Tool to generate FDE and CIE tables using libdwarf
This makes it easier to generate the right magic bits and bytes across different architectures. Change-Id: I83cf8f348f4ea92febfe463e1ffd627808e1bb44 Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
This commit is contained in:
Simon Hausmann
parent
3fcaf5eaae
commit
077a462c12
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@ -15,3 +15,4 @@ mkspecs
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src/v4/Qt5V4_resource.rc
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src/v4/Qt5V4d_resource.rc
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*.pdb
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tools/fdegen/fdegen
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@ -0,0 +1,8 @@
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TEMPLATE = app
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TARGET = fdegen
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INCLUDEPATH += .
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# Input
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SOURCES += main.cpp
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LIBS += -ldwarf -lelf
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@ -0,0 +1,372 @@
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/****************************************************************************
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**
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** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/legal
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**
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** This file is part of the V4VM module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and Digia. For licensing terms and
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** conditions see http://qt.digia.com/licensing. For further information
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** use the contact form at http://qt.digia.com/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Digia gives you certain additional
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** rights. These rights are described in the Digia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3.0 as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU General Public License version 3.0 requirements will be
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** met: http://www.gnu.org/copyleft/gpl.html.
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include <libdwarf.h>
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#include <dwarf.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#define DEBUG
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#ifdef DEBUG
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#include <libelf.h>
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#endif
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#include <qglobal.h>
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enum DwarfRegs {
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#if defined(Q_PROCESSOR_X86_64)
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// X86-64
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RAX = 0,
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RDX = 1,
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RCX = 2,
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RBX = 3,
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RSI = 4,
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RDI = 5,
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RBP = 6,
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RSP = 7,
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R8 = 8,
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R9 = 9,
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R10 = 10,
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R11 = 11,
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R12 = 12,
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R13 = 13,
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R14 = 14,
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R15 = 15,
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RIP = 16,
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InstructionPointerRegister = RIP,
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StackPointerRegister = RSP,
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StackFrameRegister = RBP
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#elif defined(Q_PROCESSOR_X86)
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// x86
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EAX = 0,
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EDX = 1,
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ECX = 2,
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EBX = 3,
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ESI = 4,
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EDI = 5,
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EBP = 6,
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ESP = 7,
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EIP = 8,
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InstructionPointerRegister = EIP,
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StackPointerRegister = ESP,
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StackFrameRegister = EBP
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#else
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#error Not ported yet
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#endif
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};
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static const DwarfRegs calleeSavedRegisters[] = {
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#if defined(Q_PROCESSOR_X86_64)
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R12,
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R14
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#endif
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};
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static const int calleeSavedRegisterCount = sizeof(calleeSavedRegisters) / sizeof(calleeSavedRegisters[0]);
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#if QT_POINTER_SIZE == 8
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#define Elf_Ehdr Elf64_Ehdr
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#define elf_newehdr elf64_newehdr
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#define Elf_Shdr Elf64_Shdr
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#define elf_getshdr elf64_getshdr
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#else
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#define Elf_Ehdr Elf32_Ehdr
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#define elf_newehdr elf32_newehdr
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#define Elf_Shdr Elf32_Shdr
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#define elf_getshdr elf32_getshdr
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#endif
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static void die(const char *msg)
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{
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fprintf(stderr, "error: %s\n", msg);
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exit(1);
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}
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static int createSectionCallback(
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char *name,
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int size,
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Dwarf_Unsigned /*type*/,
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Dwarf_Unsigned /*flags*/,
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Dwarf_Unsigned /*link*/,
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Dwarf_Unsigned /*info*/,
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Dwarf_Unsigned* /*sect_name_index*/,
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void * /*user_data*/,
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int* /*error*/)
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{
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if (strcmp(name, ".debug_frame"))
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return 0;
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fprintf(stderr, "createsection called with %s and size %d\n", name, size);
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return 1;
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}
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static unsigned char cie_init_instructions[] = {
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DW_CFA_def_cfa, StackPointerRegister, /*offset in bytes */QT_POINTER_SIZE,
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DW_CFA_offset | InstructionPointerRegister, 1,
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};
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int main()
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{
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Dwarf_Error error = 0;
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Dwarf_P_Debug dw = dwarf_producer_init_c(DW_DLC_WRITE | DW_DLC_SIZE_64,
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createSectionCallback,
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/* error handler */0,
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/* error arg */0,
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/* user data */0,
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&error);
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if (error != 0)
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die("dwarf_producer_init_c failed");
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Dwarf_Unsigned cie = dwarf_add_frame_cie(dw,
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"",
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/* code alignment factor */QT_POINTER_SIZE,
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/* data alignment factor */-QT_POINTER_SIZE,
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/* return address reg*/InstructionPointerRegister,
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cie_init_instructions,
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sizeof(cie_init_instructions),
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&error);
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if (error != 0)
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die("dwarf_add_frame_cie failed");
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Dwarf_P_Fde fde = dwarf_new_fde(dw, &error);
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if (error != 0)
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die("dwarf_new_fde failed");
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/* New entry in state machine for code offset 1 after push rbp instruction */
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dwarf_add_fde_inst(fde,
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DW_CFA_advance_loc,
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/*offset in code alignment units*/ 1,
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/* unused*/ 0,
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&error);
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/* After "push rbp" the offset to the CFA is now 2 instead of 1 */
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dwarf_add_fde_inst(fde,
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DW_CFA_def_cfa_offset_sf,
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/*offset in code alignment units*/ -2,
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/* unused*/ 0,
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&error);
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/* After "push rbp" the value of rbp is now stored at offset 1 from CFA */
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dwarf_add_fde_inst(fde,
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DW_CFA_offset,
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StackFrameRegister,
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2,
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&error);
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/* New entry in state machine for code offset 3 for mov rbp, rsp instruction */
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dwarf_add_fde_inst(fde,
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DW_CFA_advance_loc,
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/*offset in code alignment units*/ 3,
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/* unused */ 0,
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&error);
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/* After "mov rbp, rsp" the cfa is reachable via rbp */
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dwarf_add_fde_inst(fde,
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DW_CFA_def_cfa_register,
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StackFrameRegister,
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/* unused */0,
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&error);
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/* Callee saved registers */
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for (int i = 0; i < calleeSavedRegisterCount; ++i) {
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dwarf_add_fde_inst(fde,
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DW_CFA_offset,
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calleeSavedRegisters[i],
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i + 3,
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&error);
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}
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dwarf_add_frame_fde(dw, fde,
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/* die */0,
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cie,
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/*virt addr */0,
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/* length of code */0,
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/* symbol index */0,
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&error);
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if (error != 0)
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die("dwarf_add_frame_fde failed");
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dwarf_transform_to_disk_form(dw, &error);
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if (error != 0)
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die("dwarf_transform_to_disk_form failed");
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Dwarf_Unsigned len = 0;
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Dwarf_Signed elfIdx = 0;
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unsigned char *bytes = (unsigned char *)dwarf_get_section_bytes(dw, /* section */1,
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&elfIdx, &len, &error);
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if (error != 0)
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die("dwarf_get_section_bytes failed");
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// libdwarf doesn't add a terminating FDE with zero length, so let's add one
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// ourselves.
