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authorChen Gang <xili_gchen_5257@hotmail.com>2016-01-14 15:18:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-14 16:00:49 -0800
commit8f235d1a3eb7198affe7cadf676a10afb8a46a1a (patch)
tree78f5ec435417423e50a3a3d59a0af8abbf5cd15c /include/linux/pfn.h
parent3aa2385111168187f24a6db04697c6fab0fab9b4 (diff)
mm: add PHYS_PFN, use it in __phys_to_pfn()
__phys_to_pfn and __pfn_to_phys are symmetric, PHYS_PFN and PFN_PHYS are semmetric: - y = (phys_addr_t)x << PAGE_SHIFT - y >> PAGE_SHIFT = (phys_add_t)x - (unsigned long)(y >> PAGE_SHIFT) = x [akpm@linux-foundation.org: use macro arg name `x'] [arnd@arndb.de: include linux/pfn.h for PHYS_PFN definition] Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/pfn.h')
-rw-r--r--include/linux/pfn.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/pfn.h b/include/linux/pfn.h
index 7646637221f3..97f3e88aead4 100644
--- a/include/linux/pfn.h
+++ b/include/linux/pfn.h
@@ -9,5 +9,6 @@
#define PFN_UP(x) (((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
#define PFN_DOWN(x) ((x) >> PAGE_SHIFT)
#define PFN_PHYS(x) ((phys_addr_t)(x) << PAGE_SHIFT)
+#define PHYS_PFN(x) ((unsigned long)((x) >> PAGE_SHIFT))
#endif