nommu fixups

nommu fixups

[Christoph Hellwig]

Hi Andrew,

the patches are fixups developed for the RISC-V nommu port.  Can you
queue them up in -mm?

[PATCH 1/3] mm: fix the MAP_UNINITIALIZED flag

[Christoph Hellwig]

We can't expose UAPI symbols differently based on CONFIG_ symbols, as
userspace won't have them available.  Instead always define the flag,
but only respect it based on the config option.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 arch/xtensa/include/uapi/asm/mman.h    | 6 +-----
 include/uapi/asm-generic/mman-common.h | 8 +++-----
 mm/nommu.c                             | 4 +++-
 3 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
index be726062412b..ebbb48842190 100644
--- a/arch/xtensa/include/uapi/asm/mman.h
+++ b/arch/xtensa/include/uapi/asm/mman.h
@@ -56,12 +56,8 @@
 #define MAP_STACK	0x40000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x80000		/* create a huge page mapping */
 #define MAP_FIXED_NOREPLACE 0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */
-#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED
-# define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
+#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
 					 * uninitialized */
-#else
-# define MAP_UNINITIALIZED 0x0		/* Don't support this flag */
-#endif
 
 /*
  * Flags for msync
diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
index abd238d0f7a4..cb556b430e71 100644
--- a/include/uapi/asm-generic/mman-common.h
+++ b/include/uapi/asm-generic/mman-common.h
@@ -19,15 +19,13 @@
 #define MAP_TYPE	0x0f		/* Mask for type of mapping */
 #define MAP_FIXED	0x10		/* Interpret addr exactly */
 #define MAP_ANONYMOUS	0x20		/* don't use a file */
-#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED
-# define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be uninitialized */
-#else
-# define MAP_UNINITIALIZED 0x0		/* Don't support this flag */
-#endif
 
 /* 0x0100 - 0x80000 flags are defined in asm-generic/mman.h */
 #define MAP_FIXED_NOREPLACE	0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */
 
+#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be
+					 * uninitialized */
+
 /*
  * Flags for mlock
  */
diff --git a/mm/nommu.c b/mm/nommu.c
index d8c02fbe03b5..ec75a0dffd4f 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1349,7 +1349,9 @@ unsigned long do_mmap(struct file *file,
 	add_nommu_region(region);
 
 	/* clear anonymous mappings that don't ask for uninitialized data */
-	if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
+	if (!vma->vm_file &&
+	    (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) ||
+	     !(flags & MAP_UNINITIALIZED)))
 		memset((void *)region->vm_start, 0,
 		       region->vm_end - region->vm_start);
 
-- 
2.20.1

[PATCH 2/3] mm: provide a print_vma_addr stub for !CONFIG_MMU

[Christoph Hellwig]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 include/linux/mm.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dd0b5f4e1e45..69843ee0c5f8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2756,7 +2756,13 @@ extern int randomize_va_space;
 #endif
 
 const char * arch_vma_name(struct vm_area_struct *vma);
+#ifdef CONFIG_MMU
 void print_vma_addr(char *prefix, unsigned long rip);
+#else
+static inline void print_vma_addr(char *prefix, unsigned long rip)
+{
+}
+#endif
 
 void *sparse_buffer_alloc(unsigned long size);
 struct page *sparse_mem_map_populate(unsigned long pnum, int nid,
-- 
2.20.1

[PATCH 3/3] mm: stub out all of swapops.h for !CONFIG_MMU

[Christoph Hellwig]

The whole header file deals with swap entries and PTEs, none of which
can exist for nommu builds.  The current nommu ports have lots of
stubs to allow the inline functions in swapops.h to compile, but
as none of this functionality is actually used there is no point
in even providing it.  This way we don't have to provide the stubs
for the upcoming RISC-V nommu port, and can eventually remove it
from the existing ports.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/swapops.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 4d961668e5fc..b02922556846 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -6,6 +6,8 @@
 #include <linux/bug.h>
 #include <linux/mm_types.h>
 
+#ifdef CONFIG_MMU
+
 /*
  * swapcache pages are stored in the swapper_space radix tree.  We want to
  * get good packing density in that tree, so the index should be dense in
@@ -50,13 +52,11 @@ static inline pgoff_t swp_offset(swp_entry_t entry)
 	return entry.val & SWP_OFFSET_MASK;
 }
 
-#ifdef CONFIG_MMU
 /* check whether a pte points to a swap entry */
 static inline int is_swap_pte(pte_t pte)
 {
 	return !pte_none(pte) && !pte_present(pte);
 }
-#endif
 
 /*
  * Convert the arch-dependent pte representation of a swp_entry_t into an
@@ -375,4 +375,5 @@ static inline int non_swap_entry(swp_entry_t entry)
 }
 #endif
 
+#endif /* CONFIG_MMU */
 #endif /* _LINUX_SWAPOPS_H */
-- 
2.20.1