); +static DEFINE_MUTEX(kcsan_target_lock); +static unsigned long kcsan_target_addr; + /* For kcsan_prandom_u32_max(). */ static DEFINE_PER_CPU(u32, kcsan_rand_state); +void kcsan_target_set(unsigned long addr) +{ + unsigned long old; + + mutex_lock(&kcsan_target_lock); + old = READ_ONCE(kcsan_target_addr); + + if (!old && addr) { + /* Publish the address before enabling the fast-path branch. */ + WRITE_ONCE(kcsan_target_addr, addr); + static_branch_enable(&kcsan_target_key); + } else if (old && !addr) { + /* Disable the fast-path branch before invalidating the target. */ + static_branch_disable(&kcsan_target_key); + WRITE_ONCE(kcsan_target_addr, 0); + } else if (old && addr) { + WRITE_ONCE(kcsan_target_addr, addr); + } + + mutex_unlock(&kcsan_target_lock); +} + +unsigned long kcsan_target_get(void) +{ + return READ_ONCE(kcsan_target_addr); +} + static __always_inline atomic_long_t *find_watchpoint(unsigned long addr, size_t size, bool expect_write, @@ -277,6 +310,10 @@ should_watch(struct kcsan_ctx *ctx, const volatile void *ptr, size_t size, int t if (is_atomic(ctx, ptr, size, type)) return false; + if (static_branch_unlikely(&kcsan_target_key)) + return kcsan_target_matches(READ_ONCE(kcsan_target_addr), + (unsigned long)ptr, size); + if (this_cpu_dec_return(kcsan_skip) >= 0) return false; diff --git a/kernel/kcsan/kcsan.h b/kernel/kcsan/kcsan.h index ae33c2a7f07e..2a36813c3a76 100644 --- a/kernel/kcsan/kcsan.h +++ b/kernel/kcsan/kcsan.h @@ -25,6 +25,16 @@ extern unsigned int kcsan_udelay_interrupt; */ extern bool kcsan_enabled; +void kcsan_target_set(unsigned long addr); +unsigned long kcsan_target_get(void); + +static __always_inline bool +kcsan_target_matches(unsigned long target, unsigned long addr, + size_t size) +{ + return size && target >= addr && target - addr < size; +} + /* * Save/restore IRQ flags state trace dirtied by KCSAN. */ -- 2.55.0