[S390] Use do_exception() in pagetable walk usercopy functions.

The pagetable walk usercopy functions have used a modified copy of the
do_exception() function for fault handling. This lead to inconsistencies
with recent changes to do_exception(), e.g. performance counters. This
patch changes the pagetable walk usercopy code to call do_exception()
directly, eliminating the redundancy. A new parameter is added to
do_exception() to specify the fault address.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 76 insertions, 96 deletions

diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index 8377e91533d2..cbf0a8745bf4 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -93,6 +93,8 @@ extern struct uaccess_ops uaccess_mvcos;
 extern struct uaccess_ops uaccess_mvcos_switch;
 extern struct uaccess_ops uaccess_pt;
 
+extern int __handle_fault(unsigned long, unsigned long, int);
+
 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 {
         size = uaccess.copy_to_user_small(size, ptr, x);
diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
index cb5d59eab0ee..404f2de296dc 100644
--- a/arch/s390/lib/uaccess_pt.c
+++ b/arch/s390/lib/uaccess_pt.c
@@ -23,86 +23,21 @@ static inline pte_t *follow_table(struct mm_struct *mm, unsigned long addr)
 
         pgd = pgd_offset(mm, addr);
         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
-                return NULL;
+                return (pte_t *) 0x3a;
 
         pud = pud_offset(pgd, addr);
         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
-                return NULL;
+                return (pte_t *) 0x3b;
 
         pmd = pmd_offset(pud, addr);
         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
-                return NULL;
+                return (pte_t *) 0x10;
 
         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 ? FAULT_FLAG_WRITE : 0);
-        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)
+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, pfn, done, size;
@@ -114,12 +49,17 @@ retry:
         spin_lock(&mm->page_table_lock);
         do {
                 pte = follow_table(mm, uaddr);
-                if (!pte || !pte_present(*pte) ||
-                    (write_user && !pte_write(*pte)))
+                if ((unsigned long) pte < 0x1000)
                         goto fault;
+                if (!pte_present(*pte)) {
+                        pte = (pte_t *) 0x11;
+                        goto fault;
+                } else if (write_user && !pte_write(*pte)) {
+                        pte = (pte_t *) 0x04;
+                        goto fault;
+                }
 
                 pfn = pte_pfn(*pte);
-
                 offset = uaddr & (PAGE_SIZE - 1);
                 size = min(n - done, PAGE_SIZE - offset);
                 if (write_user) {
@@ -137,7 +77,7 @@ retry:
         return n - done;
 fault:
         spin_unlock(&mm->page_table_lock);
-        if (__handle_fault(mm, uaddr, write_user))
+        if (__handle_fault(uaddr, (unsigned long) pte, write_user))
                 return n - done;
         goto retry;
 }
@@ -146,30 +86,31 @@ fault:
  * 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)
+static __always_inline unsigned long __dat_user_addr(unsigned long uaddr)
 {
         struct mm_struct *mm = current->mm;
-        unsigned long pfn, ret;
+        unsigned long pfn;
         pte_t *pte;
         int rc;
 
-        ret = 0;
 retry:
         pte = follow_table(mm, uaddr);
-        if (!pte || !pte_present(*pte))
+        if ((unsigned long) pte < 0x1000)
                 goto fault;
+        if (!pte_present(*pte)) {
+                pte = (pte_t *) 0x11;
+                goto fault;
+        }
 
         pfn = pte_pfn(*pte);
-        ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
-out:
-        return ret;
+        return (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
 fault:
         spin_unlock(&mm->page_table_lock);
-        rc = __handle_fault(mm, uaddr, 0);
+        rc = __handle_fault(uaddr, (unsigned long) pte, 0);
         spin_lock(&mm->page_table_lock);
-        if (rc)
-                goto out;
-        goto retry;
+        if (!rc)
+                goto retry;
+        return 0;
 }
 
