From: Ingo Molnar <mingo@elte.hu>
To: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86_64 ia32 syscall restart fix
Date: Fri, 29 Feb 2008 16:52:07 +0100 [thread overview]
Message-ID: <20080229155207.GC27248@elte.hu> (raw)
In-Reply-To: <20080229035707.EAE862700FD@magilla.localdomain>
* Roland McGrath <roland@redhat.com> wrote:
> The code to restart syscalls after signals depends on checking for a
> negative orig_ax, and for particular negative -ERESTART* values in ax.
> These fields are 64 bits and for a 32-bit task they get zero-extended.
> The syscall restart behavior is lost, a regression from a native
> 32-bit kernel and from 64-bit tasks' behavior. This patch fixes the
> problem by doing sign-extension where it matters. For orig_ax, the
> only time the value should be -1 but winds up as 0x0ffffffff is via a
> 32-bit ptrace call. So the patch changes ptrace to sign-extend the
> 32-bit orig_eax value when it's stored; it doesn't change the checks
> on orig_ax, though it uses the new current_syscall() inline to better
> document the subtle importance of the used of signedness there. The
> ax value is stored a lot of ways and it seems hard to get them all
> sign-extended at their origins. So for that, we use the
> current_syscall_ret() to sign-extend it only for 32-bit tasks at the
> time of the -ERESTART* comparisons.
thanks, applied.
Ingo
next prev parent reply other threads:[~2008-02-29 15:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-29 3:57 [PATCH] x86_64 ia32 syscall restart fix Roland McGrath
2008-02-29 15:52 ` Ingo Molnar [this message]
2008-02-29 16:26 ` Linus Torvalds
2008-02-29 16:45 ` Ingo Molnar
2008-02-29 17:03 ` Linus Torvalds
2008-02-29 17:17 ` Ingo Molnar
2008-02-29 17:37 ` Ingo Molnar
2008-02-29 21:02 ` Andrew Morton
2008-02-29 21:20 ` Ingo Molnar
2008-03-01 5:48 ` [stable] " Greg KH
2008-02-29 22:42 ` Roland McGrath
2008-02-29 23:18 ` Linus Torvalds
2008-03-07 22:56 ` [PATCH] x86_64 ptrace orig_ax on ia32 task Roland McGrath
2008-03-07 23:18 ` Linus Torvalds
2008-03-08 1:37 ` Roland McGrath
2008-03-10 19:19 ` Chuck Ebbert
2008-03-10 19:48 ` Linus Torvalds
2008-03-10 20:01 ` Roland McGrath
2008-03-11 9:32 ` Ingo Molnar
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