From nobody Tue Nov 11 09:00:01 2025 Delivered-To: importer@patchew.org Received-SPF: none (zoho.com: 192.237.175.120 is neither permitted nor denied by domain of lists.xenproject.org) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=none (zoho.com: 192.237.175.120 is neither permitted nor denied by domain of lists.xenproject.org) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=fail(p=none dis=none) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; t=1567775795; cv=none; d=zoho.com; s=zohoarc; b=M3Sk3ymgKrnRgwCR5f21yUezrNrMeWjJg7421bssC9slEB9TSnCbY2YlpGYmopiHc7vrKgZHGDGGlZqlR2JU2B76lxSzfLVe6ZbQpYxa9AnpjLdMJH2dNFfDBSEP97crF6CxPXyQ10a1M55ZAlnfE1GZC33W4R+GmZD21qOgCU0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1567775795; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=qXmIViCZzpSqOzuVNpwmPXon+VRzhnlAaucL79XCfmI=; b=CxVUrslPG6my21vkh8vHhqaded73e3NnVbRl0XMS62sWaqY9ys1S2aMz/mHu6t+zGpcK35CM3ZSl/7D62s8R/t1DmMWTOoThTA7ULtlFZjJbLJsXMxx+kYL0OJrxzkGaya+a9G00DIqdETCxd79+40MKz61zYXy3n0Nwmyg0SA8= ARC-Authentication-Results: i=1; mx.zoho.com; dkim=fail; spf=none (zoho.com: 192.237.175.120 is neither permitted nor denied by domain of lists.xenproject.org) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1567775795689175.3212202934095; Fri, 6 Sep 2019 06:16:35 -0700 (PDT) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1i6E4A-0000sK-2C; Fri, 06 Sep 2019 13:14:18 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1i6E48-0000rz-Il for xen-devel@lists.xenproject.org; Fri, 06 Sep 2019 13:14:16 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 39c615b8-d0a8-11e9-b299-bc764e2007e4; Fri, 06 Sep 2019 13:14:16 +0000 (UTC) Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4A55A207FC; Fri, 6 Sep 2019 13:14:12 +0000 (UTC) X-Inumbo-ID: 39c615b8-d0a8-11e9-b299-bc764e2007e4 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567775655; bh=YxdWojc5fQhCsI3MCFNUb/S38/XJllDgwfcUjCixi7c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XkKh5q5Aus2YgqR1dKqCz2etHrZWowX7W3djWGR1gL3U8RvdvMP18XVzrLm0PVhvq //NYVg8iMWghQpO3BWms/dSwsIM70WgaKZlAfM2MP0Ky5XqqK7Fgu+pZ8LCj27jCCE +I0vJVlcHcRe7KlsdYNQ1IBm+oyj6BNlkGQaS2bI= From: Masami Hiramatsu To: Ingo Molnar Date: Fri, 6 Sep 2019 22:14:10 +0900 Message-Id: <156777564986.25081.4964537658500952557.stgit@devnote2> X-Mailer: git-send-email 2.20.1 In-Reply-To: <156777561745.25081.1205321122446165328.stgit@devnote2> References: <156777561745.25081.1205321122446165328.stgit@devnote2> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Subject: [Xen-devel] [PATCH -tip v4 3/4] x86: xen: insn: Decode Xen and KVM emulate-prefix signature X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Peter Zijlstra , Andrew Cooper , Randy Dunlap , x86@kernel.org, linux-kernel@vger.kernel.org, Borislav Petkov , Josh Poimboeuf , xen-devel@lists.xenproject.org, Boris Ostrovsky Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Decode Xen and KVM's emulate-prefix signature by x86 insn decoder. It is called "prefix" but actually not x86 instruction prefix, so this adds insn.emulate_prefix_size field instead of reusing insn.prefixes. If x86 decoder finds a special sequence of instructions of XEN_EMULATE_PREFIX and 'ud2a; .ascii "kvm"', it just counts the length, set insn.emulate_prefix_size and fold it with the next instruction. In other words, the signature and the next instruction is treated as a single instruction. Reported-by: Josh Poimboeuf Signed-off-by: Masami Hiramatsu Acked-by: Josh Poimboeuf --- Changes in v4: - Use asm/emulate_prefix.h instead of xen/prefix.h - Fix to add emulate_prefix.h to the checkist of perf. --- arch/x86/include/asm/insn.h | 6 +++++ arch/x86/lib/insn.c | 34 +++++++++++++++++++++++= ++++ tools/arch/x86/include/asm/emulate_prefix.h | 14 +++++++++++ tools/arch/x86/include/asm/insn.h | 6 +++++ tools/arch/x86/lib/insn.c | 34 +++++++++++++++++++++++= ++++ tools/objtool/sync-check.sh | 3 ++ tools/perf/check-headers.sh | 3 ++ 7 files changed, 98 insertions(+), 2 deletions(-) create mode 100644 tools/arch/x86/include/asm/emulate_prefix.h diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h index 154f27be8bfc..5c1ae3eff9d4 100644 --- a/arch/x86/include/asm/insn.h +++ b/arch/x86/include/asm/insn.h @@ -45,6 +45,7 @@ struct insn { struct insn_field immediate2; /* for 64bit imm or seg16 */ }; =20 + int emulate_prefix_size; insn_attr_t attr; unsigned char opnd_bytes; unsigned char addr_bytes; @@ -128,6 +129,11 @@ static inline int insn_is_evex(struct insn *insn) return (insn->vex_prefix.nbytes =3D=3D 4); } =20 +static inline int insn_has_emulate_prefix(struct insn *insn) +{ + return !!insn->emulate_prefix_size; +} + /* Ensure this instruction is decoded completely */ static inline int insn_complete(struct insn *insn) { diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c index 0b5862ba6a75..404279563891 100644 --- a/arch/x86/lib/insn.c +++ b/arch/x86/lib/insn.c @@ -13,6 +13,8 @@ #include #include =20 +#include + /* Verify next sizeof(t) bytes can be on the same instruction */ #define validate_next(t, insn, n) \ ((insn)->next_byte + sizeof(t) + n <=3D (insn)->end_kaddr) @@ -58,6 +60,36 @@ void insn_init(struct insn *insn, const void *kaddr, int= buf_len, int x86_64) insn->addr_bytes =3D 4; } =20 +static const insn_byte_t xen_prefix[] =3D { __XEN_EMULATE_PREFIX }; +static const insn_byte_t kvm_prefix[] =3D { __KVM_EMULATE_PREFIX }; + +static int __insn_get_emulate_prefix(struct insn *insn, + const insn_byte_t *prefix, size_t len) +{ + size_t i; + + for (i =3D 0; i < len; i++) { + if (peek_nbyte_next(insn_byte_t, insn, i) !=3D prefix[i]) + goto err_out; + } + + insn->emulate_prefix_size =3D len; + insn->next_byte +=3D len; + + return 1; + +err_out: + return 0; +} + +static void insn_get_emulate_prefix(struct insn *insn) +{ + if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix))) + return; + + __insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix)); +} + /** * insn_get_prefixes - scan x86 instruction prefix bytes * @insn: &struct insn containing instruction @@ -76,6 +108,8 @@ void insn_get_prefixes(struct insn *insn) if (prefixes->got) return; =20 + insn_get_emulate_prefix(insn); + nb =3D 0; lb =3D 0; b =3D peek_next(insn_byte_t, insn); diff --git a/tools/arch/x86/include/asm/emulate_prefix.h b/tools/arch/x86/i= nclude/asm/emulate_prefix.h new file mode 100644 index 000000000000..70f5b98a5286 --- /dev/null +++ b/tools/arch/x86/include/asm/emulate_prefix.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_EMULATE_PREFIX_H +#define _ASM_X86_EMULATE_PREFIX_H + +/* + * Virt escape sequences to trigger instruction emulation; + * ideally these would decode to 'whole' instruction and not destroy + * the instruction stream; sadly this is not true for the 'kvm' one :/ + */ + +#define __XEN_EMULATE_PREFIX 0x0f,0x0b,0x78,0x65,0x6e /* ud2 ; .ascii "x= en" */ +#define __KVM_EMULATE_PREFIX 0x0f,0x0b,0x6b,0x76,0x6d /* ud2 ; .ascii "kv= m" */ + +#endif diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm= /insn.h index 37a4c390750b..568854b14d0a 100644 --- a/tools/arch/x86/include/asm/insn.h +++ b/tools/arch/x86/include/asm/insn.h @@ -45,6 +45,7 @@ struct insn { struct insn_field immediate2; /* for 64bit imm or seg16 */ }; =20 + int emulate_prefix_size; insn_attr_t attr; unsigned char opnd_bytes; unsigned char addr_bytes; @@ -128,6 +129,11 @@ static inline int insn_is_evex(struct insn *insn) return (insn->vex_prefix.nbytes =3D=3D 4); } =20 +static inline int insn_has_emulate_prefix(struct insn *insn) +{ + return !!insn->emulate_prefix_size; +} + /* Ensure this instruction