From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754291AbdJIKJQ (ORCPT ); Mon, 9 Oct 2017 06:09:16 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40390 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754067AbdJIKJI (ORCPT ); Mon, 9 Oct 2017 06:09:08 -0400 From: Laurent Dufour To: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v4 20/20] powerpc/mm: Add speculative page fault Date: Mon, 9 Oct 2017 12:07:52 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1507543672-25821-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1507543672-25821-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17100910-0016-0000-0000-000004F3CD39 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17100910-0017-0000-0000-0000282E4D6E Message-Id: <1507543672-25821-21-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-09_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1710090148 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch enable the speculative page fault on the PowerPC architecture. This will try a speculative page fault without holding the mmap_sem, if it returns with VM_FAULT_RETRY, the mmap_sem is acquired and the traditional page fault processing is done. Support is only provide for BOOK3S_64 currently because: - require CONFIG_PPC_STD_MMU because checks done in set_access_flags_filter() - require BOOK3S because we can't support for book3e_hugetlb_preload() called by update_mmu_cache() Signed-off-by: Laurent Dufour --- arch/powerpc/include/asm/book3s/64/pgtable.h | 5 +++++ arch/powerpc/mm/fault.c | 17 +++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index b9aff515b4de..e85073d0a09c 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -314,6 +314,11 @@ extern unsigned long pci_io_base; /* Advertise support for _PAGE_SPECIAL */ #define __HAVE_ARCH_PTE_SPECIAL +/* Advertise that we call the Speculative Page Fault handler */ +#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_SMP) +#define __HAVE_ARCH_CALL_SPF +#endif + #ifndef __ASSEMBLY__ /* diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 4797d08581ce..fbd423515b54 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -442,6 +442,20 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, if (is_exec) flags |= FAULT_FLAG_INSTRUCTION; +#ifdef __HAVE_ARCH_CALL_SPF + if (is_user) { + /* let's try a speculative page fault without grabbing the + * mmap_sem. + */ + fault = handle_speculative_fault(mm, address, flags); + if (!(fault & VM_FAULT_RETRY)) { + perf_sw_event(PERF_COUNT_SW_SPF, 1, + regs, address); + goto done; + } + } +#endif /* __HAVE_ARCH_CALL_SPF */ + /* When running in the kernel we expect faults to occur only to * addresses in user space. All other faults represent errors in the * kernel and should generate an OOPS. Unfortunately, in the case of an @@ -526,6 +540,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, up_read(¤t->mm->mmap_sem); +#ifdef __HAVE_ARCH_CALL_SPF +done: +#endif if (unlikely(fault & VM_FAULT_ERROR)) return mm_fault_error(regs, address, fault); -- 2.7.4