Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751515AbdGQW3u (ORCPT ); Mon, 17 Jul 2017 18:29:50 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:39033 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342AbdGQW3r (ORCPT ); Mon, 17 Jul 2017 18:29:47 -0400 From: Mike Kravetz To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Matthew Wilcox , akpm@linux-foundation.org, mhocko@suse.com, ak@linux.intel.com, mtk.manpages@gmail.com, Davidlohr Bueso , khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, aarcange@redhat.com, Mike Kravetz Subject: [RFC PATCH 1/3] mm:hugetlb: Define system call hugetlb size encodings in single file Date: Mon, 17 Jul 2017 15:27:59 -0700 Message-Id: <1500330481-28476-2-git-send-email-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.7.5 In-Reply-To: <1500330481-28476-1-git-send-email-mike.kravetz@oracle.com> References: <20170328175408.GD7838@bombadil.infradead.org> <1500330481-28476-1-git-send-email-mike.kravetz@oracle.com> X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2230 Lines: 53 If hugetlb pages are requested in mmap or shmget system calls, a huge page size other than default can be requested. This is accomplished by encoding the log2 of the huge page size in the upper bits of the flag argument. asm-generic and arch specific headers all define the same values for these encodings. Put common definitions in a single header file. arch specific code can still override if desired. Signed-off-by: Mike Kravetz --- include/uapi/asm-generic/hugetlb_encode.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 include/uapi/asm-generic/hugetlb_encode.h diff --git a/include/uapi/asm-generic/hugetlb_encode.h b/include/uapi/asm-generic/hugetlb_encode.h new file mode 100644 index 0000000..aa09fc0 --- /dev/null +++ b/include/uapi/asm-generic/hugetlb_encode.h @@ -0,0 +1,30 @@ +#ifndef _ASM_GENERIC_HUGETLB_ENCODE_H_ +#define _ASM_GENERIC_HUGETLB_ENCODE_H_ + +/* + * Several system calls take a flag to request "hugetlb" huge pages. + * Without further specification, these system calls will use the + * system's default huge page size. If a system supports multiple + * huge page sizes, the desired huge page size can be specified in + * bits [26:31] of the flag arguments. The value in these 6 bits + * will encode the log2 of the huge page size. + * + * The following definitions are associated with this huge page size + * encoding in flag arguments. System call specific header files + * that use this encoding should include this file. They can then + * provide definitions based on these with their own specific prefix. + * for example #define MAP_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT. + */ + +#define HUGETLB_FLAG_ENCODE_SHIFT 26 +#define HUGETLB_FLAG_ENCODE_MASK 0x3f + +#define HUGETLB_FLAG_ENCODE_512KB (19 << MAP_HUGE_SHIFT +#define HUGETLB_FLAG_ENCODE_1MB (20 << MAP_HUGE_SHIFT) +#define HUGETLB_FLAG_ENCODE_2MB (21 << MAP_HUGE_SHIFT) +#define HUGETLB_FLAG_ENCODE_8MB (23 << MAP_HUGE_SHIFT) +#define HUGETLB_FLAG_ENCODE_16MB (24 << MAP_HUGE_SHIFT) +#define HUGETLB_FLAG_ENCODE_1GB (30 << MAP_HUGE_SHIFT) +#define HUGETLB_FLAG_ENCODE__16GB (34 << MAP_HUGE_SHIFT) + +#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */ -- 2.7.5