From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751418AbdBIEgX (ORCPT ); Wed, 8 Feb 2017 23:36:23 -0500 Received: from mail-pg0-f68.google.com ([74.125.83.68]:33097 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114AbdBIEgU (ORCPT ); Wed, 8 Feb 2017 23:36:20 -0500 From: Hoeun Ryu To: Kees Cook , Michal Marek , Andrew Morton , Emese Revfy , Ingo Molnar , =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Nicholas Piggin , Andy Lutomirski , Michal Hocko , "Eric W. Biederman" , Mateusz Guzik Cc: linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Hoeun Ryu Subject: [PATCH v2 2/2] fork: make number of cached stacks (vmapped) configurable using Kbuild Date: Thu, 9 Feb 2017 13:03:47 +0900 Message-Id: <1486613040-30555-2-git-send-email-hoeun.ryu@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1486613040-30555-1-git-send-email-hoeun.ryu@gmail.com> References: <1486613040-30555-1-git-send-email-hoeun.ryu@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Introducing NR_VMAP_STACK_CACHE, the number of cached stacks for virtually mapped kernel stack can be configurable using Kbuild system. default value is 2. Signed-off-by: Hoeun Ryu --- arch/Kconfig | 8 ++++++++ kernel/fork.c | 2 +- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/Kconfig b/arch/Kconfig index d49a8e6..066d111 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -849,6 +849,14 @@ config VMAP_STACK the stack to map directly to the KASAN shadow map using a formula that is incorrect if the stack is in vmalloc space. +config NR_VMAP_STACK_CACHE + int "Number of cached stacks" + default "2" + depends on VMAP_STACK + help + This determines how many stacks can be cached for virtually + mapped kernel stacks. + config ARCH_WANT_RELAX_ORDER bool diff --git a/kernel/fork.c b/kernel/fork.c index 7911ed2..73ba1da 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -166,7 +166,7 @@ void __weak arch_release_thread_stack(unsigned long *stack) * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB * flush. Try to minimize the number of calls by caching stacks. */ -#define NR_CACHED_STACKS 2 +#define NR_CACHED_STACKS CONFIG_NR_VMAP_STACK_CACHE static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); #endif -- 2.7.4