leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
139c949f7f
linux/arch/mips/include/asm/atomic.h
Nathan Chancellor 8790ccf8da MIPS: Compare __SYNC_loongson3_war against 0 
When building with clang when CONFIG_CPU_LOONGSON3_WORKAROUNDS is
enabled:

 In file included from lib/errseq.c:4:
 In file included from ./include/linux/atomic.h:7:
 ./arch/mips/include/asm/atomic.h:52:1: warning: converting the result of
 '<<' to a boolean always evaluates to true
 [-Wtautological-constant-compare]
 ATOMIC_OPS(atomic64, s64)
 ^
 ./arch/mips/include/asm/atomic.h:40:9: note: expanded from macro
 'ATOMIC_OPS'
         return cmpxchg(&v->counter, o, n);
                ^
 ./arch/mips/include/asm/cmpxchg.h:194:7: note: expanded from macro
 'cmpxchg'
         if (!__SYNC_loongson3_war)
              ^
 ./arch/mips/include/asm/sync.h:147:34: note: expanded from macro
 '__SYNC_loongson3_war'
 # define __SYNC_loongson3_war   (1 << 31)
                                    ^

While it is not wrong that the result of this shift is always true in a
boolean context, it is not a problem here. Regardless, the warning is
really noisy so rather than making the shift a boolean implicitly, use
it in an equality comparison so the shift is used as an integer value.

Fixes: 4d1dbfe6cb ("MIPS: atomic: Emit Loongson3 sync workarounds within asm")
Fixes: a91f2a1dba ("MIPS: cmpxchg: Omit redundant barriers for Loongson3")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2021-01-15 15:32:47 +01:00

