2009-06-12 15:26:42 +07:00
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/*
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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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2011-10-30 21:16:39 +07:00
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#include <linux/gfp.h>
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s390: allow absolute memory access for /dev/mem
Currently dev/mem for s390 provides only real memory access. This means
that the CPU prefix pages are swapped. The prefix swap for real memory
works as follows:
Each CPU owns a prefix register that points to a page aligned memory
location "P". If this CPU accesses the address range [0,0x1fff], it is
translated by the hardware to [P,P+0x1fff]. Accordingly if this CPU
accesses the address range [P,P+0x1fff], it is translated by the hardware
to [0,0x1fff]. Therefore, if [P,P+0x1fff] or [0,0x1fff] is read from
the current /dev/mem device, the incorrectly swapped memory content is
returned.
With this patch the /dev/mem architecture code is modified to provide
absolute memory access. This is done via the arch specific functions
xlate_dev_mem_ptr() and unxlate_dev_mem_ptr(). For swapped pages on
s390 the function xlate_dev_mem_ptr() now returns a new buffer with a
copy of the requested absolute memory. In case the buffer was allocated,
the unxlate_dev_mem_ptr() function frees it after /dev/mem code has
called copy_to_user().
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-05-09 21:27:36 +07:00
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#include <linux/cpu.h>
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2012-03-29 00:30:02 +07:00
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#include <asm/ctl_reg.h>
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2013-09-07 00:10:48 +07:00
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#include <asm/io.h>
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2009-06-12 15:26:42 +07:00
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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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2011-05-20 01:35:33 +07:00
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static long probe_kernel_write_odd(void *dst, const void *src, size_t size)
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2009-06-12 15:26:42 +07:00
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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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2011-05-20 01:35:33 +07:00
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long probe_kernel_write(void *dst, const void *src, size_t size)
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2009-06-12 15:26:42 +07:00
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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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2010-03-24 17:49:50 +07:00
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2012-04-11 19:28:06 +07:00
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static int __memcpy_real(void *dest, void *src, size_t count)
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2010-03-24 17:49:50 +07:00
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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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int rc = -EFAULT;
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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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2012-04-11 19:28:06 +07:00
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return rc;
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}
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/*
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* Copy memory in real mode (kernel to kernel)
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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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unsigned long flags;
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int rc;
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if (!count)
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return 0;
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local_irq_save(flags);
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__arch_local_irq_stnsm(0xfbUL);
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rc = __memcpy_real(dest, src, count);
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local_irq_restore(flags);
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2010-03-24 17:49:50 +07:00
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return rc;
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}
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2011-08-03 21:44:19 +07:00
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/*
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2012-05-24 19:35:16 +07:00
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* Copy memory in absolute mode (kernel to kernel)
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2011-08-03 21:44:19 +07:00
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*/
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2012-05-24 19:35:16 +07:00
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void memcpy_absolute(void *dest, void *src, size_t count)
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2011-08-03 21:44:19 +07:00
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{
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2012-05-24 19:35:16 +07:00
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unsigned long cr0, flags, prefix;
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2011-08-03 21:44:19 +07:00
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2012-05-24 19:35:16 +07:00
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flags = arch_local_irq_save();
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2011-08-03 21:44:19 +07:00
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__ctl_store(cr0, 0, 0);
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__ctl_clear_bit(0, 28); /* disable lowcore protection */
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2012-05-24 19:35:16 +07:00
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prefix = store_prefix();
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if (prefix) {
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local_mcck_disable();
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set_prefix(0);
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memcpy(dest, src, count);
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set_prefix(prefix);
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local_mcck_enable();
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} else {
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memcpy(dest, src, count);
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}
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2011-08-03 21:44:19 +07:00
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__ctl_load(cr0, 0, 0);
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2012-05-24 19:35:16 +07:00
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arch_local_irq_restore(flags);
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2011-08-03 21:44:19 +07:00
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}
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2011-10-30 21:16:39 +07:00
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/*
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* Copy memory from kernel (real) to user (virtual)
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*/
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2014-01-24 18:51:27 +07:00
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int copy_to_user_real(void __user *dest, void *src, unsigned long count)
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2011-10-30 21:16:39 +07:00
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{
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int offs = 0, size, rc;
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char *buf;
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buf = (char *) __get_free_page(GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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rc = -EFAULT;
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while (offs < count) {
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size = min(PAGE_SIZE, count - offs);
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if (memcpy_real(buf, src + offs, size))
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goto out;
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if (copy_to_user(dest + offs, buf, size))
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goto out;
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offs += size;
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}
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rc = 0;
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out:
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free_page((unsigned long) buf);
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return rc;
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}
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s390: allow absolute memory access for /dev/mem
Currently dev/mem for s390 provides only real memory access. This means
that the CPU prefix pages are swapped. The prefix swap for real memory
works as follows:
Each CPU owns a prefix register that points to a page aligned memory
location "P". If this CPU accesses the address range [0,0x1fff], it is
translated by the hardware to [P,P+0x1fff]. Accordingly if this CPU
accesses the address range [P,P+0x1fff], it is translated by the hardware
to [0,0x1fff]. Therefore, if [P,P+0x1fff] or [0,0x1fff] is read from
the current /dev/mem device, the incorrectly swapped memory content is
returned.
