From: Philippe Gerum <rpm@xenomai.org>
To: Florian Bezdeka <florian.bezdeka@siemens.com>
Cc: xenomai@lists.linux.dev, jan.kiszka@siemens.com
Subject: Re: [PATCH dovetail 6.8, 6.6, 6.1] x86: dovetail: Fix compat syscall handling, account for new IDT entry
Date: Tue, 23 Apr 2024 08:26:55 +0200 [thread overview]
Message-ID: <87wmoozj9l.fsf@xenomai.org> (raw)
In-Reply-To: <20240416102436.550147-1-florian.bezdeka@siemens.com>
Florian Bezdeka <florian.bezdeka@siemens.com> writes:
> The following upstream commit introduces a new IDTENTRY for handling
> compat syscall. As that commit is now backported into stable trees it
> broke compat syscall handling for dovetail.
>
> be5341eb0d43 ("x86/entry: Convert INT 0x80 emulation to IDTENTRY")
>
> We no longer end up in do_int80_syscall_32() which has the dovetail
> specific bits. We need the same handling in asm_int80_emulation().
>
> The problematic part in asm_int80_emulation() is the call to
> do_syscall_32_irqs_on() which basically overwrites regs->ax
> unconditionally. Linux does not know about the co-kernel syscalls, so
> we get -ENOSYS for each syscall result.
>
> Signed-off-by: Florian Bezdeka <florian.bezdeka@siemens.com>
> ---
> arch/x86/entry/common.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
> index 0220ca163a32..42e8cb036fff 100644
> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -212,9 +212,21 @@ DEFINE_IDTENTRY_RAW(int80_emulation)
>
> local_irq_enable();
> nr = syscall_enter_from_user_mode_work(regs, nr);
> +
> + if (dovetailing()) {
> + if (nr == EXIT_SYSCALL_OOB) {
> + hard_local_irq_disable();
> + return;
> + }
> + if (nr == EXIT_SYSCALL_TAIL)
> + goto done;
> + }
> +
> do_syscall_32_irqs_on(regs, nr);
>
> instrumentation_end();
> +
> +done:
> syscall_exit_to_user_mode(regs);
> }
> #else /* CONFIG_IA32_EMULATION */
Merged, thanks.
--
Philippe.
prev parent reply other threads:[~2024-04-23 6:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 10:24 [PATCH dovetail 6.8, 6.6, 6.1] x86: dovetail: Fix compat syscall handling, account for new IDT entry Florian Bezdeka
2024-04-23 6:26 ` Philippe Gerum [this message]
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