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qtdeclarative/tools/fdegen/main.cpp

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