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

[Joseph Myers]

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.

-- 
Joseph S. Myers
joseph@xxxxxxxxxxxxxxxx