From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D7FB1C433FE for ; Tue, 18 Oct 2022 00:10:30 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4MrvQF3mgNz3c78 for ; Tue, 18 Oct 2022 11:10:29 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=PUjIyMjq; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4601:e00::1; helo=ams.source.kernel.org; envelope-from=sashal@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=PUjIyMjq; dkim-atps=neutral Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4MrvNR4H7Nz3dqY for ; Tue, 18 Oct 2022 11:08:55 +1100 (AEDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BD8F1B81BE2; Tue, 18 Oct 2022 00:08:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74940C43470; Tue, 18 Oct 2022 00:08:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666051731; bh=UdDPVFaQJcNWxvmfRcEVJIFN+NXqk5f5+e8JCmdnTrw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PUjIyMjqLfj18wmlccfumKNbNOfJhPf5sFQZtUatuu9UEBzEH/JwnFXBdV5JVjcex vr8ir1/9WAlN7nPeNw08hKBW0XsPga2k84a2Ka61dcAbUIr9NlsreYilIcLxNFWm2y a2UvoCJvUkSc/XyTvA7mBHgefR8/SJp+k6MJUK0eWpdK8eiH1X3eJC47u/72LpwYsI aUQ0nZS+vwlRUQzXVBd4Ku1w1eMnLHnoKZW7PH2XB1VWwyT6obCNQSkrgZ1q/98pgu J7G6VgIg0gLhLvbJ2AIQiA1BC1zM3AscU0Tay6i3TAPQ5IcAO9qustyn/T7/cRRKAD obeP/77+pKmAQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 5.19 05/29] powerpc/hw_breakpoint: Avoid relying on caller synchronization Date: Mon, 17 Oct 2022 20:08:14 -0400 Message-Id: <20221018000839.2730954-5-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221018000839.2730954-1-sashal@kernel.org> References: <20221018000839.2730954-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sasha Levin , Ian Rogers , Marco Elver , Peter Zijlstra , linuxppc-dev@lists.ozlabs.org, Dmitry Vyukov Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Marco Elver [ Upstream commit f95e5a3d59011eec1257d0e76de1e1f8969d426f ] Internal data structures (cpu_bps, task_bps) of powerpc's hw_breakpoint implementation have relied on nr_bp_mutex serializing access to them. Before overhauling synchronization of kernel/events/hw_breakpoint.c, introduce 2 spinlocks to synchronize cpu_bps and task_bps respectively, thus avoiding reliance on callers synchronizing powerpc's hw_breakpoint. Reported-by: Dmitry Vyukov Signed-off-by: Marco Elver Signed-off-by: Peter Zijlstra (Intel) Acked-by: Dmitry Vyukov Acked-by: Ian Rogers Link: https://lore.kernel.org/r/20220829124719.675715-10-elver@google.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/hw_breakpoint.c | 53 ++++++++++++++++++++++------- 1 file changed, 40 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c index 2669f80b3a49..8db1a15d7acb 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -129,7 +130,14 @@ struct breakpoint { bool ptrace_bp; }; +/* + * While kernel/events/hw_breakpoint.c does its own synchronization, we cannot + * rely on it safely synchronizing internals here; however, we can rely on it + * not requesting more breakpoints than available. + */ +static DEFINE_SPINLOCK(cpu_bps_lock); static DEFINE_PER_CPU(struct breakpoint *, cpu_bps[HBP_NUM_MAX]); +static DEFINE_SPINLOCK(task_bps_lock); static LIST_HEAD(task_bps); static struct breakpoint *alloc_breakpoint(struct perf_event *bp) @@ -174,7 +182,9 @@ static int task_bps_add(struct perf_event *bp) if (IS_ERR(tmp)) return PTR_ERR(tmp); + spin_lock(&task_bps_lock); list_add(&tmp->list, &task_bps); + spin_unlock(&task_bps_lock); return 0; } @@ -182,6 +192,7 @@ static void task_bps_remove(struct perf_event *bp) { struct list_head *pos, *q; + spin_lock(&task_bps_lock); list_for_each_safe(pos, q, &task_bps) { struct breakpoint *tmp = list_entry(pos, struct breakpoint, list); @@ -191,6 +202,7 @@ static void task_bps_remove(struct perf_event *bp) break; } } + spin_unlock(&task_bps_lock); } /* @@ -200,12 +212,17 @@ static void task_bps_remove(struct perf_event *bp) static bool all_task_bps_check(struct perf_event *bp) { struct breakpoint *tmp; + bool ret = false; + spin_lock(&task_bps_lock); list_for_each_entry(tmp, &task_bps, list) { - if (!can_co_exist(tmp, bp)) - return true; + if (!can_co_exist(tmp, bp)) { + ret = true; + break; + } } - return false; + spin_unlock(&task_bps_lock); + return ret; } /* @@ -215,13 +232,18 @@ static bool all_task_bps_check(struct perf_event *bp) static bool same_task_bps_check(struct perf_event *bp) { struct breakpoint *tmp; + bool ret = false; + spin_lock(&task_bps_lock); list_for_each_entry(tmp, &task_bps, list) { if (tmp->bp->hw.target == bp->hw.target && - !can_co_exist(tmp, bp)) - return true; + !can_co_exist(tmp, bp)) { + ret = true; + break; + } } - return false; + spin_unlock(&task_bps_lock); + return ret; } static int cpu_bps_add(struct perf_event *bp) @@ -234,6 +256,7 @@ static int cpu_bps_add(struct perf_event *bp) if (IS_ERR(tmp)) return PTR_ERR(tmp); + spin_lock(&cpu_bps_lock); cpu_bp = per_cpu_ptr(cpu_bps, bp->cpu); for (i = 0; i < nr_wp_slots(); i++) { if (!cpu_bp[i]) { @@ -241,6 +264,7 @@ static int cpu_bps_add(struct perf_event *bp) break; } } + spin_unlock(&cpu_bps_lock); return 0; } @@ -249,6 +273,7 @@ static void cpu_bps_remove(struct perf_event *bp) struct breakpoint **cpu_bp; int i = 0; + spin_lock(&cpu_bps_lock); cpu_bp = per_cpu_ptr(cpu_bps, bp->cpu); for (i = 0; i < nr_wp_slots(); i++) { if (!cpu_bp[i]) @@ -260,19 +285,25 @@ static void cpu_bps_remove(struct perf_event *bp) break; } } + spin_unlock(&cpu_bps_lock); } static bool cpu_bps_check(int cpu, struct perf_event *bp) { struct breakpoint **cpu_bp; + bool ret = false; int i; + spin_lock(&cpu_bps_lock); cpu_bp = per_cpu_ptr(cpu_bps, cpu); for (i = 0; i < nr_wp_slots(); i++) { - if (cpu_bp[i] && !can_co_exist(cpu_bp[i], bp)) - return true; + if (cpu_bp[i] && !can_co_exist(cpu_bp[i], bp)) { + ret = true; + break; + } } - return false; + spin_unlock(&cpu_bps_lock); + return ret; } static bool all_cpu_bps_check(struct perf_event *bp) @@ -286,10 +317,6 @@ static bool all_cpu_bps_check(struct perf_event *bp) return false; } -/* - * We don't use any locks to serialize accesses to cpu_bps or task_bps - * because are already inside nr_bp_mutex. - */ int arch_reserve_bp_slot(struct perf_event *bp) { int ret; -- 2.35.1