[PATCH, BINUTILS, AARCH64, 7/9] Add BTI instruction

Sudakshina Das sudi.das@arm.com
Tue Oct 9 13:22:00 GMT 2018


Hi Richard

On 08/10/18 12:59, Sudakshina Das wrote:
> Hi Richard
> 
> On 05/10/18 16:43, Richard Earnshaw (lists) wrote:
>> On 19/09/18 15:29, Sudakshina Das wrote:
>>> Hi
>>>
>>> This patch is part of the patch series to add support for ARMv8.5-A
>>> extensions.
>>> (https://developer.arm.com/products/architecture/cpu-architecture/a-profile/docs/ddi0596/a/a64-base-instructions-alphabetic-order/bti-branch-target-identification) 
>>>
>>>
>>> The Branch Target Identification instructions (BTI) are allocated to
>>> existing HINT space, using HINT numbers 32, 34, 36, 38, such that
>>> bits[7:6] of the instruction identify the compatibility of the BTI
>>> instruction to different branches.
>>>          BTI {<targets>}
>>> where <targets> one of the following, specifying which type of
>>> indirection is allowed:
>>>         j : Can be a target of any BR Xn isntruction.
>>>         c : Can be a target of any BLR Xn and BR {X16|X17}.
>>>         jc: Can be a target of any free branch.
>>>
>>> A BTI instruction without any <targets> is the strictest of all and
>>> can not be a target of nay free branch.
>>>
>>> Testing done: Builds and reg tests all pass on aarch64-none-linux-gnu.
>>> and aarch64-none-elf. Updated and added new tests to check.
>>>
>>> Ok for trunk?
>>>
>>> Thanks
>>> Sudi
>>> PS. I do not have commit access so if OK can someone apply for me?
>>> Also the patch was too big to attach due to the regenerated files.
>>>
>>>
>>> *** include/ChangeLog ***
>>>
>>> 2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>
>>>
>>>     * opcode/aarch64.h (AARCH64_FEATURE_BTI): New.
>>>     (AARCH64_ARCH_V8_5): Add AARCH64_FEATURE_BTI by default.
>>>     (aarch64_opnd): Add AARCH64_OPND_BTI_TARGET.
>>>
>>> *** opcodes/ChangeLog ***
>>>
>>> 2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>
>>>
>>>     * aarch64-opc.c (aarch64_hint_options): New entries for
>>>     c, j, jc and default for BTI.
>>>     (aarch64_print_operand): Add case for AARCH64_OPND_BTI_TARGET
>>>     and create an exception for "default" option.
>>>     * aarch64-tbl.h (aarch64_feature_bti, BTI, BTI_INSN): New.
>>>     (aarch64_opcode_table): Add entry for BTI.
>>>     (AARCH64_OPERANDS): Add new description for BTI targets.
>>>     * aarch64-asm-2.c: Regenerate.
>>>     * aarch64-dis-2.c: Regenerate.
>>>     * aarch64-opc-2.c: Regenerate.
>>>
>>> *** gas/ChangeLog ***
>>>
>>> 2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>
>>>
>>>     * config/tc-aarch64.c (parse_bti_operand): New.
>>>     (process_omitted_operand): Add case for AARCH64_OPND_BTI_TARGET.
>>>     (parse_operands): Likewise.
>>>     * testsuite/gas/aarch64/system.d: Update for BTI.
>>>     * testsuite/gas/aarch64/bti.s: New.
>>>     * testsuite/gas/aarch64/bti.d: New.
>>>     * testsuite/gas/aarch64/illegal-bti.d: New.
>>>     * testsuite/gas/aarch64/illegal-bti.l: New.
>>>
>>>
>>>
>>
>> gas/config/tc-aarch64.c:
>>
>> +    case 0x22:
>> +    case 0x24:
>> +    case 0x26: break;
>> +    default:
>>
>> Put the 'break on a separate line when you have multiple cases.  Blank
>> line before the default.
>>
>> Also, if the user writes
>>
>>     bti default
>>     bti fred
>>
>> they will get a different error message for each line.  That's 
>> inconsistent.
>>
>> opcodes/aarch64-opc.c:
>>
>>       case AARCH64_OPND_BARRIER_PSB:
>> -      snprintf (buf, size, "%s", opnd->hint_option->name);
>> +    case AARCH64_OPND_BTI_TARGET:
>> +      /* BTI with no target.  */
>> +      if (opnd->hint_option->value != 0x20)
>> +    snprintf (buf, size, "%s", opnd->hint_option->name);
>>         break;
>>
>> I don't particularly like the specific exception here.  Can we find a
>> better way to do this?  Perhaps a flag bit associated with the tupple to
>> indicate that the name field should not be printed.
>>
> 
> Please find a new version attached. Since the #imm for HINT is only a
> 7-bit value. I have edited the use of the "value" in the
> aarch64_name_value_pair to encode both #imm and a Flag indicating
> that the name does not need printing.
> 

