* [PATCH] lib: add weak __clzsi2()/__clzdi2() functions
@ 2013-04-29 5:40 Chanho Min
2013-04-29 7:20 ` Geert Uytterhoeven
2013-04-30 19:47 ` Andrew Morton
0 siblings, 2 replies; 6+ messages in thread
From: Chanho Min @ 2013-04-29 5:40 UTC (permalink / raw)
To: Andrew Morton
Cc: Kyungsik Lee, Yann Collet, Bob Pearson, Richard Weinberger,
Geert Uytterhoeven, linux-kernel, sparclinux, linux-m68k,
linux-next, Chanho Min
Some architectures need __clzsi2() or __clzdi2() for __builtin_clz and
It causes build failure. They can be implemented using the fls() and
overridden by linking arch-specific versions may not be implemented yet.
Reference: https://lkml.org/lkml/2013/4/18/603
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Chanho Min <chanho.min@lge.com>
---
lib/Makefile | 2 +-
lib/clz.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 37 insertions(+), 1 deletion(-)
create mode 100644 lib/clz.c
diff --git a/lib/Makefile b/lib/Makefile
index af79e8c..e17b3ee 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -23,7 +23,7 @@ lib-y += kobject.o klist.o
obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
- gcd.o lcm.o list_sort.o uuid.o flex_array.o \
+ gcd.o lcm.o list_sort.o uuid.o flex_array.o clz.o\
bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o
obj-y += string_helpers.o
obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
diff --git a/lib/clz.c b/lib/clz.c
new file mode 100644
index 0000000..5222b2d
--- /dev/null
+++ b/lib/clz.c
@@ -0,0 +1,36 @@
+/*
+ * lib/clz.c
+ *
+ * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * __clzsi2/_clzdi2() can be overridden by linking arch-specific versions.
+ */
+
+#include <linux/export.h>
+#include <linux/kernel.h>
+
+int __weak __clzsi2(int val)
+{
+ return BITS_PER_LONG - fls(val);
+}
+EXPORT_SYMBOL(__clzsi2);
+
+#if BITS_PER_LONG == 32
+int __weak __clzdi2(long val)
+{
+ return BITS_PER_LONG - fls((int)val);
+}
+EXPORT_SYMBOL(__clzdi2);
+#elif BITS_PER_LONG == 64
+int __weak __clzdi2i(long val)
+{
+ return BITS_PER_LONG - fls64((u64)val);
+}
+EXPORT_SYMBOL(__clzdi2);
+#else
+#error BITS_PER_LONG not 32 or 64
+#endif
--
1.7.9.5
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions
2013-04-29 5:40 [PATCH] lib: add weak __clzsi2()/__clzdi2() functions Chanho Min
@ 2013-04-29 7:20 ` Geert Uytterhoeven
2013-04-30 21:46 ` Andrew Morton
2013-04-30 19:47 ` Andrew Morton
1 sibling, 1 reply; 6+ messages in thread
From: Geert Uytterhoeven @ 2013-04-29 7:20 UTC (permalink / raw)
To: Chanho Min
Cc: Andrew Morton, Kyungsik Lee, Yann Collet, Bob Pearson,
Richard Weinberger, linux-kernel, sparclinux, Linux/m68k,
Linux-Next
On Mon, Apr 29, 2013 at 7:40 AM, Chanho Min <chanho.min@lge.com> wrote:
> Some architectures need __clzsi2() or __clzdi2() for __builtin_clz and
> It causes build failure. They can be implemented using the fls() and
> overridden by linking arch-specific versions may not be implemented yet.
