diff mbox series

[v6,05/20] xen/bitops: implement fls{l}() in common logic

Message ID e7fc769a4f08ca00972faf4ce99e562d2eb3c00c.1710517542.git.oleksii.kurochko@gmail.com (mailing list archive)
State Superseded
Headers show
Series Enable build of full Xen for RISC-V | expand

Commit Message

Oleksii Kurochko March 15, 2024, 6:06 p.m. UTC
Return type was left 'int' because of the following compilation error:

./include/xen/kernel.h:18:21: error: comparison of distinct pointer types lacks a cast [-Werror]
       18 |         (void) (&_x == &_y);            \
          |                     ^~
    common/page_alloc.c:1843:34: note: in expansion of macro 'min'
     1843 |         unsigned int inc_order = min(MAX_ORDER, flsl(e - s) - 1);

generic_fls{l} was used instead of __builtin_clz{l}(x) as if x is 0,
the result in undefined.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
Changes in V6:
 - new patch for the patch series.
---
 xen/arch/arm/include/asm/arm32/bitops.h |  2 +-
 xen/arch/arm/include/asm/arm64/bitops.h |  6 ++----
 xen/arch/arm/include/asm/bitops.h       |  7 ++-----
 xen/arch/ppc/include/asm/bitops.h       |  3 ---
 xen/arch/x86/include/asm/bitops.h       |  6 ++++--
 xen/common/bitops.c                     | 22 ++++++++++++++++++++++
 xen/include/xen/bitops.h                | 24 ++++++++++++++++++++++++
 7 files changed, 55 insertions(+), 15 deletions(-)

Comments

Jan Beulich March 20, 2024, 3:39 p.m. UTC | #1
On 15.03.2024 19:06, Oleksii Kurochko wrote:
> Return type was left 'int' because of the following compilation error:
> 
> ./include/xen/kernel.h:18:21: error: comparison of distinct pointer types lacks a cast [-Werror]
>        18 |         (void) (&_x == &_y);            \
>           |                     ^~
>     common/page_alloc.c:1843:34: note: in expansion of macro 'min'
>      1843 |         unsigned int inc_order = min(MAX_ORDER, flsl(e - s) - 1);
> 
> generic_fls{l} was used instead of __builtin_clz{l}(x) as if x is 0,
> the result in undefined.
> 
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

Assuming Andrew's pending change goes in as posted, I'm okay with this to
(as simply following suit). Without that having happened, I can't very
well offer an ack here. Just one nit:

> --- a/xen/include/xen/bitops.h
> +++ b/xen/include/xen/bitops.h
> @@ -69,6 +69,30 @@ static inline int generic_flsl(unsigned long x)
>  
>  #include <asm/bitops.h>
>  
> +static always_inline __pure int fls(unsigned int x)
> +{
> +    if (__builtin_constant_p(x))

Style (missing blanks immediately inside the parentheses), also again ...

> +        return generic_fls(x);
> +
> +#ifndef arch_fls
> +#define arch_fls generic_fls
> +#endif
> +
> +    return arch_fls(x);
> +}
> +
> +static always_inline __pure int flsl(unsigned long x)
> +{
> +    if (__builtin_constant_p(x))

... here.

Jan
diff mbox series

Patch

diff --git a/xen/arch/arm/include/asm/arm32/bitops.h b/xen/arch/arm/include/asm/arm32/bitops.h
index d0309d47c1..5552d4e945 100644
--- a/xen/arch/arm/include/asm/arm32/bitops.h
+++ b/xen/arch/arm/include/asm/arm32/bitops.h
@@ -1,7 +1,7 @@ 
 #ifndef _ARM_ARM32_BITOPS_H
 #define _ARM_ARM32_BITOPS_H
 
-#define flsl fls
+#define arch_flsl fls
 
 /*
  * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
diff --git a/xen/arch/arm/include/asm/arm64/bitops.h b/xen/arch/arm/include/asm/arm64/bitops.h
index 0efde29068..5f5d97faa0 100644
--- a/xen/arch/arm/include/asm/arm64/bitops.h
+++ b/xen/arch/arm/include/asm/arm64/bitops.h
@@ -22,17 +22,15 @@  static /*__*/always_inline unsigned long __ffs(unsigned long word)
  */
 #define ffz(x)  __ffs(~(x))
 
-static inline int flsl(unsigned long x)
+static inline int arch_flsl(unsigned long x)
 {
         uint64_t ret;
 
-        if (__builtin_constant_p(x))
-               return generic_flsl(x);
-
         asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
 
         return BITS_PER_LONG - ret;
 }
+#define arch_flsl arch_flsl
 
 /* Based on linux/include/asm-generic/bitops/find.h */
 
diff --git a/xen/arch/arm/include/asm/bitops.h b/xen/arch/arm/include/asm/bitops.h
index 5104334e48..bcf7b48731 100644
--- a/xen/arch/arm/include/asm/bitops.h
+++ b/xen/arch/arm/include/asm/bitops.h
@@ -145,17 +145,14 @@  static inline int test_bit(int nr, const volatile void *addr)
  * the clz instruction for much better code efficiency.
  */
 
