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arch/s390/mm/maccess.c
3.56 KB
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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> |
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#include <linux/gfp.h> |
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#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. */ |
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static long probe_kernel_write_odd(void *dst, const void *src, size_t size) |
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{ 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 " " icm 0,0,0(%3) " "0: l 0,0(%1) " " lra %1,0(%1) " "1: ex %2,0(1) " "2: stura 0,%1 " " la %0,0 " "3: " 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; } |
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long probe_kernel_write(void *dst, const void *src, size_t size) |
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{ 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; } |
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/* * Copy memory in real mode (kernel to kernel) */ |
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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; |
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flags = __arch_local_irq_stnsm(0xf8UL); |
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asm volatile ( "0: mvcle %1,%2,0x0 " "1: jo 0b " " lhi %0,0x0 " "2: " EX_TABLE(1b,2b) : "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1), "+d" (_len2), "=m" (*((long *) dest)) : "m" (*((long *) src)) : "cc", "memory"); |
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arch_local_irq_restore(flags); |
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return rc; } |
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/* * Copy memory to absolute zero */ void copy_to_absolute_zero(void *dest, void *src, size_t count) { unsigned long cr0; BUG_ON((unsigned long) dest + count >= sizeof(struct _lowcore)); preempt_disable(); __ctl_store(cr0, 0, 0); __ctl_clear_bit(0, 28); /* disable lowcore protection */ memcpy_real(dest + store_prefix(), src, count); __ctl_load(cr0, 0, 0); preempt_enable(); } |
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/* * Copy memory from kernel (real) to user (virtual) */ int copy_to_user_real(void __user *dest, void *src, size_t count) { int offs = 0, size, rc; char *buf; buf = (char *) __get_free_page(GFP_KERNEL); if (!buf) return -ENOMEM; rc = -EFAULT; while (offs < count) { size = min(PAGE_SIZE, count - offs); if (memcpy_real(buf, src + offs, size)) goto out; if (copy_to_user(dest + offs, buf, size)) goto out; offs += size; } rc = 0; out: free_page((unsigned long) buf); return rc; } /* * Copy memory from user (virtual) to kernel (real) */ int copy_from_user_real(void *dest, void __user *src, size_t count) { int offs = 0, size, rc; char *buf; buf = (char *) __get_free_page(GFP_KERNEL); if (!buf) return -ENOMEM; rc = -EFAULT; while (offs < count) { size = min(PAGE_SIZE, count - offs); if (copy_from_user(buf, src + offs, size)) goto out; if (memcpy_real(dest + offs, buf, size)) goto out; offs += size; } rc = 0; out: free_page((unsigned long) buf); return rc; } |