From mboxrd@z Thu Jan 1 00:00:00 1970 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 7A7EDFBE1; Mon, 11 Dec 2023 18:36:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bDaLSs6D" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F39ECC433C8; Mon, 11 Dec 2023 18:36:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1702319779; bh=Ibf14BlzmqR6ginzJtsRRFzdOdoY7qWxenIxQgDreqw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bDaLSs6Dc8vzW7HZB7vbQtVXmmIXJd0dmWlj0ghVDgCZnBk87qb8SulAKdkJSjM7i DYTEgdwVMGPJx5gK4VRBj+c4QA9STOJpM265+edOnlB7dqr49W6HycrCtCd7KH51gx 4zUWoJ2+gplw9zFTNGZuK5WS2ZdlkAuvZU9MWT6s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Aurelien Jarno , Jiaxun Yang , Thomas Bogendoerfer Subject: [PATCH 6.6 230/244] MIPS: kernel: Clear FPU states when setting up kernel threads Date: Mon, 11 Dec 2023 19:22:03 +0100 Message-ID: <20231211182056.341834152@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231211182045.784881756@linuxfoundation.org> References: <20231211182045.784881756@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Bogendoerfer commit a58a173444a68412bb08849bd81c679395f20ca0 upstream. io_uring sets up the io worker kernel thread via a syscall out of an user space prrocess. This process might have used FPU and since copy_thread() didn't clear FPU states for kernel threads a BUG() is triggered for using FPU inside kernel. Move code around to always clear FPU state for user and kernel threads. Cc: stable@vger.kernel.org Reported-by: Aurelien Jarno Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1055021 Suggested-by: Jiaxun Yang Reviewed-by: Jiaxun Yang Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman --- arch/mips/kernel/process.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -121,6 +121,19 @@ int copy_thread(struct task_struct *p, c /* Put the stack after the struct pt_regs. */ childksp = (unsigned long) childregs; p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK; + + /* + * New tasks lose permission to use the fpu. This accelerates context + * switching for most programs since they don't use the fpu. + */ + clear_tsk_thread_flag(p, TIF_USEDFPU); + clear_tsk_thread_flag(p, TIF_USEDMSA); + clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE); + +#ifdef CONFIG_MIPS_MT_FPAFF + clear_tsk_thread_flag(p, TIF_FPUBOUND); +#endif /* CONFIG_MIPS_MT_FPAFF */ + if (unlikely(args->fn)) { /* kernel thread */ unsigned long status = p->thread.cp0_status; @@ -149,20 +162,8 @@ int copy_thread(struct task_struct *p, c p->thread.reg29 = (unsigned long) childregs; p->thread.reg31 = (unsigned long) ret_from_fork; - /* - * New tasks lose permission to use the fpu. This accelerates context - * switching for most programs since they don't use the fpu. - */ childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); - clear_tsk_thread_flag(p, TIF_USEDFPU); - clear_tsk_thread_flag(p, TIF_USEDMSA); - clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE); - -#ifdef CONFIG_MIPS_MT_FPAFF - clear_tsk_thread_flag(p, TIF_FPUBOUND); -#endif /* CONFIG_MIPS_MT_FPAFF */ - #ifdef CONFIG_MIPS_FP_SUPPORT atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE); #endif