From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id A99796B0009 for ; Thu, 8 Feb 2018 05:09:25 -0500 (EST) Received: by mail-pf0-f197.google.com with SMTP id i15so1949092pfa.22 for ; Thu, 08 Feb 2018 02:09:25 -0800 (PST) Received: from mga03.intel.com (mga03.intel.com. [134.134.136.65]) by mx.google.com with ESMTPS id 33-v6si2571912ply.512.2018.02.08.02.09.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 08 Feb 2018 02:09:24 -0800 (PST) From: Wei Wang Subject: [PATCH v28 3/4] mm/page_poison: add a function to expose page poison val to kernel modules Date: Thu, 8 Feb 2018 17:50:19 +0800 Message-Id: <1518083420-11108-4-git-send-email-wei.w.wang@intel.com> In-Reply-To: <1518083420-11108-1-git-send-email-wei.w.wang@intel.com> References: <1518083420-11108-1-git-send-email-wei.w.wang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, akpm@linux-foundation.org Cc: pbonzini@redhat.com, wei.w.wang@intel.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com, huangzhichao@huawei.com Move the PAGE_POISON value to page_poison.c and add a function to enable callers from a kernel module to get the poison value if the page poisoning feature is in use. This also avoids callers directly checking PAGE_POISON regardless of whether the feature is enabled. Signed-off-by: Wei Wang Cc: Andrew Morton Cc: Michal Hocko Cc: Michael S. Tsirkin --- include/linux/mm.h | 2 ++ include/linux/poison.h | 7 ------- mm/page_poison.c | 24 ++++++++++++++++++++++++ 3 files changed, 26 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 1c77d88..d95e5d3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2469,11 +2469,13 @@ extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, extern bool page_poisoning_enabled(void); extern void kernel_poison_pages(struct page *page, int numpages, int enable); extern bool page_is_poisoned(struct page *page); +extern bool page_poison_val_get(u8 *val); #else static inline bool page_poisoning_enabled(void) { return false; } static inline void kernel_poison_pages(struct page *page, int numpages, int enable) { } static inline bool page_is_poisoned(struct page *page) { return false; } +static inline bool page_poison_val_get(u8 *val) { return false; }; #endif #ifdef CONFIG_DEBUG_PAGEALLOC diff --git a/include/linux/poison.h b/include/linux/poison.h index 15927eb..348bf67 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -30,13 +30,6 @@ */ #define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA) -/********** mm/debug-pagealloc.c **********/ -#ifdef CONFIG_PAGE_POISONING_ZERO -#define PAGE_POISON 0x00 -#else -#define PAGE_POISON 0xaa -#endif - /********** mm/page_alloc.c ************/ #define TAIL_MAPPING ((void *) 0x400 + POISON_POINTER_DELTA) diff --git a/mm/page_poison.c b/mm/page_poison.c index e83fd44..9a07973 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -7,6 +7,13 @@ #include #include +/********** mm/debug-pagealloc.c **********/ +#ifdef CONFIG_PAGE_POISONING_ZERO +#define PAGE_POISON 0x00 +#else +#define PAGE_POISON 0xaa +#endif + static bool want_page_poisoning __read_mostly; static int early_page_poison_param(char *buf) @@ -30,6 +37,23 @@ bool page_poisoning_enabled(void) debug_pagealloc_enabled())); } +/** + * page_poison_val_get - get the page poison value if page poisoning is enabled + * @val: the caller's memory to get the page poison value + * + * Return true with @val stores the poison value if page poisoning is enabled. + * Otherwise, return false with @val unchanged. + */ +bool page_poison_val_get(u8 *val) +{ + if (!page_poisoning_enabled()) + return false; + + *val = PAGE_POISON; + return true; +} +EXPORT_SYMBOL_GPL(page_poison_val_get); + static void poison_page(struct page *page) { void *addr = kmap_atomic(page); -- 2.7.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org