/* Embedded type MMU with HW exec support. This is a bit more complicated
* as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
* instead we "filter out" the exec permission for non clean pages.
*/
static pte_t set_pte_filter(pte_t pte)
{
struct page *pg;
/* No exec permission in the first place, move on */
if (!(pte_val(pte) & _PAGE_EXEC) || !pte_looks_normal(pte))
return pte;
/* If you set _PAGE_EXEC on weird pages you're on your own */
pg = maybe_pte_to_page(pte);
if (unlikely(!pg))
return pte;
/* If the page clean, we move on */
if (test_bit(PG_arch_1, &pg->flags))
return pte;
/* If it's an exec fault, we flush the cache and make it clean */
if (is_exec_fault()) {
flush_dcache_icache_page(pg);
set_bit(PG_arch_1, &pg->flags);
return pte;
}
/* Else, we filter out _PAGE_EXEC */
return __pte(pte_val(pte) & ~_PAGE_EXEC);
}
static pte_t set_pte_filter(pte_t pte, unsigned long addr)
{
struct page *pg;
if (!(pte_val(pte) & _PAGE_EXEC) || !pte_looks_normal(pte))
return pte;
pg = maybe_pte_to_page(pte);
if (unlikely(!pg))
return pte;
if (test_bit(PG_arch_1, &pg->flags))
return pte;
if (is_exec_fault()) {
flush_dcache_icache_page(pg);
set_bit(PG_arch_1, &pg->flags);
return pte;
}
return __pte(pte_val(pte) & ~_PAGE_EXEC);
}
static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
int dirty)
{
struct page *pg;
if (dirty || (pte_val(pte) & _PAGE_EXEC) || !is_exec_fault())
return pte;
#ifdef CONFIG_DEBUG_VM
if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
return pte;
#endif
pg = maybe_pte_to_page(pte);
if (unlikely(!pg))
goto bail;
if (test_bit(PG_arch_1, &pg->flags))
goto bail;
flush_dcache_icache_page(pg);
set_bit(PG_arch_1, &pg->flags);
bail:
return __pte(pte_val(pte) | _PAGE_EXEC);
}
static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
int dirty)
{
struct page *pg;
/* So here, we only care about exec faults, as we use them
* to recover lost _PAGE_EXEC and perform I$/D$ coherency
* if necessary. Also if _PAGE_EXEC is already set, same deal,
* we just bail out
*/
if (dirty || (pte_val(pte) & _PAGE_EXEC) || !is_exec_fault())
return pte;
#ifdef CONFIG_DEBUG_VM
/* So this is an exec fault, _PAGE_EXEC is not set. If it was
* an error we would have bailed out earlier in do_page_fault()
* but let's make sure of it
*/
if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
return pte;
#endif /* CONFIG_DEBUG_VM */
/* If you set _PAGE_EXEC on weird pages you're on your own */
pg = maybe_pte_to_page(pte);
if (unlikely(!pg))
goto bail;
/* If the page is already clean, we move on */
if (test_bit(PG_arch_1, &pg->flags))
goto bail;
/* Clean the page and set PG_arch_1 */
flush_dcache_icache_page(pg);
set_bit(PG_arch_1, &pg->flags);
bail:
return __pte(pte_val(pte) | _PAGE_EXEC);
}
/* Other embedded CPUs with HW exec support per-page, we flush on exec
* fault if HWEXEC is not set
*/
static inline int pte_need_exec_flush(pte_t pte, int set_pte)
{
return pte_looks_normal(pte) && is_exec_fault() &&
!(pte_val(pte) & _PAGE_HWEXEC);
}