mm/sparse.c: make sparse_init_one_section void and remove check

[linux.git] / lib / reciprocal_div.c

diff --git a/lib/reciprocal_div.c b/lib/reciprocal_div.c
index fcb4ce682c6fae37d71aa6138007b51cd0d8a2b3..bf043258fa0082b4cc1100a982d2ed38e21b1c0e 100644 (file)
--- a/lib/reciprocal_div.c
+++ b/lib/reciprocal_div.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <linux/bug.h>
 #include <linux/kernel.h>
 #include <asm/div64.h>
 #include <linux/reciprocal_div.h>
@@ -26,3 +27,43 @@ struct reciprocal_value reciprocal_value(u32 d)
        return R;
 }
 EXPORT_SYMBOL(reciprocal_value);
+
+struct reciprocal_value_adv reciprocal_value_adv(u32 d, u8 prec)
+{
+       struct reciprocal_value_adv R;
+       u32 l, post_shift;
+       u64 mhigh, mlow;
+
+       /* ceil(log2(d)) */
+       l = fls(d - 1);
+       /* NOTE: mlow/mhigh could overflow u64 when l == 32. This case needs to
+        * be handled before calling "reciprocal_value_adv", please see the
+        * comment at include/linux/reciprocal_div.h.
+        */
+       WARN(l == 32,
+            "ceil(log2(0x%08x)) == 32, %s doesn't support such divisor",
+            d, __func__);
+       post_shift = l;
+       mlow = 1ULL << (32 + l);
+       do_div(mlow, d);
+       mhigh = (1ULL << (32 + l)) + (1ULL << (32 + l - prec));
+       do_div(mhigh, d);
+
+       for (; post_shift > 0; post_shift--) {
+               u64 lo = mlow >> 1, hi = mhigh >> 1;
+
+               if (lo >= hi)
+                       break;
+
+               mlow = lo;
+               mhigh = hi;
+       }
+
+       R.m = (u32)mhigh;
+       R.sh = post_shift;
+       R.exp = l;
+       R.is_wide_m = mhigh > U32_MAX;
+
+       return R;
+}
+EXPORT_SYMBOL(reciprocal_value_adv);