| /* |
| * arch/s390/lib/uaccess_pt.c |
| * |
| * User access functions based on page table walks for enhanced |
| * system layout without hardware support. |
| * |
| * Copyright IBM Corp. 2006 |
| * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com) |
| */ |
| |
| #include <linux/errno.h> |
| #include <linux/hardirq.h> |
| #include <linux/mm.h> |
| #include <asm/uaccess.h> |
| #include <asm/futex.h> |
| #include "uaccess.h" |
| |
| static inline pte_t *follow_table(struct mm_struct *mm, unsigned long addr) |
| { |
| pgd_t *pgd; |
| pud_t *pud; |
| pmd_t *pmd; |
| |
| pgd = pgd_offset(mm, addr); |
| if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) |
| return NULL; |
| |
| pud = pud_offset(pgd, addr); |
| if (pud_none(*pud) || unlikely(pud_bad(*pud))) |
| return NULL; |
| |
| pmd = pmd_offset(pud, addr); |
| if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) |
| return NULL; |
| |
| return pte_offset_map(pmd, addr); |
| } |
| |
| static int __handle_fault(struct mm_struct *mm, unsigned long address, |
| int write_access) |
| { |
| struct vm_area_struct *vma; |
| int ret = -EFAULT; |
| int fault; |
| |
| if (in_atomic()) |
| return ret; |
| down_read(&mm->mmap_sem); |
| vma = find_vma(mm, address); |
| if (unlikely(!vma)) |
| goto out; |
| if (unlikely(vma->vm_start > address)) { |
| if (!(vma->vm_flags & VM_GROWSDOWN)) |
| goto out; |
| if (expand_stack(vma, address)) |
| goto out; |
| } |
| |
| if (!write_access) { |
| /* page not present, check vm flags */ |
| if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
| goto out; |
| } else { |
| if (!(vma->vm_flags & VM_WRITE)) |
| goto out; |
| } |
| |
| survive: |
| fault = handle_mm_fault(mm, vma, address, write_access); |
| if (unlikely(fault & VM_FAULT_ERROR)) { |
| if (fault & VM_FAULT_OOM) |
| goto out_of_memory; |
| else if (fault & VM_FAULT_SIGBUS) |
| goto out_sigbus; |
| BUG(); |
| } |
| if (fault & VM_FAULT_MAJOR) |
| current->maj_flt++; |
| else |
| current->min_flt++; |
| ret = 0; |
| out: |
| up_read(&mm->mmap_sem); |
| return ret; |
| |
| out_of_memory: |
| up_read(&mm->mmap_sem); |
| if (is_global_init(current)) { |
| yield(); |
| down_read(&mm->mmap_sem); |
| goto survive; |
| } |
| printk("VM: killing process %s\n", current->comm); |
| return ret; |
| |
| out_sigbus: |
| up_read(&mm->mmap_sem); |
| current->thread.prot_addr = address; |
| current->thread.trap_no = 0x11; |
| force_sig(SIGBUS, current); |
| return ret; |
| } |
| |
| static 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, pfn, done, size; |
| pte_t *pte; |
| void *from, *to; |
| |
| done = 0; |
| retry: |
| spin_lock(&mm->page_table_lock); |
| do { |
| pte = follow_table(mm, uaddr); |
| if (!pte || !pte_present(*pte) || |
| (write_user && !pte_write(*pte))) |
| goto fault; |
| |
| pfn = pte_pfn(*pte); |
| if (!pfn_valid(pfn)) |
| goto out; |
| |
| offset = uaddr & (PAGE_SIZE - 1); |
| size = min(n - done, PAGE_SIZE - offset); |
| if (write_user) { |
| to = (void *)((pfn << PAGE_SHIFT) + offset); |
| from = kptr + done; |
| } else { |
| from = (void *)((pfn << PAGE_SHIFT) + offset); |
| to = kptr + done; |
| } |
| memcpy(to, from, size); |
| done += size; |
| uaddr += size; |
| } while (done < n); |
| out: |
| spin_unlock(&mm->page_table_lock); |
| return n - done; |
| fault: |
| spin_unlock(&mm->page_table_lock); |
| if (__handle_fault(mm, uaddr, 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 unsigned long __dat_user_addr(unsigned long uaddr) |
| { |
| struct mm_struct *mm = current->mm; |
| unsigned long pfn, ret; |
| pte_t *pte; |
| int rc; |
| |
| ret = 0; |
| retry: |
| pte = follow_table(mm, uaddr); |
| if (!pte || !pte_present(*pte)) |
| goto fault; |
| |
| pfn = pte_pfn(*pte); |
| if (!pfn_valid(pfn)) |
| goto out; |
| |
| ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1)); |
| out: |
| return ret; |
| fault: |
| spin_unlock(&mm->page_table_lock); |
| rc = __handle_fault(mm, uaddr, 0); |
| spin_lock(&mm->page_table_lock); |
| if (rc) |
| goto out; |
| goto retry; |
| } |
| |
| 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)) { |
| memcpy(to, (void __kernel __force *) from, n); |
| return 0; |
| } |
| 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)) { |
| memcpy((void __kernel __force *) to, from, n); |
| return 0; |
| } |
| return __user_copy_pt((unsigned long) to, (void *) from, n, 1); |
| } |
| |
| static size_t clear_user_pt(size_t n, void __user *to) |
| { |
| long done, size, ret; |
| |
| if (segment_eq(get_fs(), KERNEL_DS)) { |
