From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0F029378839; Tue, 7 Jul 2026 19:06:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783451177; cv=none; b=fhx9QYMOc16cOXscb1NQ8mQ/1UNYGhjYkT1rTOiItZ0QCELUCtkpFFTUmxpI0t1sIqGGIYI2Cg/50LOTy2ozQ5xPpLFSPjVcmEc5CKHSRkoSULpVXDSQ18Yx6xYm74kLFbqhi6jtVg6oRWPxP/pxP2nj9Olh3NHIeu+LheOk0X8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783451177; c=relaxed/simple; bh=ihmrVJArIw5Arei7GCnzmo+eXzjadSV5bTzArssQBXw=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=pUMisNMdGfNP2RX6Kl66pFEJgJtcWdjbfduOL5qKKnzuKhVenNo0gpEiRnYAu6JXSdtkiSKF44p6sYjY6+w0lsb0ckn8zUUiL2yx11ptUnUDJKSlr0abltFY2UCKOyDAWTsw5RxhMnAE/IOZA8N+ut7w5VxGLqaUl7qrAJ4IIRQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VY1zowse; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VY1zowse" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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