Commit bd0d63f8 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Michael Ellerman

powerpc/mm: Move page fault VMA access checks to a helper

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent d2e0d2c5
......@@ -222,6 +222,37 @@ static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
return is_exec || (address >= TASK_SIZE);
}
static bool access_error(bool is_write, bool is_exec,
struct vm_area_struct *vma)
{
/*
* Allow execution from readable areas if the MMU does not
* provide separate controls over reading and executing.
*
* Note: That code used to not be enabled for 4xx/BookE.
* It is now as I/D cache coherency for these is done at
* set_pte_at() time and I see no reason why the test
* below wouldn't be valid on those processors. This -may-
* break programs compiled with a really old ABI though.
*/
if (is_exec) {
return !(vma->vm_flags & VM_EXEC) &&
(cpu_has_feature(CPU_FTR_NOEXECUTE) ||
!(vma->vm_flags & (VM_READ | VM_WRITE)));
}
if (is_write) {
if (unlikely(!(vma->vm_flags & VM_WRITE)))
return true;
return false;
}
if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
return true;
return false;
}
#ifdef CONFIG_PPC_SMLPAR
static inline void cmo_account_page_fault(void)
{
......@@ -461,30 +492,8 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
return bad_area(regs, address);
good_area:
if (is_exec) {
/*
* Allow execution from readable areas if the MMU does not
* provide separate controls over reading and executing.
*
* Note: That code used to not be enabled for 4xx/BookE.
* It is now as I/D cache coherency for these is done at
* set_pte_at() time and I see no reason why the test
* below wouldn't be valid on those processors. This -may-
* break programs compiled with a really old ABI though.
*/
if (unlikely(!(vma->vm_flags & VM_EXEC) &&
(cpu_has_feature(CPU_FTR_NOEXECUTE) ||
!(vma->vm_flags & (VM_READ | VM_WRITE)))))
return bad_area(regs, address);
/* a write */
} else if (is_write) {
if (unlikely(!(vma->vm_flags & VM_WRITE)))
return bad_area(regs, address);
/* a read */
} else {
if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
return bad_area(regs, address);
}
if (unlikely(access_error(is_write, is_exec, vma)))
return bad_area(regs, address);
/*
* If for any reason at all we couldn't handle the fault,
......
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