>
> Reference: https://lkml.org/lkml/2013/4/18/603
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Chanho Min <chanho.min@lge.com>
Thanks, this fixes the link error on m68k, so
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions
2013-04-29 5:40 [PATCH] lib: add weak __clzsi2()/__clzdi2() functions Chanho Min
2013-04-29 7:20 ` Geert Uytterhoeven
@ 2013-04-30 19:47 ` Andrew Morton
1 sibling, 0 replies; 6+ messages in thread
From: Andrew Morton @ 2013-04-30 19:47 UTC (permalink / raw)
To: Chanho Min
Cc: Kyungsik Lee, Yann Collet, Bob Pearson, Richard Weinberger,
Geert Uytterhoeven, linux-kernel, sparclinux, linux-m68k,
linux-next
On Mon, 29 Apr 2013 14:40:05 +0900 Chanho Min <chanho.min@lge.com> wrote:
> Some architectures need __clzsi2() or __clzdi2() for __builtin_clz and
> It causes build failure. They can be implemented using the fls() and
> overridden by linking arch-specific versions may not be implemented yet.
>
> Reference: https://lkml.org/lkml/2013/4/18/603
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Chanho Min <chanho.min@lge.com>
>
> ...
>
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -23,7 +23,7 @@ lib-y += kobject.o klist.o
>
> obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
> bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
> - gcd.o lcm.o list_sort.o uuid.o flex_array.o \
> + gcd.o lcm.o list_sort.o uuid.o flex_array.o clz.o\
> bsearch.o find_last_bit.o find_next_bit.o llist.o memweight.o kfifo.o
> obj-y += string_helpers.o
> obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
> diff --git a/lib/clz.c b/lib/clz.c
> new file mode 100644
> index 0000000..5222b2d
> --- /dev/null
> +++ b/lib/clz.c
> @@ -0,0 +1,36 @@
> +/*
> + * lib/clz.c
> + *
> + * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * __clzsi2/_clzdi2() can be overridden by linking arch-specific versions.
> + */
> +
> +#include <linux/export.h>
> +#include <linux/kernel.h>
> +
> +int __weak __clzsi2(int val)
> +{
> + return BITS_PER_LONG - fls(val);
> +}
> +EXPORT_SYMBOL(__clzsi2);
> +
> +#if BITS_PER_LONG == 32
> +int __weak __clzdi2(long val)
> +{
> + return BITS_PER_LONG - fls((int)val);
> +}
> +EXPORT_SYMBOL(__clzdi2);
> +#elif BITS_PER_LONG == 64
> +int __weak __clzdi2i(long val)
This is a typo, surely? I'll switch it to __clzdi2.
> +{
> + return BITS_PER_LONG - fls64((u64)val);
> +}
> +EXPORT_SYMBOL(__clzdi2);
> +#else
> +#error BITS_PER_LONG not 32 or 64
> +#endif
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions
2013-04-29 7:20 ` Geert Uytterhoeven
@ 2013-04-30 21:46 ` Andrew Morton
2013-05-01 7:35 ` Geert Uytterhoeven
2013-05-02 0:58 ` 민찬호
0 siblings, 2 replies; 6+ messages in thread
From: Andrew Morton @ 2013-04-30 21:46 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Chanho Min, Kyungsik Lee, Yann Collet, Bob Pearson,
Richard Weinberger, linux-kernel, sparclinux, Linux/m68k,
Linux-Next
On Mon, 29 Apr 2013 09:20:25 +0200 Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Mon, Apr 29, 2013 at 7:40 AM, Chanho Min <chanho.min@lge.com> wrote:
> > Some architectures need __clzsi2() or __clzdi2() for __builtin_clz and
> > It causes build failure. They can be implemented using the fls() and
> > overridden by linking arch-specific versions may not be implemented yet.
> >
> > Reference: https://lkml.org/lkml/2013/4/18/603
> > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> > Signed-off-by: Chanho Min <chanho.min@lge.com>
>
> Thanks, this fixes the link error on m68k, so
>
> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
It doesn't work for alpha (gcc-4.4.4):
ERROR: "__ctzdi2" [lib/lz4/lz4hc_compress.ko] undefined!
ERROR: "__ctzdi2" [lib/lz4/lz4_compress.ko] undefined!
akpm3:/usr/src/25> nm vmlinux|grep ctzd
akpm3:/usr/src/25>
I assume the linker threw the code away.
