fls: change parameter to unsigned int

When testing in userspace, UBSAN pointed out that shifting into the sign
bit is undefined behaviour.  It doesn't really make sense to ask for the
highest set bit of a negative value, so just turn the argument type into
an unsigned int.

Some architectures (eg ppc) already had it declared as an unsigned int,
so I don't expect too many problems.

Link: http://lkml.kernel.org/r/20181105221117.31828-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

13 files changed, 16 insertions, 17 deletions

diff --git a/arch/alpha/include/asm/bitops.h b/arch/alpha/include/asm/bitops.h
index ca43f4d0b937..5adca78830b5 100644
--- a/arch/alpha/include/asm/bitops.h
+++ b/arch/alpha/include/asm/bitops.h
@@ -391,9 +391,9 @@ static inline unsigned long __fls(unsigned long x)
 	return fls64(x) - 1;
 }
 
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
-	return fls64((unsigned int) x);
+	return fls64(x);
 }
 
 /*
diff --git a/arch/arc/include/asm/bitops.h b/arch/arc/include/asm/bitops.h
index 8da87feec59a..ee9246184033 100644
--- a/arch/arc/include/asm/bitops.h
+++ b/arch/arc/include/asm/bitops.h
@@ -278,7 +278,7 @@ static inline __attribute__ ((const)) int clz(unsigned int x)
 	return res;
 }
 
-static inline int constant_fls(int x)
+static inline int constant_fls(unsigned int x)
 {
 	int r = 32;
 
@@ -312,7 +312,7 @@ static inline int constant_fls(int x)
  * @result: [1-32]
  * fls(1) = 1, fls(0x80000000) = 32, fls(0) = 0
  */
-static inline __attribute__ ((const)) int fls(unsigned long x)
+static inline __attribute__ ((const)) int fls(unsigned int x)
 {
 	if (__builtin_constant_p(x))
 	       return constant_fls(x);
diff --git a/arch/c6x/include/asm/bitops.h b/arch/c6x/include/asm/bitops.h
index f0ab012401b6..8b68234ace18 100644
--- a/arch/c6x/include/asm/bitops.h
+++ b/arch/c6x/include/asm/bitops.h
@@ -54,7 +54,7 @@ static inline unsigned long __ffs(unsigned long x)
  * This is defined the same way as ffs.
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
 	if (!x)
 		return 0;
diff --git a/arch/csky/include/asm/bitops.h b/arch/csky/include/asm/bitops.h
index 335f2883fb1e..43b9838bff63 100644
--- a/arch/csky/include/asm/bitops.h
+++ b/arch/csky/include/asm/bitops.h
@@ -40,7 +40,7 @@ static __always_inline unsigned long __ffs(unsigned long x)
 /*
  * asm-generic/bitops/fls.h
  */
-static __always_inline int fls(int x)
+static __always_inline int fls(unsigned int x)
 {
 	asm volatile(
 		"ff1 %0\n"
diff --git a/arch/hexagon/include/asm/bitops.h b/arch/hexagon/include/asm/bitops.h
index 2691a1857d20..bee974262387 100644
--- a/arch/hexagon/include/asm/bitops.h
+++ b/arch/hexagon/include/asm/bitops.h
@@ -211,7 +211,7 @@ static inline long ffz(int x)
  * This is defined the same way as ffs.
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
 	int r;
 
diff --git a/arch/ia64/include/asm/bitops.h b/arch/ia64/include/asm/bitops.h
index 56a774bf13fa..2f24ee6459d2 100644
--- a/arch/ia64/include/asm/bitops.h
+++ b/arch/ia64/include/asm/bitops.h
@@ -388,8 +388,7 @@ ia64_fls (unsigned long x)
  * Find the last (most significant) bit set.  Returns 0 for x==0 and
  * bits are numbered from 1..32 (e.g., fls(9) == 4).
  */
-static inline int
-fls (int t)
+static inline int fls(unsigned int t)
 {
 	unsigned long x = t & 0xffffffffu;
 
diff --git a/arch/m68k/include/asm/bitops.h b/arch/m68k/include/asm/bitops.h
index d979f38af751..10133a968c8e 100644
--- a/arch/m68k/include/asm/bitops.h
+++ b/arch/m68k/include/asm/bitops.h
@@ -502,7 +502,7 @@ static inline unsigned long __ffs(unsigned long x)
 /*
  *	fls: find last bit set.
  */
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
 	int cnt;
 
diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index f2a840fb6a9a..c4675957b21b 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -555,7 +555,7 @@ static inline unsigned long __ffs(unsigned long word)
  * This is defined the same way as ffs.
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
 	int r;
 
diff --git a/arch/openrisc/include/asm/bitops/fls.h b/arch/openrisc/include/asm/bitops/fls.h
index 9efbf9ad86c4..57de5a1115bf 100644
--- a/arch/openrisc/include/asm/bitops/fls.h
+++ b/arch/openrisc/include/asm/bitops/fls.h
@@ -15,7 +15,7 @@
 
 #ifdef CONFIG_OPENRISC_HAVE_INST_FL1
 
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
 	int ret;
 
diff --git a/arch/parisc/include/asm/bitops.h b/arch/parisc/include/asm/bitops.h
index 53252d4f9a57..a09eaebfdfd0 100644
--- a/arch/parisc/include/asm/bitops.h
+++ b/arch/parisc/include/asm/bitops.h
@@ -188,7 +188,7 @@ static __inline__ int ffs(int x)
  * fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
 
-static __inline__ int fls(int x)
+static __inline__ int fls(unsigned int x)
 {
 	int ret;
 	if (!x)
diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index 86e5b2fdee3c..d1f8a4d94cca 100644
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -397,9 +397,9 @@ static inline int fls64(unsigned long word)
  * This is defined the same way as ffs.
  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  */
-static inline int fls(int word)
+static inline int fls(unsigned int word)
 {
-	return fls64((unsigned int)word);
+	return fls64(word);
 }
 
 #else /* CONFIG_HAVE_MARCH_Z9_109_FEATURES */
diff --git a/arch/unicore32/include/asm/bitops.h b/arch/unicore32/include/asm/bitops.h
index c0cbdbe17168..de5853761c22 100644
--- a/arch/unicore32/include/asm/bitops.h
+++ b/arch/unicore32/include/asm/bitops.h
@@ -22,7 +22,7 @@
  * the cntlz instruction for much better code efficiency.
  */
 
-static inline int fls(int x)
+static inline int fls(unsigned int x)
 {
 	int ret;
 
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index 124f9195eb3e..ad7b210aa3f6 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -448,7 +448,7 @@ static __always_inline int ffs(int x)
  * set bit if value is nonzero. The last (most significant) bit is
  * at position 32.
  */
-static __always_inline int fls(int x)
+static __always_inline int fls(unsigned int x)
 {
 	int r;