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From: Roland McGrath <roland@redhat.com>
To: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Ingo Molnar <mingo@elte.hu>, Oleg Nesterov <oleg@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org,
	Haavard Skinnemoen <hskinnemoen@atmel.com>
Subject: Re: [PATCH] consider stack access while checking for alternate signal stack
Date: Mon, 19 Oct 2009 11:08:10 -0700 (PDT)	[thread overview]
Message-ID: <20091019180810.3CB751E@magilla.sf.frob.com> (raw)
In-Reply-To: Sebastian Andrzej Siewior's message of  Monday, 19 October 2009 10:02:39 +0200 <20091019080239.GB25783@Chamillionaire.breakpoint.cc>

AFAICT all you want is the following, and I'm not sure it requires all that
much explanation.  I've probably missed some subtlety.


Thanks,
Roland

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2090,7 +2090,13 @@ static inline int is_si_special(const struct siginfo *info)
 
 static inline int on_sig_stack(unsigned long sp)
 {
-	return (sp - current->sas_ss_sp < current->sas_ss_size);
+#ifdef CONFIG_STACK_GROWSUP
+	return sp >= current->sas_ss_sp &&
+		sp - current->sas_ss_sp < current->sas_ss_size;
+#else
+	return sp > current->sas_ss_sp &&
+		sp - current->sas_ss_sp <= current->sas_ss_size;
+#endif
 }
 

  reply	other threads:[~2009-10-19 18:08 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-18 19:12 Sebastian Andrzej Siewior
2009-10-19  4:09 ` Haavard Skinnemoen
2009-10-19  7:58   ` Sebastian Andrzej Siewior
2009-10-19  9:26     ` Haavard Skinnemoen
2009-10-19  7:33 ` Ingo Molnar
2009-10-19  8:02   ` Sebastian Andrzej Siewior
2009-10-19 18:08     ` Roland McGrath [this message]
2009-10-19 19:30       ` Sebastian Andrzej Siewior
2009-10-20 21:11         ` Roland McGrath
2009-10-21  8:28           ` Sebastian Andrzej Siewior
2009-10-25 14:37           ` [PATCH v2] consider the kind of stack incrementation " Sebastian Andrzej Siewior
2009-11-04 17:27             ` [tip:core/signal] signal: Fix alternate signal stack check tip-bot for Sebastian Andrzej Siewior

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