From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266458AbUGOX6e (ORCPT ); Thu, 15 Jul 2004 19:58:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266460AbUGOX6e (ORCPT ); Thu, 15 Jul 2004 19:58:34 -0400 Received: from mail1.speakeasy.net ([216.254.0.201]:59305 "EHLO mail1.speakeasy.net") by vger.kernel.org with ESMTP id S266458AbUGOX6H (ORCPT ); Thu, 15 Jul 2004 19:58:07 -0400 Date: Thu, 15 Jul 2004 16:57:59 -0700 Message-Id: <200407152357.i6FNvxiu020873@magilla.sf.frob.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Andi Kleen X-Fcc: ~/Mail/linus Cc: akpm@osdl.org, torvalds@osdl.org, linux-kernel@vger.kernel.org, jparadis@redhat.com, cagney@redhat.com, discuss@x86-64.org Subject: Re: [PATCH] x86-64 singlestep through sigreturn system call In-Reply-To: Andi Kleen's message of Friday, 16 July 2004 00:06:18 +0200 <20040716000618.0441d268.ak@suse.de> X-Shopping-List: (1) Cataclysmic chocolate (2) Reluctant commendations (3) Atlantic L'eggs (4) Naugahyde Pencil porno Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Anyways, even if I applied your patch there would be still inconsistency > because there are several other system calls that use IRET. So I don't > see much advantage in adding a special case just for sigreturn. Now that I see that the difference is due to iret being used, I have a different solution that handles all cases. The following patch replaces both my previous patch for x86-64 native behavior and my patch for x86-64's ia32 support. This patch just directly clones Davide Libenzi's i386 code for x86-64 in both 64-bit and 32-bit cases. With this, the behavior of single-stepping all system calls is consistent. The syscall exit tracing caused by TIF_SINGLESTEP is superfluous in the case of sysret returns, but harmlessly so (since continuing afterward with PTRACE_CONT will have cleared TF as well as TIF_SINGLESTEP). I figured that little bit of extra processing in the single-step case was better than adding code to ignore the flag in the sysret case. Thanks, Roland Signed-off-by: Roland McGrath Index: linux-2.6/arch/x86_64/kernel/entry.S =================================================================== RCS file: /home/roland/redhat/bkcvs/linux-2.5/arch/x86_64/kernel/entry.S,v retrieving revision 1.22 diff -b -p -u -r1.22 entry.S --- linux-2.6/arch/x86_64/kernel/entry.S 12 Apr 2004 20:29:12 -0000 1.22 +++ linux-2.6/arch/x86_64/kernel/entry.S 15 Jul 2004 23:45:59 -0000 @@ -297,7 +297,7 @@ int_very_careful: sti SAVE_REST /* Check for syscall exit trace */ - testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),%edx + testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edx jz int_signal pushq %rdi leaq 8(%rsp),%rdi # &ptregs -> arg1 Index: linux-2.6/arch/x86_64/kernel/ptrace.c =================================================================== RCS file: /home/roland/redhat/bkcvs/linux-2.5/arch/x86_64/kernel/ptrace.c,v retrieving revision 1.16 diff -b -p -u -r1.16 ptrace.c --- linux-2.6/arch/x86_64/kernel/ptrace.c 31 May 2004 03:07:42 -0000 1.16 +++ linux-2.6/arch/x86_64/kernel/ptrace.c 15 Jul 2004 23:56:44 -0000 @@ -88,6 +88,7 @@ void ptrace_disable(struct task_struct * { long tmp; + clear_tsk_thread_flag(child, TIF_SINGLESTEP); tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG; put_stack_long(child, EFL_OFFSET, tmp); } @@ -344,6 +345,7 @@ asmlinkage long sys_ptrace(long request, set_tsk_thread_flag(child,TIF_SYSCALL_TRACE); else clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE); + clear_tsk_thread_flag(child, TIF_SINGLESTEP); child->exit_code = data; /* make sure the single step bit is not set. */ tmp = get_stack_long(child, EFL_OFFSET); @@ -395,6 +397,7 @@ asmlinkage long sys_ptrace(long request, ret = 0; if (child->state == TASK_ZOMBIE) /* already dead */ break; + clear_tsk_thread_flag(child, TIF_SINGLESTEP); child->exit_code = SIGKILL; /* make sure the single step bit is not set. */ tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG; @@ -416,6 +419,7 @@ asmlinkage long sys_ptrace(long request, } tmp = get_stack_long(child, EFL_OFFSET) | TRAP_FLAG; put_stack_long(child, EFL_OFFSET, tmp); + set_tsk_thread_flag(child, TIF_SINGLESTEP); child->exit_code = data; /* give it a chance to run. */ wake_up_process(child); @@ -528,7 +532,8 @@ asmlinkage void syscall_trace_leave(stru if (unlikely(current->audit_context)) audit_syscall_exit(current, regs->rax); - if (test_thread_flag(TIF_SYSCALL_TRACE) + if ((test_thread_flag(TIF_SYSCALL_TRACE) + || test_thread_flag(TIF_SINGLESTEP)) && (current->ptrace & PT_PTRACED)) syscall_trace(regs); }