1/* 2 * Access kernel memory without faulting -- s390 specific implementation. 3 * 4 * Copyright IBM Corp. 2009 5 * 6 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>, 7 * 8 */ 9 10#include <linux/uaccess.h> 11#include <linux/kernel.h> 12#include <linux/types.h> 13#include <linux/errno.h> 14#include <asm/system.h> 15 16/* 17 * This function writes to kernel memory bypassing DAT and possible 18 * write protection. It copies one to four bytes from src to dst 19 * using the stura instruction. 20 * Returns the number of bytes copied or -EFAULT. 21 */ 22static long probe_kernel_write_odd(void *dst, void *src, size_t size) 23{ 24 unsigned long count, aligned; 25 int offset, mask; 26 int rc = -EFAULT; 27 28 aligned = (unsigned long) dst & ~3UL; 29 offset = (unsigned long) dst & 3; 30 count = min_t(unsigned long, 4 - offset, size); 31 mask = (0xf << (4 - count)) & 0xf; 32 mask >>= offset; 33 asm volatile( 34 " bras 1,0f\n" 35 " icm 0,0,0(%3)\n" 36 "0: l 0,0(%1)\n" 37 " lra %1,0(%1)\n" 38 "1: ex %2,0(1)\n" 39 "2: stura 0,%1\n" 40 " la %0,0\n" 41 "3:\n" 42 EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b) 43 : "+d" (rc), "+a" (aligned) 44 : "a" (mask), "a" (src) : "cc", "memory", "0", "1"); 45 return rc ? rc : count; 46} 47 48long probe_kernel_write(void *dst, void *src, size_t size) 49{ 50 long copied = 0; 51 52 while (size) { 53 copied = probe_kernel_write_odd(dst, src, size); 54 if (copied < 0) 55 break; 56 dst += copied; 57 src += copied; 58 size -= copied; 59 } 60 return copied < 0 ? -EFAULT : 0; 61} 62 63int memcpy_real(void *dest, void *src, size_t count) 64{ 65 register unsigned long _dest asm("2") = (unsigned long) dest; 66 register unsigned long _len1 asm("3") = (unsigned long) count; 67 register unsigned long _src asm("4") = (unsigned long) src; 68 register unsigned long _len2 asm("5") = (unsigned long) count; 69 unsigned long flags; 70 int rc = -EFAULT; 71 72 if (!count) 73 return 0; 74 flags = __raw_local_irq_stnsm(0xf8UL); 75 asm volatile ( 76 "0: mvcle %1,%2,0x0\n" 77 "1: jo 0b\n" 78 " lhi %0,0x0\n" 79 "2:\n" 80 EX_TABLE(1b,2b) 81 : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1), 82 "+d" (_len2), "=m" (*((long *) dest)) 83 : "m" (*((long *) src)) 84 : "cc", "memory"); 85 __raw_local_irq_ssm(flags); 86 return rc; 87} 88