// SPDX-License-Identifier: GPL-2.0 /* * simple_ring_buffer is used by the pKVM hypervisor which does not have access * to all kernel symbols.  Whatever is undefined when compiling this file is * compiler and tooling-generated symbols that can safely be ignored for * simple_ring_buffer. */ #include <linux/atomic.h>#include <linux/string.h>#include <asm/page.h> void undefsyms_base(void *p, int n); static char page[PAGE_SIZE] __aligned(PAGE_SIZE); void undefsyms_base(void *p, int n){	char buffer[256] = { 0 }; 	u32 u = 0;	memset((char * volatile)page, 8, PAGE_SIZE);	memset((char * volatile)buffer, 8, sizeof(buffer));	memcpy((void * volatile)p, buffer, sizeof(buffer));	cmpxchg((u32 * volatile)&u, 0, 8);	WARN_ON(n == 0xdeadbeef);}