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[S390] Use do_exception() in pagetable walk usercopy functions.
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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 <[email protected]>
Signed-off-by: Martin Schwidefsky <[email protected]>
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@gerald-schaefer
gerald-schaefer authored and Martin Schwidefsky committed Dec 7, 2009
1 parent 1ab947d commit 6c1e3e7
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Showing 3 changed files with 76 additions and 96 deletions.
2 changes: 2 additions & 0 deletions arch/s390/include/asm/uaccess.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down
147 changes: 51 additions & 96 deletions arch/s390/lib/uaccess_pt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -114,12 +49,17 @@ static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
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) {
Expand All @@ -137,7 +77,7 @@ static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
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;
}
Expand All @@ -146,30 +86,31 @@ static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
* 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)
Expand Down Expand Up @@ -234,8 +175,12 @@ static size_t strnlen_user_pt(size_t count, const char __user *src)
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);
Expand All @@ -249,9 +194,8 @@ static size_t strnlen_user_pt(size_t count, const char __user *src)
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;
}

Expand Down Expand Up @@ -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;
Expand All @@ -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;
}

Expand All @@ -329,7 +284,7 @@ static size_t copy_in_user_pt(size_t n, void __user *to,
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;
}
Expand Down
23 changes: 23 additions & 0 deletions arch/s390/mm/fault.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -442,6 +442,29 @@ void __kprobes do_asce_exception(struct pt_regs *regs, long int_code)
}
#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.
Expand Down

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