92fe31329c
To save the registers for all CPUs a sigp "store status" is done that stores the registers to address absolute zero. To access storage at absolute zero, normally the address of the prefix register of the accessing CPU has to be used. This does not work when large pages are active (currently only under LPAR). In order to fix that problem, instead of memcpy memcpy_real is used, which switches to real mode where prefixing works. Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
88 lines
2.1 KiB
C
88 lines
2.1 KiB
C
/*
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* Access kernel memory without faulting -- s390 specific implementation.
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*
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* Copyright IBM Corp. 2009
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*
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* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
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*
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*/
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#include <linux/uaccess.h>
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <asm/system.h>
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/*
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* This function writes to kernel memory bypassing DAT and possible
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* write protection. It copies one to four bytes from src to dst
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* using the stura instruction.
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* Returns the number of bytes copied or -EFAULT.
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*/
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static long probe_kernel_write_odd(void *dst, void *src, size_t size)
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{
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unsigned long count, aligned;
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int offset, mask;
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int rc = -EFAULT;
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aligned = (unsigned long) dst & ~3UL;
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offset = (unsigned long) dst & 3;
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count = min_t(unsigned long, 4 - offset, size);
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mask = (0xf << (4 - count)) & 0xf;
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mask >>= offset;
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asm volatile(
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" bras 1,0f\n"
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" icm 0,0,0(%3)\n"
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"0: l 0,0(%1)\n"
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" lra %1,0(%1)\n"
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"1: ex %2,0(1)\n"
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"2: stura 0,%1\n"
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" la %0,0\n"
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"3:\n"
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EX_TABLE(0b,3b) EX_TABLE(1b,3b) EX_TABLE(2b,3b)
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: "+d" (rc), "+a" (aligned)
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: "a" (mask), "a" (src) : "cc", "memory", "0", "1");
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return rc ? rc : count;
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}
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long probe_kernel_write(void *dst, void *src, size_t size)
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{
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long copied = 0;
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while (size) {
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copied = probe_kernel_write_odd(dst, src, size);
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if (copied < 0)
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break;
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dst += copied;
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src += copied;
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size -= copied;
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}
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return copied < 0 ? -EFAULT : 0;
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}
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int memcpy_real(void *dest, void *src, size_t count)
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{
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register unsigned long _dest asm("2") = (unsigned long) dest;
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register unsigned long _len1 asm("3") = (unsigned long) count;
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register unsigned long _src asm("4") = (unsigned long) src;
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register unsigned long _len2 asm("5") = (unsigned long) count;
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unsigned long flags;
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int rc = -EFAULT;
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if (!count)
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return 0;
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flags = __raw_local_irq_stnsm(0xf8UL);
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asm volatile (
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"0: mvcle %1,%2,0x0\n"
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"1: jo 0b\n"
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" lhi %0,0x0\n"
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"2:\n"
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EX_TABLE(1b,2b)
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: "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1),
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"+d" (_len2), "=m" (*((long *) dest))
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: "m" (*((long *) src))
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: "cc", "memory");
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__raw_local_irq_ssm(flags);
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return rc;
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}
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