 size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
@@ -234,8 +175,12 @@ retry:
         spin_lock(&mm->page_table_lock);
         do {
                 pte = follow_table(mm, uaddr);
-                if (!pte || !pte_present(*pte))
+                if ((unsigned long) pte < 0x1000)
+                        goto fault;
+                if (!pte_present(*pte)) {
+                        pte = (pte_t *) 0x11;
                         goto fault;
+                }
 
                 pfn = pte_pfn(*pte);
                 offset = uaddr & (PAGE_SIZE-1);
@@ -249,9 +194,8 @@ retry:
         return done + 1;
 fault:
         spin_unlock(&mm->page_table_lock);
-        if (__handle_fault(mm, uaddr, 0)) {
+        if (__handle_fault(uaddr, (unsigned long) pte, 0))
                 return 0;
-        }
         goto retry;
 }
 
@@ -284,7 +228,7 @@ static size_t copy_in_user_pt(size_t n, void __user *to,
 {
         struct mm_struct *mm = current->mm;
         unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
-                      uaddr, done, size;
+                      uaddr, done, size, error_code;
         unsigned long uaddr_from = (unsigned long) from;
         unsigned long uaddr_to = (unsigned long) to;
         pte_t *pte_from, *pte_to;
@@ -298,17 +242,28 @@ static size_t copy_in_user_pt(size_t n, void __user *to,
 retry:
         spin_lock(&mm->page_table_lock);
         do {
+                write_user = 0;
+                uaddr = uaddr_from;
                 pte_from = follow_table(mm, uaddr_from);
-                if (!pte_from || !pte_present(*pte_from)) {
-                        uaddr = uaddr_from;
-                        write_user = 0;
+                error_code = (unsigned long) pte_from;
+                if (error_code < 0x1000)
+                        goto fault;
+                if (!pte_present(*pte_from)) {
+                        error_code = 0x11;
                         goto fault;
                 }
 
+                write_user = 1;
+                uaddr = uaddr_to;
                 pte_to = follow_table(mm, uaddr_to);
-                if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
-                        uaddr = uaddr_to;
-                        write_user = 1;
+                error_code = (unsigned long) pte_to;
+                if (error_code < 0x1000)
+                        goto fault;
+                if (!pte_present(*pte_to)) {
+                        error_code = 0x11;
+                        goto fault;
+                } else if (!pte_write(*pte_to)) {
+                        error_code = 0x04;
                         goto fault;
                 }
 
@@ -329,7 +284,7 @@ retry:
         return n - done;
 fault:
         spin_unlock(&mm->page_table_lock);
-        if (__handle_fault(mm, uaddr, write_user))
+        if (__handle_fault(uaddr, error_code, write_user))
                 return n - done;
         goto retry;
 }
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 5a9e9a77dc16..fc102e70d9c2 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -442,6 +442,29 @@ no_context:
 }
 #endif
 
+int __handle_fault(unsigned long uaddr, unsigned long int_code, int write_user)
+{
+        struct pt_regs regs;
+        int access, fault;
+
+        regs.psw.mask = psw_kernel_bits;
+        if (!irqs_disabled())
+                regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
+        regs.psw.addr = (unsigned long) __builtin_return_address(0);
+        regs.psw.addr |= PSW_ADDR_AMODE;
+        uaddr &= PAGE_MASK;
+        access = write_user ? VM_WRITE : VM_READ;
+        fault = do_exception(&regs, access, uaddr | 2);
+        if (unlikely(fault)) {
+                if (fault & VM_FAULT_OOM) {
+                        pagefault_out_of_memory();
+                        fault = 0;
+                } else if (fault & VM_FAULT_SIGBUS)
+                        do_sigbus(&regs, int_code, uaddr);
+        }
+        return fault ? -EFAULT : 0;
+}
+
 #ifdef CONFIG_PFAULT 
 /*
  * 'pfault' pseudo page faults routines.