From 1c76d3a9fbef7862810990017d56b023e2515e99 Mon Sep 17 00:00:00 2001
From: Doug Moore <dougm@FreeBSD.org>
Date: Tue, 28 May 2019 15:47:00 +0000
Subject: [PATCH] Implement the ffs and fls functions, and their longer
 counterparts, in cpufunc, in terms of __builtin_ffs and the like, for arm32
 v6 and v7 architectures, and use those, rather than the simple libkern
 implementations, in building arm32 kernels.

Reviewed by: manu
Approved by: kib, markj (mentors)
Tested by: iz-rpi03_hs-karlsruhe.de, mikael.urankar_gmail.com, ian
Differential Revision: https://reviews.freebsd.org/D20412
---
 sys/arm/include/cpufunc.h | 58 +++++++++++++++++++++++++++++++++++++++
 sys/conf/files.arm        | 12 ++++----
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/sys/arm/include/cpufunc.h b/sys/arm/include/cpufunc.h
index 00fc1ba5bba..12030b4aa51 100644
--- a/sys/arm/include/cpufunc.h
+++ b/sys/arm/include/cpufunc.h
@@ -359,6 +359,64 @@ extern u_int	arm_cache_level;
 extern u_int	arm_cache_loc;
 extern u_int	arm_cache_type[14];
 
+#if __ARM_ARCH >= 6
+#define	HAVE_INLINE_FFS
+
+static __inline __pure2 int
+ffs(int mask)
+{
+
+	return (__builtin_ffs(mask));
+}
+
+#define	HAVE_INLINE_FFSL
+
+static __inline __pure2 int
+ffsl(long mask)
+{
+
+	return (__builtin_ffsl(mask));
+}
+
+#define	HAVE_INLINE_FFSLL
+
+static __inline __pure2 int
+ffsll(long long mask)
+{
+
+	return (__builtin_ffsll(mask));
+}
+
+#define	HAVE_INLINE_FLS
+
+static __inline __pure2 int
+fls(int mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clz((u_int)mask));
+}
+
+#define	HAVE_INLINE_FLSL
+
+static __inline __pure2 int
+flsl(long mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clzl((u_long)mask));
+}
+
+#define	HAVE_INLINE_FLSLL
+
+static __inline __pure2 int
+flsll(long long mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clzll((unsigned long long)mask));
+}
+#endif
 #else	/* !_KERNEL */
 
 static __inline void
diff --git a/sys/conf/files.arm b/sys/conf/files.arm
index 32137db6aec..6134b20e117 100644
--- a/sys/conf/files.arm
+++ b/sys/conf/files.arm
@@ -129,7 +129,7 @@ kern/subr_devmap.c		standard
 kern/subr_sfbuf.c		standard
 libkern/arm/aeabi_unwind.c	standard
 libkern/arm/divsi3.S		standard
-libkern/arm/ffs.S		standard
+libkern/arm/ffs.S		optional	!armv7 !armv6
 libkern/arm/ldivmod.S		standard
 libkern/arm/ldivmod_helper.c	standard
 libkern/arm/memclr.S		standard
@@ -139,11 +139,11 @@ libkern/arm/muldi3.c		standard
 libkern/ashldi3.c		standard
 libkern/ashrdi3.c		standard
 libkern/divdi3.c		standard
-libkern/ffsl.c			standard
-libkern/ffsll.c			standard
-libkern/fls.c			standard
-libkern/flsl.c			standard
-libkern/flsll.c			standard
+libkern/ffsl.c			optional	!armv7 !armv6
+libkern/ffsll.c			optional	!armv7 !armv6
+libkern/fls.c			optional	!armv7 !armv6
+libkern/flsl.c			optional	!armv7 !armv6
+libkern/flsll.c			optional	!armv7 !armv6
 libkern/lshrdi3.c		standard
 libkern/memcmp.c		standard
 libkern/moddi3.c		standard