arch/mips/kernel/cmpxchg.c:44:12: warning: converting the result of '<<' to a boolean always evaluates to true

From: kernel test robot
Date: Thu Dec 03 2020 - 02:25:53 EST

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tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 34816d20f173a90389c8a7e641166d8ea9dce70a
commit: afe956c577b2d5a3d9834e4424587c1ebcf90c4c kbuild: Enable -Wtautological-compare
date: 8 months ago
config: mips-randconfig-r021-20201203 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 32c501dd88b62787d3a5ffda7aabcf4650dbe3cd)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install mips cross compiling tool for clang build
# apt-get install binutils-mips-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=afe956c577b2d5a3d9834e4424587c1ebcf90c4c
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout afe956c577b2d5a3d9834e4424587c1ebcf90c4c
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> arch/mips/kernel/cmpxchg.c:44:12: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
load32 = cmpxchg(ptr32, old32, new32);
^
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)
^
>> arch/mips/kernel/cmpxchg.c:44:12: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
arch/mips/include/asm/cmpxchg.h:204:7: 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)
^
arch/mips/kernel/cmpxchg.c:100:12: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
load32 = cmpxchg(ptr32, old32, new32);
^
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)
^
arch/mips/kernel/cmpxchg.c:100:12: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
arch/mips/include/asm/cmpxchg.h:204:7: 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)
^
4 warnings generated.
Assembler messages:
Fatal error: invalid -march= option: `mips64r2'
clang-12: error: assembler command failed with exit code 1 (use -v to see invocation)
--
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
>> arch/mips/include/asm/atomic.h:49:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
ATOMIC_OPS(atomic, int)
^
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
>> arch/mips/include/asm/atomic.h:49:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
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:204:7: 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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
>> arch/mips/include/asm/atomic.h:49:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
arch/mips/include/asm/atomic.h:45:9: note: expanded from macro 'ATOMIC_OPS'
return xchg(&v->counter, n); \
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:53:1: 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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:53:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
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:204:7: 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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:53:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
arch/mips/include/asm/atomic.h:45:9: note: expanded from macro 'ATOMIC_OPS'
return xchg(&v->counter, n); \
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:258:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
ATOMIC_SIP_OP(atomic, int, subu, ll, sc)
^
arch/mips/include/asm/atomic.h:252:7: note: expanded from macro 'ATOMIC_SIP_OP'
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:12:
In file included from ./arch/mips/include/generated/asm/current.h:1:
In file included from include/asm-generic/current.h:5:
In file included from include/linux/thread_info.h:38:
In file included from arch/mips/include/asm/thread_info.h:16:
In file included from arch/mips/include/asm/processor.h:14:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:262:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
^
arch/mips/include/asm/atomic.h:252:7: note: expanded from macro 'ATOMIC_SIP_OP'
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:15:
In file included from include/linux/sem.h:5:
In file included from include/uapi/linux/sem.h:5:
In file included from include/linux/ipc.h:7:
In file included from include/linux/rhashtable-types.h:14:
In file included from include/linux/mutex.h:21:
>> include/linux/debug_locks.h:17:9: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
return xchg(&debug_locks, 0);
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:15:
In file included from include/linux/sem.h:5:
In file included from include/uapi/linux/sem.h:5:
In file included from include/linux/ipc.h:7:
In file included from include/linux/rhashtable-types.h:15:
In file included from include/linux/workqueue.h:9:
In file included from include/linux/timer.h:6:
In file included from include/linux/ktime.h:24:
In file included from include/linux/time.h:74:
In file included from include/linux/time32.h:13:
In file included from include/linux/timex.h:65:
In file included from arch/mips/include/asm/timex.h:19:
In file included from arch/mips/include/asm/cpu-type.h:12:
In file included from include/linux/smp.h:15:
>> include/linux/llist.h:222:9: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
return xchg(&head->first, NULL);
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/cpu-probe.c:12:
In file included from include/linux/ptrace.h:6:
In file included from include/linux/sched.h:15:
In file included from include/linux/sem.h:5:
In file included from include/uapi/linux/sem.h:5:
In file included from include/linux/ipc.h:7:
In file included from include/linux/rhashtable-types.h:15:
In file included from include/linux/workqueue.h:9:
In file included from include/linux/timer.h:6:
In file included from include/linux/ktime.h:25:
include/linux/jiffies.h:13:10: fatal error: 'generated/timeconst.h' file not found
#include <generated/timeconst.h>
^~~~~~~~~~~~~~~~~~~~~~~
10 warnings and 1 error generated.
--
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
>> arch/mips/include/asm/atomic.h:49:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
ATOMIC_OPS(atomic, int)
^
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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
>> arch/mips/include/asm/atomic.h:49:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
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:204:7: 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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
>> arch/mips/include/asm/atomic.h:49:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
arch/mips/include/asm/atomic.h:45:9: note: expanded from macro 'ATOMIC_OPS'
return xchg(&v->counter, n); \
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:53:1: 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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:53:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
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:204:7: 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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:53:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
arch/mips/include/asm/atomic.h:45:9: note: expanded from macro 'ATOMIC_OPS'
return xchg(&v->counter, n); \
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:258:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
ATOMIC_SIP_OP(atomic, int, subu, ll, sc)
^
arch/mips/include/asm/atomic.h:252:7: note: expanded from macro 'ATOMIC_SIP_OP'
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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:8:
In file included from include/linux/cpumask.h:13:
In file included from include/linux/atomic.h:7:
arch/mips/include/asm/atomic.h:262:1: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
^
arch/mips/include/asm/atomic.h:252:7: note: expanded from macro 'ATOMIC_SIP_OP'
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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:11:
In file included from include/linux/hardirq.h:8:
In file included from include/linux/vtime.h:5:
In file included from include/linux/context_tracking_state.h:5:
In file included from include/linux/percpu.h:7:
In file included from include/linux/smp.h:15:
>> include/linux/llist.h:222:9: warning: converting the result of '<<' to a boolean always evaluates to true [-Wtautological-constant-compare]
return xchg(&head->first, NULL);
^
arch/mips/include/asm/cmpxchg.h:102:7: note: expanded from macro 'xchg'
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)
^
In file included from arch/mips/kernel/irq.c:14:
In file included from include/linux/interrupt.h:11:
In file included from include/linux/hardirq.h:9:
In file included from arch/mips/include/asm/hardirq.h:16:
In file included from include/asm-generic/hardirq.h:13:
In file included from include/linux/irq.h:19:
In file included from include/linux/topology.h:33:
In file included from include/linux/mmzone.h:19:
include/linux/page-flags-layout.h:6:10: fatal error: 'generated/bounds.h' file not found
#include <generated/bounds.h>
^~~~~~~~~~~~~~~~~~~~
9 warnings and 1 error generated.
..

