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Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v8)
- From: Mathieu Desnoyers <mathieu dot desnoyers at efficios dot com>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: Will Deacon <will dot deacon at arm dot com>, carlos <carlos at redhat dot com>, Florian Weimer <fweimer at redhat dot com>, Szabolcs Nagy <szabolcs dot nagy at arm dot com>, libc-alpha <libc-alpha at sourceware dot org>, Thomas Gleixner <tglx at linutronix dot de>, Ben Maurer <bmaurer at fb dot com>, Peter Zijlstra <peterz at infradead dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>, Boqun Feng <boqun dot feng at gmail dot com>, Dave Watson <davejwatson at fb dot com>, Paul Turner <pjt at google dot com>, Rich Felker <dalias at libc dot org>, linux-kernel <linux-kernel at vger dot kernel dot org>, linux-api <linux-api at vger dot kernel dot org>
- Date: Thu, 18 Apr 2019 11:37:14 -0400 (EDT)
- Subject: Re: [PATCH 1/5] 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