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Diffstat (limited to 'arch/s390/lib/uaccess_pt.c')
-rw-r--r--arch/s390/lib/uaccess_pt.c476
1 files changed, 476 insertions, 0 deletions
diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
new file mode 100644
index 00000000..1bf40ef5
--- /dev/null
+++ b/arch/s390/lib/uaccess_pt.c
@@ -0,0 +1,476 @@
+/*
+ * User access functions based on page table walks for enhanced
+ * system layout without hardware support.
+ *
+ * Copyright IBM Corp. 2006, 2012
+ * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
+ */
+
+#include <linux/errno.h>
+#include <linux/hardirq.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <asm/uaccess.h>
+#include <asm/futex.h>
+#include "uaccess.h"
+
+#ifndef CONFIG_64BIT
+#define AHI "ahi"
+#define SLR "slr"
+#else
+#define AHI "aghi"
+#define SLR "slgr"
+#endif
+
+static size_t strnlen_kernel(size_t count, const char __user *src)
+{
+ register unsigned long reg0 asm("0") = 0UL;
+ unsigned long tmp1, tmp2;
+
+ asm volatile(
+ " la %2,0(%1)\n"
+ " la %3,0(%0,%1)\n"
+ " "SLR" %0,%0\n"
+ "0: srst %3,%2\n"
+ " jo 0b\n"
+ " la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
+ " "SLR" %0,%1\n"
+ "1:\n"
+ EX_TABLE(0b,1b)
+ : "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
+ : "d" (reg0) : "cc", "memory");
+ return count;
+}
+
+static size_t copy_in_kernel(size_t count, void __user *to,
+ const void __user *from)
+{
+ unsigned long tmp1;
+
+ asm volatile(
+ " "AHI" %0,-1\n"
+ " jo 5f\n"
+ " bras %3,3f\n"
+ "0:"AHI" %0,257\n"
+ "1: mvc 0(1,%1),0(%2)\n"
+ " la %1,1(%1)\n"
+ " la %2,1(%2)\n"
+ " "AHI" %0,-1\n"
+ " jnz 1b\n"
+ " j 5f\n"
+ "2: mvc 0(256,%1),0(%2)\n"
+ " la %1,256(%1)\n"
+ " la %2,256(%2)\n"
+ "3:"AHI" %0,-256\n"
+ " jnm 2b\n"
+ "4: ex %0,1b-0b(%3)\n"
+ "5:"SLR" %0,%0\n"
+ "6:\n"
+ EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
+ : "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
+ : : "cc", "memory");
+ return count;
+}
+
+/*
+ * Returns kernel address for user virtual address. If the returned address is
+ * >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occured and the address
+ * contains the (negative) exception code.
+ */
+#ifdef CONFIG_64BIT
+
+static unsigned long follow_table(struct mm_struct *mm,
+ unsigned long address, int write)
+{
+ unsigned long *table = (unsigned long *)__pa(mm->pgd);
+
+ if (unlikely(address > mm->context.asce_limit - 1))
+ return -0x38UL;
+ switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
+ case _ASCE_TYPE_REGION1:
+ table = table + ((address >> 53) & 0x7ff);
+ if (unlikely(*table & _REGION_ENTRY_INV))
+ return -0x39UL;
+ table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+ /* fallthrough */
+ case _ASCE_TYPE_REGION2:
+ table = table + ((address >> 42) & 0x7ff);
+ if (unlikely(*table & _REGION_ENTRY_INV))
+ return -0x3aUL;
+ table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+ /* fallthrough */
+ case _ASCE_TYPE_REGION3:
+ table = table + ((address >> 31) & 0x7ff);
+ if (unlikely(*table & _REGION_ENTRY_INV))
+ return -0x3bUL;
+ table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+ /* fallthrough */
+ case _ASCE_TYPE_SEGMENT:
+ table = table + ((address >> 20) & 0x7ff);
+ if (unlikely(*table & _SEGMENT_ENTRY_INV))
+ return -0x10UL;
+ if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
+ if (write && (*table & _SEGMENT_ENTRY_RO))
+ return -0x04UL;
+ return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
+ (address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
+ }
+ table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
+ }
+ table = table + ((address >> 12) & 0xff);
+ if (unlikely(*table & _PAGE_INVALID))
+ return -0x11UL;
+ if (write && (*table & _PAGE_RO))
+ return -0x04UL;
+ return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
+}
+
+#else /* CONFIG_64BIT */
+
+static unsigned long follow_table(struct mm_struct *mm,
+ unsigned long address, int write)
+{
+ unsigned long *table = (unsigned long *)__pa(mm->pgd);
+
+ table = table + ((address >> 20) & 0x7ff);
+ if (unlikely(*table & _SEGMENT_ENTRY_INV))
+ return -0x10UL;
+ table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
+ table = table + ((address >> 12) & 0xff);
+ if (unlikely(*table & _PAGE_INVALID))
+ return -0x11UL;
+ if (write && (*table & _PAGE_RO))
+ return -0x04UL;
+ return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
+}
+
+#endif /* CONFIG_64BIT */
+
+static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr,
+ size_t n, int write_user)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long offset, done, size, kaddr;
+ void *from, *to;
+
+ done = 0;
+retry:
+ spin_lock(&mm->page_table_lock);
+ do {
+ kaddr = follow_table(mm, uaddr, write_user);
+ if (IS_ERR_VALUE(kaddr))
+ goto fault;
+
+ offset = uaddr & ~PAGE_MASK;
+ size = min(n - done, PAGE_SIZE - offset);
+ if (write_user) {
+ to = (void *) kaddr;
+ from = kptr + done;
+ } else {
+ from = (void *) kaddr;
+ to = kptr + done;
+ }
+ memcpy(to, from, size);
+ done += size;
+ uaddr += size;
+ } while (done < n);
+ spin_unlock(&mm->page_table_lock);
+ return n - done;
+fault:
+ spin_unlock(&mm->page_table_lock);
+ if (__handle_fault(uaddr, -kaddr, write_user))
+ return n - done;
+ goto retry;
+}
+
+/*
+ * Do DAT for user address by page table walk, return kernel address.
