From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: [PATCH mm-unstable RFC 01/26] mm/debug_vm_pgtable: more pte_swp_exclusive() sanity checks Date: Tue, 6 Dec 2022 15:47:05 +0100 Message-ID: <20221206144730.163732-2-david@redhat.com> References: <20221206144730.163732-1-david@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=/7myZ/wth2VK5AlWMEoSI8Nboc/6WWYOjnUiROh70DI=; b=CmCuj24g1SEWY3 KwL9zuxDABbQ1qlC+Ss3ENK8PnqDpG6Cr6QFcU8fJf4Yt9xy1MTi78n2BV/Zr2qisixHT9aZ06UxF sPPuJJpEKHLAGzaIYaCkBYd0tZIgiynSoZ5j5svzMaL57ycidH57f6dCc83EagpaUBVR9Nkmrbrco nfETBOBkboDLzmGcTnasLKAEJYT+72bzQtda0rBBtay5PZ73auoWsvXU/NYPjGiM4U3TaAhAcxQB2 d+c2eAi6K44AbeQ/tHH98Qx7jghgowufQ/Gh1gtA7Py/2ZU5CYPfIGiE6ZP4de60YkX2Mt7T112YG cuOHW2E5fqCIetyk+NNw==; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670338085; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/J/bI9dhyjQ/usSRNhI5biIirU1QHLlTc54Jeh9AEr0=; b=gXOb4ViwSO1ZfU8fYrFfIMBNieujLRu9JHoJnjJyXrqD2uLvtrLVa60btp532unt5GWKbg j4C8p2XsW2crtiZveCPFOBRfLupUqtn11+mpRh0RZTzoS6PaifdSk2iJbJRWC8/q5i5LF7 UiTZaGVgzRq3ybLdeSkIIcp66gZkQ88= In-Reply-To: <20221206144730.163732-1-david@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+glud-user-mode-linux-devel=m.gmane-mx.org@lists.infradead.org To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Hugh Dickins , John Hubbard , Jason Gunthorpe , Mike Rapoport , Yang Shi , Vlastimil Babka , Nadav Amit , Andrea Arcangeli , Peter Xu , linux-mm@kvack.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org We want to implement __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures. Let's extend our sanity checks, especially testing that our PTE bit does not affect: * is_swap_pte() -> pte_present() and pte_none() * the swap entry + type * pte_swp_soft_dirty() Especially, the pfn_pte() is dodgy when the swap PTE layout differs heavily from ordinary PTEs. Let's properly construct a swap PTE from swap type+offset. Signed-off-by: David Hildenbrand --- mm/debug_vm_pgtable.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index c631ade3f1d2..0506622016d9 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -807,13 +807,34 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) { static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args) { #ifdef __HAVE_ARCH_PTE_SWP_EXCLUSIVE - pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot); + unsigned long max_swapfile_size = generic_max_swapfile_size(); + swp_entry_t entry, entry2; + pte_t pte; pr_debug("Validating PTE swap exclusive\n"); + + /* Create a swp entry with all possible bits set */ + entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, + max_swapfile_size - 1); + + pte = swp_entry_to_pte(entry); + WARN_ON(pte_swp_exclusive(pte)); + WARN_ON(!is_swap_pte(pte)); + entry2 = pte_to_swp_entry(pte); + WARN_ON(memcmp(&entry, &entry2, sizeof(entry))); + pte = pte_swp_mkexclusive(pte); WARN_ON(!pte_swp_exclusive(pte)); + WARN_ON(!is_swap_pte(pte)); + WARN_ON(pte_swp_soft_dirty(pte)); + entry2 = pte_to_swp_entry(pte); + WARN_ON(memcmp(&entry, &entry2, sizeof(entry))); + pte = pte_swp_clear_exclusive(pte); WARN_ON(pte_swp_exclusive(pte)); + WARN_ON(!is_swap_pte(pte)); + entry2 = pte_to_swp_entry(pte); + WARN_ON(memcmp(&entry, &entry2, sizeof(entry))); #endif /* __HAVE_ARCH_PTE_SWP_EXCLUSIVE */ } -- 2.38.1