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authorPeter Zijlstra <peterz@infradead.org>2025-11-21 11:21:20 +0100
committerPeter Zijlstra <peterz@infradead.org>2025-11-21 11:21:20 +0100
commit2ace52718376fdb56aca863da2eebe70d7e2ddb1 (patch)
tree494517cf79608fa93840a3c84ee5e6118da5f26f /lib/math/gcd.c
parenta53d0cf7f1cb3182ad533ff5cacfa5fd29c419ad (diff)
parent11991999a20145b7f8af21202d0cac6b1f90a6e4 (diff)
Merge branch 'objtool/core'
Bring in the UDB and objtool data annotations to avoid conflicts while further extending the bug exceptions. Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Diffstat (limited to 'lib/math/gcd.c')
-rw-r--r--lib/math/gcd.c27
1 files changed, 15 insertions, 12 deletions
diff --git a/lib/math/gcd.c b/lib/math/gcd.c
index e3b042214d1b..62efca6787ae 100644
--- a/lib/math/gcd.c
+++ b/lib/math/gcd.c
@@ -11,22 +11,16 @@
* has decent hardware division.
*/
+DEFINE_STATIC_KEY_TRUE(efficient_ffs_key);
+
#if !defined(CONFIG_CPU_NO_EFFICIENT_FFS)
/* If __ffs is available, the even/odd algorithm benchmarks slower. */
-/**
- * gcd - calculate and return the greatest common divisor of 2 unsigned longs
- * @a: first value
- * @b: second value
- */
-unsigned long gcd(unsigned long a, unsigned long b)
+static unsigned long binary_gcd(unsigned long a, unsigned long b)
{
unsigned long r = a | b;
- if (!a || !b)
- return r;
-
b >>= __ffs(b);
if (b == 1)
return r & -r;
@@ -44,9 +38,15 @@ unsigned long gcd(unsigned long a, unsigned long b)
}
}
-#else
+#endif
/* If normalization is done by loops, the even/odd algorithm is a win. */
+
+/**
+ * gcd - calculate and return the greatest common divisor of 2 unsigned longs
+ * @a: first value
+ * @b: second value
+ */
unsigned long gcd(unsigned long a, unsigned long b)
{
unsigned long r = a | b;
@@ -54,6 +54,11 @@ unsigned long gcd(unsigned long a, unsigned long b)
if (!a || !b)
return r;
+#if !defined(CONFIG_CPU_NO_EFFICIENT_FFS)
+ if (static_branch_likely(&efficient_ffs_key))
+ return binary_gcd(a, b);
+#endif
+
/* Isolate lsbit of r */
r &= -r;
@@ -80,6 +85,4 @@ unsigned long gcd(unsigned long a, unsigned long b)
}
}
-#endif
-
EXPORT_SYMBOL_GPL(gcd);