With this patch the /dev/mem architecture code is modified to provide
absolute memory access. This is done via the arch specific functions
xlate_dev_mem_ptr() and unxlate_dev_mem_ptr(). For swapped pages on
s390 the function xlate_dev_mem_ptr() now returns a new buffer with a
copy of the requested absolute memory. In case the buffer was allocated,
the unxlate_dev_mem_ptr() function frees it after /dev/mem code has
called copy_to_user().
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-05-09 21:27:36 +07:00
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/*
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* Check if physical address is within prefix or zero page
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*/
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static int is_swapped(unsigned long addr)
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{
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unsigned long lc;
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int cpu;
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if (addr < sizeof(struct _lowcore))
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return 1;
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for_each_online_cpu(cpu) {
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lc = (unsigned long) lowcore_ptr[cpu];
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if (addr > lc + sizeof(struct _lowcore) - 1 || addr < lc)
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continue;
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return 1;
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}
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return 0;
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}
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/*
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* Convert a physical pointer for /dev/mem access
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*
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* For swapped prefix pages a new buffer is returned that contains a copy of
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* the absolute memory. The buffer size is maximum one page large.
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*/
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void *xlate_dev_mem_ptr(unsigned long addr)
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{
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void *bounce = (void *) addr;
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unsigned long size;
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get_online_cpus();
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preempt_disable();
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if (is_swapped(addr)) {
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size = PAGE_SIZE - (addr & ~PAGE_MASK);
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bounce = (void *) __get_free_page(GFP_ATOMIC);
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if (bounce)
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2012-05-24 19:35:16 +07:00
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memcpy_absolute(bounce, (void *) addr, size);
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s390: allow absolute memory access for /dev/mem
Currently dev/mem for s390 provides only real memory access. This means
that the CPU prefix pages are swapped. The prefix swap for real memory
works as follows:
Each CPU owns a prefix register that points to a page aligned memory
location "P". If this CPU accesses the address range [0,0x1fff], it is
translated by the hardware to [P,P+0x1fff]. Accordingly if this CPU
accesses the address range [P,P+0x1fff], it is translated by the hardware
to [0,0x1fff]. Therefore, if [P,P+0x1fff] or [0,0x1fff] is read from
the current /dev/mem device, the incorrectly swapped memory content is
returned.
With this patch the /dev/mem architecture code is modified to provide
absolute memory access. This is done via the arch specific functions
xlate_dev_mem_ptr() and unxlate_dev_mem_ptr(). For swapped pages on
s390 the function xlate_dev_mem_ptr() now returns a new buffer with a
copy of the requested absolute memory. In case the buffer was allocated,
the unxlate_dev_mem_ptr() function frees it after /dev/mem code has
called copy_to_user().
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-05-09 21:27:36 +07:00
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}
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preempt_enable();
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put_online_cpus();
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return bounce;
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}
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/*
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* Free converted buffer for /dev/mem access (if necessary)
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*/
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void unxlate_dev_mem_ptr(unsigned long addr, void *buf)
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{
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if ((void *) addr != buf)
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free_page((unsigned long) buf);
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}
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