| memset((void __kernel __force *) to, 0, n); |
| return 0; |
| } |
| done = 0; |
| do { |
| if (n - done > PAGE_SIZE) |
| size = PAGE_SIZE; |
| else |
| size = n - done; |
| ret = __user_copy_pt((unsigned long) to + done, |
| &empty_zero_page, size, 1); |
| done += 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) |
| { |
| char *addr; |
| unsigned long uaddr = (unsigned long) src; |
| struct mm_struct *mm = current->mm; |
| unsigned long offset, pfn, done, len; |
| pte_t *pte; |
| size_t len_str; |
| |
| if (segment_eq(get_fs(), KERNEL_DS)) |
| return strnlen((const char __kernel __force *) src, count) + 1; |
| done = 0; |
| retry: |
| spin_lock(&mm->page_table_lock); |
| do { |
| pte = follow_table(mm, uaddr); |
| if (!pte || !pte_present(*pte)) |
| goto fault; |
| |
| pfn = pte_pfn(*pte); |
| if (!pfn_valid(pfn)) { |
| done = -1; |
| goto out; |
| } |
| |
| offset = uaddr & (PAGE_SIZE-1); |
| addr = (char *)(pfn << PAGE_SHIFT) + offset; |
| len = min(count - done, PAGE_SIZE - offset); |
| len_str = strnlen(addr, len); |
| done += len_str; |
| uaddr += len_str; |
| } while ((len_str == len) && (done < count)); |
| out: |
| spin_unlock(&mm->page_table_lock); |
| return done + 1; |
| fault: |
| spin_unlock(&mm->page_table_lock); |
| if (__handle_fault(mm, uaddr, 0)) { |
| return 0; |
| } |
| goto retry; |
| } |
| |
| static size_t strncpy_from_user_pt(size_t count, const char __user *src, |
| char *dst) |
| { |
| size_t n = strnlen_user_pt(count, src); |
| |
| if (!n) |
| return -EFAULT; |
| if (n > count) |
| n = count; |
| if (segment_eq(get_fs(), KERNEL_DS)) { |
| memcpy(dst, (const char __kernel __force *) src, n); |
| if (dst[n-1] == '\0') |
| return n-1; |
| else |
| return n; |
| } |
| if (__user_copy_pt((unsigned long) src, dst, n, 0)) |
| return -EFAULT; |
| if (dst[n-1] == '\0') |
| return n-1; |
| else |
| return n; |
| } |
| |
| 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_from, offset_to, offset_max, pfn_from, pfn_to, |
| uaddr, done, size; |
| unsigned long uaddr_from = (unsigned long) from; |
| unsigned long uaddr_to = (unsigned long) to; |
| pte_t *pte_from, *pte_to; |
| int write_user; |
| |
| done = 0; |
| retry: |
| spin_lock(&mm->page_table_lock); |
| do { |
| pte_from = follow_table(mm, uaddr_from); |
| if (!pte_from || !pte_present(*pte_from)) { |
| uaddr = uaddr_from; |
| write_user = 0; |
| goto fault; |
| } |
| |
| pte_to = follow_table(mm, uaddr_to); |
| if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) { |
| uaddr = uaddr_to; |
| write_user = 1; |
| goto fault; |
| } |
| |
| pfn_from = pte_pfn(*pte_from); |
| if (!pfn_valid(pfn_from)) |
| goto out; |
| pfn_to = pte_pfn(*pte_to); |
| if (!pfn_valid(pfn_to)) |
| goto out; |
| |
| offset_from = uaddr_from & (PAGE_SIZE-1); |
| offset_to = uaddr_from & (PAGE_SIZE-1); |
| offset_max = max(offset_from, offset_to); |
| size = min(n - done, PAGE_SIZE - offset_max); |
| |
| memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to, |
| (void *)(pfn_from << PAGE_SHIFT) + offset_from, size); |
| done += size; |
| uaddr_from += size; |
| uaddr_to += size; |
| } while (done < n); |
| out: |
| spin_unlock(&mm->page_table_lock); |
| return n - done; |
| fault: |
| spin_unlock(&mm->page_table_lock); |
| if (__handle_fault(mm, uaddr, 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" ); |
| |
| int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old) |
| { |
| int oldval = 0, newval, ret; |
| |
| spin_lock(¤t->mm->page_table_lock); |
| uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr); |
| if (!uaddr) { |
| spin_unlock(¤t->mm->page_table_lock); |
| return -EFAULT; |
| } |
| get_page(virt_to_page(uaddr)); |
| spin_unlock(¤t->mm->page_table_lock); |
| 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; |
| } |
| put_page(virt_to_page(uaddr)); |
| *old = oldval; |
| return ret; |
| } |
| |
| int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval) |
| { |
| int ret; |
| |
| if (!current->mm) |
| return -EFAULT; |
| spin_lock(¤t->mm->page_table_lock); |
| uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr); |
| if (!uaddr) { |
| spin_unlock(¤t->mm->page_table_lock); |
| return -EFAULT; |
| } |
| get_page(virt_to_page(uaddr)); |
| spin_unlock(¤t->mm->page_table_lock); |
| asm volatile(" cs %1,%4,0(%5)\n" |
| "0: lr %0,%1\n" |
| "1:\n" |
| EX_TABLE(0b,1b) |
| : "=d" (ret), "+d" (oldval), "=m" (*uaddr) |
| : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr) |
| : "cc", "memory" ); |
| 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, |
| }; |