[RFC PATCH v8 08/14] arm64/mm: disable section/contiguous mappings if XPFO is enabled

[Khalid Aziz <khalid.aziz@oracle.com>]

From: Tycho Andersen <tycho@docker.com>

XPFO doesn't support section/contiguous mappings yet, so let's disable it
if XPFO is turned on.

Thanks to Laura Abbot for the simplification from v5, and Mark Rutland for
pointing out we need NO_CONT_MAPPINGS too.

CC: linux-arm-kernel@lists.infradead.org
Signed-off-by: Tycho Andersen <tycho@docker.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
---
 arch/arm64/mm/mmu.c  | 2 +-
 include/linux/xpfo.h | 4 ++++
 mm/xpfo.c            | 6 ++++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index d1d6601b385d..f4dd27073006 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -451,7 +451,7 @@ static void __init map_mem(pgd_t *pgdp)
 	struct memblock_region *reg;
 	int flags = 0;
 
-	if (debug_pagealloc_enabled())
+	if (debug_pagealloc_enabled() || xpfo_enabled())
 		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	/*
diff --git a/include/linux/xpfo.h b/include/linux/xpfo.h
index 1ae05756344d..8b029918a958 100644
--- a/include/linux/xpfo.h
+++ b/include/linux/xpfo.h
@@ -47,6 +47,8 @@ void xpfo_temp_map(const void *addr, size_t size, void **mapping,
 void xpfo_temp_unmap(const void *addr, size_t size, void **mapping,
 		     size_t mapping_len);
 
+bool xpfo_enabled(void);
+
 #else /* !CONFIG_XPFO */
 
 static inline void xpfo_kmap(void *kaddr, struct page *page) { }
@@ -69,6 +71,8 @@ static inline void xpfo_temp_unmap(const void *addr, size_t size,
 }
 
 
+static inline bool xpfo_enabled(void) { return false; }
+
 #endif /* CONFIG_XPFO */
 
 #endif /* _LINUX_XPFO_H */
diff --git a/mm/xpfo.c b/mm/xpfo.c
index 92ca6d1baf06..150784ae0f08 100644
--- a/mm/xpfo.c
+++ b/mm/xpfo.c
@@ -71,6 +71,12 @@ struct page_ext_operations page_xpfo_ops = {
 	.init = init_xpfo,
 };
 
+bool __init xpfo_enabled(void)
+{
+	return !xpfo_disabled;
+}
+EXPORT_SYMBOL(xpfo_enabled);
+
 static inline struct xpfo *lookup_xpfo(struct page *page)
 {
 	struct page_ext *page_ext = lookup_page_ext(page);
-- 
2.17.1