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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 D8812C4743D for ; Sat, 5 Jun 2021 00:00:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3A1861207 for ; Sat, 5 Jun 2021 00:00:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229886AbhFEABv (ORCPT ); Fri, 4 Jun 2021 20:01:51 -0400 Received: from smtp-fw-33001.amazon.com ([207.171.190.10]:50500 "EHLO smtp-fw-33001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229847AbhFEABv (ORCPT ); Fri, 4 Jun 2021 20:01:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1622851205; x=1654387205; h=from:to:cc:subject:date:message-id:mime-version; bh=s3t6VihAkPp9eTSAWs95/T+GZwYoZ0V/3Fe9pqxjazo=; b=Nw5UXHuj19E+dPdEa8BM0g7s4n2X+pKKsiu2L0RMBPNC+hTgm30cr9vd PAc8kiSIAxfX7K0NDAhbzB9WbCgu8RD/KC8kQswhPEZBgMUnaRDakK7Lj qGYdPWLD7tNseE4VBMbVbby2iwUwiW5obE7bAFptq7jG2dUP4pWO54g9M s=; X-IronPort-AV: E=Sophos;i="5.83,249,1616457600"; d="scan'208";a="129358420" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-1a-e34f1ddc.us-east-1.amazon.com) ([10.25.36.210]) by smtp-border-fw-33001.sea14.amazon.com with ESMTP; 05 Jun 2021 00:00:04 +0000 Received: from EX13MTAUWC002.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan3.iad.amazon.com [10.40.159.166]) by email-inbound-relay-1a-e34f1ddc.us-east-1.amazon.com (Postfix) with ESMTPS id D3003A052A; Fri, 4 Jun 2021 23:59:59 +0000 (UTC) Received: from EX13D30UWC001.ant.amazon.com (10.43.162.128) by EX13MTAUWC002.ant.amazon.com (10.43.162.240) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Fri, 4 Jun 2021 23:59:59 +0000 Received: from u3c3f5cfe23135f.ant.amazon.com (10.43.161.201) by EX13D30UWC001.ant.amazon.com (10.43.162.128) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Fri, 4 Jun 2021 23:59:58 +0000 From: Suraj Jitindar Singh To: CC: , , , , , , , , , , Suraj Jitindar Singh Subject: [RFC PATCH 1/1] arm64: implement live patching Date: Fri, 4 Jun 2021 16:59:30 -0700 Message-ID: <20210604235930.603-1-surajjs@amazon.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.43.161.201] X-ClientProxiedBy: EX13D32UWA004.ant.amazon.com (10.43.160.193) To EX13D30UWC001.ant.amazon.com (10.43.162.128) Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org It's my understanding that the two pieces of work required to enable live patching on arm are in flight upstream; - Reliable stack traces as implemented by Madhavan T. Venkataraman [1] - Objtool as implemented by Julien Thierry [2] This is the remaining part required to enable live patching on arm. Based on work by Torsten Duwe [3] Allocate a task flag used to represent the patch pending state for the task. Also implement generic functions klp_arch_set_pc() & klp_get_ftrace_location(). In klp_arch_set_pc() it is sufficient to set regs->pc as in ftrace_common_return() the return address is loaded from the stack. ldr x9, [sp, #S_PC] ret x9 In klp_get_ftrace_location() it is necessary to advance the address by AARCH64_INSN_SIZE (4) to point to the BL in the callsite as 2 nops were placed at the start of the function, one to be patched to save the LR and another to be patched to branch to the ftrace call, and klp_get_ftrace_location() is expected to return the address of the BL. It may also be necessary to advance the address by another AARCH64_INSN_SIZE if CONFIG_ARM64_BTI_KERNEL is enabled due to the instruction placed at the branch target to satisfy BTI, Signed-off-by: Suraj Jitindar Singh [1] https://lkml.org/lkml/2021/5/26/1212 [2] https://lkml.org/lkml/2021/3/3/1135 [3] https://lkml.org/lkml/2018/10/26/536 --- arch/arm64/Kconfig | 3 ++ arch/arm64/include/asm/livepatch.h | 42 ++++++++++++++++++++++++++++ arch/arm64/include/asm/thread_info.h | 4 ++- arch/arm64/kernel/signal.c | 4 +++ 4 files changed, 52 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/asm/livepatch.h diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b098dabed8c2..c4636990c01d 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -187,6 +187,7 @@ config ARM64 select HAVE_GCC_PLUGINS select HAVE_HW_BREAKPOINT if PERF_EVENTS select HAVE_IRQ_TIME_ACCOUNTING + select HAVE_LIVEPATCH select HAVE_NMI select HAVE_PATA_PLATFORM select HAVE_PERF_EVENTS @@ -1946,3 +1947,5 @@ source "arch/arm64/kvm/Kconfig" if CRYPTO source "arch/arm64/crypto/Kconfig" endif + +source "kernel/livepatch/Kconfig" diff --git a/arch/arm64/include/asm/livepatch.h b/arch/arm64/include/asm/livepatch.h new file mode 100644 index 000000000000..72d7cd86f158 --- /dev/null +++ b/arch/arm64/include/asm/livepatch.h @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * livepatch.h - arm64-specific Kernel Live Patching Core + */ +#ifndef _ASM_ARM64_LIVEPATCH_H +#define _ASM_ARM64_LIVEPATCH_H + +#include + +static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip) +{ + struct pt_regs *regs = ftrace_get_regs(fregs); + + regs->pc = ip; +} + +/* + * klp_get_ftrace_location is expected to return the address of the BL to the + * relevant ftrace handler in the callsite. The location of this can vary based + * on several compilation options. + * CONFIG_DYNAMIC_FTRACE_WITH_REGS + * - Inserts 2 nops on function entry the second of which is the BL + * referenced above. (See ftrace_init_nop() for the callsite sequence) + * (this is required by livepatch and must be selected) + * CONFIG_ARM64_BTI_KERNEL: + * - Inserts a hint #0x22 on function entry if the function is called + * indirectly (to satisfy BTI requirements), which is inserted before + * the two nops from above. + */ +#define klp_get_ftrace_location klp_get_ftrace_location +static inline unsigned long klp_get_ftrace_location(unsigned long faddr) +{ + unsigned long addr = faddr + AARCH64_INSN_SIZE; + +#if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) + addr = ftrace_location_range(addr, addr + AARCH64_INSN_SIZE); +#endif + + return addr; +} + +#endif /* _ASM_ARM64_LIVEPATCH_H */ diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 6623c99f0984..cca936d53a40 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -67,6 +67,7 @@ int arch_dup_task_struct(struct task_struct *dst, #define TIF_UPROBE 4 /* uprobe breakpoint or singlestep */ #define TIF_MTE_ASYNC_FAULT 5 /* MTE Asynchronous Tag Check Fault */ #define TIF_NOTIFY_SIGNAL 6 /* signal notifications exist */ +#define TIF_PATCH_PENDING 7 /* pending live patching update */ #define TIF_SYSCALL_TRACE 8 /* syscall trace active */ #define TIF_SYSCALL_AUDIT 9 /* syscall auditing */ #define TIF_SYSCALL_TRACEPOINT 10 /* syscall tracepoint for ftrace */ @@ -97,11 +98,12 @@ int arch_dup_task_struct(struct task_struct *dst, #define _TIF_SVE (1 << TIF_SVE) #define _TIF_MTE_ASYNC_FAULT (1 << TIF_MTE_ASYNC_FAULT) #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) +#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \ _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \ - _TIF_NOTIFY_SIGNAL) + _TIF_NOTIFY_SIGNAL | _TIF_PATCH_PENDING) #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 6237486ff6bb..d1eedb0589a7 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -932,6 +933,9 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, (void __user *)NULL, current); } + if (thread_flags & _TIF_PATCH_PENDING) + klp_update_patch_state(current); + if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) do_signal(regs); -- 2.17.1