PR/43128: Paul Koning: Threads support in ptrace() is insufficient for gdb to
debug threaded live apps: Add an optional lwpid in PT_STEP and PT_CONTINUE to indicate which lwp to operate on, and implement the glue required to make it work.
This commit is contained in:
christos
parent
1819dce19c
commit
ca843a73b0
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@ -1,7 +1,7 @@
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.\" $NetBSD: ptrace.2,v 1.31 2010/03/22 19:30:55 joerg Exp $
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.\" $NetBSD: ptrace.2,v 1.32 2010/04/06 13:50:22 christos Exp $
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.\"
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.\" This file is in the public domain.
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.Dd March 12, 2007
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.Dd April 6, 2010
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.Dt PTRACE 2
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.Os
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.Sh NAME
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@ -149,7 +149,9 @@ new value for the program counter), or
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to indicate that execution is to pick up where it left off.
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.Fa data
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provides a signal number to be delivered to the traced process as it
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resumes execution, or 0 if no signal is to be sent.
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resumes execution, or 0 if no signal is to be sent. If a negative
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value is supplied, that is the negative of the LWP ID of the thread to
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be resumed, and only that thread executes.
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.It Dv PT_KILL
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The traced process terminates, as if
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.Dv PT_CONTINUE
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@ -256,8 +258,8 @@ This
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call currently does not stop the child process so it can generate
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inconsistent data.
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.It Dv PT_LWPINFO
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Returns information about the specific thread from the process specified
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in the
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Returns information about a thread from the list of threads for the
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process specified in the
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.Fa pid
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argument.
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The
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@ -274,8 +276,15 @@ struct ptrace_lwpinfo {
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.Pp
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where
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.Fa pl_lwpid
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contains the thread for which to get info.
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contains a thread LWP ID. Information is returned for the thread
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following the one with the specified ID in the process thread list,
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or for the first thread if
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.Fa pl_lwpid
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is 0.
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Upon return
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.Fa pl_lwpid
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contains the LWP ID of the thread that was found, or 0 if there is
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no thread after the one whose LWP ID was supplied in the call.
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.Fa pl_event
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contains the event that stopped the thread.
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Possible
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@ -303,6 +312,14 @@ lists which requests exist on a given machine.
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Execution continues as in request PT_CONTINUE; however
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as soon as possible after execution of at least one
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instruction, execution stops again.
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If the
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.Fa data
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argument is greater than 0, it contains the LWP ID of the thread to be
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stepped, and any other threads are continued. If the
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.Fa data
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argument is less than zero, it contains the negative of the LWP ID of
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the
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thread to be stepped, and only that thread executes.
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.It Dv PT_GETREGS
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This request reads the traced process' machine registers into the
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.Dq Li "struct reg"
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@ -310,6 +327,10 @@ This request reads the traced process' machine registers into the
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.In machine/reg.h )
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pointed to by
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.Fa addr .
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The
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.Fa data
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argument contains the LWP ID of the thread whose registers are to
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be read. If zero is supplied, the first thread of the process is read.
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.It Dv PT_SETREGS
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This request is the converse of
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.Dv PT_GETREGS ;
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@ -319,6 +340,10 @@ it loads the traced process' machine registers from the
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.In machine/reg.h )
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pointed to by
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.Fa addr .
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The
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.Fa data
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argument contains the LWP ID of the thread whose registers are to
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be written. If zero is supplied, the first thread of the process is written.
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.It Dv PT_GETFPREGS
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This request reads the traced process' floating-point registers into
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the
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@ -327,6 +352,11 @@ the
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.In machine/reg.h )
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pointed to by
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.Fa addr .
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The
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.Fa data
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argument contains the LWP ID of the thread whose registers are to
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be read. If zero is supplied, the first thread of the process is
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read.
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.It Dv PT_SETFPREGS
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This request is the converse of
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.Dv PT_GETFPREGS ;
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@ -336,6 +366,11 @@ it loads the traced process' floating-point registers from the
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.In machine/reg.h )
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pointed to by
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.Fa addr .
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The
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.Fa data
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argument contains the LWP ID of the thread whose registers are to
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be written. If zero is supplied, the first thread of the process is
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written.
