Re: [Qemu-devel] [RFC 4/4] disas: implement host disassembly output for aarch64

[Claudio Fontana]

Hallo Andreas,

On 16.09.2013 08:53, Andreas Färber wrote:
> Am 11.09.2013 15:08, schrieb Claudio Fontana:
>> use C++ libvixl to implement output, for now only enabled for the host output
>> disasm, since we don't have the aarch64 target yet.
>>
>> Signed-off-by: Claudio Fontana <address@hidden>
>> ---
>>  configure                   |  6 +++++
>>  disas.c                     |  2 ++
>>  disas/Makefile.objs         |  7 ++++++
>>  disas/aarch64-cxx.cc        | 53 
>> +++++++++++++++++++++++++++++++++++++++++++++
>>  disas/aarch64.c             | 45 ++++++++++++++++++++++++++++++++++++++
>>  disas/libvixl/Makefile.objs |  6 +++++
>>  include/disas/bfd.h         |  1 +
>>  7 files changed, 120 insertions(+)
>>  create mode 100644 disas/aarch64-cxx.cc
>>  create mode 100644 disas/aarch64.c
>>  create mode 100644 disas/libvixl/Makefile.objs
>>
>> diff --git a/configure b/configure
>> index 6b73d99..1a2648a 100755
>> --- a/configure
>> +++ b/configure
>> @@ -4443,6 +4443,12 @@ ldflags=""
>>  
>>  for i in $ARCH $TARGET_BASE_ARCH ; do
>>    case "$i" in
>> +  aarch64)
>> +    if test "x${cxx}" != "x"; then
>> +      echo "CONFIG_AARCH64_DIS=y"  >> $config_target_mak
>> +      echo "CONFIG_AARCH64_DIS=y"  >> config-all-disas.mak
>> +    fi
>> +  ;;
>>    alpha)
>>      echo "CONFIG_ALPHA_DIS=y"  >> $config_target_mak
>>      echo "CONFIG_ALPHA_DIS=y"  >> config-all-disas.mak
>> diff --git a/disas.c b/disas.c
>> index 0203ef2..cc20c4a 100644
>> --- a/disas.c
>> +++ b/disas.c
>> @@ -356,6 +356,8 @@ void disas(FILE *out, void *code, unsigned long size)
>>  #elif defined(_ARCH_PPC)
>>      s.info.disassembler_options = (char *)"any";
>>      print_insn = print_insn_ppc;
>> +#elif defined(__aarch64__)
>> +    print_insn = print_insn_aarch64;
>>  #elif defined(__alpha__)
>>      print_insn = print_insn_alpha;
>>  #elif defined(__sparc__)
>> diff --git a/disas/Makefile.objs b/disas/Makefile.objs
>> index 3b1e77a..f468c22 100644
>> --- a/disas/Makefile.objs
>> +++ b/disas/Makefile.objs
>> @@ -1,3 +1,10 @@
>> +ifeq ($(CONFIG_AARCH64_DIS),y)
>> +libvixldir = $(SRC_PATH)/disas/libvixl/src
>> +QEMU_CFLAGS += -I$(libvixldir) -Wno-undef
>> +common-obj-$(CONFIG_AARCH64_DIS) += libvixl/
>> +common-obj-$(CONFIG_AARCH64_DIS) += aarch64.o aarch64-cxx.o
>> +endif
>> +
>>  common-obj-$(CONFIG_ALPHA_DIS) += alpha.o
>>  common-obj-$(CONFIG_ARM_DIS) += arm.o
>>  common-obj-$(CONFIG_CRIS_DIS) += cris.o
>> diff --git a/disas/aarch64-cxx.cc b/disas/aarch64-cxx.cc
>> new file mode 100644
>> index 0000000..524f5ae
>> --- /dev/null
>> +++ b/disas/aarch64-cxx.cc
>> @@ -0,0 +1,53 @@
>> +/*
>> + * Aarch64 disassembly output wrapper to libvixl - C++ part
>> + * Copyright (c) 2013 Linaro Limited
>> + * Written by Claudio Fontana
>> + *
>> + * This program is free software: you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation, either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include "a64/simulator-a64.h"
>> +#include "a64/macro-assembler-a64.h"
>> +
>> +extern "C" {
>> +    int vixl_is_initialized(int);
>> +    int vixl_init(FILE *f);
>> +    int vixl_decode_insn(uint8_t *bytes);
>> +}
>> +
>> +using namespace vixl;
>> +
>> +static Decoder *vixl_decoder = NULL;
>> +static Disassembler *vixl_disasm = NULL;
>> +
>> +int vixl_is_initialized(int unused)
>> +{
>> +    return vixl_decoder != NULL;
>> +}
>> +
>> +/* Disassemble Aarch64 bytecode - wrappers */
>> +int vixl_init(FILE *f) {
>> +    vixl_decoder = new Decoder();
>> +    vixl_disasm = new PrintDisassembler(f);
>> +    vixl_decoder->AppendVisitor(vixl_disasm);
>> +    return 1;
>> +}
>> +
>> +int vixl_decode_insn(uint8_t *bytes)
>> +{
>> +    Instr instr;
>> +    instr = bytes[0] | bytes[1] << 8 | bytes[2] << 16 | bytes[3] << 24;
>> +    vixl_decoder->Decode(reinterpret_cast<Instruction*>(&instr));
>> +    return 1;
>> +}
>> diff --git a/disas/aarch64.c b/disas/aarch64.c
>> new file mode 100644
>> index 0000000..7e44837
>> --- /dev/null
>> +++ b/disas/aarch64.c
>> @@ -0,0 +1,45 @@
>> +/*
>> + * Aarch64 disassembly output wrapper to libvixl - C part
>> + * Copyright (c) 2013 Linaro Limited
>> + * Written by Claudio Fontana
>> + *
>> + * This program is free software: you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation, either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include "disas/bfd.h"
>> +#define INSN_SIZE 4
>> +
>> +extern int vixl_is_initialized(int);
>> +extern int vixl_init(FILE *);
>> +extern int vixl_decode_insn(uint8_t *);
>> +
>> +/* Disassemble Aarch64 bytecode. */
>> +int print_insn_aarch64(uint64_t addr, disassemble_info *info)
>> +{
>> +    uint8_t bytes[INSN_SIZE];
>> +    int status;
>> +
>> +    if (!vixl_is_initialized(0)) {
>> +        vixl_init(info->stream);
>> +    }
>> +
>> +    status = info->read_memory_func(addr, bytes, INSN_SIZE, info);
>> +    if (status != 0) {
>> +        info->memory_error_func(status, addr, info);
>> +        return -1;
>> +    }
>> +
>> +    vixl_decode_insn(bytes);
>> +    return INSN_SIZE;
>> +}
> 
> Why split this into two mini files? You're already using extern "C" {
> ... } in the C++ file for the prototypes anyway.
> 
> Apart from that the library integration looks surprisingly clean. :)
> 
> Cheers,
> Andreas

