diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/futex.h | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index 01f227e14254..b59b5a52637e 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -5,6 +5,119 @@ #include <linux/uaccess.h> #include <asm/errno.h> +#ifndef CONFIG_SMP +/* + * The following implementation only for uniprocessor machines. + * For UP, it's relies on the fact that pagefault_disable() also disables + * preemption to ensure mutual exclusion. + * + */ + +/** + * futex_atomic_op_inuser() - Atomic arithmetic operation with constant + * argument and comparison of the previous + * futex value with another constant. + * + * @encoded_op: encoded operation to execute + * @uaddr: pointer to user space address + * + * Return: + * 0 - On success + * <0 - On error + */ +static inline int +futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) +{ + int op = (encoded_op >> 28) & 7; + int cmp = (encoded_op >> 24) & 15; + int oparg = (encoded_op << 8) >> 20; + int cmparg = (encoded_op << 20) >> 20; + int oldval, ret; + u32 tmp; + + if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) + oparg = 1 << oparg; + + pagefault_disable(); + + ret = -EFAULT; + if (unlikely(get_user(oldval, uaddr) != 0)) + goto out_pagefault_enable; + + ret = 0; + tmp = oldval; + + switch (op) { + case FUTEX_OP_SET: + tmp = oparg; + break; + case FUTEX_OP_ADD: + tmp += oparg; + break; + case FUTEX_OP_OR: + tmp |= oparg; + break; + case FUTEX_OP_ANDN: + tmp &= ~oparg; + break; + case FUTEX_OP_XOR: + tmp ^= oparg; + break; + default: + ret = -ENOSYS; + } + + if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) + ret = -EFAULT; + +out_pagefault_enable: + pagefault_enable(); + + if (ret == 0) { + switch (cmp) { + case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; + case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; + case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; + case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; + case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; + case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; + default: ret = -ENOSYS; + } + } + return ret; +} + +/** + * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the + * uaddr with newval if the current value is + * oldval. + * @uval: pointer to store content of @uaddr + * @uaddr: pointer to user space address + * @oldval: old value + * @newval: new value to store to @uaddr + * + * Return: + * 0 - On success + * <0 - On error + */ +static inline int +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, + u32 oldval, u32 newval) +{ + u32 val; + + if (unlikely(get_user(val, uaddr) != 0)) + return -EFAULT; + + if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) + return -EFAULT; + + *uval = val; + + return 0; +} + +#else static inline int futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) { @@ -54,4 +167,5 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, return -ENOSYS; } +#endif /* CONFIG_SMP */ #endif |