There is no option to perform 64bit integer sqrt on 32bit platform. Added stronger typed int_sqrt64 enables the 64bit calculations to be performed on 32bit platforms. Although int_sqrt() is a rough approximation, the same algorithm is used in int_sqrt64() as good enough on 32bit platform.
Signed-off-by: Crt Mori <[email protected]> --- include/linux/kernel.h | 1 + lib/int_sqrt.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 0ad4c3044cf9..09f53063f2c9 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -459,6 +459,7 @@ extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); unsigned long int_sqrt(unsigned long); +u64 int_sqrt64(u64 x); extern void bust_spinlocks(int yes); extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */ diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c index 1ef4cc344977..de5836448ea3 100644 --- a/lib/int_sqrt.c +++ b/lib/int_sqrt.c @@ -36,3 +36,29 @@ unsigned long int_sqrt(unsigned long x) return y; } EXPORT_SYMBOL(int_sqrt); + +/** + * int_sqrt64 - strongly typed int_sqrt function + * @x: 64bit integer of which to calculate the sqrt + */ +u64 int_sqrt64(u64 x) +{ + u64 b, m, y = 0; + + if (x <= 1) + return x; + + m = 1ULL << (64 - 2); + while (m != 0) { + b = y + m; + y >>= 1; + + if (x >= b) { + x -= b; + y += m; + } + m >>= 2; + } + return y; +} +EXPORT_SYMBOL(int_sqrt64); -- 2.15.0
