Re: [PATCH 3/5] Add support for ARM breakpoint types in GDBServer.

[Antoine Tremblay <antoine.tremblay@ericsson.com>]

On 09/29/2015 04:32 AM, Yao Qi wrote:
> Antoine Tremblay <antoine.tremblay@ericsson.com> writes:
>
>> This will contain more stuff as I post the next patch sets for single
>> stepping etc.. I would like to keep a more general name.
>>
>> It's basically all coming from arm-tdep.c but I don't want to name it
>> common/arm-tdep.c to avoid confusion and Makefile problems.
>>
>> arm-ctdep.c ?
>>
>
> How about arm.c?
>

There's already arm.h in there I think I can actually merge what is in 
there with what I have, and create arm.c.

>>> Please move this file to arch/ directory rather than common/
>>
>> It seems weird to me to have common objects somewhere else then in
>> common/ , if common becomes more a lib we don't want it all over the
>> place no ?
>>
>> Would creating a common/arch be acceptable ? I guess we would have to
>> move things like x86-xstate.h etc.. there too ?
>
> common/ was created in order to share code between GDB and GDBserver, see
> https://sourceware.org/gdb/wiki/Common After that, we find that we'll
> end up with moving most of gdb files into common/ and we'd better move
> different common things into different common directory.  Nowadays, we
> have nat/ common/ and arch/ directories for common things.  arm.c should
> be put in arch/ directory.

Ok I understand thanks for explaining.

>
>>>> diff --git a/gdb/configure.tgt b/gdb/configure.tgt
>>>> index c42b4df..e831f59 100644
>>>> --- a/gdb/configure.tgt
>>>> +++ b/gdb/configure.tgt
>>>> @@ -89,7 +89,7 @@ arm*-wince-pe | arm*-*-mingw32ce*)
>>>>    	;;
>>>>    arm*-*-linux*)
>>>>    	# Target: ARM based machine running GNU/Linux
>>>> -	gdb_target_obs="arm-tdep.o arm-linux-tdep.o glibc-tdep.o \
>>>> +	gdb_target_obs="arm-common.o arm-tdep.o arm-linux-tdep.o glibc-tdep.o \
>>>>    			solib-svr4.o symfile-mem.o linux-tdep.o linux-record.o"
>>>>    	build_gdbserver=yes
>>>
>>> since arm-common.o is moved out of arm-tdep.o, so it should be added to
>>> every target which uses arm-tdep.o, such as aarch64*-*-linux*,
>>> arm*-wince-pe, etc.
>>
>> Even if they don't use it ? But ok.
>>
>
> No, they use it.  This patch moves thumb_insn_size to arm-common.o, but
> thumb_insn_size is used by arm-tdep.c.  If we don't add arm-common.o to
> every target which uses arm-tdep.o, the build will fail on these targets
>
> build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:846: undefined reference to `thumb_insn_size'
> build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:846: undefined reference to `thumb_insn_size'
> arm-tdep.o: In function `arm_adjust_breakpoint_address':
> build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:5417: undefined reference to `thumb_insn_size'
> build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:5467: undefined reference to `thumb_insn_size'
> arm-tdep.o: In function `arm_breakpoint_from_pc':
> build/gdb/aarch64/gdb/../../../../binutils-gdb/gdb/arm-tdep.c:8858: undefined reference to `thumb_insn_size'
>

Indeed, thanks

>>>
>>>> diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
>>>> index 367c704..15ecb70 100644
>>>> --- a/gdb/gdbserver/linux-arm-low.c
>>>> +++ b/gdb/gdbserver/linux-arm-low.c
>>>> @@ -30,6 +30,8 @@
>>>>    #include "nat/gdb_ptrace.h"
>>>>    #include <signal.h>
>>>>
>>>> +#include "common/arm-common.h"
>>>> +
>>>>    /* Defined in auto-generated files.  */
>>>>    void init_registers_arm (void);
>>>>    extern const struct target_desc *tdesc_arm;
>>>> @@ -234,19 +236,28 @@ arm_set_pc (struct regcache *regcache, CORE_ADDR pc)
>>>>    }
>>>>
>>>>    /* Correct in either endianness.  */
>>>> -static const unsigned long arm_breakpoint = 0xef9f0001;
>>>> -#define arm_breakpoint_len 4
>>>> -static const unsigned short thumb_breakpoint = 0xde01;
>>>> -static const unsigned short thumb2_breakpoint[] = { 0xf7f0, 0xa000 };
>>>> +#define arm_abi_breakpoint 0xef9f0001UL
>>>>
>>>>    /* For new EABI binaries.  We recognize it regardless of which ABI
>>>>       is used for gdbserver, so single threaded debugging should work
>>>>       OK, but for multi-threaded debugging we only insert the current
>>>>       ABI's breakpoint instruction.  For now at least.  */
>>>> -static const unsigned long arm_eabi_breakpoint = 0xe7f001f0;
>>>> +#define arm_eabi_breakpoint 0xe7f001f0UL
>>>> +
>>>> +#ifndef __ARM_EABI__
>>>> +static const unsigned long arm_breakpoint = arm_abi_breakpoint;
>>>> +#else
>>>> +static const unsigned long arm_breakpoint = arm_eabi_breakpoint;
>>>> +#endif
>>>> +
>>>> +#define arm_breakpoint_len 4
>>>> +static const unsigned short thumb_breakpoint = 0xde01;
>>>> +#define thumb_breakpoint_len 2
>>>> +static const unsigned short thumb2_breakpoint[] = { 0xf7f0, 0xa000 };
>>>> +#define thumb2_breakpoint_len 4
>>>
>>> I am confused by your changes here.  Why do you change them?
>>>
>>
>> Before arm_breakpoint_from_pc would be :
>>
>> #ifndef __ARM_EABI__
>>    return (const unsigned char *) &arm_breakpoint;
>> #else
>> -  return (const unsigned char *) &arm_eabi_breakpoint;
>> #endif
>>
>> And arm_breakpoint_at would check for the arm_breakpoint ||
>> arm_eabi_breakpoint.
>>
>> Thus the selected arm_breakpoint would be what that function returned
>> and arm_breakpoint was arm_abi_breakpoint.
>>
>> It felt more clear to me to name those for what they are : 2 separate
>> entities arm_abi_breakpoint and arm_eabi_breakpoint and set the
>> current used one as arm_breakpoint.
>>
>> This allows a cleaner breakpoint_from_pc as it just returns
>> arm_breakpoint rather than having the #ifdef in that function.
>>
>> Any other reference to the arm_breakpoint would also be clear of #ifdefs...
>
> Please don't combine movement and refactoring.  This patch is about
> movement, so let us do movement only.  Refactor can be done separately.
>

Ok , would you find it acceptable still to include the refactoring in 
the series as the next patch or should I create it out of series ?