[PATCH v7 06/19] xen/bitops: put __ffs() into linux compatible header

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

The mentioned macros exist only because of Linux compatible purpose.

The patch defines __ffs() in terms of Xen bitops and it is safe
to define in this way ( as __ffs() - 1 ) as considering that __ffs()
was defined as __builtin_ctzl(x), which has undefined behavior when x=0,
so it is assumed that such cases are not encountered in the current code.

To not include <xen/linux-compat.h> to Xen library files __ffs() and __ffz()
were defined locally in find-next-bit.c.

Except __ffs() usage in find-next-bit.c only one usage of __ffs() leave
in smmu-v3.c. It seems that it __ffs can be changed to ffsl(x)-1 in
this file, but to keep smmu-v3.c looks close to linux it was deciced just
to define __ffs() in xen/linux-compat.h and include it in smmu-v3.c

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in V7:
 - introduce ffz(),__ffs() locally in find-next-bit.c
 - drop inclusion of <xen/linux-compat.h> in find-next-bit.c.
 - update the commit message.
---
Changes in V6:
 - new patch for the patch series.
---
 xen/arch/arm/include/asm/arm64/bitops.h | 21 ---------------------
 xen/arch/ppc/include/asm/bitops.h       | 12 ------------
 xen/drivers/passthrough/arm/smmu-v3.c   |  2 ++
 xen/include/xen/linux-compat.h          |  2 ++
 xen/lib/find-next-bit.c                 |  3 +++
 5 files changed, 7 insertions(+), 33 deletions(-)

diff --git a/xen/arch/arm/include/asm/arm64/bitops.h 
b/xen/arch/arm/include/asm/arm64/bitops.h
index 5f5d97faa0..2deb134388 100644
--- a/xen/arch/arm/include/asm/arm64/bitops.h
+++ b/xen/arch/arm/include/asm/arm64/bitops.h
@@ -1,27 +1,6 @@
 #ifndef _ARM_ARM64_BITOPS_H
 #define _ARM_ARM64_BITOPS_H
 
-/* Based on linux/include/asm-generic/bitops/builtin-__ffs.h */
-/**
- * __ffs - find first bit in word.
- * @word: The word to search
- *
- * Undefined if no bit exists, so code should check against 0 first.
- */
-static /*__*/always_inline unsigned long __ffs(unsigned long word)
-{
-        return __builtin_ctzl(word);
-}
-
-/* Based on linux/include/asm-generic/bitops/ffz.h */
-/*
- * ffz - find first zero in word.
- * @word: The word to search
- *
- * Undefined if no zero exists, so code should check against ~0UL first.
- */
-#define ffz(x)  __ffs(~(x))
-
 static inline int arch_flsl(unsigned long x)
 {
         uint64_t ret;
diff --git a/xen/arch/ppc/include/asm/bitops.h 
b/xen/arch/ppc/include/asm/bitops.h
index a17060c7c2..2237b9f8f4 100644
--- a/xen/arch/ppc/include/asm/bitops.h
+++ b/xen/arch/ppc/include/asm/bitops.h
@@ -130,16 +130,4 @@ static inline int test_and_set_bit(unsigned int nr, 
volatile void *addr)
 #define hweight16(x) __builtin_popcount((uint16_t)(x))
 #define hweight8(x)  __builtin_popcount((uint8_t)(x))
 
-/* Based on linux/include/asm-generic/bitops/builtin-__ffs.h */
-/**
- * __ffs - find first bit in word.
- * @word: The word to search
- *
- * Undefined if no bit exists, so code should check against 0 first.
- */
-static always_inline unsigned long __ffs(unsigned long word)
-{
-    return __builtin_ctzl(word);
-}
-
 #endif /* _ASM_PPC_BITOPS_H */
diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
b/xen/drivers/passthrough/arm/smmu-v3.c
index b1c40c2c0a..6904962467 100644
--- a/xen/drivers/passthrough/arm/smmu-v3.c
+++ b/xen/drivers/passthrough/arm/smmu-v3.c
@@ -72,12 +72,14 @@
  */
 
 #include <xen/acpi.h>
+#include <xen/bitops.h>
 #include <xen/config.h>
 #include <xen/delay.h>
 #include <xen/errno.h>
 #include <xen/err.h>
 #include <xen/irq.h>
 #include <xen/lib.h>
+#include <xen/linux-compat.h>
 #include <xen/list.h>
 #include <xen/mm.h>
 #include <xen/rbtree.h>
diff --git a/xen/include/xen/linux-compat.h b/xen/include/xen/linux-compat.h
index 62ba71485c..10db80df57 100644
--- a/xen/include/xen/linux-compat.h
+++ b/xen/include/xen/linux-compat.h
@@ -19,4 +19,6 @@ typedef int64_t __s64;
 
 typedef paddr_t phys_addr_t;
 
+#define __ffs(x) (ffsl(x) - 1)
+
 #endif /* __XEN_LINUX_COMPAT_H__ */
diff --git a/xen/lib/find-next-bit.c b/xen/lib/find-next-bit.c
index ca6f82277e..761b027398 100644
--- a/xen/lib/find-next-bit.c
+++ b/xen/lib/find-next-bit.c
@@ -12,6 +12,9 @@
 
 #include <asm/byteorder.h>
 
+#define __ffs(x) (ffsl(x) - 1)
+#define ffz(x) __ffs(~(x))
+
 #ifndef find_next_bit
 /*
  * Find the next set bit in a memory region.
-- 
2.43.0