diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arc/include/asm/syscalls.h | 1 | ||||
| -rw-r--r-- | arch/arc/include/uapi/asm/unistd.h | 9 | ||||
| -rw-r--r-- | arch/arc/kernel/process.c | 33 |
3 files changed, 39 insertions, 4 deletions
diff --git a/arch/arc/include/asm/syscalls.h b/arch/arc/include/asm/syscalls.h index e56f9fcc5581..772b67ca56e7 100644 --- a/arch/arc/include/asm/syscalls.h +++ b/arch/arc/include/asm/syscalls.h @@ -17,6 +17,7 @@ int sys_clone_wrapper(int, int, int, int, int); int sys_cacheflush(uint32_t, uint32_t uint32_t); int sys_arc_settls(void *); int sys_arc_gettls(void); +int sys_arc_usr_cmpxchg(int *, int, int); #include <asm-generic/syscalls.h> diff --git a/arch/arc/include/uapi/asm/unistd.h b/arch/arc/include/uapi/asm/unistd.h index 41fa2ec9e02c..9a34136d84b2 100644 --- a/arch/arc/include/uapi/asm/unistd.h +++ b/arch/arc/include/uapi/asm/unistd.h @@ -27,18 +27,19 @@ #define NR_syscalls __NR_syscalls +/* Generic syscall (fs/filesystems.c - lost in asm-generic/unistd.h */ +#define __NR_sysfs (__NR_arch_specific_syscall + 3) + /* ARC specific syscall */ #define __NR_cacheflush (__NR_arch_specific_syscall + 0) #define __NR_arc_settls (__NR_arch_specific_syscall + 1) #define __NR_arc_gettls (__NR_arch_specific_syscall + 2) +#define __NR_arc_usr_cmpxchg (__NR_arch_specific_syscall + 4) __SYSCALL(__NR_cacheflush, sys_cacheflush) __SYSCALL(__NR_arc_settls, sys_arc_settls) __SYSCALL(__NR_arc_gettls, sys_arc_gettls) - - -/* Generic syscall (fs/filesystems.c - lost in asm-generic/unistd.h */ -#define __NR_sysfs (__NR_arch_specific_syscall + 3) +__SYSCALL(__NR_arc_usr_cmpxchg, sys_arc_usr_cmpxchg) __SYSCALL(__NR_sysfs, sys_sysfs) #undef __SYSCALL diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c index be1972bd2729..59aa43cb146e 100644 --- a/arch/arc/kernel/process.c +++ b/arch/arc/kernel/process.c @@ -41,6 +41,39 @@ SYSCALL_DEFINE0(arc_gettls) return task_thread_info(current)->thr_ptr; } +SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new) +{ + int uval; + int ret; + + /* + * This is only for old cores lacking LLOCK/SCOND, which by defintion + * can't possibly be SMP. Thus doesn't need to be SMP safe. + * And this also helps reduce the overhead for serializing in + * the UP case + */ + WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); + + if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) + return -EFAULT; + + preempt_disable(); + + ret = __get_user(uval, uaddr); + if (ret) + goto done; + + if (uval != expected) + ret = -EAGAIN; + else + ret = __put_user(new, uaddr); + +done: + preempt_enable(); + + return ret; +} + void arch_cpu_idle(void) { /* sleep, but enable all interrupts before committing */ |