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

Mathieu Desnoyers
2019-04-18T15:37:19Z

----- On Apr 18, 2019, at 10:48 AM, Joseph Myers joseph@codesourcery.com wrote:

> On Thu, 18 Apr 2019, Mathieu Desnoyers wrote:
>
>> The approach above should work for arm32 be8 vs be32 linker weirdness.
>>
>> For aarch64, I think we can simply do:
>>
>> /*
>> * aarch64 -mbig-endian generates mixed endianness code vs data:
>> * little-endian code and big-endian data. Ensure the RSEQ_SIG signature
>> * matches code endianness.
>> */
>> #define RSEQ_SIG_CODE 0xd428bc00 /* BRK #0x45E0. */
>>
>> #ifdef __ARM_BIG_ENDIAN
>> #define RSEQ_SIG_DATA 0x00bc28d4 /* BRK #0x45E0. */
>> #else
>> #define RSEQ_SIG_DATA RSEQ_SIG_CODE
>> #endif
>>
>> #define RSEQ_SIG RSEQ_SIG_DATA
>>
>> Feedback is most welcome,
>
> You'll also need __ASSEMBLER__ conditionals in the installed sys/rseq.h
> header so that it only defines constants and doesn't include any C
> declarations in that case, if RSEQ_SIG_CODE is meant to be usable in .S
> files rather than just inline asm in C files.

Good point!

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.