From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, rostedt@goodmis.org, hpa@zytor.com,
torvalds@linuxfoundation.org
Cc: linux-kernel@vger.kernel.org, linux-toolchains@vger.kernel.org,
peterz@infradead.org, jpoimboe@redhat.com,
alexei.starovoitov@gmail.com, mhiramat@kernel.org
Subject: [PATCH 2/2] objtool,x86: Use asm/nops.h
Date: Fri, 12 Mar 2021 12:32:55 +0100 [thread overview]
Message-ID: <20210312115749.136357911@infradead.org> (raw)
In-Reply-To: 20210312113253.305040674@infradead.org
Since the kernel will rely on a single canonical set of NOPs, make
sure objtool uses the exact same ones.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/arch/x86/include/asm/nops.h | 81 ++++++++++++++++++++++++++++++++++++++
tools/objtool/arch/x86/decode.c | 13 +++---
tools/objtool/sync-check.sh | 1
3 files changed, 90 insertions(+), 5 deletions(-)
--- /dev/null
+++ b/tools/arch/x86/include/asm/nops.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_NOPS_H
+#define _ASM_X86_NOPS_H
+
+/*
+ * Define nops for use with alternative() and for tracing.
+ */
+
+#ifndef CONFIG_64BIT
+
+/*
+ * Generic 32bit nops from GAS:
+ *
+ * 1: nop
+ * 2: movl %esi,%esi
+ * 3: leal 0x0(%esi),%esi
+ * 4: leal 0x0(%esi,%eiz,1),%esi
+ * 5: leal %ds:0x0(%esi,%eiz,1),%esi
+ * 6: leal 0x0(%esi),%esi
+ * 7: leal 0x0(%esi,%eiz,1),%esi
+ * 8: leal %ds:0x0(%esi,%eiz,1),%esi
+ *
+ * Except 5 and 8, which are DS prefixed 4 and 7 resp, where GAS would emit 2
+ * nop instructions.
+ */
+#define BYTES_NOP1 0x90
+#define BYTES_NOP2 0x89,0xf6
+#define BYTES_NOP3 0x8d,0x76,0x00
+#define BYTES_NOP4 0x8d,0x74,0x26,0x00
+#define BYTES_NOP5 0x3e,BYTES_NOP4
+#define BYTES_NOP6 0x8d,0xb6,0x00,0x00,0x00,0x00
+#define BYTES_NOP7 0x8d,0xb4,0x26,0x00,0x00,0x00,0x00
+#define BYTES_NOP8 0x3e,BYTES_NOP7
+
+#else
+
+/*
+ * Generic 64bit nops from GAS:
+ *
+ * 1: nop
+ * 2: osp nop
+ * 3: nopl (%eax)
+ * 4: nopl 0x00(%eax)
+ * 5: nopl 0x00(%eax,%eax,1)
+ * 6: osp nopl 0x00(%eax,%eax,1)
+ * 7: nopl 0x00000000(%eax)
+ * 8: nopl 0x00000000(%eax,%eax,1)
+ */
+#define BYTES_NOP1 0x90
+#define BYTES_NOP2 0x66,BYTES_NOP1
+#define BYTES_NOP3 0x0f,0x1f,0x00
+#define BYTES_NOP4 0x0f,0x1f,0x40,0x00
+#define BYTES_NOP5 0x0f,0x1f,0x44,0x00,0x00
+#define BYTES_NOP6 0x66,BYTES_NOP5
+#define BYTES_NOP7 0x0f,0x1f,0x80,0x00,0x00,0x00,0x00
+#define BYTES_NOP8 0x0f,0x1f,0x84,0x00,0x00,0x00,0x00,0x00
+
+#endif /* CONFIG_64BIT */
+
+#ifdef __ASSEMBLY__
+#define _ASM_MK_NOP(x) .byte x
+#else
+#define _ASM_MK_NOP(x) ".byte " __stringify(x) "\n"
+#endif
+
+#define ASM_NOP1 _ASM_MK_NOP(BYTES_NOP1)
+#define ASM_NOP2 _ASM_MK_NOP(BYTES_NOP2)
+#define ASM_NOP3 _ASM_MK_NOP(BYTES_NOP3)
+#define ASM_NOP4 _ASM_MK_NOP(BYTES_NOP4)
+#define ASM_NOP5 _ASM_MK_NOP(BYTES_NOP5)
+#define ASM_NOP6 _ASM_MK_NOP(BYTES_NOP6)
+#define ASM_NOP7 _ASM_MK_NOP(BYTES_NOP7)
+#define ASM_NOP8 _ASM_MK_NOP(BYTES_NOP8)
+
+#define ASM_NOP_MAX 8
+
+#ifndef __ASSEMBLY__
+extern const unsigned char * const x86_nops[];
+#endif
+
+#endif /* _ASM_X86_NOPS_H */
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -11,6 +11,9 @@
#include "../../../arch/x86/lib/inat.c"
#include "../../../arch/x86/lib/insn.c"