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.\" .It Dv PT_SYSCALL
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.\" This request is like
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.\" .Dv PT_CONTINUE
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_lwp.c,v 1.141 2010/03/01 21:10:17 darran Exp $ */
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/* $NetBSD: kern_lwp.c,v 1.142 2010/04/06 13:50:22 christos Exp $ */
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/*-
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* Copyright (c) 2001, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc.
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@ -209,7 +209,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.141 2010/03/01 21:10:17 darran Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.142 2010/04/06 13:50:22 christos Exp $");
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#include "opt_ddb.h"
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#include "opt_lockdebug.h"
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@ -374,6 +374,44 @@ lwp_continue(struct lwp *l)
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setrunnable(l);
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}
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/*
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* Restart a stopped LWP.
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*
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* Must be called with p_lock held, and the LWP NOT locked. Will unlock the
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* LWP before return.
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*/
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void
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lwp_unstop(struct lwp *l)
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{
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struct proc *p = l->l_proc;
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KASSERT(mutex_owned(proc_lock));
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KASSERT(mutex_owned(p->p_lock));
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lwp_lock(l);
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/* If not stopped, then just bail out. */
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if (l->l_stat != LSSTOP) {
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lwp_unlock(l);
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return;
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}
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p->p_stat = SACTIVE;
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p->p_sflag &= ~PS_STOPPING;
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if (!p->p_waited)
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p->p_pptr->p_nstopchild--;
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if (l->l_wchan == NULL) {
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/* setrunnable() will release the lock. */
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setrunnable(l);
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} else {
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l->l_stat = LSSLEEP;
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p->p_nrlwps++;
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lwp_unlock(l);
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}
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}
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/*
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* Wait for an LWP within the current process to exit. If 'lid' is
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* non-zero, we are waiting for a specific LWP.
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@ -1396,11 +1434,25 @@ lwp_delref(struct lwp *l)
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struct proc *p = l->l_proc;
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mutex_enter(p->p_lock);
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lwp_delref2(l);
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mutex_exit(p->p_lock);
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}
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/*
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* Remove one reference to an LWP. If this is the last reference,
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* then we must finalize the LWP's death. The proc mutex is held
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* on entry.
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*/
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void
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lwp_delref2(struct lwp *l)
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{
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struct proc *p = l->l_proc;
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KASSERT(mutex_owned(p->p_lock));
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KASSERT(l->l_stat != LSZOMB);
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KASSERT(l->l_refcnt > 0);
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if (--l->l_refcnt == 0)
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cv_broadcast(&p->p_lwpcv);
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mutex_exit(p->p_lock);
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}
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/*
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_sig.c,v 1.304 2010/03/03 00:47:31 yamt Exp $ */
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/* $NetBSD: kern_sig.c,v 1.305 2010/04/06 13:50:22 christos Exp $ */
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/*-
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* Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
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@ -66,7 +66,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.304 2010/03/03 00:47:31 yamt Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.305 2010/04/06 13:50:22 christos Exp $");
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#include "opt_ptrace.h"
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#include "opt_compat_sunos.h"
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@ -1725,9 +1725,10 @@ sigchecktrace(void)
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/*
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* If we are no longer being traced, or the parent didn't
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* give us a signal, look for more signals.
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* give us a signal, or we're stopping, look for more signals.
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*/
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if ((p->p_slflag & PSL_TRACED) == 0 || p->p_xstat == 0)
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if ((p->p_slflag & PSL_TRACED) == 0 || p->p_xstat == 0 ||
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(p->p_sflag & PS_STOPPING) != 0)
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return 0;
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/*
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@ -1,4 +1,4 @@
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/* $NetBSD: sys_process.c,v 1.153 2009/12/17 01:25:10 rmind Exp $ */
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/* $NetBSD: sys_process.c,v 1.154 2010/04/06 13:50:22 christos Exp $ */
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/*-
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* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
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@ -118,7 +118,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.153 2009/12/17 01:25:10 rmind Exp $");
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__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.154 2010/04/06 13:50:22 christos Exp $");
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#include "opt_ptrace.h"
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#include "opt_ktrace.h"
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@ -227,7 +227,7 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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syscallarg(int) data;
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} */
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struct proc *p = l->l_proc;
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struct lwp *lt;
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struct lwp *lt, *lt2;
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struct proc *t; /* target process */
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struct uio uio;
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struct iovec iov;
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@ -235,7 +235,8 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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struct ptrace_lwpinfo pl;
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struct vmspace *vm;
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int error, write, tmp, req, pheld;
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int signo;
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int signo = 0;
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int resume_all;
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ksiginfo_t ksi;
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char *path;
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int len;
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@ -463,6 +464,7 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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write = 0;
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*retval = 0;
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tmp = 0;
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resume_all = 1;
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switch (req) {
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case PT_TRACE_ME:
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@ -596,6 +598,44 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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}
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p->p_trace_enabled = trace_is_enabled(p);
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/*
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* Pick up the LWPID, if supplied. There are two cases:
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* data < 0 : step or continue single thread, lwp = -data
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* data > 0 in PT_STEP : step this thread, continue others
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* For operations other than PT_STEP, data > 0 means
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* data is the signo to deliver to the process.
