Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932442AbVJYWF7 (ORCPT ); Tue, 25 Oct 2005 18:05:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932423AbVJYWFn (ORCPT ); Tue, 25 Oct 2005 18:05:43 -0400 Received: from [151.97.230.9] ([151.97.230.9]:56037 "EHLO ssc.unict.it") by vger.kernel.org with ESMTP id S932425AbVJYWFc (ORCPT ); Tue, 25 Oct 2005 18:05:32 -0400 From: "Paolo 'Blaisorblade' Giarrusso" Subject: [PATCH 03/11] uml: fix signal code x86-64 [for 2.6.15] Date: Wed, 26 Oct 2005 00:01:18 +0200 To: Jeff Dike Cc: linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Message-Id: <20051025220117.20010.78137.stgit@zion.home.lan> In-Reply-To: <20051025220053.20010.56979.stgit@zion.home.lan> References: <20051025220053.20010.56979.stgit@zion.home.lan> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2539 Lines: 62 From: Paolo 'Blaisorblade' Giarrusso The problems in this area came to light while fixing a compile failure with GCC 4, in commit bcb01b8a67476e6f748086e626df8424cc27036d. I went comparing this code with x86_64 frame construction (which we should ABI compatible with) and resync'ed the code a bit. It isn't yet perfect, because we don't yet save floating point context. But that will come later. Please give a critical eye, even because things currently have no reported misbehaviour, and this code is complex enough. CC: Andi Kleen Signed-off-by: Paolo 'Blaisorblade' Giarrusso --- arch/um/sys-x86_64/signal.c | 19 ++++++++++++++++--- 1 files changed, 16 insertions(+), 3 deletions(-) diff --git a/arch/um/sys-x86_64/signal.c b/arch/um/sys-x86_64/signal.c --- a/arch/um/sys-x86_64/signal.c +++ b/arch/um/sys-x86_64/signal.c @@ -164,6 +164,7 @@ struct rt_sigframe #define round_down(m, n) (((m) / (n)) * (n)) +/* Taken from arch/x86_64/kernel/signal.c:setup_rt_frame(). */ int setup_signal_stack_si(unsigned long stack_top, int sig, struct k_sigaction *ka, struct pt_regs * regs, siginfo_t *info, sigset_t *set) @@ -173,9 +174,21 @@ int setup_signal_stack_si(unsigned long int err = 0; struct task_struct *me = current; - frame = (struct rt_sigframe __user *) - round_down(stack_top - sizeof(struct rt_sigframe), 16) - 8; - frame = (struct rt_sigframe *) ((unsigned long) frame - 128); + /* Leave space on the stack for the Red Zone, and for saving FP + * registers, even if this doesn't happen. We don't have a way to test + * used_math(), so we do that inconditionally. + * + * XXX: RED-PEN: currently, we're using a Red Zone also for any + * alternate stack set up by sigaltstack(), which x86-64 doesn't do + * (because there shouldn't be any code executing there). This could + * cause failures if user setup a too little alternate stack.*/ + + fp = (struct rt_sigframe *) round_down(stack_top - 128 - + sizeof(struct _fpstate), 16); + + /* Now leave the space for the rest of signal frame. */ + frame = (void __user *) round_down((unsigned long) fp - + sizeof(struct rt_sigframe), 16) - 8; if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate))) goto out; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/