With new macros for the bti operands:

*** include/ChangeLog ***

2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>

	* opcode/aarch64.h (AARCH64_FEATURE_BTI): New.
	(AARCH64_ARCH_V8_5): Add AARCH64_FEATURE_BTI by default.
	(aarch64_opnd): Add AARCH64_OPND_BTI_TARGET.
	(HINT_OPD_CSYNC, HINT_OPD_C, HINT_OPD_J): New macros to
	define HINT #imm values.
	(HINT_OPD_JC, HINT_OPD_NULL): Likewise.

*** opcodes/ChangeLog ***

2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>

	* aarch64-opc.h (HINT_OPD_NOPRINT, HINT_ENCODE): New.
  	(HINT_FLAG, HINT_VALUE): New macros to encode NO_PRINT flag
	with the hint immediate.
	* aarch64-opc.c (aarch64_hint_options): New entries for
	c, j, jc and default (with HINT_OPD_F_NOPRINT flag) for BTI.
	(aarch64_print_operand): Add case for AARCH64_OPND_BTI_TARGET
	while checking for HINT_OPD_F_NOPRINT flag.
	* aarch64-dis.c (aarch64_ext_hint): Use new HINT_VALUE to
	extract value.
	* aarch64-tbl.h (aarch64_feature_bti, BTI, BTI_INSN): New.
	(aarch64_opcode_table): Add entry for BTI.
	(AARCH64_OPERANDS): Add new description for BTI targets.
	* aarch64-asm-2.c: Regenerate.
	* aarch64-dis-2.c: Regenerate.
	* aarch64-opc-2.c: Regenerate.

*** gas/ChangeLog ***

2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>

	* config/tc-aarch64.c (parse_bti_operand): New.
	(process_omitted_operand): Add case for AARCH64_OPND_BTI_TARGET.
	(parse_operands): Likewise.
	* testsuite/gas/aarch64/system.d: Update for BTI.
	* testsuite/gas/aarch64/bti.s: New.
	* testsuite/gas/aarch64/bti.d: New.
	* testsuite/gas/aarch64/illegal-bti.d: New.
	* testsuite/gas/aarch64/illegal-bti.l: New.

Thanks
Sudi

> *** include/ChangeLog ***
> 
> 2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>
> 
>      * opcode/aarch64.h (AARCH64_FEATURE_BTI): New.
>      (AARCH64_ARCH_V8_5): Add AARCH64_FEATURE_BTI by default.
>      (aarch64_opnd): Add AARCH64_OPND_BTI_TARGET.
> 
> *** opcodes/ChangeLog ***
> 
> 2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>
> 
>      * aarch64-opc.h (HINT_OPD_NOPRINT, HINT_ENCODE): New.
>       (HINT_FLAG, HINT_VALUE): New macros to encode NO_PRINT flag
>      with the hint immediate.
>      * aarch64-opc.c (aarch64_hint_options): New entries for
>      c, j, jc and default (with HINT_NOPRINT flag) for BTI.
>      (aarch64_print_operand): Add case for AARCH64_OPND_BTI_TARGET
>      while checking for HINT_OPD_NOPRINT flag.
>      * aarch64-dis.c (aarch64_ext_hint): Use new HINT_VALUE to
>      extract value.
>      * aarch64-tbl.h (aarch64_feature_bti, BTI, BTI_INSN): New.
>      (aarch64_opcode_table): Add entry for BTI.
>      (AARCH64_OPERANDS): Add new description for BTI targets.
>      * aarch64-asm-2.c: Regenerate.
>      * aarch64-dis-2.c: Regenerate.
>      * aarch64-opc-2.c: Regenerate.
> 
> *** gas/ChangeLog ***
> 
> 2018-xx-xx  Sudakshina Das  <sudi.das@arm.com>
> 
>      * config/tc-aarch64.c (parse_bti_operand): New.
>      (process_omitted_operand): Add case for AARCH64_OPND_BTI_TARGET.
>      (parse_operands): Likewise.
>      * testsuite/gas/aarch64/system.d: Update for BTI.
>      * testsuite/gas/aarch64/bti.s: New.
>      * testsuite/gas/aarch64/bti.d: New.
>      * testsuite/gas/aarch64/illegal-bti.d: New.
>      * testsuite/gas/aarch64/illegal-bti.l: New.
> 
> 
> Thanks
> Sudi
> 

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