From: Andy Lutomirski <luto@amacapital.net>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>, X86 ML <x86@kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
David Miller <davem@davemloft.net>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
Kees Cook <keescook@chromium.org>
Subject: SPARC issue (Re: [PATCH] Rename is_compat_task to in_compat_syscall)
Date: Tue, 19 Jan 2016 14:14:43 -0800 [thread overview]
Message-ID: <CALCETrVso3Dd7qyf0FMDB7_nFK0wtX6_SrE7rcd48ZE_rOkFQw@mail.gmail.com> (raw)
On Tue, Jan 19, 2016 at 1:55 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Tue, Jan 19, 2016 at 01:47:24PM -0800, Andy Lutomirski wrote:
>> Essentially all users of is_compat_task in the kernel are trying to
>> determine whether they are executing in the context of a compat
>> syscall. On at least x86_64 and sparc, these are not at all the
>> same question.
>>
>> On x86_64 and sparc, therefore, is_compat_task doesn't return the
>> overall compat state of the task; it returns true if the task is
>> currently in a compat syscall.
>
> The hell it does. Andy, TIF_32BIT is *NOT* set on syscall entry; it is
> set by execve(). And 64bit task (with that bit clear) can bloody well
> issue 32bit syscalls. Really.
It does on x86. It does not on sparc. But syscall_get_arch on sparc
*also* doesn't appear to work right.
davem, how can I check the current syscall bitness on sparc? It's not
obvious to me that it's possible.
Everyone should consider this patch withdrawn until I figure out
what's going on with sparc.
--Andy
next reply other threads:[~2016-01-19 22:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 22:14 Andy Lutomirski [this message]
2016-01-19 22:18 ` SPARC issue David Miller
2016-01-19 23:11 ` Andy Lutomirski
2016-01-19 23:37 ` Andy Lutomirski
2016-01-20 2:33 ` David Miller
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