From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CED1C282C4 for ; Mon, 4 Feb 2019 20:01:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2184D2081B for ; Mon, 4 Feb 2019 20:01:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727639AbfBDUBd (ORCPT ); Mon, 4 Feb 2019 15:01:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60838 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725854AbfBDUBd (ORCPT ); Mon, 4 Feb 2019 15:01:33 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 766BC356E5; Mon, 4 Feb 2019 20:01:32 +0000 (UTC) Received: from t460s.bristot.redhat.com (ovpn-117-55.phx2.redhat.com [10.3.117.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 299BE9DA8C; Mon, 4 Feb 2019 20:01:21 +0000 (UTC) From: Daniel Bristot de Oliveira To: linux-kernel@vger.kernel.org Cc: bristot@redhat.com, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Greg Kroah-Hartman , Masami Hiramatsu , "Steven Rostedt (VMware)" , Jiri Kosina , Josh Poimboeuf , "Peter Zijlstra (Intel)" , Chris von Recklinghausen , Jason Baron , Scott Wood , Marcelo Tosatti , Clark Williams , x86@kernel.org Subject: [PATCH V4 9/9] x86/jump_label: Batch jump label updates Date: Mon, 4 Feb 2019 20:59:02 +0100 Message-Id: <9604e1d5aa1aa847f3cdb0fce9e3d331f8fbb447.1549308412.git.bristot@redhat.com> In-Reply-To: References: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Mon, 04 Feb 2019 20:01:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, the jump label of a static key is transformed via the arch specific function: void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type) The new approach (batch mode) uses two arch functions, the first has the same arguments of the arch_jump_label_transform(), and is the function: void arch_jump_label_transform_queue(struct jump_entry *entry, enum jump_label_type type) Rather than transforming the code, it adds the jump_entry in a queue of entries to be updated. This functions returns 1 in the case of a successful enqueue of an entry. If it returns 0, the caller must to apply the queue and then try to queue again, for instance, because the queue is full. This function expects the caller to sort the entries by the address before enqueueuing then. This is already done by the arch independent code, though. After queuing all jump_entries, the function: void arch_jump_label_transform_apply(void) Applies the changes in the queue. Signed-off-by: Daniel Bristot de Oliveira Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Greg Kroah-Hartman Cc: Masami Hiramatsu Cc: "Steven Rostedt (VMware)" Cc: Jiri Kosina Cc: Josh Poimboeuf Cc: "Peter Zijlstra (Intel)" Cc: Chris von Recklinghausen Cc: Jason Baron Cc: Scott Wood Cc: Marcelo Tosatti Cc: Clark Williams Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- arch/x86/include/asm/jump_label.h | 2 + arch/x86/kernel/jump_label.c | 88 +++++++++++++++++++++++++++++++ 2 files changed, 90 insertions(+) diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 65191ce8e1cf..06c3cc22a058 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -2,6 +2,8 @@ #ifndef _ASM_X86_JUMP_LABEL_H #define _ASM_X86_JUMP_LABEL_H +#define HAVE_JUMP_LABEL_BATCH + #define JUMP_LABEL_NOP_SIZE 5 #ifdef CONFIG_X86_64 diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c index 2ef687db5a87..3c81cf8f06ca 100644 --- a/arch/x86/kernel/jump_label.c +++ b/arch/x86/kernel/jump_label.c @@ -15,6 +15,7 @@ #include #include #include +#include union jump_code_union { char code[JUMP_LABEL_NOP_SIZE]; @@ -130,6 +131,93 @@ void arch_jump_label_transform(struct jump_entry *entry, mutex_unlock(&text_mutex); } +struct text_to_poke *entry_vector; +unsigned int entry_vector_max_elem __read_mostly; +unsigned int entry_vector_nr_elem; + +void arch_jump_label_init(void) +{ + entry_vector = (void *) __get_free_page(GFP_KERNEL); + + if (WARN_ON_ONCE(!entry_vector)) + return; + + entry_vector_max_elem = PAGE_SIZE / sizeof(struct text_to_poke); + return; +} + +int arch_jump_label_transform_queue(struct jump_entry *entry, + enum jump_label_type type) +{ + void *entry_code; + struct text_to_poke *tp; + + /* + * Batch mode disabled before being able to allocate memory: + * Fallback to the non-batching mode. + */ + if (unlikely(!entry_vector_max_elem)) { + if (!slab_is_available() || early_boot_irqs_disabled) + goto fallback; + + arch_jump_label_init(); + } + + /* + * No more space in the vector, tell upper layer to apply + * the queue before continuing. + */ + if (entry_vector_nr_elem == entry_vector_max_elem) + return 0; + + tp = &entry_vector[entry_vector_nr_elem]; + + entry_code = (void *)jump_entry_code(entry); + + /* + * The int3 handler will do a bsearch in the queue, so we need entries + * to be sorted. We can survive an unsorted list by rejecting the entry, + * forcing the generic jump_label code to apply the queue. Warning once, + * to raise the attention to the case of an unsorted entry that is + * better not happen, because, in the worst case we will perform in the + * same way as we do without batching - with some more overhead. + */ + if (entry_vector_nr_elem > 0) { + int prev_idx = entry_vector_nr_elem - 1; + struct text_to_poke *prev_tp = &entry_vector[prev_idx]; + + if (WARN_ON_ONCE(prev_tp->addr > entry_code)) + return 0; + } + + __jump_label_set_jump_code(entry, type, + (union jump_code_union *) &tp->opcode, 0); + + tp->addr = entry_code; + tp->handler = entry_code + JUMP_LABEL_NOP_SIZE; + tp->len = JUMP_LABEL_NOP_SIZE; + + entry_vector_nr_elem++; + + return 1; + +fallback: + arch_jump_label_transform(entry, type); + return 1; +} + +void arch_jump_label_transform_apply(void) +{ + if (early_boot_irqs_disabled || !entry_vector_nr_elem) + return; + + mutex_lock(&text_mutex); + text_poke_bp_batch(entry_vector, entry_vector_nr_elem); + mutex_unlock(&text_mutex); + + entry_vector_nr_elem = 0; +} + static enum { JL_STATE_START, JL_STATE_NO_UPDATE, -- 2.17.1