[PATCH 1/2] ARM: mmu: have zero_page_remappable() check MMU status

[Ahmad Fatoum]

zero_page_access() and zero_page_faulting() call remap_range(), which
assumes the TTBR was initialized to page tables set up by barebox.

It's thus not safe to call them from generic code prior to enabling the
MMU, but we are doing just that. In preparation for fixing, let's make
zero_page_remappable reflect MMU status.

While at it, also drop the duplicate zero_page_access() prototype.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/arm/cpu/mmu-common.c |  5 +++++
 include/zero_page.h       | 12 ++++++------
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/arm/cpu/mmu-common.c b/arch/arm/cpu/mmu-common.c
index 033ba01ea4c8..92e06b06077f 100644
--- a/arch/arm/cpu/mmu-common.c
+++ b/arch/arm/cpu/mmu-common.c
@@ -81,6 +81,11 @@ void *dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *dma_ha
 	return dma_alloc_map(dev, size, dma_handle, MAP_WRITECOMBINE);
 }
 
+bool zero_page_remappable(void)
+{
+	return get_cr() & CR_M;
+}
+
 void zero_page_access(void)
 {
 	remap_range(0x0, PAGE_SIZE, MAP_CACHED);
diff --git a/include/zero_page.h b/include/zero_page.h
index 8dd66a1efb9b..072e71be581e 100644
--- a/include/zero_page.h
+++ b/include/zero_page.h
@@ -20,12 +20,12 @@ void zero_page_faulting(void);
  */
 void zero_page_access(void);
 
-void zero_page_access(void);
-
-static inline bool zero_page_remappable(void)
-{
-	return true;
-}
+/**
+ * zero_page_remappable() - check if zero page can be remapped
+ *
+ * Check if MMU is enabled and zero page remapping support is available.
+ */
+bool zero_page_remappable(void);
 
 #else
 
-- 
2.47.3