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-rw-r--r--arch/powerpc/mm/pgtable.c167
1 files changed, 116 insertions, 51 deletions
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index b6b32487e74..83f1551ec2c 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -128,28 +128,6 @@ void pte_free_finish(void)
#endif /* CONFIG_SMP */
-/*
- * Handle i/d cache flushing, called from set_pte_at() or ptep_set_access_flags()
- */
-static pte_t do_dcache_icache_coherency(pte_t pte)
-{
- unsigned long pfn = pte_pfn(pte);
- struct page *page;
-
- if (unlikely(!pfn_valid(pfn)))
- return pte;
- page = pfn_to_page(pfn);
-
- if (!PageReserved(page) && !test_bit(PG_arch_1, &page->flags)) {
- pr_devel("do_dcache_icache_coherency... flushing\n");
- flush_dcache_icache_page(page);
- set_bit(PG_arch_1, &page->flags);
- }
- else
- pr_devel("do_dcache_icache_coherency... already clean\n");
- return __pte(pte_val(pte) | _PAGE_HWEXEC);
-}
-
static inline int is_exec_fault(void)
{
return current->thread.regs && TRAP(current->thread.regs) == 0x400;
@@ -157,49 +135,139 @@ static inline int is_exec_fault(void)
/* We only try to do i/d cache coherency on stuff that looks like
* reasonably "normal" PTEs. We currently require a PTE to be present
- * and we avoid _PAGE_SPECIAL and _PAGE_NO_CACHE
+ * and we avoid _PAGE_SPECIAL and _PAGE_NO_CACHE. We also only do that
+ * on userspace PTEs
*/
static inline int pte_looks_normal(pte_t pte)
{
return (pte_val(pte) &
- (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE)) ==
- (_PAGE_PRESENT);
+ (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE | _PAGE_USER)) ==
+ (_PAGE_PRESENT | _PAGE_USER);
}
-#if defined(CONFIG_PPC_STD_MMU)
+struct page * maybe_pte_to_page(pte_t pte)
+{
+ unsigned long pfn = pte_pfn(pte);
+ struct page *page;
+
+ if (unlikely(!pfn_valid(pfn)))
+ return NULL;
+ page = pfn_to_page(pfn);
+ if (PageReserved(page))
+ return NULL;
+ return page;
+}
+
+#if defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0
+
/* Server-style MMU handles coherency when hashing if HW exec permission
- * is supposed per page (currently 64-bit only). Else, we always flush
- * valid PTEs in set_pte.
+ * is supposed per page (currently 64-bit only). If not, then, we always
+ * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
+ * support falls into the same category.
*/
-static inline int pte_need_exec_flush(pte_t pte, int set_pte)
+
+static pte_t set_pte_filter(pte_t pte)
{
- return set_pte && pte_looks_normal(pte) &&
- !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
- cpu_has_feature(CPU_FTR_NOEXECUTE));
+ pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
+ if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
+ cpu_has_feature(CPU_FTR_NOEXECUTE))) {
+ struct page *pg = maybe_pte_to_page(pte);
+ if (!pg)
+ return pte;
+ if (!test_bit(PG_arch_1, &pg->flags)) {
+ flush_dcache_icache_page(pg);
+ set_bit(PG_arch_1, &pg->flags);
+ }
+ }
+ return pte;
}
-#elif _PAGE_HWEXEC == 0
-/* Embedded type MMU without HW exec support (8xx only so far), we flush
- * the cache for any present PTE
- */
-static inline int pte_need_exec_flush(pte_t pte, int set_pte)
+
+static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
+ int dirty)
{
- return set_pte && pte_looks_normal(pte);
+ return pte;
}
-#else
-/* Other embedded CPUs with HW exec support per-page, we flush on exec
- * fault if HWEXEC is not set
+
+#else /* defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0 */
+
+/* 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 inline int pte_need_exec_flush(pte_t pte, int set_pte)
+static pte_t set_pte_filter(pte_t pte)
{
- return pte_looks_normal(pte) && is_exec_fault() &&
- !(pte_val(pte) & _PAGE_HWEXEC);
+ 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);
}
-#endif
+
+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);
+}
+
+#endif /* !(defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0) */
/*
* set_pte stores a linux PTE into the linux page table.
*/
-void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)
+void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+ pte_t pte)
{
#ifdef CONFIG_DEBUG_VM
WARN_ON(pte_present(*ptep));
@@ -208,9 +276,7 @@ void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte
* this context might not have been activated yet when this
* is called.
*/
- pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
- if (pte_need_exec_flush(pte, 1))
- pte = do_dcache_icache_coherency(pte);
+ pte = set_pte_filter(pte);
/* Perform the setting of the PTE */
__set_pte_at(mm, addr, ptep, pte, 0);
@@ -227,8 +293,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
pte_t *ptep, pte_t entry, int dirty)
{
int changed;
- if (!dirty && pte_need_exec_flush(entry, 0))
- entry = do_dcache_icache_coherency(entry);
+ entry = set_access_flags_filter(entry, vma, dirty);
changed = !pte_same(*(ptep), entry);
if (changed) {
if (!(vma->vm_flags & VM_HUGETLB))
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-18 12:42:19 +0000