+ * This function needs to be called with current->mm->page_table_lock held.
+ */
+static __always_inline unsigned long __dat_user_addr(unsigned long uaddr,
+ int write)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long kaddr;
+ int rc;
+
+retry:
+ kaddr = follow_table(mm, uaddr, write);
+ if (IS_ERR_VALUE(kaddr))
+ goto fault;
+
+ return kaddr;
+fault:
+ spin_unlock(&mm->page_table_lock);
+ rc = __handle_fault(uaddr, -kaddr, write);
+ spin_lock(&mm->page_table_lock);
+ if (!rc)
+ goto retry;
+ return 0;
+}
+
+size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
+{
+ size_t rc;
+
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return copy_in_kernel(n, (void __user *) to, from);
+ rc = __user_copy_pt((unsigned long) from, to, n, 0);
+ if (unlikely(rc))
+ memset(to + n - rc, 0, rc);
+ return rc;
+}
+
+size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
+{
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return copy_in_kernel(n, to, (void __user *) from);
+ return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
+}
+
+static size_t clear_user_pt(size_t n, void __user *to)
+{
+ void *zpage = (void *) empty_zero_page;
+ long done, size, ret;
+
+ done = 0;
+ do {
+ if (n - done > PAGE_SIZE)
+ size = PAGE_SIZE;
+ else
+ size = n - done;
+ if (segment_eq(get_fs(), KERNEL_DS))
+ ret = copy_in_kernel(n, to, (void __user *) zpage);
+ else
+ ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
+ done += size;
+ to += size;
+ if (ret)
+ return ret + n - done;
+ } while (done < n);
+ return 0;
+}
+
+static size_t strnlen_user_pt(size_t count, const char __user *src)
+{
+ unsigned long uaddr = (unsigned long) src;
+ struct mm_struct *mm = current->mm;
+ unsigned long offset, done, len, kaddr;
+ size_t len_str;
+
+ if (unlikely(!count))
+ return 0;
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return strnlen_kernel(count, src);
+ done = 0;
+retry:
+ spin_lock(&mm->page_table_lock);
+ do {
+ kaddr = follow_table(mm, uaddr, 0);
+ if (IS_ERR_VALUE(kaddr))
+ goto fault;
+
+ offset = uaddr & ~PAGE_MASK;
+ len = min(count - done, PAGE_SIZE - offset);
+ len_str = strnlen((char *) kaddr, len);
+ done += len_str;
+ uaddr += len_str;
+ } while ((len_str == len) && (done < count));
+ spin_unlock(&mm->page_table_lock);
+ return done + 1;
+fault:
+ spin_unlock(&mm->page_table_lock);
+ if (__handle_fault(uaddr, -kaddr, 0))
+ return 0;
+ goto retry;
+}
+
+static size_t strncpy_from_user_pt(size_t count, const char __user *src,
+ char *dst)
+{
+ size_t done, len, offset, len_str;
+
+ if (unlikely(!count))
+ return 0;
+ done = 0;
+ do {
+ offset = (size_t)src & ~PAGE_MASK;
+ len = min(count - done, PAGE_SIZE - offset);
+ if (segment_eq(get_fs(), KERNEL_DS)) {
+ if (copy_in_kernel(len, (void __user *) dst, src))
+ return -EFAULT;
+ } else {
+ if (__user_copy_pt((unsigned long) src, dst, len, 0))
+ return -EFAULT;
+ }
+ len_str = strnlen(dst, len);
+ done += len_str;
+ src += len_str;
+ dst += len_str;
+ } while ((len_str == len) && (done < count));
+ return done;
+}
+
+static size_t copy_in_user_pt(size_t n, void __user *to,
+ const void __user *from)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long offset_max, uaddr, done, size, error_code;
+ unsigned long uaddr_from = (unsigned long) from;
+ unsigned long uaddr_to = (unsigned long) to;
+ unsigned long kaddr_to, kaddr_from;
+ int write_user;
+
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return copy_in_kernel(n, to, from);
+ done = 0;
+retry:
+ spin_lock(&mm->page_table_lock);
+ do {
+ write_user = 0;
+ uaddr = uaddr_from;
+ kaddr_from = follow_table(mm, uaddr_from, 0);
+ error_code = kaddr_from;
+ if (IS_ERR_VALUE(error_code))
+ goto fault;
+
