On 11/12/18 6:24 PM, Sudakshina Das wrote:
> Hi Sam
>
> On 02/11/18 17:31, Sam Tebbs wrote:
>> Hi all,
>>
>> The -mbranch-protection option combines the functionality of
>> -msign-return-address and the BTI features new in Armv8.5 to better reflect
>> their relationship. This new option therefore supersedes and deprecates the
>> existing -msign-return-address option.
>>
>> -mbranch-protection=[none|standard|<types>] - Turns on different types of branch
>> protection available where:
>>
>>        * "none": Turn of all types of branch protection
>>        * "standard" : Turns on all the types of protection to their respective
>>          standard levels.
>>        * <types> can be "+" separated protection types:
>>
>>        	* "bti" : Branch Target Identification Mechanism.
>> 	* "pac-ret{+leaf+b-key}": Return Address Signing. The default return
>> 	  address signing is enabled by signing functions that save the return
>> 	  address to memory (non-leaf functions will practically always do this)
>> 	  using the a-key. The optional tuning arguments allow the user to
>> 	  extend the scope of return address signing to include leaf functions
>> 	  and to change the key to b-key. The tuning arguments must proceed the
>> 	  protection type "pac-ret".
>>
>> Thus -mbranch-protection=standard -> -mbranch-protection=bti+pac-ret.
>>
>> Its mapping to -msign-return-address is as follows:
>>
>>        * -mbranch-protection=none -> -msign-return-address=none
>>        * -mbranch-protection=standard -> -msign-return-address=leaf
>>        * -mbranch-protection=pac-ret -> -msign-return-address=non-leaf
>>        * -mbranch-protection=pac-ret+leaf -> -msign-return-address=all
>>
>> This patch implements the option's skeleton and the "none", "standard" and
>> "pac-ret" types (along with its "leaf" subtype).
>>
>> The previous patch in this series is here:
>> https://gcc.gnu.org/ml/gcc-patches/2018-11/msg00103.html
>>
>> Bootstrapped successfully and tested on aarch64-none-elf with no regressions.
>>
>> OK for trunk?
>>
> Thank for doing this. I am not a maintainer so you will need a
> maintainer's approval. Only nit, that I would add is that it would
> be good to have more test coverage, specially for the new parsing
> functions that have been added and the errors that are added.
>
> Example checking a few valid and invalid combinations of the options
> like:
> -mbranch-protection=pac-ret -mbranch-protection=none //disables
> everything
> -mbranch-protection=leaf  //errors out
> -mbranch-protection=none+pac-ret //errors out
> ... etc
> Also instead of removing all the old deprecated options, you can keep
> one (or a copy of one) to check for the deprecated warning.

Hi Sudi,

Thanks for the feedback, I've incorporated your suggestions into the 
attached patch and the updated changelog.

gcc/ChangeLog:

2018-11-22  Sam Tebbs<sam.tebbs@arm.com>

	* config/aarch64/aarch64.c (BRANCH_PROTEC_STR_MAX,
	aarch64_parse_branch_protection,
	struct aarch64_branch_protec_type,
	aarch64_handle_no_branch_protection,
	aarch64_handle_standard_branch_protection,
	aarch64_validate_mbranch_protection,
	aarch64_handle_pac_ret_protection,
	aarch64_handle_attr_branch_protection,
	accepted_branch_protection_string,
	aarch64_pac_ret_subtypes,
	aarch64_branch_protec_types,
	aarch64_handle_pac_ret_leaf): Define.
	(aarch64_override_options_after_change_1): Add check for
	accepted_branch_protection_string.
	(aarch64_override_options): Add check for
	accepted_branch_protection_string.
	(aarch64_option_save): Save accepted_branch_protection_string.
	(aarch64_option_restore): Save
	accepted_branch_protection_string.
	* config/aarch64/aarch64.c (aarch64_attributes): Add branch-protection.
	* config/aarch64/aarch64.opt: Add mbranch-protection. Deprecate
	msign-return-address.
	* doc/invoke.texi: Add mbranch-protection.

gcc/testsuite/ChangeLog:

2018-11-22  Sam Tebbs<sam.tebbs@arm.com>

	* (gcc.target/aarch64/return_address_sign_1.c,
	gcc.target/aarch64/return_address_sign_2.c,
	gcc.target/aarch64/return_address_sign_3.c (__attribute__)): Change
	option to -mbranch-protection.
	* gcc.target/aarch64/(branch-protection-option.c,
	branch-protection-option-2.c, branch-protection-attr.c,
	branch-protection-attr-2.c): New file.