1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * simple_ring_buffer is used by the pKVM hypervisor which does not have access 5 * to all kernel symbols. Whatever is undefined when compiling this file is 6 * compiler and tooling-generated symbols that can safely be ignored for 7 * simple_ring_buffer. 8 */ 9 10 #include <linux/atomic.h> 11 #include <linux/string.h> 12 #include <asm/local.h> 13 #include <asm/page.h> 14 15 void undefsyms_base(void *p, int n); 16 17 static char page[PAGE_SIZE] __aligned(PAGE_SIZE); 18 19 void undefsyms_base(void *p, int n) 20 { 21 char buffer[256] = { 0 }; 22 u32 u = 0; 23 24 memset((char * volatile)page, 8, PAGE_SIZE); 25 memset((char * volatile)buffer, 8, sizeof(buffer)); 26 memcpy((void * volatile)p, buffer, sizeof(buffer)); 27 cmpxchg((u32 * volatile)&u, 0, 8); 28 cmpxchg((unsigned long *)p, 0, 8); 29 local_set((local_t *)p, 8); 30 WARN_ON(n == 0xdeadbeef); 31 } 32