From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH v2 0/5] linux: Avoid va_list for generic syscall wrappers if possible
Date: Wed, 5 Apr 2023 11:04:16 -0300 [thread overview]
Message-ID: <45d5946a-1269-3d7f-08ca-6fe7c0fdfa68@linaro.org> (raw)
In-Reply-To: <PAWPR08MB89822CB484CCE39EFD7FFD4183909@PAWPR08MB8982.eurprd08.prod.outlook.com>
On 05/04/23 10:19, Wilco Dijkstra via Libc-alpha wrote:
> Hi,
>
>> Maybe we can use a custom C implementation (like RISC-V) as well. But
>> strictly speaking the RISC-V syscall.c is invoking undefined behavior
>> (like my proposal) so I agree with assembly here.
>
> How does assembly code not invoke the exact same undefined behaviour?
> In both cases you rely on variable arguments being passed in the same
> way as integer args - this is true in many ABIs. The goal is to avoid introducing
> unnecessary assembly and use generic implementations where possible.
>
> So if that C version works as well as assembler on LoongArch and assuming
> that bare syscall() performance is essential, then why not use it?
After this discussion, it seems that RISCV implementation is essentially
broken and it would be better to either provide a arch-specific assembly
implementation and/or use the generic C one and fix the code generation
issue.
next prev parent reply other threads:[~2023-04-05 14:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-05 13:19 Wilco Dijkstra
2023-04-05 14:04 ` Adhemerval Zanella Netto [this message]
2023-04-07 7:31 ` caiyinyu
-- strict thread matches above, loose matches on Subject: below --
2023-04-04 10:12 Wilco Dijkstra
2023-03-25 14:08 Xi Ruoyao
2023-03-27 14:04 ` Carlos O'Donell
2023-03-27 14:44 ` Xi Ruoyao
2023-03-27 14:45 ` Xi Ruoyao
2023-03-27 14:51 ` Xi Ruoyao
2023-04-04 1:25 ` caiyinyu
2023-04-04 12:12 ` Xi Ruoyao
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