[...]
CC init/main.o
include/asm/bitops.h: In function `start_kernel':
include/asm/bitops.h:76: warning: asm operand 2 probably doesn't match
constraints
include/asm/bitops.h:76: warning: asm operand 2 probably doesn't match
constraints
include/asm/bitops.h:76: warning: asm operand 2 probably doesn't match
constraints
include/asm/bitops.h:76: error: impossible constraint in `asm'
include/asm/bitops.h:76: error: impossible constraint in `asm'
include/asm/bitops.h:76: error: impossible constraint in `asm'
make[1]: *** [init/main.o] Error 1
[...]
The build error is caused by the ages old gcc bug where gcc at the time of
analyzing the constraints is unable to figure out that an "i" constraint
actually can be satisfied and thus will abort unless an "r" is added to
the constraint. For the actual code generation gcc will only ever use the
"i" constraint.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The third operand to 'ins' must be a constant int, not a register.
[Ralf: The bug was actually intensional. Some versions used to throw an
error under certain circumstances for code like:
static inline void f(unsigned nr, unsigned *p)
{
unsigned short bit = nr & 5;
if (__builtin_constant_p(bit)) {
__asm__ __volatile__ (" foo %0, %1" : "=m" (*p) : "i" (bit));
} else {
/* Do something else. */
}
}
because gcc was not able to figure out that the "i" constraint was possibly
at the early stage when the constraint are getting verified. The solution
was using "ri" instead of "i". The "ri" would keep gcc happy but in the
end for code generation always the "i" constraint would be satisfied. The
problem afair originally appeared in the i386 io.h and also hit it's mips
equivalent. From there the workaround spread to many of the inline
assembler functions.]
Signed-off-by: David Daney <ddaney@avtrex.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
56a6b1eb7b was a bit too conservative and
left __ilog2 around which is only used as an internal function for other
bitops.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Only MIPS32 and MIPS64 CPUs implement clz/dclz. Therefore don't export
__ilog2() for non MIPS32/MIPS64 cpus and use generic __fls bitop code for
these cpus.
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Implement __fls on all 64-bit archs:
alpha has an implementation of fls64.
Added __fls(x) = fls64(x) - 1.
ia64 has fls, but not __fls.
Added __fls based on code of fls.
mips and powerpc have __ilog2, which is the same as __fls.
Added __fls = __ilog2.
parisc, s390, sh and sparc64:
Include generic __fls.
x86_64 already has __fls.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
forbid asm/bitops.h direct inclusion
Because of compile errors that may occur after bit changes if asm/bitops.h is
included directly without e.g. linux/kernel.h which includes linux/bitops.h,
forbid direct inclusion of asm/bitops.h. Thanks to Adrian Bunk.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/atomic_ops.txt defines these primitives must contain a memory
barrier both before and after their memory operation. This is consistent with
the atomic ops implementation on mips.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix a sparse warning caused by 2c921d07f8c641e691b0dfd80a5cfe14c60ec489
include2/asm/bitops.h:313:23: warning: symbol 'res' shadows an earlier one
include2/asm/bitops.h:309:16: originally declared here
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Add R2 optimized variants of clear_bit, set_bit and test_and_clear_bit.
With gcc 4.1.1 this saves 1592 bytes on a defconfig (minus IPv6) kernel.
Turns out that R2 bitop instructions are no gain for the other bitop
functions.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Now that finally all supported versions of binutils have functioning
support for .subsection use .subsection to tweak the branch prediction
I did not modify the R10000 errata variants because it seems unclear if
this will invalidate the workaround which actually relies on the cheesy
prediction of branch likely to cause a misspredict if the sc was
successful.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
With recent rewrite for generic bitops, fls() for 32bit kernel with
MIPS64_CPU is broken. Also, ffs(), fls() should be defined the same
way as the libc and compiler built-in routines (returns int instead of
unsigned long).
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
