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Date:   Thu, 18 Apr 2019 11:37:14 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To:     Joseph Myers <joseph@codesourcery.com>
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        Boqun Feng <boqun.feng@gmail.com>,
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        Rich Felker <dalias@libc.org>,
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Subject: Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup
 and thread creation (v8)
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Thread-Topic: glibc: Perform rseq(2) registration at C startup and thread creation (v8)
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----- 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.
http://www.efficios.com