+ write_user = 1;
+ uaddr = uaddr_to;
+ kaddr_to = follow_table(mm, uaddr_to, 1);
+ error_code = (unsigned long) kaddr_to;
+ if (IS_ERR_VALUE(error_code))
+ goto fault;
+
+ offset_max = max(uaddr_from & ~PAGE_MASK,
+ uaddr_to & ~PAGE_MASK);
+ size = min(n - done, PAGE_SIZE - offset_max);
+
+ memcpy((void *) kaddr_to, (void *) kaddr_from, size);
+ done += size;
+ uaddr_from += size;
+ uaddr_to += size;
+ } while (done < n);
+ spin_unlock(&mm->page_table_lock);
+ return n - done;
+fault:
+ spin_unlock(&mm->page_table_lock);
+ if (__handle_fault(uaddr, -error_code, write_user))
+ return n - done;
+ goto retry;
+}
+
+#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
+ asm volatile("0: l %1,0(%6)\n" \
+ "1: " insn \
+ "2: cs %1,%2,0(%6)\n" \
+ "3: jl 1b\n" \
+ " lhi %0,0\n" \
+ "4:\n" \
+ EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
+ : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
+ "=m" (*uaddr) \
+ : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
+ "m" (*uaddr) : "cc" );
+
+static int __futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
+{
+ int oldval = 0, newval, ret;
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("lr %2,%5\n",
+ ret, oldval, newval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("lr %2,%1\nar %2,%5\n",
+ ret, oldval, newval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("lr %2,%1\nor %2,%5\n",
+ ret, oldval, newval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
+ ret, oldval, newval, uaddr, oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
+ ret, oldval, newval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+ if (ret == 0)
+ *old = oldval;
+ return ret;
+}
+
+int futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
+{
+ int ret;
+
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return __futex_atomic_op_pt(op, uaddr, oparg, old);
+ spin_lock(&current->mm->page_table_lock);
+ uaddr = (u32 __force __user *)
+ __dat_user_addr((__force unsigned long) uaddr, 1);
+ if (!uaddr) {
+ spin_unlock(&current->mm->page_table_lock);
+ return -EFAULT;
+ }
+ get_page(virt_to_page(uaddr));
+ spin_unlock(&current->mm->page_table_lock);
+ ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
+ put_page(virt_to_page(uaddr));
+ return ret;
+}
+
+static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
+ u32 oldval, u32 newval)
+{
+ int ret;
+
+ asm volatile("0: cs %1,%4,0(%5)\n"
+ "1: la %0,0\n"
+ "2:\n"
+ EX_TABLE(0b,2b) EX_TABLE(1b,2b)
+ : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
+ : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
+ : "cc", "memory" );
+ *uval = oldval;
+ return ret;
+}
+
+int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
+ u32 oldval, u32 newval)
+{
+ int ret;
+
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
+ spin_lock(&current->mm->page_table_lock);
+ uaddr = (u32 __force __user *)
+ __dat_user_addr((__force unsigned long) uaddr, 1);
+ if (!uaddr) {
+ spin_unlock(&current->mm->page_table_lock);
+ return -EFAULT;
+ }
+ get_page(virt_to_page(uaddr));
+ spin_unlock(&current->mm->page_table_lock);
+ ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
+ put_page(virt_to_page(uaddr));
+ return ret;
+}
+
+struct uaccess_ops uaccess_pt = {
+ .copy_from_user = copy_from_user_pt,
+ .copy_from_user_small = copy_from_user_pt,
+ .copy_to_user = copy_to_user_pt,
+ .copy_to_user_small = copy_to_user_pt,
+ .copy_in_user = copy_in_user_pt,
+ .clear_user = clear_user_pt,
+ .strnlen_user = strnlen_user_pt,
+ .strncpy_from_user = strncpy_from_user_pt,
+ .futex_atomic_op = futex_atomic_op_pt,
+ .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
+};
generated by cgit v1.3.1 (git 2.54.0) at 2026-08-15 20:43:42 +0000