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unsigned char *newBytes = (unsigned char *)alloca(len + 4);
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memcpy(newBytes, bytes, len);
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newBytes[len] = 0;
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newBytes[len + 1] = 0;
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newBytes[len + 2] = 0;
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newBytes[len + 3] = 0;
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newBytes[len + 4] = 0;
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bytes = newBytes;
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len += 4;
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// Reset CIE-ID back to 0 as expected for .eh_frames
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bytes[4] = 0;
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bytes[5] = 0;
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bytes[6] = 0;
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bytes[7] = 0;
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unsigned fde_offset = bytes[0] + 4;
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bytes[fde_offset + 4] = fde_offset + 4;
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printf("static const unsigned char cie_fde_data[] = {\n");
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int i = 0;
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while (i < len) {
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printf(" ");
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for (int j = 0; i < len && j < 8; ++j, ++i)
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printf("0x%x, ", bytes[i]);
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printf("\n");
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}
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printf("};\n");
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printf("static const int fde_offset = %d;\n", fde_offset);
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printf("static const int initial_location_offset = %d;\n", fde_offset + 8);
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printf("static const int address_range_offset = %d;\n", fde_offset + 8 + QT_POINTER_SIZE);
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#ifdef DEBUG
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{
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if (elf_version(EV_CURRENT) == EV_NONE)
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die("wrong elf version");
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int fd = open("debug.o", O_WRONLY | O_CREAT, 0777);
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if (fd < 0)
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die("cannot create debug.o");
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Elf *e = elf_begin(fd, ELF_C_WRITE, 0);
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if (!e)
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die("elf_begin failed");
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Elf_Ehdr *ehdr = elf_newehdr(e);
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if (!ehdr)
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die(elf_errmsg(-1));
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ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
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#if defined(Q_PROCESSOR_X86_64)
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ehdr->e_machine = EM_X86_64;
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#elif defined(Q_PROCESSOR_X86)
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ehdr->e_machine = EM_386;
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#else
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#error port me :)
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#endif
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ehdr->e_type = ET_EXEC;
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ehdr->e_version = EV_CURRENT;
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Elf_Scn *section = elf_newscn(e);
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if (!section)
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die("elf_newscn failed");
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Elf_Data *data = elf_newdata(section);
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if (!data)
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die(elf_errmsg(-1));
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data->d_align = 4;
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data->d_off = 0;
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data->d_buf = bytes;
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data->d_size = len;
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data->d_type = ELF_T_BYTE;
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data->d_version = EV_CURRENT;
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Elf_Shdr *shdr = elf_getshdr(section);
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if (!shdr)
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die(elf_errmsg(-1));
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shdr->sh_name = 1;
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shdr->sh_type = SHT_PROGBITS;
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shdr->sh_entsize = 0;
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char stringTable[] = {
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0,
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'.', 'e', 'h', '_', 'f', 'r', 'a', 'm', 'e', 0,
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'.', 's', 'h', 's', 't', 'r', 't', 'a', 'b', 0
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};
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section = elf_newscn(e);
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if (!section)
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die("elf_newscn failed");
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data = elf_newdata(section);
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if (!data)
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die(elf_errmsg(-1));
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data->d_align = 1;
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data->d_off = 0;
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data->d_buf = stringTable;
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data->d_size = sizeof(stringTable);
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data->d_type = ELF_T_BYTE;
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data->d_version = EV_CURRENT;
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shdr = elf_getshdr(section);
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if (!shdr)
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die(elf_errmsg(-1));
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shdr->sh_name = 11;
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shdr->sh_type = SHT_STRTAB;
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shdr->sh_flags = SHF_STRINGS | SHF_ALLOC;
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shdr->sh_entsize = 0;
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ehdr->e_shstrndx = elf_ndxscn(section);
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if (elf_update(e, ELF_C_WRITE) < 0)
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die(elf_errmsg(-1));
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elf_end(e);
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close(fd);
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}
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#endif
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dwarf_producer_finish(dw, &error);
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if (error != 0)
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die("dwarf_producer_finish failed");
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return 0;
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}
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