2 * Access kernel memory without faulting -- s390 specific implementation.
4 * Copyright IBM Corp. 2009
6 * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
10 #include <linux/uaccess.h>
11 #include <linux/kernel.h>
12 #include <linux/types.h>
13 #include <linux/errno.h>
14 #include <linux/gfp.h>
15 #include <linux/cpu.h>
16 #include <asm/ctl_reg.h>
20 * This function writes to kernel memory bypassing DAT and possible
21 * write protection. It copies one to four bytes from src to dst
22 * using the stura instruction.
23 * Returns the number of bytes copied or -EFAULT.
25 static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
27 unsigned long count, aligned;
31 aligned = (unsigned long) dst & ~3UL;
32 offset = (unsigned long) dst & 3;
33 count = min_t(unsigned long, 4 - offset, size);
34 mask = (0xf << (4 - count)) & 0xf;
45 EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
46 : "+d" (rc), "+a" (aligned)
47 : "a" (mask), "a" (src) : "cc", "memory", "0", "1");
48 return rc ? rc : count;
51 long probe_kernel_write(void *dst, const void *src, size_t size)
56 copied = probe_kernel_write_odd(dst, src, size);
63 return copied < 0 ? -EFAULT : 0;
66 static int __memcpy_real(void *dest, void *src, size_t count)
68 register unsigned long _dest asm("2") = (unsigned long) dest;
69 register unsigned long _len1 asm("3") = (unsigned long) count;
70 register unsigned long _src asm("4") = (unsigned long) src;
71 register unsigned long _len2 asm("5") = (unsigned long) count;
75 "0: mvcle %1,%2,0x0\n"
80 : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1),
81 "+d" (_len2), "=m" (*((long *) dest))
82 : "m" (*((long *) src))
88 * Copy memory in real mode (kernel to kernel)
90 int memcpy_real(void *dest, void *src, size_t count)
97 local_irq_save(flags);
98 __arch_local_irq_stnsm(0xfbUL);
99 rc = __memcpy_real(dest, src, count);
100 local_irq_restore(flags);
105 * Copy memory in absolute mode (kernel to kernel)
107 void memcpy_absolute(void *dest, void *src, size_t count)
109 unsigned long cr0, flags, prefix;
111 flags = arch_local_irq_save();
112 __ctl_store(cr0, 0, 0);
113 __ctl_clear_bit(0, 28); /* disable lowcore protection */
114 prefix = store_prefix();
116 local_mcck_disable();
118 memcpy(dest, src, count);
122 memcpy(dest, src, count);
124 __ctl_load(cr0, 0, 0);
125 arch_local_irq_restore(flags);
129 * Copy memory from kernel (real) to user (virtual)
131 int copy_to_user_real(void __user *dest, void *src, size_t count)
133 int offs = 0, size, rc;
136 buf = (char *) __get_free_page(GFP_KERNEL);
140 while (offs < count) {
141 size = min(PAGE_SIZE, count - offs);
142 if (memcpy_real(buf, src + offs, size))
144 if (copy_to_user(dest + offs, buf, size))
150 free_page((unsigned long) buf);
155 * Copy memory from user (virtual) to kernel (real)
157 int copy_from_user_real(void *dest, void __user *src, size_t count)
159 int offs = 0, size, rc;
162 buf = (char *) __get_free_page(GFP_KERNEL);
166 while (offs < count) {
167 size = min(PAGE_SIZE, count - offs);
168 if (copy_from_user(buf, src + offs, size))
170 if (memcpy_real(dest + offs, buf, size))
176 free_page((unsigned long) buf);
181 * Check if physical address is within prefix or zero page
183 static int is_swapped(unsigned long addr)
188 if (addr < sizeof(struct _lowcore))
190 for_each_online_cpu(cpu) {
191 lc = (unsigned long) lowcore_ptr[cpu];
192 if (addr > lc + sizeof(struct _lowcore) - 1 || addr < lc)
200 * Convert a physical pointer for /dev/mem access
202 * For swapped prefix pages a new buffer is returned that contains a copy of
203 * the absolute memory. The buffer size is maximum one page large.
205 void *xlate_dev_mem_ptr(unsigned long addr)
207 void *bounce = (void *) addr;
212 if (is_swapped(addr)) {
213 size = PAGE_SIZE - (addr & ~PAGE_MASK);
214 bounce = (void *) __get_free_page(GFP_ATOMIC);
216 memcpy_absolute(bounce, (void *) addr, size);
224 * Free converted buffer for /dev/mem access (if necessary)
226 void unxlate_dev_mem_ptr(unsigned long addr, void *buf)
228 if ((void *) addr != buf)
229 free_page((unsigned long) buf);