vim +44 arch/mips/kernel/cmpxchg.c

b70eb30056dc845 Paul Burton 2017-06-09 9
b70eb30056dc845 Paul Burton 2017-06-09 10 unsigned long __xchg_small(volatile void *ptr, unsigned long val, unsigned int size)
b70eb30056dc845 Paul Burton 2017-06-09 11 {
b70eb30056dc845 Paul Burton 2017-06-09 12 u32 old32, new32, load32, mask;
b70eb30056dc845 Paul Burton 2017-06-09 13 volatile u32 *ptr32;
b70eb30056dc845 Paul Burton 2017-06-09 14 unsigned int shift;
b70eb30056dc845 Paul Burton 2017-06-09 15
b70eb30056dc845 Paul Burton 2017-06-09 16 /* Check that ptr is naturally aligned */
b70eb30056dc845 Paul Burton 2017-06-09 17 WARN_ON((unsigned long)ptr & (size - 1));
b70eb30056dc845 Paul Burton 2017-06-09 18
b70eb30056dc845 Paul Burton 2017-06-09 19 /* Mask value to the correct size. */
b70eb30056dc845 Paul Burton 2017-06-09 20 mask = GENMASK((size * BITS_PER_BYTE) - 1, 0);
b70eb30056dc845 Paul Burton 2017-06-09 21 val &= mask;
b70eb30056dc845 Paul Burton 2017-06-09 22
b70eb30056dc845 Paul Burton 2017-06-09 23 /*
b70eb30056dc845 Paul Burton 2017-06-09 24 * Calculate a shift & mask that correspond to the value we wish to
b70eb30056dc845 Paul Burton 2017-06-09 25 * exchange within the naturally aligned 4 byte integerthat includes
b70eb30056dc845 Paul Burton 2017-06-09 26 * it.
b70eb30056dc845 Paul Burton 2017-06-09 27 */
b70eb30056dc845 Paul Burton 2017-06-09 28 shift = (unsigned long)ptr & 0x3;
b70eb30056dc845 Paul Burton 2017-06-09 29 if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
b70eb30056dc845 Paul Burton 2017-06-09 30 shift ^= sizeof(u32) - size;
b70eb30056dc845 Paul Burton 2017-06-09 31 shift *= BITS_PER_BYTE;
b70eb30056dc845 Paul Burton 2017-06-09 32 mask <<= shift;
b70eb30056dc845 Paul Burton 2017-06-09 33
b70eb30056dc845 Paul Burton 2017-06-09 34 /*
b70eb30056dc845 Paul Burton 2017-06-09 35 * Calculate a pointer to the naturally aligned 4 byte integer that
b70eb30056dc845 Paul Burton 2017-06-09 36 * includes our byte of interest, and load its value.
b70eb30056dc845 Paul Burton 2017-06-09 37 */
b70eb30056dc845 Paul Burton 2017-06-09 38 ptr32 = (volatile u32 *)((unsigned long)ptr & ~0x3);
b70eb30056dc845 Paul Burton 2017-06-09 39 load32 = *ptr32;
b70eb30056dc845 Paul Burton 2017-06-09 40
b70eb30056dc845 Paul Burton 2017-06-09 41 do {
b70eb30056dc845 Paul Burton 2017-06-09 42 old32 = load32;
b70eb30056dc845 Paul Burton 2017-06-09 43 new32 = (load32 & ~mask) | (val << shift);
b70eb30056dc845 Paul Burton 2017-06-09 @44 load32 = cmpxchg(ptr32, old32, new32);
b70eb30056dc845 Paul Burton 2017-06-09 45 } while (load32 != old32);
b70eb30056dc845 Paul Burton 2017-06-09 46
b70eb30056dc845 Paul Burton 2017-06-09 47 return (load32 & mask) >> shift;
b70eb30056dc845 Paul Burton 2017-06-09 48 }
3ba7f44d2b19166 Paul Burton 2017-06-09 49

:::::: The code at line 44 was first introduced by commit
:::::: b70eb30056dc84568f3d32440d9be6a558025843 MIPS: cmpxchg: Implement 1 byte & 2 byte xchg()

:::::: TO: Paul Burton <paul.burton@xxxxxxxxxx>
:::::: CC: Ralf Baechle <ralf@xxxxxxxxxxxxxx>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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