[PATCH 3/7] xen/bitops: Implement ffsl() in common logic

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Exactly as per ffs() in the previous patch.  Express the upper bound of the
testing in terms of BITS_PER_LONG as it varies between architectures.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
CC: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
CC: consulting@xxxxxxxxxxx <consulting@xxxxxxxxxxx>
CC: Simone Ballarin <simone.ballarin@xxxxxxxxxxx>
CC: Federico Serafini <federico.serafini@xxxxxxxxxxx>
CC: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
---
 xen/arch/arm/include/asm/bitops.h |  2 +-
 xen/arch/ppc/include/asm/bitops.h |  1 -
 xen/arch/x86/include/asm/bitops.h | 30 +++++++++++++-----------------
 xen/common/bitops.c               |  7 +++++++
 xen/include/xen/bitops.h          | 12 ++++++++++++
 5 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/xen/arch/arm/include/asm/bitops.h 
b/xen/arch/arm/include/asm/bitops.h
index 09c6064274a7..59ae8ed150b6 100644
--- a/xen/arch/arm/include/asm/bitops.h
+++ b/xen/arch/arm/include/asm/bitops.h
@@ -158,7 +158,7 @@ static inline int fls(unsigned int x)
 
 
 #define arch_ffs(x) ({ unsigned int __t = (x); fls(ISOLATE_LSB(__t)); })
-#define ffsl(x) ({ unsigned long __t = (x); flsl(ISOLATE_LSB(__t)); })
+#define arch_ffsl(x) ({ unsigned long __t = (x); flsl(ISOLATE_LSB(__t)); })
 
 /**
  * find_first_set_bit - find the first set bit in @word
diff --git a/xen/arch/ppc/include/asm/bitops.h 
b/xen/arch/ppc/include/asm/bitops.h
index 635a3b4e3e33..ecec2a826660 100644
--- a/xen/arch/ppc/include/asm/bitops.h
+++ b/xen/arch/ppc/include/asm/bitops.h
@@ -173,7 +173,6 @@ static inline int __test_and_clear_bit(int nr, volatile 
void *addr)
 
 #define flsl(x) generic_flsl(x)
 #define fls(x) generic_fls(x)
-#define ffsl(x) ({ unsigned long t_ = (x); flsl(t_ & -t_); })
 
 /* Based on linux/include/asm-generic/bitops/ffz.h */
 /*
diff --git a/xen/arch/x86/include/asm/bitops.h 
b/xen/arch/x86/include/asm/bitops.h
index 2c5b103cbbd9..99342877e32f 100644
--- a/xen/arch/x86/include/asm/bitops.h
+++ b/xen/arch/x86/include/asm/bitops.h
@@ -413,23 +413,6 @@ static inline unsigned int find_first_set_bit(unsigned 
long word)
     return (unsigned int)word;
 }
 
-/**
- * ffs - find first bit set
- * @x: the word to search
- *
- * This is defined the same way as the libc and compiler builtin ffs routines.
- */
-static inline int ffsl(unsigned long x)
-{
-    long r;
-
-    asm ( "bsf %1,%0\n\t"
-          "jnz 1f\n\t"
-          "mov $-1,%0\n"
-          "1:" : "=r" (r) : "rm" (x));
-    return (int)r+1;
-}
-
 static inline unsigned int arch_ffs(unsigned int x)
 {
     int r = -1;
@@ -448,6 +431,19 @@ static inline unsigned int arch_ffs(unsigned int x)
 }
 #define arch_ffs arch_ffs
 
+static inline unsigned int arch_ffsl(unsigned long x)
+{
+    long r = -1;
+
+    /* See arch_ffs() for safety discussion. */
+    asm ( "bsf %[val], %[res]"
+          : [res] "+r" (r)
+          : [val] "rm" (x) );
+
+    return r + 1;
+}
+#define arch_ffsl arch_ffsl
+
 /**
  * fls - find last bit set
  * @x: the word to search
diff --git a/xen/common/bitops.c b/xen/common/bitops.c
index 484df68768ad..eceffe5029d6 100644
--- a/xen/common/bitops.c
+++ b/xen/common/bitops.c
@@ -40,6 +40,13 @@ static void test_ffs(void)
     CHECK(ffs, 0, 0);
     CHECK(ffs, 1, 1);
     CHECK(ffs, 0x80000000U, 32);
+
+    /* unsigned int ffsl(unsigned long) */
+    CHECK(ffsl, 0, 0);
+    CHECK(ffsl, 1, 1);
+    CHECK(ffsl, 1UL << (BITS_PER_LONG - 1), BITS_PER_LONG);
+    if ( BITS_PER_LONG > 32 )
+        CHECK(ffsl, 1UL << 32, 33);
 }
 
 static int __init cf_check test_bitops(void)
diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h
index fb3645d9cf87..a37b42342bc5 100644
--- a/xen/include/xen/bitops.h
+++ b/xen/include/xen/bitops.h
@@ -125,6 +125,18 @@ static always_inline __pure unsigned int ffs(unsigned int 
x)
     return arch_ffs(x);
 }
 
+static always_inline __pure unsigned int ffsl(unsigned long x)
+{
+    if ( __builtin_constant_p(x) )
+        return __builtin_ffsl(x);
+
+#ifndef arch_ffsl
+#define arch_ffsl __builtin_ffsl
+#endif
+
+    return arch_ffsl(x);
+}
+
 /* --------------------- Please tidy below here --------------------- */
 
 #ifndef find_next_bit
-- 
2.30.2