'\" te
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.TH SYNC_INSTRUCTION_MEMORY 3C "Feb 12, 1997"
.SH NAME
sync_instruction_memory \- make modified instructions executable
.SH SYNOPSIS
.LP
.nf
\fBvoid\fR \fBsync_instruction_memory\fR(\fBcaddr_t\fR \fIaddr\fR, \fBint\fR \fIlen\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBsync_instruction_memory()\fR function performs whatever steps are
required to make instructions modified by a program executable.
.sp
.LP
Some processor architectures, including some  SPARC processors, have separate
and independent instruction and data caches which are not kept consistent by
hardware.  For example, if the instruction cache contains an instruction from
some address and the program then stores a new instruction at that address, the
new instruction may not be immediately visible to the instruction fetch
mechanism. Software must explicitly invalidate the instruction cache entries
for new or changed mappings of pages that might contain executable
instructions.  The \fBsync_instruction_memory()\fR function performs this
function, and/or any other functions needed to make modified instructions
between \fIaddr\fR and \fIaddr\fR+\fIlen\fR visible. A program should call
\fBsync_instruction_memory()\fR after modifying instructions and before
executing them.
.sp
.LP
On processors with unified caches (one cache for both instructions and data)
and pipelines which are flushed by a branch instruction, such as the x86
architecture, the function may do nothing and just return.
.sp
.LP
The changes are immediately visible to the thread calling
\fBsync_instruction_memory()\fR when the call returns, even if the thread
should migrate to another processor during or after the call. The changes
become visible to other threads in the same manner that stores do; that is,
they eventually become visible, but the latency is implementation-dependent.
.sp
.LP
The result of executing \fBsync_instruction_memory()\fR are unpredictable if
\fIaddr\fR through \fIaddr\fR+\fIlen\fR-1 are not valid for the address space
of the program making the call.
.SH RETURN VALUES
.sp
.LP
No values are returned.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR attributes (7)