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 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 7AA03C44503 for ; Tue, 7 Jul 2026 19:06:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:Subject:Cc:To:From:Message-ID:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: List-Owner; bh=LBj+ZkGRdAQN74z4D94PD8p6NaRtGe8kKF18FGUoSBc=; b=vdXnVOn99LMPgf PPvre1BHrBeR22oCLJsmxsA2qq0y1c0WkPqBzmq4SEYYxxeEWkAGjvyODISeyyYWaUjuuGIp7MVd9 1qKcsj8Bc0oLX6v7vzqN5uIha5gEPPnhyBDABmJtD509jmT/M7STkmDC0ntujhK+xluOWvNoCRPl0 eNNF/KOenuVsnHfgNRFxE0ZGxHmnW4Ye+iLBBNr+/ybMgGQkTVy12lV1pxcPB9r7Ltx/yTzJfifPT TniUReIhfoMLMAKfQnJ+AtNF1jmUwsayJTEj+2+sIfdzWfSC7//IuqXOT3pH5nc0CmUbrcX7569ZA tqtvw5WHGpVQh0scL6Ag==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whB7X-0000000Fgpm-0aoE; Tue, 07 Jul 2026 19:06:15 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1whB7S-0000000FgkQ-1a9d; Tue, 07 Jul 2026 19:06:10 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id CAD1561384; Tue, 7 Jul 2026 19:06:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B438D1F00A3D; Tue, 7 Jul 2026 19:06:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783451169; bh=LBj+ZkGRdAQN74z4D94PD8p6NaRtGe8kKF18FGUoSBc=; h=Date:From:To:Cc:Subject:References; b=VY1zowsespAaLkdQfjN21WoDu0I2bpmruM24iQyJPomLBoNcfhRcxHp71u2Qaoz8w 2Y6R/xVT7Yp0jxQTc8E5PWuftOuCpOuAgoGxlRSnJZdeLFmp/X5t3iL3htCKZRfn3+ ZILTZaA9qyxubwDpKLYazC72ZykMomE0EWqkxhprvJrhHU6PoirMY9t5PUOI4e22OR 1Mzlboe/bN4bCNA4g1TTcbgSS+G0cMdMv/Ny3g+iZse0ddGOTpczuxmdM6Qdp/eE7e Cdr45b4mkb4xZpki9QM7BPX+TNtyRnQRDjpUHUDvask5gaQC50oiZ/ZZKDlC+8+3Ru MjqY28jZMNheA== Date: Tue, 07 Jul 2026 21:06:07 +0200 Message-ID: <20260707190253.816918647@kernel.org> User-Agent: quilt/0.69 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Michael Ellerman , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, Kees Cook , Huacai Chen , loongarch@lists.linux.dev, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Sven Schnelle , linux-s390@vger.kernel.org, x86@kernel.org, Mark Rutland , Jinjie Ruan , Andy Lutomirski , Oleg Nesterov , Richard Henderson , Russell King , Catalin Marinas , Guo Ren , Geert Uytterhoeven , Thomas Bogendoerfer , Helge Deller , Yoshinori Sato , Richard Weinberger , Chris Zankel , linux-arm-kernel@lists.infradead.org, linux-alpha@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-um@lists.infradead.org, Arnd Bergmann , Vineet Gupta , Will Deacon , Brian Cain , Michal Simek , Dinh Nguyen , "David S. Miller" , Andreas Larsson , linux-snps-arc@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, =?UTF-8?q?Michal=20Such=C3=A1nek?= , Jonathan Corbet , linux-doc@vger.kernel.org Subject: [patch 03/18] entry: Provide [syscall_]enter_from_user_mode_randomize_stack() References: <20260707181957.433213175@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-BeenThere: linux-um@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-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org Randomizing the syscall stack can only happen after state is established via enter_from_user_mode() or syscall_enter_from_user_mode(). The earlier it happens the better. Provide two new macros to consolidate that: - enter_from_user_mode_randomize_stack() enter_from_user_mode(); add_random_kstack_offset_irqsoff(); - syscall_enter_from_user_mode_randomize_stack() enter_from_user_mode_randomize_stack(); syscall_enter_from_user_mode_work(); to reduce boiler plate code. Those are macros and not inline functions as the latter would limit the stack randomization scope to the inline function itself. Signed-off-by: Thomas Gleixner --- include/linux/entry-common.h | 56 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -150,6 +151,61 @@ static __always_inline long syscall_ente } /** + * enter_from_user_mode_randomize_stack - Establish state and add stack randomization + * before invoking syscall_enter_from_user_mode_work() + * @regs: Pointer to currents pt_regs + * + * Invoked from architecture specific syscall entry code with interrupts + * disabled. The calling code has to be non-instrumentable. When the function + * returns all state is correct, interrupts are still disabled and the + * subsequent functions can be instrumented. + * + * Implemented as a macro so that the stack randomization is effective + * throughout the function in which it is invoked. An inline would only make it + * effective in the scope of the inline function. + */ +#define enter_from_user_mode_randomize_stack(regs) \ +do { \ + enter_from_user_mode(regs); \ + instrumentation_begin(); \ + add_random_kstack_offset_irqsoff(); \ + instrumentation_end(); \ +} while (0) + +/** + * syscall_enter_from_user_mode_randomize_stack - Establish state and check and handle work + * before invoking a syscall + * @regs: Pointer to currents pt_regs + * @syscall: The syscall number + * + * Invoked from architecture specific syscall entry code with interrupts + * disabled. The calling code has to be non-instrumentable. When the + * function returns all state is correct, interrupts are enabled and the + * subsequent functions can be instrumented. + * + * This is the combination of enter_from_user_mode_randomize_stack() and + * syscall_enter_from_user_mode_work() to be used when there is no + * architecture specific work to be done between the two. + * + * Returns: The original or a modified syscall number. See + * syscall_enter_from_user_mode_work() for further explanation. + * + * Implemented as a macro to make stack randomization effective in the calling + * scope. + */ +#define syscall_enter_from_user_mode_randomize_stack(regs, syscall) \ +({ \ + enter_from_user_mode_randomize_stack(regs); \ + \ + instrumentation_begin(); \ + local_irq_enable(); \ + long _ret = syscall_enter_from_user_mode_work(regs, syscall); \ + instrumentation_end(); \ + \ + _ret; \ +}) + +/** * syscall_enter_from_user_mode - Establish state and check and handle work * before invoking a syscall * @regs: Pointer to currents pt_regs