The reason I split this into two files is that the c++ compiler did not digest 
the bfd.h include.

So I thought to have a .cc file which does not actually need anything from QEMU 
at all,
and a .c file which deals with the QEMU dependencies and provides the final 
symbol.

Ciao,

Claudio

>> diff --git a/disas/libvixl/Makefile.objs b/disas/libvixl/Makefile.objs
>> new file mode 100644
>> index 0000000..43ba29c
>> --- /dev/null
>> +++ b/disas/libvixl/Makefile.objs
>> @@ -0,0 +1,6 @@
>> +libvixl_OBJS = src/utils.o \
>> +               src/a64/instructions-a64.o \
>> +               src/a64/decoder-a64.o \
>> +               src/a64/disasm-a64.o
>> +
>> +common-obj-$(CONFIG_AARCH64_DIS) += $(libvixl_OBJS)
>> diff --git a/include/disas/bfd.h b/include/disas/bfd.h
>> index 803b6ef..73017da 100644
>> --- a/include/disas/bfd.h
>> +++ b/include/disas/bfd.h
>> @@ -379,6 +379,7 @@ int print_insn_h8300            (bfd_vma, 
>> disassemble_info*);
>>  int print_insn_h8300h           (bfd_vma, disassemble_info*);
>>  int print_insn_h8300s           (bfd_vma, disassemble_info*);
>>  int print_insn_h8500            (bfd_vma, disassemble_info*);
>> +int print_insn_aarch64          (bfd_vma, disassemble_info*);
>>  int print_insn_alpha            (bfd_vma, disassemble_info*);
>>  disassembler_ftype arc_get_disassembler (int, int);
>>  int print_insn_arm              (bfd_vma, disassemble_info*);
>>