From patchwork Sun Sep 11 15:48:31 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Konrad Rzeszutek Wilk X-Patchwork-Id: 9325469 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 82FCB607D3 for ; Sun, 11 Sep 2016 15:51:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 74DE228AA1 for ; Sun, 11 Sep 2016 15:51:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 69A6D28B55; Sun, 11 Sep 2016 15:51:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 28E5428AA1 for ; Sun, 11 Sep 2016 15:51:47 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bj70D-0001j6-2E; Sun, 11 Sep 2016 15:49:05 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bj70B-0001ii-9T for xen-devel@lists.xenproject.org; Sun, 11 Sep 2016 15:49:03 +0000 Received: from [85.158.137.68] by server-12.bemta-3.messagelabs.com id CA/A5-09160-EEC75D75; Sun, 11 Sep 2016 15:49:02 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrNLMWRWlGSWpSXmKPExsXSO6nOVfdtzdV wg72T5Cy+b5nM5MDocfjDFZYAxijWzLyk/IoE1oxT91cwF7TbVXzesJGtgfG8URcjF4eQQBuT xJHrZ9kgnC+MEhMWNTFCOBsZJT71rGeGcCYwSjS1NgA5HBxsAiYSb1Y5djFycogIREj0vjzFA mIzC5RJPFz8hBXEFhZwlNi0+CkziM0ioCrRcmsVI4jNK+Aqcf3mexaQMRIC8hLPbteDhDkF3C QmPHkA1ioEVNJ64D87iC0hYChx+uE2xgmMfAsYGVYxahSnFpWlFukameklFWWmZ5TkJmbm6Bo aGOvlphYXJ6an5iQmFesl5+duYgQGSj0DA+MOxoa9focYJTmYlER5z+ZcCRfiS8pPqcxILM6I LyrNSS0+xCjDwaEkwZtVdDVcSLAoNT21Ii0zBxiyMGkJDh4lEd4vIGne4oLE3OLMdIjUKUZFK XHeFJCEAEgiozQPrg0WJ5cYZaWEeRkZGBiEeApSi3IzS1DlXzGKczAqCfO+BpnCk5lXAjf9Fd BiJqDFT7deBllckoiQkmpgLHkl/c/pzeKPK/sjGdoPpD5d0W1Tuuv0Ej+x8t9u9qv1/85Qe2J dwfwqy25ByJHdJxb4d11aUqpeeZ9X6raWun+4x8WFR5SsQwu9HsfNvnpM1JLv6zL3CXE2M7dt kw9mObf/vHHc7kT1X5EfuPRKHGe0rrul2/It5ohBgfQZhR/rjr1z3WZhpMRSnJFoqMVcVJwIA Dut2MWOAgAA X-Env-Sender: konrad.wilk@oracle.com X-Msg-Ref: server-14.tower-31.messagelabs.com!1473608939!60081946!1 X-Originating-IP: [141.146.126.69] X-SpamReason: No, hits=0.0 required=7.0 tests=sa_preprocessor: VHJ1c3RlZCBJUDogMTQxLjE0Ni4xMjYuNjkgPT4gMjc3MjE4\n X-StarScan-Received: X-StarScan-Version: 8.84; banners=-,-,- X-VirusChecked: Checked Received: (qmail 29905 invoked from network); 11 Sep 2016 15:49:01 -0000 Received: from aserp1040.oracle.com (HELO aserp1040.oracle.com) (141.146.126.69) by server-14.tower-31.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 11 Sep 2016 15:49:01 -0000 Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id u8BFmsWf022646 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 11 Sep 2016 15:48:55 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0021.oracle.com (8.13.8/8.13.8) with ESMTP id u8BFmsoW019528 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 11 Sep 2016 15:48:54 GMT Received: from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17]) by userv0121.oracle.com (8.13.8/8.13.8) with ESMTP id u8BFmrAZ021203; Sun, 11 Sep 2016 15:48:53 GMT Received: from localhost.localdomain.com (/209.6.196.81) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 11 Sep 2016 08:48:53 -0700 From: Konrad Rzeszutek Wilk To: xen-devel@lists.xenproject.org, konrad@kernel.org, ross.lagerwall@citrix.com Date: Sun, 11 Sep 2016 11:48:31 -0400 Message-Id: <1473608912-5913-4-git-send-email-konrad.wilk@oracle.com> X-Mailer: git-send-email 2.4.11 In-Reply-To: <1473608912-5913-1-git-send-email-konrad.wilk@oracle.com> References: <1473608912-5913-1-git-send-email-konrad.wilk@oracle.com> X-Source-IP: userv0021.oracle.com [156.151.31.71] Cc: andrew.cooper3@citrix.com, Jan Beulich , Konrad Rzeszutek Wilk Subject: [Xen-devel] [PATCH v5 3/4] livepatch: NOP if func->new_addr is zero. X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP