SYNC_INSTRUCTION_MEMORY(3C) Standard C Library Functions
NAME
sync_instruction_memory - make modified instructions executable
SYNOPSIS
void sync_instruction_memory(
caddr_t addr,
int len);
DESCRIPTION
The
sync_instruction_memory() function performs whatever steps are
required to make instructions modified by a program executable.
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
sync_instruction_memory() function performs this function, and/or
any other functions needed to make modified instructions between
addr and
addr+
len visible. A program should call
sync_instruction_memory() after modifying instructions and before executing them.
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.
The changes are immediately visible to the thread calling
sync_instruction_memory() 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.
The result of executing
sync_instruction_memory() are unpredictable
if
addr through
addr+
len-1 are not valid for the address space of the
program making the call.
RETURN VALUES
No values are returned.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | MT-Safe |
+---------------+-----------------+
SEE ALSO
attributes(7) February 12, 1997 SYNC_INSTRUCTION_MEMORY(3C)
