From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757418Ab0BKXy1 (ORCPT ); Thu, 11 Feb 2010 18:54:27 -0500 Received: from mail-yw0-f189.google.com ([209.85.211.189]:36441 "EHLO mail-yw0-f189.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757340Ab0BKXyZ convert rfc822-to-8bit (ORCPT ); Thu, 11 Feb 2010 18:54:25 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=T1mS4cXJM97/m7UOK3a4VveBVIMbqCF83+vzrEOZckQlNqHkKZeFtksxbqHisudypO y8pPusEttRWbeJ204rxOxXpGqDxjuaStwYdwC0A2VNSNK+ICIhFEM94Sp/W3GY+OB2XK s+7kQL778d2bz7DWQGtNsqZAyyXx/XhyVabaI= MIME-Version: 1.0 In-Reply-To: <20100211204653.34BB3900@magilla.sf.frob.com> References: <20100202185907.GE3630@lst.de> <1265881389-26925-2-git-send-email-vapier@gentoo.org> <20100211204653.34BB3900@magilla.sf.frob.com> From: Mike Frysinger Date: Thu, 11 Feb 2010 18:54:04 -0500 Message-ID: <8bd0f97a1002111554ib69bd48rc3c5f4af65058281@mail.gmail.com> Subject: Re: [PATCH 1/2] Blackfin: initial tracehook support To: Roland McGrath Cc: Christoph Hellwig , oleg@redhat.com, Andrew Morton , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 11, 2010 at 15:46, Roland McGrath wrote: >>  config BLACKFIN >>       def_bool y >>       select HAVE_ARCH_KGDB >> +     select HAVE_ARCH_TRACEHOOK > > Don't define this until you have all its constituents as listed in the > arch/Kconfig comment.  I don't see user_regset support. where is user_regset actually used ? i only see it in fs/binfmt_elf.c and core dumps, neither of which work on nommu systems (or at least on Blackfin systems). >> +static inline void >> +syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, >> +                      unsigned int i, unsigned int n, unsigned long *args) >> +{ >> +     /* wtf is "i" ? */ >> +     BUG_ON(i); > > i is the starting number.  args[0] gets the i'th argument, > args[n - 1] gets the i+n-1'th argument. i dont see anyone calling syscall_get_arguments() with i!=0, and a few other arches are doing the BUG_ON(i) thing too. but should be easy to implement this with memory walking code ... >> +asmlinkage void syscall_trace_leave(struct pt_regs *regs) >> +{ >> +     if (test_thread_flag(TIF_SYSCALL_TRACE)) >> +             tracehook_report_syscall_exit(regs, 0); >>  } > > Is it in fact true that single-step reports still come normally after a > syscall instruction? this is unchanged from the previous Blackfin behavior, and it's how most arches behaved in 2.6.32. but looking in latest mainline, it seems people are changing to: if (test_thread_flag(TIF_SINGLESTEP) || test_thread_flag(TIF_SYSCALL_TRACE)) tracehook_report_syscall_exit(regs, 0); so changing Blackfin too should be straightforward i guess >> @@ -213,7 +213,7 @@ >>        */ >>       if (regs->syscfg & TRACE_BITS) { >>               regs->syscfg &= ~TRACE_BITS; >> -             ptrace_notify(SIGTRAP); >> +             tracehook_signal_handler(sig, info, ka, regs, 1); >>       } > > This call should be made unconditionally, and it should be made after the > signal mask changes have been made (i.e. at the end of handle_signal).  I > think it's wrong to clear the single-step flag here.  Instead, pass > (regs->syscfg & TRACE_BITS) as the last argument. > > With ptrace, it makes no difference one way or the other because it will > always either explicitly clear or explicitly set single-step before it > resumes.  But in future, it will matter. sounds like this issue is unrelated to tracehook and how we've been doing signal/ptrace stuff has always been a little broken ... i'll move it to how most arches seem to do it -- in do_signal after a successful call to handle_signal and after clearing TIF_RESTORE_SIGMASK. thanks for the review -mike