is decoded completely */ static inline int insn_complete(struct insn *insn) { diff --git a/tools/arch/x86/lib/insn.c b/tools/arch/x86/lib/insn.c index 79e048f1d902..0151dfc6da61 100644 --- a/tools/arch/x86/lib/insn.c +++ b/tools/arch/x86/lib/insn.c @@ -13,6 +13,8 @@ #include "../include/asm/inat.h" #include "../include/asm/insn.h" =20 +#include "../include/asm/emulate_prefix.h" + /* Verify next sizeof(t) bytes can be on the same instruction */ #define validate_next(t, insn, n) \ ((insn)->next_byte + sizeof(t) + n <=3D (insn)->end_kaddr) @@ -58,6 +60,36 @@ void insn_init(struct insn *insn, const void *kaddr, int= buf_len, int x86_64) insn->addr_bytes =3D 4; } =20 +static const insn_byte_t xen_prefix[] =3D { __XEN_EMULATE_PREFIX }; +static const insn_byte_t kvm_prefix[] =3D { __KVM_EMULATE_PREFIX }; + +static int __insn_get_emulate_prefix(struct insn *insn, + const insn_byte_t *prefix, size_t len) +{ + size_t i; + + for (i =3D 0; i < len; i++) { + if (peek_nbyte_next(insn_byte_t, insn, i) !=3D prefix[i]) + goto err_out; + } + + insn->emulate_prefix_size =3D len; + insn->next_byte +=3D len; + + return 1; + +err_out: + return 0; +} + +static void insn_get_emulate_prefix(struct insn *insn) +{ + if (__insn_get_emulate_prefix(insn, xen_prefix, sizeof(xen_prefix))) + return; + + __insn_get_emulate_prefix(insn, kvm_prefix, sizeof(kvm_prefix)); +} + /** * insn_get_prefixes - scan x86 instruction prefix bytes * @insn: &struct insn containing instruction @@ -76,6 +108,8 @@ void insn_get_prefixes(struct insn *insn) if (prefixes->got) return; =20 + insn_get_emulate_prefix(insn); + nb =3D 0; lb =3D 0; b =3D peek_next(insn_byte_t, insn); diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh index 0a832e265a50..9bd04bbed01e 100755 --- a/tools/objtool/sync-check.sh +++ b/tools/objtool/sync-check.sh @@ -4,6 +4,7 @@ FILES=3D' arch/x86/include/asm/inat_types.h arch/x86/include/asm/orc_types.h +arch/x86/include/asm/emulate_prefix.h arch/x86/lib/x86-opcode-map.txt arch/x86/tools/gen-insn-attr-x86.awk ' @@ -46,6 +47,6 @@ done check arch/x86/include/asm/inat.h '-I "^#include [\"<]\(asm/\)*inat_ty= pes.h[\">]"' check arch/x86/include/asm/insn.h '-I "^#include [\"<]\(asm/\)*inat.h[= \">]"' check arch/x86/lib/inat.c '-I "^#include [\"<]\(../include/\)*= asm/insn.h[\">]"' -check arch/x86/lib/insn.c '-I "^#include [\"<]\(../include/\)*= asm/in\(at\|sn\).h[\">]"' +check arch/x86/lib/insn.c '-I "^#include [\"<]\(../include/\)*= asm/in\(at\|sn\).h[\">]" -I "^#include [\"<]\(../include/\)*asm/emulate_pre= fix.h[\">]"' =20 cd - diff --git a/tools/perf/check-headers.sh b/tools/perf/check-headers.sh index e2e0f06c97d0..988b1879ec98 100755 --- a/tools/perf/check-headers.sh +++ b/tools/perf/check-headers.sh @@ -27,6 +27,7 @@ arch/x86/include/asm/disabled-features.h arch/x86/include/asm/required-features.h arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/inat_types.h +arch/x86/include/asm/emulate_prefix.h arch/x86/include/uapi/asm/prctl.h arch/x86/lib/x86-opcode-map.txt arch/x86/tools/gen-insn-attr-x86.awk @@ -115,7 +116,7 @@ check lib/ctype.c '-I "^EXPORT_SYMBOL" -I "^#inc= lude " -B check arch/x86/include/asm/inat.h '-I "^#include [\"<]\(asm/\)*inat_ty= pes.h[\">]"' check arch/x86/include/asm/insn.h '-I "^#include [\"<]\(asm/\)*inat.h[= \">]"' check arch/x86/lib/inat.c '-I "^#include [\"<]\(../include/\)*asm/in= sn.h[\">]"' -check arch/x86/lib/insn.c '-I "^#include [\"<]\(../include/\)*asm/in= \(at\|sn\).h[\">]"' +check arch/x86/lib/insn.c '-I "^#include [\"<]\(../include/\)*= asm/in\(at\|sn\).h[\">]" -I "^#include [\"<]\(../include/\)*asm/emulate_pre= fix.h[\">]"' =20 # diff non-symmetric files check_2 tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/s= yscalls/syscall_64.tbl _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel