diff options
Diffstat (limited to 'arch/arc')
| -rw-r--r-- | arch/arc/include/asm/futex.h | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h new file mode 100644 index 000000000000..4dc64ddebece --- /dev/null +++ b/arch/arc/include/asm/futex.h @@ -0,0 +1,151 @@ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Vineetg: August 2010: From Android kernel work + */ + +#ifndef _ASM_FUTEX_H +#define _ASM_FUTEX_H + +#include <linux/futex.h> +#include <linux/preempt.h> +#include <linux/uaccess.h> +#include <asm/errno.h> + +#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\ + \ + __asm__ __volatile__( \ + "1: ld %1, [%2] \n" \ + insn "\n" \ + "2: st %0, [%2] \n" \ + " mov %0, 0 \n" \ + "3: \n" \ + " .section .fixup,\"ax\" \n" \ + " .align 4 \n" \ + "4: mov %0, %4 \n" \ + " b 3b \n" \ + " .previous \n" \ + " .section __ex_table,\"a\" \n" \ + " .align 4 \n" \ + " .word 1b, 4b \n" \ + " .word 2b, 4b \n" \ + " .previous \n" \ + \ + : "=&r" (ret), "=&r" (oldval) \ + : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \ + : "cc", "memory") + +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 = 0, ret; + + if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) + oparg = 1 << oparg; + + if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) + return -EFAULT; + + pagefault_disable(); /* implies preempt_disable() */ + + switch (op) { + case FUTEX_OP_SET: + __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_ADD: + __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_OR: + __futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_ANDN: + __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg); + break; + case FUTEX_OP_XOR: + __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg); + break; + default: + ret = -ENOSYS; + } + + pagefault_enable(); /* subsumes preempt_enable() */ + + if (!ret) { + 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; +} + +/* Compare-xchg with preemption disabled. + * Notes: + * -Best-Effort: Exchg happens only if compare succeeds. + * If compare fails, returns; leaving retry/looping to upper layers + * -successful cmp-xchg: return orig value in @addr (same as cmp val) + * -Compare fails: return orig value in @addr + * -user access r/w fails: return -EFAULT + */ +static inline int +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval, + u32 newval) +{ + u32 val; + + if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) + return -EFAULT; + + pagefault_disable(); /* implies preempt_disable() */ + + /* TBD : can use llock/scond */ + __asm__ __volatile__( + "1: ld %0, [%3] \n" + " brne %0, %1, 3f \n" + "2: st %2, [%3] \n" + "3: \n" + " .section .fixup,\"ax\" \n" + "4: mov %0, %4 \n" + " b 3b \n" + " .previous \n" + " .section __ex_table,\"a\" \n" + " .align 4 \n" + " .word 1b, 4b \n" + " .word 2b, 4b \n" + " .previous\n" + : "=&r"(val) + : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT) + : "cc", "memory"); + + pagefault_enable(); /* subsumes preempt_enable() */ + + *uval = val; + return val; +} + +#endif |