268 lines
7.9 KiB
C
Raw Blame History

/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc..
*
* But use these as seldom as possible since they are much more slower
* than regular operations.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996, 97, 99, 2000, 03, 04, 06 by Ralf Baechle
*/
#ifndef _ASM_ATOMIC_H
#define _ASM_ATOMIC_H
#include <linux/irqflags.h>
#include <linux/types.h>
#include <asm/barrier.h>
#include <asm/compiler.h>
#include <asm/cpu-features.h>
#include <asm/cmpxchg.h>
#include <asm/llsc.h>
#include <asm/sync.h>
#include <asm/war.h>
#define ATOMIC_OPS(pfx, type) \
static __always_inline type pfx##_read(const pfx##_t *v) \
{ \
return READ_ONCE(v->counter); \
} \
\
static __always_inline void pfx##_set(pfx##_t *v, type i) \
{ \
WRITE_ONCE(v->counter, i); \
} \
\
static __always_inline type pfx##_cmpxchg(pfx##_t *v, type o, type n) \
{ \
return cmpxchg(&v->counter, o, n); \
} \
\
static __always_inline type pfx##_xchg(pfx##_t *v, type n) \
{ \
return xchg(&v->counter, n); \
}
ATOMIC_OPS(atomic, int)
#ifdef CONFIG_64BIT
# define ATOMIC64_INIT(i) { (i) }
ATOMIC_OPS(atomic64, s64)
#endif
#define ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc) \
static __inline__ void pfx##_##op(type i, pfx##_t * v) \
{ \
type temp; \
\
if (!kernel_uses_llsc) { \
unsigned long flags; \
\
raw_local_irq_save(flags); \
v->counter c_op i; \
raw_local_irq_restore(flags); \
return; \
} \
\
__asm__ __volatile__( \
" .set push \n" \
" .set " MIPS_ISA_LEVEL " \n" \
" " __SYNC(full, loongson3_war) " \n" \
"1: " #ll " %0, %1 # " #pfx "_" #op " \n" \
" " #asm_op " %0, %2 \n" \
" " #sc " %0, %1 \n" \
"\t" __SC_BEQZ "%0, 1b \n" \
" .set pop \n" \
: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter) \
: "Ir" (i) : __LLSC_CLOBBER); \
}
#define ATOMIC_OP_RETURN(pfx, op, type, c_op, asm_op, ll, sc) \
static __inline__ type pfx##_##op##_return_relaxed(type i, pfx##_t * v) \
{ \
type temp, result; \
\
if (!kernel_uses_llsc) { \
unsigned long flags; \
\
raw_local_irq_save(flags); \
result = v->counter; \
result c_op i; \
v->counter = result; \
raw_local_irq_restore(flags); \
return result; \
} \
\
__asm__ __volatile__( \
" .set push \n" \
" .set " MIPS_ISA_LEVEL " \n" \
" " __SYNC(full, loongson3_war) " \n" \
"1: " #ll " %1, %2 # " #pfx "_" #op "_return\n" \
" " #asm_op " %0, %1, %3 \n" \
" " #sc " %0, %2 \n" \
"\t" __SC_BEQZ "%0, 1b \n" \
" " #asm_op " %0, %1, %3 \n" \
" .set pop \n" \
: "=&r" (result), "=&r" (temp), \
"+" GCC_OFF_SMALL_ASM() (v->counter) \
: "Ir" (i) : __LLSC_CLOBBER); \
\
return result; \
}
#define ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc) \
static __inline__ type pfx##_fetch_##op##_relaxed(type i, pfx##_t * v) \
{ \
int temp, result; \
\
if (!kernel_uses_llsc) { \
unsigned long flags; \
\
raw_local_irq_save(flags); \
result = v->counter; \
v->counter c_op i; \
raw_local_irq_restore(flags); \
return result; \
} \
\
__asm__ __volatile__( \
" .set push \n" \
" .set " MIPS_ISA_LEVEL " \n" \
" " __SYNC(full, loongson3_war) " \n" \
"1: " #ll " %1, %2 # " #pfx "_fetch_" #op "\n" \
" " #asm_op " %0, %1, %3 \n" \
" " #sc " %0, %2 \n" \
"\t" __SC_BEQZ "%0, 1b \n" \
" .set pop \n" \
" move %0, %1 \n" \
: "=&r" (result), "=&r" (temp), \
"+" GCC_OFF_SMALL_ASM() (v->counter) \
: "Ir" (i) : __LLSC_CLOBBER); \
\
return result; \
}
#undef ATOMIC_OPS
#define ATOMIC_OPS(pfx, op, type, c_op, asm_op, ll, sc) \
ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc) \
ATOMIC_OP_RETURN(pfx, op, type, c_op, asm_op, ll, sc) \
ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)
ATOMIC_OPS(atomic, add, int, +=, addu, ll, sc)
ATOMIC_OPS(atomic, sub, int, -=, subu, ll, sc)
#define atomic_add_return_relaxed atomic_add_return_relaxed
#define atomic_sub_return_relaxed atomic_sub_return_relaxed
#define atomic_fetch_add_relaxed atomic_fetch_add_relaxed
#define atomic_fetch_sub_relaxed atomic_fetch_sub_relaxed
#ifdef CONFIG_64BIT
ATOMIC_OPS(atomic64, add, s64, +=, daddu, lld, scd)
ATOMIC_OPS(atomic64, sub, s64, -=, dsubu, lld, scd)
# define atomic64_add_return_relaxed atomic64_add_return_relaxed
# define atomic64_sub_return_relaxed atomic64_sub_return_relaxed
# define atomic64_fetch_add_relaxed atomic64_fetch_add_relaxed
# define atomic64_fetch_sub_relaxed atomic64_fetch_sub_relaxed
#endif /* CONFIG_64BIT */
#undef ATOMIC_OPS
#define ATOMIC_OPS(pfx, op, type, c_op, asm_op, ll, sc) \
ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc) \
ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)
ATOMIC_OPS(atomic, and, int, &=, and, ll, sc)
ATOMIC_OPS(atomic, or, int, |=, or, ll, sc)
ATOMIC_OPS(atomic, xor, int, ^=, xor, ll, sc)
#define atomic_fetch_and_relaxed atomic_fetch_and_relaxed
#define atomic_fetch_or_relaxed atomic_fetch_or_relaxed
#define atomic_fetch_xor_relaxed atomic_fetch_xor_relaxed
#ifdef CONFIG_64BIT
ATOMIC_OPS(atomic64, and, s64, &=, and, lld, scd)
ATOMIC_OPS(atomic64, or, s64, |=, or, lld, scd)
ATOMIC_OPS(atomic64, xor, s64, ^=, xor, lld, scd)
# define atomic64_fetch_and_relaxed atomic64_fetch_and_relaxed
# define atomic64_fetch_or_relaxed atomic64_fetch_or_relaxed
# define atomic64_fetch_xor_relaxed atomic64_fetch_xor_relaxed
#endif
#undef ATOMIC_OPS
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
/*
* atomic_sub_if_positive - conditionally subtract integer from atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically test @v and subtract @i if @v is greater or equal than @i.
* The function returns the old value of @v minus @i.
*/
#define ATOMIC_SIP_OP(pfx, type, op, ll, sc) \
static __inline__ int pfx##_sub_if_positive(type i, pfx##_t * v) \
{ \
type temp, result; \
\
smp_mb__before_atomic(); \
\
if (!kernel_uses_llsc) { \
unsigned long flags; \
\
raw_local_irq_save(flags); \
result = v->counter; \
result -= i; \
if (result >= 0) \
v->counter = result; \
raw_local_irq_restore(flags); \
smp_mb__after_atomic(); \
return result; \
} \
\
__asm__ __volatile__( \
" .set push \n" \
" .set " MIPS_ISA_LEVEL " \n" \
" " __SYNC(full, loongson3_war) " \n" \
"1: " #ll " %1, %2 # atomic_sub_if_positive\n" \
" .set pop \n" \
" " #op " %0, %1, %3 \n" \
" move %1, %0 \n" \
" bltz %0, 2f \n" \
" .set push \n" \
" .set " MIPS_ISA_LEVEL " \n" \
" " #sc " %1, %2 \n" \
" " __SC_BEQZ "%1, 1b \n" \
"2: " __SYNC(full, loongson3_war) " \n" \
" .set pop \n" \
: "=&r" (result), "=&r" (temp), \
"+" GCC_OFF_SMALL_ASM() (v->counter) \
: "Ir" (i) \
: __LLSC_CLOBBER); \
\
/* \
* In the Loongson3 workaround case we already have a \
* completion barrier at 2: above, which is needed due to the \
* bltz that can branch to code outside of the LL/SC loop. As \
* such, we don't need to emit another barrier here. \
*/ \
if (__SYNC_loongson3_war == 0) \
smp_mb__after_atomic(); \
\
return result; \
}
ATOMIC_SIP_OP(atomic, int, subu, ll, sc)
#define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
#ifdef CONFIG_64BIT
ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
#define atomic64_dec_if_positive(v) atomic64_sub_if_positive(1, v)
#endif
#undef ATOMIC_SIP_OP
#endif /* _ASM_ATOMIC_H */
Reference in New Issue View Git Blame Copy Permalink