Module Name: src
Committed By: kamil
Date: Sun Feb 25 16:53:51 UTC 2018
Modified Files:
src/share/man/man2: ucontext.2
Log Message:
Document _UC_MACHINE_*() in ucontext(2)
Document:
- _UC_MACHINE_SP()
- _UC_MACHINE_FP()
- _UC_MACHINE_PC()
- _UC_MACHINE_INTRV()
- _UC_MACHINE_SET_PC()
Document fragileness of the frame-pointer accessor.
Sponsored by <The NetBSD Foundation>
To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/share/man/man2/ucontext.2
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man2/ucontext.2
diff -u src/share/man/man2/ucontext.2:1.6 src/share/man/man2/ucontext.2:1.7
--- src/share/man/man2/ucontext.2:1.6 Thu Apr 29 06:07:35 2010
+++ src/share/man/man2/ucontext.2 Sun Feb 25 16:53:51 2018
@@ -1,4 +1,4 @@
-.\" $NetBSD: ucontext.2,v 1.6 2010/04/29 06:07:35 jruoho Exp $
+.\" $NetBSD: ucontext.2,v 1.7 2018/02/25 16:53:51 kamil Exp $
.\"
.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd April 29, 2010
+.Dd February 25, 2018
.Dt UCONTEXT 2
.Os
.Sh NAME
@@ -35,6 +35,11 @@
.Nd user context
.Sh SYNOPSIS
.In ucontext.h
+.Fn _UC_MACHINE_SP "&uc"
+.Fn _UC_MACHINE_FP "&uc"
+.Fn _UC_MACHINE_PC "&uc"
+.Fn _UC_MACHINE_INTRV "&uc"
+.Fn _UC_MACHINE_SET_PC "&uc"
.Sh DESCRIPTION
The
.Vt ucontext_t
@@ -86,6 +91,36 @@ it may consist of general registers, flo
and other machine-specific information.
Its description is beyond the scope of this manual page;
portable applications should not access this structure member.
+.Pp
+The
+.Fn _UC_MACHINE_SP ,
+.Fn _UC_MACHINE_FP ,
+.Fn _UC_MACHINE_PC ,
+.Fn _UC_MACHINE_INTRV
+and
+.Fn _UC_MACHINE_SET_PC
+auxiliary macros are designed to perform respectively the following operations:
+.Bl -dash
+.It
+read stack pointer ,
+.It
+read frame pointer (base pointer) ,
+.It
+read program counter ,
+.It
+read interrupt vector ,
+.It
+write program counter .
+.El
+.Pp
+The frame pointer macro does not guarantee to retrieve a reliable value
+and should not be used in a code unless no other debugging format is
+easily accessible.
+A compiler might optimize the frame pointer register in a function,
+reusing as a general purpose register storage
+.Ar -fomit-frame-pointer
+or emit function prologues only before parts that need them
+.Ar -fshrink-wrap .
.Sh SEE ALSO
.Xr _exit 2 ,
.Xr getcontext 2 ,
