[src/trunk]: src/lib/libc/sys Document new calls and be more clear about PT_S...

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/4c11367b4b57
branches:  trunk
changeset: 822797:4c11367b4b57
user:      kamil <kamil%NetBSD.org@localhost>
date:      Sat Apr 08 00:56:38 2017 +0000

description:
Document new calls and be more clear about PT_SYSCALL* in ptrace(2)

Document PT_SETSTEP and PT_CLEARSTEP in ptrace(2).

Try to explain more details of PT_SYSCALL and PT_SYSCALLEMU.

The description of PT_*STEP has been obtained from FreeBSD.

Sponsored by <The NetBSD Foundation>

diffstat:

 lib/libc/sys/ptrace.2 |  14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diffs (38 lines):

diff -r 0588fcfe865f -r 4c11367b4b57 lib/libc/sys/ptrace.2
--- a/lib/libc/sys/ptrace.2     Sat Apr 08 00:25:49 2017 +0000
+++ b/lib/libc/sys/ptrace.2     Sat Apr 08 00:56:38 2017 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: ptrace.2,v 1.64 2017/04/07 07:21:58 pgoyette Exp $
+.\"    $NetBSD: ptrace.2,v 1.65 2017/04/08 00:56:38 kamil Exp $
 .\"
 .\" This file is in the public domain.
 .Dd April 7, 2017
@@ -404,9 +404,17 @@
 .Dq Li "sizeof(struct ptrace_lwpinfo)" .
 .It Dv PT_SYSCALL
 Stops a process before and after executing each system call.
+Otherwise this operation is the same as
+.Dv PT_CONTINUE .
 .It Dv PT_SYSCALLEMU
 Intercept and ignore a system call before it has been executed, for use with
 .Dv PT_SYSCALL .
+This operation shall be called for syscall entry trap from
+.Dv PT_STSCALL .
+To resume execution after intercepting the system call,
+another
+.Dv PT_SYSCALL
+shall be used.
 .It Dv PT_SET_EVENT_MASK
 This request can be used to specify which events in the traced process
 should be reported to the tracing process.
@@ -626,6 +634,10 @@
 .Fa data
 argument is less than zero, it contains the negative of the LWP ID of
 the thread to be stepped, and only that thread executes.
+.It Dv PT_SETSTEP
+This request will turn on single stepping of the specified process.
+.It Dv PT_CLEARSTEP
+This request will turn off single stepping of the specified process.
 .It Dv PT_GETREGS
 This request reads the traced process' machine registers into the
 .Dq Li "struct reg"