CACHEFLUSH(2) Linux Programmer's Manual CACHEFLUSH(2)

cacheflush - flush contents of instruction and/or data cache

#include <asm/cachectl.h>
int cacheflush(char *addr, int nbytes, int cache);

cacheflush() flushes the contents of the indicated cache(s) for the user addresses in the range addr to (addr+nbytes-1). cache may be one of:
Flush the instruction cache.
Write back to memory and invalidate the affected valid cache lines.

cacheflush() returns 0 on success or -1 on error. If errors are detected, errno will indicate the error.

Some or all of the address range addr to (addr+nbytes-1) is not accessible.
cache is not one of ICACHE, DCACHE, or BCACHE (but see BUGS).

Historically, this system call was available on all MIPS UNIX variants including RISC/os, IRIX, Ultrix, NetBSD, OpenBSD, and FreeBSD (and also on some non-UNIX MIPS operating systems), so that the existence of this call in MIPS operating systems is a de-facto standard.

cacheflush() should not be used in programs intended to be portable. On Linux, this call first appeared on the MIPS architecture, but nowadays, Linux provides a cacheflush() system call on some other architectures, but with different arguments.

Linux kernels older than version 2.6.11 ignore the addr and nbytes arguments, making this function fairly expensive. Therefore, the whole cache is always flushed.
This function always behaves as if BCACHE has been passed for the cache argument and does not do any error checking on the cache argument.
2017-09-15 Linux