From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759278AbZFSCMs (ORCPT ); Thu, 18 Jun 2009 22:12:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752721AbZFSCMk (ORCPT ); Thu, 18 Jun 2009 22:12:40 -0400 Received: from mail-ew0-f210.google.com ([209.85.219.210]:54007 "EHLO mail-ew0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752693AbZFSCMk (ORCPT ); Thu, 18 Jun 2009 22:12:40 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=Pu8VCaRFT5YUXIF7GBLCYfCzdFqui7ughyphlD2A690KBR2r6OrE9JnVyHsu53wK3J GHkzbivvc2Pj1tpa9TH0AsvgH15oXw9Dws3B74wex2UQtFOXPhfbrW8B4O/QijVGHQWt RQzx6UDiQoECxT3SG3NhdI3bIvKccRVsO7rsQ= Date: Fri, 19 Jun 2009 04:12:37 +0200 From: Frederic Weisbecker To: Jason Baron Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, rostedt@goodmis.org, peterz@infradead.org, mathieu.desnoyers@polymtl.ca, jiayingz@google.com, bligh@google.com, roland@redhat.com, fche@redhat.com Subject: Re: [PATCH 4/7] add syscall tracepoints Message-ID: <20090619021237.GB7903@nowhere> References: <46da2de326aa9ea1a9764cd421dd2ded70218c47.1244837725.git.jbaron@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46da2de326aa9ea1a9764cd421dd2ded70218c47.1244837725.git.jbaron@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 12, 2009 at 05:24:54PM -0400, Jason Baron wrote: > > add two tracepoints in syscall exit and entry path, conditioned on > TIF_SYSCALL_FTRACE. Supports the syscall trace event code. > > > Signed-off-by: Jason Baron > > --- > arch/x86/kernel/ptrace.c | 6 ++++-- > include/trace/syscall.h | 18 ++++++++++++++++++ > kernel/tracepoint.c | 38 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 60 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c > index 09ecbde..1c7301a 100644 > --- a/arch/x86/kernel/ptrace.c > +++ b/arch/x86/kernel/ptrace.c > @@ -36,6 +36,8 @@ > #include > > #include > +DEFINE_TRACE(syscall_enter); > +DEFINE_TRACE(syscall_exit); > > #include "tls.h" > > @@ -1498,7 +1500,7 @@ asmregparm long syscall_trace_enter(struct pt_regs *regs) > ret = -1L; > > if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE))) > - ftrace_syscall_enter(regs); > + trace_syscall_enter(regs, regs->orig_ax); > > if (unlikely(current->audit_context)) { > if (IS_IA32) > @@ -1524,7 +1526,7 @@ asmregparm void syscall_trace_leave(struct pt_regs *regs) > audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax); > > if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE))) > - ftrace_syscall_exit(regs); > + trace_syscall_exit(regs, regs->ax); > > if (test_thread_flag(TIF_SYSCALL_TRACE)) > tracehook_report_syscall_exit(regs, 0); > diff --git a/include/trace/syscall.h b/include/trace/syscall.h > index 8cfe515..d5d8310 100644 > --- a/include/trace/syscall.h > +++ b/include/trace/syscall.h > @@ -2,6 +2,24 @@ > #define _TRACE_SYSCALL_H > > #include > +#include > + > +extern void syscall_regfunc(void); > +extern void syscall_unregfunc(void); > + > +DECLARE_TRACE_REG(syscall_enter, > + TP_PROTO(struct pt_regs *regs, long id), > + TP_ARGS(regs, id), > + syscall_regfunc, > + syscall_unregfunc > +); > + > +DECLARE_TRACE_REG(syscall_exit, > + TP_PROTO(struct pt_regs *regs, long ret), > + TP_ARGS(regs, ret), > + syscall_regfunc, > + syscall_unregfunc > +); > > /* > * A syscall entry in the ftrace syscalls array. > diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c > index 1ef5d3a..5b34ff9 100644 > --- a/kernel/tracepoint.c > +++ b/kernel/tracepoint.c At a first glance I wasn't sure tracepoint.c is the right place for these. But indeed putting those two callbacks here avoids any dependency to the syscall tracer when someone else needs the syscall tracepoints. Well, I guess we can keep them there. > @@ -24,6 +24,7 @@ > #include > #include > #include > +#include > > extern struct tracepoint __start___tracepoints[]; > extern struct tracepoint __stop___tracepoints[]; > @@ -577,3 +578,40 @@ static int init_tracepoints(void) > __initcall(init_tracepoints); > > #endif /* CONFIG_MODULES */ > + > +DEFINE_MUTEX(regfunc_mutex); > +int sys_tracepoint_refcount; Looks like regfunc_mutex is only there to protect sys_tracepoint_refcount. May be you can just make it atomic_t? Thanks, Frederic. > + > +void syscall_regfunc(void) > +{ > + unsigned long flags; > + struct task_struct *g, *t; > + > + mutex_lock(®func_mutex); > + if (!sys_tracepoint_refcount) { > + read_lock_irqsave(&tasklist_lock, flags); > + do_each_thread(g, t) { > + set_tsk_thread_flag(t, TIF_SYSCALL_FTRACE); > + } while_each_thread(g, t); > + read_unlock_irqrestore(&tasklist_lock, flags); > + } > + sys_tracepoint_refcount++; > + mutex_unlock(®func_mutex); > +} > + > +void syscall_unregfunc(void) > +{ > + unsigned long flags; > + struct task_struct *g, *t; > + > + mutex_lock(®func_mutex); > + sys_tracepoint_refcount--; > + if (!sys_tracepoint_refcount) { > + read_lock_irqsave(&tasklist_lock, flags); > + do_each_thread(g, t) { > + clear_tsk_thread_flag(t, TIF_SYSCALL_FTRACE); > + } while_each_thread(g, t); > + read_unlock_irqrestore(&tasklist_lock, flags); > + } > + mutex_unlock(®func_mutex); > +} > -- > 1.6.0.6 >