-static inline int fls(unsigned int x)
+static inline int arch_fls(unsigned int x)
 {
         int ret;
 
-        if (__builtin_constant_p(x))
-               return generic_fls(x);
-
         asm("clz\t%"__OP32"0, %"__OP32"1" : "=r" (ret) : "r" (x));
         return 32 - ret;
 }
-
+#define arch_fls arch_fls
 
 #define arch_ffs(x) ({ unsigned int __t = (x); fls(ISOLATE_LSB(__t)); })
 #define arch_ffsl(x) ({ unsigned long __t = (x); flsl(ISOLATE_LSB(__t)); })
diff --git a/xen/arch/ppc/include/asm/bitops.h b/xen/arch/ppc/include/asm/bitops.h
index 989d341a44..16447a4be6 100644
--- a/xen/arch/ppc/include/asm/bitops.h
+++ b/xen/arch/ppc/include/asm/bitops.h
@@ -171,9 +171,6 @@  static inline int __test_and_clear_bit(int nr, volatile void *addr)
     return (old & mask) != 0;
 }
 
-#define flsl(x) generic_flsl(x)
-#define fls(x) generic_fls(x)
-
 /* Based on linux/include/asm-generic/bitops/ffz.h */
 /*
  * ffz - find first zero in word.
diff --git a/xen/arch/x86/include/asm/bitops.h b/xen/arch/x86/include/asm/bitops.h
index dd439b69a0..87e91a1b7b 100644
--- a/xen/arch/x86/include/asm/bitops.h
+++ b/xen/arch/x86/include/asm/bitops.h
@@ -438,7 +438,7 @@  static always_inline unsigned int arch_ffsl(unsigned long x)
  *
  * This is defined the same way as ffs.
  */
-static inline int flsl(unsigned long x)
+static always_inline int arch_flsl(unsigned long x)
 {
     long r;
 
@@ -448,8 +448,9 @@  static inline int flsl(unsigned long x)
           "1:" : "=r" (r) : "rm" (x));
     return (int)r+1;
 }
+#define arch_flsl arch_flsl
 
-static inline int fls(unsigned int x)
+static always_inline int arch_fls(unsigned int x)
 {
     int r;
 
@@ -459,6 +460,7 @@  static inline int fls(unsigned int x)
           "1:" : "=r" (r) : "rm" (x));
     return r + 1;
 }
+#define arch_fls arch_fls
 
 /**
  * hweightN - returns the hamming weight of a N-bit word
diff --git a/xen/common/bitops.c b/xen/common/bitops.c
index a8c32f6767..95bc47176b 100644
--- a/xen/common/bitops.c
+++ b/xen/common/bitops.c
@@ -62,9 +62,31 @@  static void test_ffs(void)
     CHECK(ffs64, (uint64_t)0x8000000000000000, 64);
 }
 
+static void test_fls(void)
+{
+    /* unsigned int ffs(unsigned int) */
+    CHECK(fls, 1, 1);
+    CHECK(fls, 3, 2);
+    CHECK(fls, 3U << 30, 32);
+
+    /* unsigned int flsl(unsigned long) */
+    CHECK(flsl, 1, 1);
+    CHECK(flsl, 1UL << (BITS_PER_LONG - 1), BITS_PER_LONG);
+#if BITS_PER_LONG > 32
+    CHECK(flsl, 3UL << 32, 34);
+#endif
+
+    /* unsigned int fls64(uint64_t) */
+    CHECK(fls64, 1, 1);
+    CHECK(fls64, 0x00000000C0000000ULL, 32);
+    CHECK(fls64, 0x0000000180000000ULL, 33);
+    CHECK(fls64, 0xC000000000000000ULL, 64);
+}
+
 static int __init cf_check test_bitops(void)
 {
     test_ffs();
+    test_fls();
 
     return 0;
 }
diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h
index f14ad0d33a..fac8f768ff 100644
--- a/xen/include/xen/bitops.h
+++ b/xen/include/xen/bitops.h
@@ -69,6 +69,30 @@  static inline int generic_flsl(unsigned long x)
 
 #include <asm/bitops.h>
 
+static always_inline __pure int fls(unsigned int x)
+{
+    if (__builtin_constant_p(x))
+        return generic_fls(x);
+
+#ifndef arch_fls
+#define arch_fls generic_fls
+#endif
+
+    return arch_fls(x);
+}
+
+static always_inline __pure int flsl(unsigned long x)
+{
+    if (__builtin_constant_p(x))
+        return generic_flsl(x);
+
+#ifndef arch_flsl
+#define arch_flsl generic_flsl
+#endif
+
+    return arch_flsl(x);
+}
+
 /*
  * Find First Set bit.  Bits are labelled from 1.
  */