svn commit: r287386 - in head/sys: kern sys

[John Baldwin]

Author: jhb
Date: Tue Sep  1 22:24:54 2015
New Revision: 287386
URL: https://svnweb.freebsd.org/changeset/base/287386

Log:
  Export current system call code and argument count for system call entry
  and exit events. procfs stop events for system call tracing report these
  values (argument count for system call entry and code for system call exit),
  but ptrace() does not provide this information. (Note that while the system
  call code can be determined in an ABI-specific manner during system call
  entry, it is not generally available during system call exit.)
  
  The values are exported via new fields at the end of struct ptrace_lwpinfo
  available via PT_LWPINFO.
  
  Reviewed by:	kib
  MFC after:	1 week
  Differential Revision:	https://reviews.freebsd.org/D3536

Modified:
  head/sys/kern/subr_syscall.c
  head/sys/kern/sys_process.c
  head/sys/sys/proc.h
  head/sys/sys/ptrace.h

Modified: head/sys/kern/subr_syscall.c
==============================================================================
--- head/sys/kern/subr_syscall.c	Tue Sep  1 21:52:56 2015	(r287385)
+++ head/sys/kern/subr_syscall.c	Tue Sep  1 22:24:54 2015	(r287386)
@@ -85,6 +85,8 @@ syscallenter(struct thread *td, struct s
 		STOPEVENT(p, S_SCE, sa->narg);
 		if (p->p_flag & P_TRACED && p->p_stops & S_PT_SCE) {
 			PROC_LOCK(p);
+			td->td_dbg_sc_code = sa->code;
+			td->td_dbg_sc_narg = sa->narg;
 			ptracestop((td), SIGTRAP);
 			PROC_UNLOCK(p);
 		}
@@ -94,6 +96,10 @@ syscallenter(struct thread *td, struct s
 			 * debugger modified registers or memory.
 			 */
 			error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
+			PROC_LOCK(p);
+			td->td_dbg_sc_code = sa->code;
+			td->td_dbg_sc_narg = sa->narg;
+			PROC_UNLOCK(p);
 #ifdef KTRACE
 			if (KTRPOINT(td, KTR_SYSCALL))
 				ktrsyscall(sa->code, sa->narg, sa->args);

Modified: head/sys/kern/sys_process.c
==============================================================================
--- head/sys/kern/sys_process.c	Tue Sep  1 21:52:56 2015	(r287385)
+++ head/sys/kern/sys_process.c	Tue Sep  1 22:24:54 2015	(r287386)
@@ -97,6 +97,8 @@ struct ptrace_lwpinfo32 {
 	struct siginfo32 pl_siginfo;	/* siginfo for signal */
 	char	pl_tdname[MAXCOMLEN + 1];	/* LWP name. */
 	int	pl_child_pid;		/* New child pid */
+	u_int		pl_syscall_code;
+	u_int		pl_syscall_narg;
 };
 
 #endif
@@ -481,6 +483,8 @@ ptrace_lwpinfo_to32(const struct ptrace_
 	siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
 	strcpy(pl32->pl_tdname, pl->pl_tdname);
 	pl32->pl_child_pid = pl->pl_child_pid;
+	pl32->pl_syscall_code = pl->pl_syscall_code;
+	pl32->pl_syscall_narg = pl->pl_syscall_narg;
 }
 #endif /* COMPAT_FREEBSD32 */
 
@@ -1211,6 +1215,13 @@ kern_ptrace(struct thread *td, int req, 
 		pl->pl_sigmask = td2->td_sigmask;
 		pl->pl_siglist = td2->td_siglist;
 		strcpy(pl->pl_tdname, td2->td_name);
+		if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
+			pl->pl_syscall_code = td2->td_dbg_sc_code;
+			pl->pl_syscall_narg = td2->td_dbg_sc_narg;
+		} else {
+			pl->pl_syscall_code = 0;
+			pl->pl_syscall_narg = 0;
+		}
 #ifdef COMPAT_FREEBSD32
 		if (wrap32)
 			ptrace_lwpinfo_to32(pl, pl32);

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h	Tue Sep  1 21:52:56 2015	(r287385)
+++ head/sys/sys/proc.h	Tue Sep  1 22:24:54 2015	(r287386)
@@ -174,6 +174,7 @@ struct procdesc;
 struct racct;
 struct sbuf;
 struct sleepqueue;
+struct syscall_args;
 struct td_sched;
 struct thread;
 struct trapframe;
@@ -282,6 +283,8 @@ struct thread {
 	int		td_no_sleeping;	/* (k) Sleeping disabled count. */
 	int		td_dom_rr_idx;	/* (k) RR Numa domain selection. */
 	void		*td_su;		/* (k) FFS SU private */
+	u_int		td_dbg_sc_code;	/* (c) Syscall code to debugger. */
+	u_int		td_dbg_sc_narg;	/* (c) Syscall arg count to debugger.*/
 #define	td_endzero td_sigmask
 
 /* Copied during fork1() or create_thread(). */
@@ -979,7 +982,6 @@ void	userret(struct thread *, struct tra
 
 void	cpu_exit(struct thread *);
 void	exit1(struct thread *, int, int) __dead2;
-struct syscall_args;
 int	cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa);
 void	cpu_fork(struct thread *, struct proc *, struct thread *, int);
 void	cpu_set_fork_handler(struct thread *, void (*)(void *), void *);

Modified: head/sys/sys/ptrace.h
==============================================================================
--- head/sys/sys/ptrace.h	Tue Sep  1 21:52:56 2015	(r287385)
+++ head/sys/sys/ptrace.h	Tue Sep  1 22:24:54 2015	(r287386)
@@ -113,6 +113,8 @@ struct ptrace_lwpinfo {
 	struct __siginfo pl_siginfo;	/* siginfo for signal */
 	char		pl_tdname[MAXCOMLEN + 1]; /* LWP name */
 	int		pl_child_pid;	/* New child pid */
+	u_int		pl_syscall_code;
+	u_int		pl_syscall_narg;
 };
 
 /* Argument structure for PT_VM_ENTRY. */