linux-kernel - Re: [RFC/PATCH 3/7] [TEMPORARY] x86/entry/32: Sanity check for work

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Date:	Wed, 8 Jul 2015 12:25:28 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Rik van Riel <riel@...hat.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Denys Vlasenko <vda.linux@...glemail.com>,
	Borislav Petkov <bp@...en8.de>,
	Kees Cook <keescook@...omium.org>,
	Brian Gerst <brgerst@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [RFC/PATCH 3/7] [TEMPORARY] x86/entry/32: Sanity check for work_notifysig

[cc: Al -- saying I'm cc-ing you in the patch 0 description doesn't make it so.]

On Wed, Jul 8, 2015 at 12:24 PM, Andy Lutomirski <luto@...nel.org> wrote:
> 44fbbb3dc687c added an unnecessary check.  Add a temporary assertion
> to confirm that it's unnecessary.
>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
>  arch/x86/entry/entry_32.S | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
> index a36d5df6a749..d36afad80ad1 100644
> --- a/arch/x86/entry/entry_32.S
> +++ b/arch/x86/entry/entry_32.S
> @@ -491,10 +491,13 @@ work_notifysig:                                   # deal with pending signals and
>  #endif
>         TRACE_IRQS_ON
>         ENABLE_INTERRUPTS(CLBR_NONE)
> +       /* Temporary sanity check */
>         movb    PT_CS(%esp), %bl
>         andb    $SEGMENT_RPL_MASK, %bl
>         cmpb    $USER_RPL, %bl
> -       jb      resume_kernel
> +       jnb     2f
> +       ud2
> +2:
>         xorl    %edx, %edx
>         call    do_notify_resume
>         jmp     resume_userspace
> --
> 2.4.3
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
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