Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v8)

Szabolcs Nagy
2019-04-23T11:16:11Z

On 18/04/2019 19:17, Mathieu Desnoyers wrote:
> ----- On Apr 18, 2019, at 1:37 PM, Szabolcs Nagy Szabolcs.Nagy@arm.com wrote:
>> you have to add a documentation comment somewhere
>> explaining if RSEQ_SIG is the value that's passed to
>> the kernel and then aarch64 asm code has to use
>>
>> .inst endianfixup(RSEQ_SIG) // or
>> .word RSEQ_SIG
>
> Using ".word" won't allow objdump to show the instruction it
> maps to. It will consider it as data. So .inst is preferred here.

is there some specific reason you prefer .inst?

disassembling a canary value as data (that is
never executed, but loaded and compared by the
kernel as data) sounds more semantically correct
to me than showing it as an instruction.

i guess having it as an instruction can avoid
issues if some tools dislike .word in .text,
but otherwise .word seems better.