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From: Al Viro <viro@zeniv.linux.org.uk>
To: Andrew Jones <ajones@ventanamicro.com>
Cc: linux-riscv@lists.infradead.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: fix a nasty sigreturn bug...
Date: Fri, 2 Sep 2022 18:59:37 +0100	[thread overview]
Message-ID: <YxJEiSq/CGaL6Gm9@ZenIV> (raw)
In-Reply-To: <20220902092245.ande6fvievnbn35h@kamzik>

On Fri, Sep 02, 2022 at 11:22:45AM +0200, Andrew Jones wrote:

> So, for riscv, where in do_signal and handle_signal syscall restarting
> is avoided when regs->cause != EXC_SYSCALL and it's common to set cause
> to -1 to avoid it, then it makes sense to set regs->cause != EXEC_SYSCALL
> in rt_sigreturn or in restore_sigcontext, which rt_sigreturn calls, as
> well.
> 
> So the only question I have is whether or not the cause assignment
> is better in restore_sigcontext() like other architectures? At least,
> since rt_sigreturn is the only caller of restore_sigcontext, it can't
> break anything putting it there atm...

	The only reason for doing that in restore_sigcontext() is that for
old architectures there'd been separate sigreturn(2) and rt_sigreturn(2).
Doing that in the helper shared by both avoided duplication; since
there's no such thing on riscv...

	Matter of taste, really - I have a slight preference for doing that
closer to the syscall surface, but it's no more than that.

WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: Andrew Jones <ajones@ventanamicro.com>
Cc: linux-riscv@lists.infradead.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: fix a nasty sigreturn bug...
Date: Fri, 2 Sep 2022 18:59:37 +0100	[thread overview]
Message-ID: <YxJEiSq/CGaL6Gm9@ZenIV> (raw)
In-Reply-To: <20220902092245.ande6fvievnbn35h@kamzik>

On Fri, Sep 02, 2022 at 11:22:45AM +0200, Andrew Jones wrote:

> So, for riscv, where in do_signal and handle_signal syscall restarting
> is avoided when regs->cause != EXC_SYSCALL and it's common to set cause
> to -1 to avoid it, then it makes sense to set regs->cause != EXEC_SYSCALL
> in rt_sigreturn or in restore_sigcontext, which rt_sigreturn calls, as
> well.
> 
> So the only question I have is whether or not the cause assignment
> is better in restore_sigcontext() like other architectures? At least,
> since rt_sigreturn is the only caller of restore_sigcontext, it can't
> break anything putting it there atm...

	The only reason for doing that in restore_sigcontext() is that for
old architectures there'd been separate sigreturn(2) and rt_sigreturn(2).
Doing that in the helper shared by both avoided duplication; since
there's no such thing on riscv...

	Matter of taste, really - I have a slight preference for doing that
closer to the syscall surface, but it's no more than that.

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2022-09-02 17:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-24  1:55 [PATCH] riscv: fix a nasty sigreturn bug Al Viro
2021-09-24  1:55 ` Al Viro
2022-09-02  0:13 ` Al Viro
2022-09-02  0:13   ` Al Viro
2022-09-02  9:22 ` Andrew Jones
2022-09-02  9:22   ` Andrew Jones
2022-09-02 17:59   ` Al Viro [this message]
2022-09-02 17:59     ` Al Viro
2022-09-15 18:48     ` Palmer Dabbelt
2022-09-15 18:48       ` Palmer Dabbelt

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