+#define CONFIG_64BIT 1
+#include <asm/nops.h>
+
#include <asm/orc_types.h>
#include <objtool/check.h>
#include <objtool/elf.h>
@@ -640,11 +643,11 @@ void arch_initial_func_cfi_state(struct
const char *arch_nop_insn(int len)
{
static const char nops[5][5] = {
- /* 1 */ { 0x90 },
- /* 2 */ { 0x66, 0x90 },
- /* 3 */ { 0x0f, 0x1f, 0x00 },
- /* 4 */ { 0x0f, 0x1f, 0x40, 0x00 },
- /* 5 */ { 0x0f, 0x1f, 0x44, 0x00, 0x00 },
+ { BYTES_NOP1 },
+ { BYTES_NOP2 },
+ { BYTES_NOP3 },
+ { BYTES_NOP4 },
+ { BYTES_NOP5 },
};
if (len < 1 || len > 5) {
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -10,6 +10,7 @@ FILES="include/linux/objtool.h"
if [ "$SRCARCH" = "x86" ]; then
FILES="$FILES
+arch/x86/include/asm/nops.h
arch/x86/include/asm/inat_types.h
arch/x86/include/asm/orc_types.h
arch/x86/include/asm/emulate_prefix.h
next prev parent reply other threads:[~2021-03-12 12:00 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 11:32 [PATCH 0/2] x86: Remove ideal_nops[] Peter Zijlstra
2021-03-12 11:32 ` [PATCH 1/2] x86: Remove dynamic NOP selection Peter Zijlstra
2021-03-12 12:09 ` Peter Zijlstra
2021-03-12 20:36 ` Linus Torvalds
2021-03-15 18:00 ` [tip: x86/cpu] " tip-bot2 for Peter Zijlstra
2024-01-20 6:58 ` [PATCH 1/2] " Thorsten Glaser
2024-01-20 8:22 ` H. Peter Anvin
2024-01-20 16:53 ` Thorsten Glaser
2024-01-21 23:21 ` H. Peter Anvin
2024-01-21 23:58 ` Thorsten Glaser
2024-01-22 0:15 ` H. Peter Anvin
2024-01-22 0:56 ` Steven Rostedt
2024-01-22 1:17 ` Thorsten Glaser
2024-01-22 2:04 ` H. Peter Anvin
2024-01-22 2:15 ` H. Peter Anvin
2024-01-22 2:22 ` Steven Rostedt
2024-01-22 2:31 ` H. Peter Anvin
2024-01-20 17:00 ` Linus Torvalds
2024-01-20 17:19 ` Thorsten Glaser
2024-01-20 18:21 ` disassemblers (was Re: [PATCH 1/2] x86: Remove dynamic NOP selection) Thorsten Glaser
2024-01-21 22:36 ` [PATCH 1/2] x86: Remove dynamic NOP selection David Laight
2024-01-21 23:10 ` H. Peter Anvin
2021-03-12 11:32 ` Peter Zijlstra [this message]
2021-03-15 18:00 ` [tip: x86/cpu] objtool/x86: Use asm/nops.h tip-bot2 for Peter Zijlstra
2021-03-12 14:29 ` [PATCH 0/2] x86: Remove ideal_nops[] Sedat Dilek
2021-03-12 14:47 ` Borislav Petkov
2021-03-12 17:26 ` Steven Rostedt
2021-03-12 17:35 ` Sedat Dilek
2021-03-12 17:46 ` Borislav Petkov
2021-03-12 17:47 ` Steven Rostedt
2021-03-12 18:13 ` Sedat Dilek
2021-03-12 19:03 ` Sedat Dilek
2021-03-12 20:59 ` Borislav Petkov
2021-03-13 5:26 ` Sedat Dilek
2021-03-13 8:49 ` Borislav Petkov
2021-03-13 11:23 ` Borislav Petkov
2021-03-13 12:10 ` Sedat Dilek
2021-03-13 12:15 ` Borislav Petkov
2021-03-13 12:38 ` Sedat Dilek
2021-03-13 12:49 ` Borislav Petkov
2021-03-13 12:58 ` Sedat Dilek
2021-03-13 13:29 ` Borislav Petkov
2021-03-13 13:47 ` Sedat Dilek
2021-03-15 17:04 ` Sedat Dilek
2021-03-15 17:15 ` Borislav Petkov
2021-03-15 17:19 ` Sedat Dilek
2021-03-15 17:23 ` Borislav Petkov
2021-03-15 18:10 ` Peter Zijlstra
2021-03-15 18:23 ` Sedat Dilek
2021-03-15 22:14 ` Peter Zijlstra
2021-03-16 5:56 ` Sedat Dilek
2021-03-27 12:08 ` Sedat Dilek
2021-03-27 20:02 ` Linus Torvalds
2021-03-30 12:31 ` Sedat Dilek
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