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*/
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tmp = SCARG(uap, data);
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if (tmp >= 0) {
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#ifdef PT_STEP
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if (req == PT_STEP)
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signo = 0;
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else
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#endif
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{
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signo = tmp;
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tmp = 0; /* don't search for LWP */
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}
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}
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else
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tmp = -tmp;
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if (tmp > 0) {
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if (req == PT_DETACH) {
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error = EINVAL;
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break;
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}
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lwp_delref2 (lt);
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lt = lwp_find(t, tmp);
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if (lt == NULL) {
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error = ESRCH;
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break;
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}
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lwp_addref(lt);
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resume_all = 0;
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signo = 0;
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}
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/*
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* From the 4.4BSD PRM:
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* "The data argument is taken as a signal number and the
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@ -609,7 +649,7 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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*/
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/* Check that the data is a valid signal number or zero. */
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if (SCARG(uap, data) < 0 || SCARG(uap, data) >= NSIG) {
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if (signo < 0 || signo >= NSIG) {
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error = EINVAL;
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break;
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}
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@ -623,7 +663,17 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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#ifdef PT_STEP
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/*
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* Arrange for a single-step, if that's requested and possible.
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* More precisely, set the single step status as requested for
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* the requested thread, and clear it for other threads.
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*/
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LIST_FOREACH(lt2, &t->p_lwps, l_sibling) {
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if (lt != lt2)
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{
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lwp_lock(lt2);
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process_sstep(lt2, 0);
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lwp_unlock(lt2);
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}
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}
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error = process_sstep(lt, req == PT_STEP);
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if (error)
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break;
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@ -640,8 +690,6 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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/* not being traced any more */
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t->p_opptr = NULL;
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}
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signo = SCARG(uap, data);
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sendsig:
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/* Finally, deliver the requested signal (or none). */
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if (t->p_stat == SSTOP) {
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@ -651,7 +699,10 @@ sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
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* an LWP runs to see it.
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*/
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t->p_xstat = signo;
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proc_unstop(t);
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if (resume_all)
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proc_unstop(t);
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else
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lwp_unstop(lt);
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} else if (signo != 0) {
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KSI_INIT_EMPTY(&ksi);
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ksi.ksi_signo = signo;
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@ -1,4 +1,4 @@
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/* $NetBSD: lwp.h,v 1.128 2010/02/21 02:11:39 darran Exp $ */
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/* $NetBSD: lwp.h,v 1.129 2010/04/06 13:50:22 christos Exp $ */
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/*-
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* Copyright (c) 2001, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc.
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@ -298,6 +298,7 @@ void lwp_relock(lwp_t *, kmutex_t *);
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int lwp_trylock(lwp_t *);
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void lwp_addref(lwp_t *);
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void lwp_delref(lwp_t *);
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void lwp_delref2(lwp_t *);
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void lwp_drainrefs(lwp_t *);
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bool lwp_alive(lwp_t *);
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lwp_t *lwp_find_first(proc_t *);
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@ -307,6 +308,7 @@ lwp_t *lwp_find_first(proc_t *);
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void lwpinit(void);
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int lwp_wait1(lwp_t *, lwpid_t, lwpid_t *, int);
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void lwp_continue(lwp_t *);
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void lwp_unstop(lwp_t *);
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void cpu_setfunc(lwp_t *, void (*)(void *), void *);
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void startlwp(void *);
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void upcallret(lwp_t *);
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