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- /*
- * Access kernel memory without faulting -- s390 specific implementation.
- *
- * Copyright IBM Corp. 2009
- *
- * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
- *
- */
- #include <linux/uaccess.h>
- #include <linux/kernel.h>
- #include <linux/types.h>
- #include <linux/errno.h>
- #include <asm/system.h>
- /*
- * This function writes to kernel memory bypassing DAT and possible
- * write protection. It copies one to four bytes from src to dst
- * using the stura instruction.
- * Returns the number of bytes copied or -EFAULT.
- */
- static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
- {
- unsigned long count, aligned;
- int offset, mask;
- int rc = -EFAULT;
- aligned = (unsigned long) dst & ~3UL;
- offset = (unsigned long) dst & 3;
- count = min_t(unsigned long, 4 - offset, size);
- mask = (0xf << (4 - count)) & 0xf;
- mask >>= offset;
- asm volatile(
- " bras 1,0f\n"
- " icm 0,0,0(%3)\n"
- "0: l 0,0(%1)\n"
- " lra %1,0(%1)\n"
- "1: ex %2,0(1)\n"
- "2: stura 0,%1\n"
- " la %0,0\n"
- "3:\n"
- EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
- : "+d" (rc), "+a" (aligned)
- : "a" (mask), "a" (src) : "cc", "memory", "0", "1");
- return rc ? rc : count;
- }
- long probe_kernel_write(void *dst, const void *src, size_t size)
- {
- long copied = 0;
- while (size) {
- copied = probe_kernel_write_odd(dst, src, size);
- if (copied < 0)
- break;
- dst += copied;
- src += copied;
- size -= copied;
- }
- return copied < 0 ? -EFAULT : 0;
- }
- int memcpy_real(void *dest, void *src, size_t count)
- {
- register unsigned long _dest asm("2") = (unsigned long) dest;
- register unsigned long _len1 asm("3") = (unsigned long) count;
- register unsigned long _src asm("4") = (unsigned long) src;
- register unsigned long _len2 asm("5") = (unsigned long) count;
- unsigned long flags;
- int rc = -EFAULT;
- if (!count)
- return 0;
- flags = __arch_local_irq_stnsm(0xf8UL);
- asm volatile (
- "0: mvcle %1,%2,0x0\n"
- "1: jo 0b\n"
- " lhi %0,0x0\n"
- "2:\n"
- EX_TABLE(1b,2b)
- : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1),
- "+d" (_len2), "=m" (*((long *) dest))
- : "m" (*((long *) src))
- : "cc", "memory");
- arch_local_irq_restore(flags);
- return rc;
- }
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