From: "Björn Töpel" <bjorn@kernel.org>
To: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
linux-riscv@lists.infradead.org
Cc: "Björn Töpel" <bjorn@rivosinc.com>,
linux-kernel@vger.kernel.org, linux@rivosinc.com,
"Palmer Dabbelt" <palmer@rivosinc.com>,
"Rémi Denis-Courmont" <remi@remlab.net>,
"Darius Rad" <darius@bluespec.com>,
"Andy Chiu" <andy.chiu@sifive.com>
Subject: Re: [PATCH v2] riscv: Discard vector state on syscalls
Date: Mon, 26 Jun 2023 20:04:13 +0200 [thread overview]
Message-ID: <87sfaem76q.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <87y1k6m827.fsf@all.your.base.are.belong.to.us>
Björn Töpel <bjorn@kernel.org> writes:
> Björn Töpel <bjorn@kernel.org> writes:
>
>> From: Björn Töpel <bjorn@rivosinc.com>
>>
>> The RISC-V vector specification states:
>> Executing a system call causes all caller-saved vector registers
>> (v0-v31, vl, vtype) and vstart to become unspecified.
>
> A bit of a corner case, but this will make sigreturn syscalls discard
> the vector state as well.
>
> Is that an issue? E.g. a user cannot build userspace context switching
> application. Does arm64 SVE handle sigreturn in a special way?
NVM; My bad. The vector state is cleared on *entry*, but then the
registers passed on signal stack is restored as usual.
Sorry for the noise! We're all good!
Björn
next prev parent reply other threads:[~2023-06-26 18:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-26 16:57 Björn Töpel
2023-06-26 17:45 ` Björn Töpel
2023-06-26 18:04 ` Björn Töpel [this message]
2023-06-27 15:15 ` Andy Chiu
2023-06-28 10:35 ` Björn Töpel
2023-06-28 17:03 ` Andy Chiu
2023-06-29 5:52 ` Björn Töpel
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