The NOP functionality will NOP any of the code at the 'old_addr' or at 'name' if the 'new_addr' is zero. The purpose of this is to NOP out calls, such as: e8 <4-bytes-offset> (5 byte insn), or on ARM a 4 byte insn for branching. We need the EIP of where we need to the NOP, and that can be provided via the `old_addr` or `name`. If the `old_addr` is provided we will NOP 'new_size' amount of bytes at that location. The amount is up to 31 instructions if desired (which is the size of the opaque member). If there is a need to NOP more then either more 'struct livepatch_func' structures need to be present or we have to implement a variable size buffer. While at it, also unify the code on x86 patching so it is a bit simpler (instead of two seperate writes just make it one memcpy). Signed-off-by: Konrad Rzeszutek Wilk --- Cc: Konrad Rzeszutek Wilk Cc: Ross Lagerwall Cc: Jan Beulich Cc: Andrew Cooper v3: First submission v4: Fix description - e9 -> e8 Remove the restriction of only doing 5 or 4 bytes. Redo the patching code to deal with variable size of new_size. Expand the amount of bytes we can NOP. Move the PATCH_INSN_SIZE definition in platform specific headers Move the get_len to livepatch_get_insn_len inline function. --- docs/misc/livepatch.markdown | 7 +++++-- xen/arch/x86/alternative.c | 2 +- xen/arch/x86/livepatch.c | 38 +++++++++++++++++++++++++------------- xen/common/livepatch.c | 3 ++- xen/include/asm-x86/alternative.h | 1 + xen/include/asm-x86/livepatch.h | 21 +++++++++++++++++++++ xen/include/xen/livepatch.h | 9 +++++++++ 7 files changed, 64 insertions(+), 17 deletions(-) create mode 100644 xen/include/asm-x86/livepatch.h diff --git a/docs/misc/livepatch.markdown b/docs/misc/livepatch.markdown index 07be0af..e2ea351 100644 --- a/docs/misc/livepatch.markdown +++ b/docs/misc/livepatch.markdown @@ -320,10 +320,13 @@ The size of the structure is 64 bytes on 64-bit hypervisors. It will be * `new_addr` is the address of the function that is replacing the old function. The address is filled in during relocation. The value **MUST** be - the address of the new function in the file. + either the address of the new function in the file, or zero if we are NOPing out + at `old_addr` (and `new_size` **MUST** not be zero). * `old_size` and `new_size` contain the sizes of the respective functions in bytes. - The value of `old_size` **MUST** not be zero. + The value of `old_size` **MUST** not be zero. If the value of `new_addr` is + zero then `new_size` determines how many instruction bytes to NOP (up to + opaque size modulo smallest platform instruction - 1 byte x86 and 4 bytes on ARM). * `version` is to be one. diff --git a/xen/arch/x86/alternative.c b/xen/arch/x86/alternative.c index 05e3eb8..6eaa10f 100644 --- a/xen/arch/x86/alternative.c +++ b/xen/arch/x86/alternative.c @@ -101,7 +101,7 @@ static void __init arch_init_ideal_nops(void) } /* Use this to add nops to a buffer, then text_poke the whole buffer. */ -static void init_or_livepatch add_nops(void *insns, unsigned int len) +void init_or_livepatch add_nops(void *insns, unsigned int len) { while ( len > 0 ) { diff --git a/xen/arch/x86/livepatch.c b/xen/arch/x86/livepatch.c index 725b3f6..2f54d7b 100644 --- a/xen/arch/x86/livepatch.c +++ b/xen/arch/x86/livepatch.c @@ -12,8 +12,7 @@ #include #include - -#define PATCH_INSN_SIZE 5 +#include int arch_livepatch_quiesce(void) { @@ -31,8 +30,8 @@ void arch_livepatch_revive(void) int arch_livepatch_verify_func(const struct livepatch_func *func) { - /* No NOP patching yet. */ - if ( !func->new_size ) + /* If NOPing only do up to maximum amount we can put in the ->opaque. */ + if ( !func->new_addr && func->new_size > sizeof(func->opaque) ) return -EOPNOTSUPP; if ( func->old_size < PATCH_INSN_SIZE ) @@ -43,23 +42,36 @@ int arch_livepatch_verify_func(const struct livepatch_func *func) void arch_livepatch_apply_jmp(struct livepatch_func *func) { - int32_t val; uint8_t *old_ptr; - - BUILD_BUG_ON(PATCH_INSN_SIZE > sizeof(func->opaque)); - BUILD_BUG_ON(PATCH_INSN_SIZE != (1 + sizeof(val))); + uint8_t insn[sizeof(func->opaque)]; + size_t len; old_ptr = func->old_addr; - memcpy(func->opaque, old_ptr, PATCH_INSN_SIZE); + len = arch_livepatch_insn_len(func); + if ( !len ) + return; + + memcpy(func->opaque, old_ptr, len); + if ( func->new_addr ) + { + int32_t val; + + BUILD_BUG_ON(PATCH_INSN_SIZE != (1 + sizeof(val))); + + insn[0] = 0xe9; + val = func->new_addr - func->old_addr - PATCH_INSN_SIZE; + + memcpy(&insn[1], &val, sizeof(val)); + } + else + add_nops(&insn, len); - *old_ptr++ = 0xe9; /* Relative jump */ - val = func->new_addr - func->old_addr - PATCH_INSN_SIZE; - memcpy(old_ptr, &val, sizeof(val)); + memcpy(old_ptr, insn, len); } void arch_livepatch_revert_jmp(const struct livepatch_func *func) { - memcpy(func->old_addr, func->opaque, PATCH_INSN_SIZE); + memcpy(func->old_addr, func->opaque, arch_livepatch_insn_len(func)); } /* Serialise the CPU pipeline. */ diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c index 23e4d51..f218c25 100644 --- a/xen/common/livepatch.c +++ b/xen/common/livepatch.c @@ -510,7 +510,8 @@ static int prepare_payload(struct payload *payload, return -EOPNOTSUPP; } - if ( !f->new_addr || !f->new_size ) + /* 'old_addr', 'new_addr', 'new_size' can all be zero. */ + if ( !f->old_size ) { dprintk(XENLOG_ERR, LIVEPATCH "%s: Address or size fields are zero!\n", elf->name); diff --git a/xen/include/asm-x86/alternative.h b/xen/include/asm-x86/alternative.h index 67fc0d2..db4f08e 100644 --- a/xen/include/asm-x86/alternative.h +++ b/xen/include/asm-x86/alternative.h @@ -27,6 +27,7 @@ struct alt_instr { #define ALT_ORIG_PTR(a) __ALT_PTR(a, instr_offset) #define ALT_REPL_PTR(a) __ALT_PTR(a, repl_offset) +extern void add_nops(void *insns, unsigned int len); /* Similar to alternative_instructions except it can be run with IRQs enabled. */ extern void apply_alternatives(const struct alt_instr *start, const struct alt_instr *end); diff --git a/xen/include/asm-x86/livepatch.h b/xen/include/asm-x86/livepatch.h new file mode 100644 index 0000000..63ea079 --- /dev/null +++ b/xen/include/asm-x86/livepatch.h @@ -0,0 +1,21 @@ +/* + * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved. + * + */ + +#ifndef __XEN_X86_LIVEPATCH_H__ +#define __XEN_X86_LIVEPATCH_H__ + +#define PATCH_INSN_SIZE 5 + +#endif /* __XEN_X86_LIVEPATCH_H__ */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h index 243e240..8258e02 100644 --- a/xen/include/xen/livepatch.h +++ b/xen/include/xen/livepatch.h @@ -66,7 +66,16 @@ int arch_livepatch_secure(const void *va, unsigned int pages, enum va_type types void arch_livepatch_init(void); #include /* For struct livepatch_func. */ +#include /* For PATCH_INSN_SIZE. */ int arch_livepatch_verify_func(const struct livepatch_func *func); + +static inline size_t arch_livepatch_insn_len(const struct livepatch_func *func) +{ + if ( !func->new_addr ) + return func->new_size; + + return PATCH_INSN_SIZE; +} /* * These functions are called around the critical region patching live code, * for an architecture to take make appropratie global state adjustments.