Date: Wed, 29 Apr 2009 21:08:52 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Christoph Hellwig <hch@lst.de>, chris@zankel.net, cooloney@kernel.org,
       deller@gmx.de, geert@linux-m68k.org, gerg@uclinux.org,
       hskinnemoen@atmel.com, jdike@addtoit.com, jesper.nilsson@axis.com,
       kyle@mcmartin.ca, linux@arm.linux.org.uk, ralf@linux-mips.org,
       rth@twiddle.net, starvik@axis.com, takata@linux-m32r.org,
       ysato@users.sourceforge.jp, zippel@linux-m68k.org
Cc: Roland McGrath <roland@redhat.com>, linux-kernel@vger.kernel.org,
       linux-arch@vger.kernel.org
Subject: Fwd: arch/ && tracehook_report_syscall_xxx()
Message-ID: <20090429190852.GA14515@redhat.com>
References: <20090427180455.GA32509@redhat.com> <20090427182919.B923DFC3BF@magilla.sf.frob.com> <20090427183218.GA31596@lst.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20090427183218.GA31596@lst.de>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1983
Lines: 82

On 04/27, Christoph Hellwig wrote:
>
> I've poked a few arch maintainers in the past to separate the enter/exit
> path and usually got the desired changes :)

I'd like to try your method!

So. Dear maintainers of

	alpha
	arm
	avr32
	blackfin
	cris
	h8300
	m32r
	m68k
	m68knommu
	mips
	parisc
	um
	xtensa

. Could you please convert your syscall trace code to use
tracehook_report_syscall_entry/tracehook_report_syscall_exit ?


For example, let's look at more or less typical arch/alpha/kernel/ptrace.c,

	asmlinkage void
	syscall_trace(void)
	{
		if (!test_thread_flag(TIF_SYSCALL_TRACE))
			return;
		if (!(current->ptrace & PT_PTRACED))
			return;
		/* The 0x80 provides a way for the tracing parent to distinguish
		   between a syscall stop and SIGTRAP delivery */
		ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
					 ? 0x80 : 0));

		/*
		 * This isn't the same as continuing with a signal, but it will do
		 * for normal use.  strace only continues with a signal if the
		 * stopping signal is not SIGTRAP.  -brl
		 */
		if (current->exit_code) {
			send_sig(current->exit_code, current, 1);
			current->exit_code = 0;
		}
	}

it would be really nice to turn it into something like

	asmlinkage void
	syscall_trace(int entryexit)
	{
		if (!test_thread_flag(TIF_SYSCALL_TRACE))
			return;

		if (entryexit)
			tracehook_report_syscall_entry(task_pt_regs(current));
		else
			tracehook_report_syscall_exit(task_pt_regs(current), stepping);
	}

Also, tracehook_report_syscall_entry() might want to abort this system
call (please see the comment above this helper), it would be great to
take the returned value into account.


arch/* play with ptrace internals which should be changed soon, not good.

Thanks!

Oleg.

--
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/