How's about we stop using __builtin_ctz[ll]() altogether? Use N-fls()?
btw, this:
int __weak __clzsi2(int val)
{
return BITS_PER_LONG - fls(val);
}
looks wrong. It will give a different result for 32- and 64-bit.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions
2013-04-30 21:46 ` Andrew Morton
@ 2013-05-01 7:35 ` Geert Uytterhoeven
2013-05-02 0:58 ` 민찬호
1 sibling, 0 replies; 6+ messages in thread
From: Geert Uytterhoeven @ 2013-05-01 7:35 UTC (permalink / raw)
To: Andrew Morton
Cc: Chanho Min, Kyungsik Lee, Yann Collet, Bob Pearson,
Richard Weinberger, linux-kernel, sparclinux, Linux/m68k,
Linux-Next
On Tue, Apr 30, 2013 at 11:46 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Mon, 29 Apr 2013 09:20:25 +0200 Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>> On Mon, Apr 29, 2013 at 7:40 AM, Chanho Min <chanho.min@lge.com> wrote:
>> > Some architectures need __clzsi2() or __clzdi2() for __builtin_clz and
>> > It causes build failure. They can be implemented using the fls() and
>> > overridden by linking arch-specific versions may not be implemented yet.
>> >
>> > Reference: https://lkml.org/lkml/2013/4/18/603
>> > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
>> > Signed-off-by: Chanho Min <chanho.min@lge.com>
>>
>> Thanks, this fixes the link error on m68k, so
>>
>> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
>
> It doesn't work for alpha (gcc-4.4.4):
>
> ERROR: "__ctzdi2" [lib/lz4/lz4hc_compress.ko] undefined!
> ERROR: "__ctzdi2" [lib/lz4/lz4_compress.ko] undefined!
>
> akpm3:/usr/src/25> nm vmlinux|grep ctzd
> akpm3:/usr/src/25>
>
> I assume the linker threw the code away.
No, the link errors are for __ctzdi2, not __clzdi2.
__ctzdi2 can be implemented using __ffs().
> How's about we stop using __builtin_ctz[ll]() altogether? Use N-fls()?
That was my first suggestion ;-)
> btw, this:
>
> int __weak __clzsi2(int val)
> {
> return BITS_PER_LONG - fls(val);
> }
>
> looks wrong. It will give a different result for 32- and 64-bit.
Indeed. It should be hardcoded 32.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: add weak __clzsi2()/__clzdi2() functions
2013-04-30 21:46 ` Andrew Morton
2013-05-01 7:35 ` Geert Uytterhoeven
@ 2013-05-02 0:58 ` 민찬호
1 sibling, 0 replies; 6+ messages in thread
From: 민찬호 @ 2013-05-02 0:58 UTC (permalink / raw)
To: Geert Uytterhoeven
Cc: Andrew Morton, 이경식,
Yann Collet, Bob Pearson, Richard Weinberger, linux-kernel,
sparclinux, Linux/m68k, Linux-Next
>No, the link errors are for __ctzdi2, not __clzdi2.
>__ctzdi2 can be implemented using __ffs().
>> How's about we stop using __builtin_ctz[ll]() altogether? Use N-fls()?
>
>That was my first suggestion ;-)
>
Do we remove existing __builtin_ct[l]z?
Some architecture's __builtin_clz will be more optimized than N-fls
IMHO, This is not only about __builtin- but also supporting another
libgcc functions in kernel.
Some future user may need __clz[t]s[d]i2 symbol also.
>> btw, this:
>>
>> int __weak __clzsi2(int val)
>> {
>> return BITS_PER_LONG - fls(val);
>> }
>>
>> looks wrong. It will give a different result for 32- and 64-bit.
>
>Indeed. It should be hardcoded 32.
>
I will re-work this for 64-bit, and ctz also.
Thanks
Chanho Min
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-04-29 5:40 [PATCH] lib: add weak __clzsi2()/__clzdi2() functions Chanho Min
2013-04-29 7:20 ` Geert Uytterhoeven
2013-04-30 21:46 ` Andrew Morton
2013-05-01 7:35 ` Geert Uytterhoeven
2013-05-02 0:58 ` 민찬호
2013-04-30 19:47 ` Andrew Morton
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