From patchwork Sun Mar 13 01:22:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 12779010 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 CB3DEC433F5 for ; Sun, 13 Mar 2022 01:24:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=IiiLFhSVnFyBi77aiz5GVNJVmh8iHTUhAu6+MUYO0fk=; b=hCUn1IVtUHMB6j oN5KsY/ijkYfNTlFtkuTT2A6RNK/nwjiMxb4WmlsAHLAV148woXUVCNmvpWuo6sqKdTbLjk3inLQr 6Y/34mn3m0DRYZHbcDcOPIv7hsZID4HmCosml6yX3OKjlmC2yL2cKf99opmB8YDW/QvoXfSlJAJ15 MZfirYCDeXiGQDlF/FatUgVKwADrib6koeHKrFrCUWF5suZNpemhYD5X/UHbqltCk+icpDn2TxLkD 12c3GMCoFLgjJI/DPC6/a8ZeSfwe51/gfE2enky+gdc0YoA1Weg8O84TCZrQsyIQP3kZpsaaP5Yuv RilXJf3yskitGp8a2QIA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nTCwT-0025yW-Go; Sun, 13 Mar 2022 01:22:41 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nTCwP-0025y2-Ov; Sun, 13 Mar 2022 01:22:39 +0000 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 dfw.source.kernel.org (Postfix) with ESMTPS id 3F88060DEE; Sun, 13 Mar 2022 01:22:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22CFDC340EC; Sun, 13 Mar 2022 01:22:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647134556; bh=2YQxyoOOki3WVR0j2UQxO+ys6flh/Qon049D3a/0iu4=; h=From:To:Cc:Subject:Date:From; b=X8p7gwzI+mEmzlREpKziVcY64DsccPFAFM4hgwI1QNXHep1omrAqPvLt0uDzeEV2k que4wgyhPK2NY4Dj+CM3UDAZDPLA5n+H/349nJobRRVQhjbBzUoLcILzj977Dq2ljV v28IIMz2kFn4vbwfzfpb0bh3Ytmp4FjOwgs3oJmyGAd8YBNB/xMuitxgmNkaBHog7c f8ySilpnVPW1S97/HZORNWobKILN3ZuSn+iE2avxdH9g70BsSF15kvXeWiEHb9GR88 XCuUluRfu+4bJ7EG2jMlJJVAF5kbYIOykB+MES5V145Mnvpp4+OrrYagW+hwZsVKNE pnCWpXW9Ja8dg== From: guoren@kernel.org To: guoren@kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, linux-xtensa@linux-xtensa.org, Guo Ren , Max Filippov , Will Deacon , Catalin Marinas , Palmer Dabbelt , Masami Hiramatsu , Chris Zankel , Arnd Bergmann Subject: [PATCH V2] arch: patch_text: Fixup last cpu should be master Date: Sun, 13 Mar 2022 09:22:21 +0800 Message-Id: <20220313012221.1755483-1-guoren@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220312_172237_936247_19B4D923 X-CRM114-Status: GOOD ( 17.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Guo Ren These patch_text implementations are using stop_machine_cpuslocked infrastructure with atomic cpu_count. The original idea: When the master CPU patch_text, the others should wait for it. But current implementation is using the first CPU as master, which couldn't guarantee the remaining CPUs are waiting. This patch changes the last CPU as the master to solve the potential risk. Signed-off-by: Guo Ren Signed-off-by: Guo Ren Reviewed-by: Max Filippov Cc: Will Deacon Cc: Catalin Marinas Cc: Palmer Dabbelt Cc: Peter Zijlstra Cc: Chris Zankel Cc: Arnd Bergmann Reviewed-by: Catalin Marinas Acked-by: Palmer Dabbelt # RISC-V Reviewed-by: Masami Hiramatsu --- Changes in V2: - Fixup last cpu should be num_online_cpus() by Max Filippov - Fixup typos found by Max Filippov --- arch/arm64/kernel/patching.c | 4 ++-- arch/csky/kernel/probes/kprobes.c | 2 +- arch/riscv/kernel/patch.c | 2 +- arch/xtensa/kernel/jump_label.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/patching.c b/arch/arm64/kernel/patching.c index 771f543464e0..33e0fabc0b79 100644 --- a/arch/arm64/kernel/patching.c +++ b/arch/arm64/kernel/patching.c @@ -117,8 +117,8 @@ static int __kprobes aarch64_insn_patch_text_cb(void *arg) int i, ret = 0; struct aarch64_insn_patch *pp = arg; - /* The first CPU becomes master */ - if (atomic_inc_return(&pp->cpu_count) == 1) { + /* The last CPU becomes master */ + if (atomic_inc_return(&pp->cpu_count) == num_online_cpus()) { for (i = 0; ret == 0 && i < pp->insn_cnt; i++) ret = aarch64_insn_patch_text_nosync(pp->text_addrs[i], pp->new_insns[i]); diff --git a/arch/csky/kernel/probes/kprobes.c b/arch/csky/kernel/probes/kprobes.c index 42920f25e73c..34ba684d5962 100644 --- a/arch/csky/kernel/probes/kprobes.c +++ b/arch/csky/kernel/probes/kprobes.c @@ -30,7 +30,7 @@ static int __kprobes patch_text_cb(void *priv) struct csky_insn_patch *param = priv; unsigned int addr = (unsigned int)param->addr; - if (atomic_inc_return(¶m->cpu_count) == 1) { + if (atomic_inc_return(¶m->cpu_count) == num_online_cpus()) { *(u16 *) addr = cpu_to_le16(param->opcode); dcache_wb_range(addr, addr + 2); atomic_inc(¶m->cpu_count); diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 0b552873a577..765004b60513 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -104,7 +104,7 @@ static int patch_text_cb(void *data) struct patch_insn *patch = data; int ret = 0; - if (atomic_inc_return(&patch->cpu_count) == 1) { + if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) { ret = patch_text_nosync(patch->addr, &patch->insn, GET_INSN_LENGTH(patch->insn)); diff --git a/arch/xtensa/kernel/jump_label.c b/arch/xtensa/kernel/jump_label.c index 61cf6497a646..b67efcd7e32c 100644 --- a/arch/xtensa/kernel/jump_label.c +++ b/arch/xtensa/kernel/jump_label.c @@ -40,7 +40,7 @@ static int patch_text_stop_machine(void *data) { struct patch *patch = data; - if (atomic_inc_return(&patch->cpu_count) == 1) { + if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) { local_patch_text(patch->addr, patch->data, patch->sz); atomic_inc(&patch->cpu_count); } else {