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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_ARM_FUTEX_H
#define _ASM_ARM_FUTEX_H
#ifdef __KERNEL__
#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/errno.h>
#define __futex_atomic_ex_table(err_reg) \
"3:\n" \
" .pushsection __ex_table,\"a\"\n" \
" .align 3\n" \
" .long 1b, 4f, 2b, 4f\n" \
" .popsection\n" \
" .pushsection .text.fixup,\"ax\"\n" \
" .align 2\n" \
"4: mov %0, " err_reg "\n" \
" b 3b\n" \
" .popsection"
#ifdef CONFIG_SMP
#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
({ \
unsigned int __ua_flags; \
smp_mb(); \
prefetchw(uaddr); \
__ua_flags = uaccess_save_and_enable(); \
__asm__ __volatile__( \
"1: ldrex %1, [%3]\n" \
" " insn "\n" \
"2: strex %2, %0, [%3]\n" \
" teq %2, #0\n" \
" bne 1b\n" \
" mov %0, #0\n" \
__futex_atomic_ex_table("%5") \
: "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
: "cc", "memory"); \
uaccess_restore(__ua_flags); \
})
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
unsigned int __ua_flags;
int ret;
u32 val;
if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
smp_mb();
/* Prefetching cannot fault */
prefetchw(uaddr);
__ua_flags = uaccess_save_and_enable();
__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
"1: ldrex %1, [%4]\n"
" teq %1, %2\n"
" ite eq @ explicit IT needed for the 2b label\n"
"2: strexeq %0, %3, [%4]\n"
" movne %0, #0\n"
" teq %0, #0\n"
" bne 1b\n"
__futex_atomic_ex_table("%5")
: "=&r" (ret), "=&r" (val)
: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
: "cc", "memory");
uaccess_restore(__ua_flags);
smp_mb();
*uval = val;
return ret;
}
#else /* !SMP, we can work around lack of atomic ops by disabling preemption */
#include <linux/preempt.h>
#include <asm/domain.h>
#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
({ \
unsigned int __ua_flags = uaccess_save_and_enable(); \
__asm__ __volatile__( \
"1: " TUSER(ldr) " %1, [%3]\n" \
" " insn "\n" \
"2: " TUSER(str) " %0, [%3]\n" \
" mov %0, #0\n" \
__futex_atomic_ex_table("%5") \
: "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
: "cc", "memory"); \
uaccess_restore(__ua_flags); \
})
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
unsigned int __ua_flags;
int ret = 0;
u32 val;
if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
preempt_disable();
__ua_flags = uaccess_save_and_enable();
__asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n"
" .syntax unified\n"
"1: " TUSER(ldr) " %1, [%4]\n"
" teq %1, %2\n"
" it eq @ explicit IT needed for the 2b label\n"
"2: " TUSERCOND(str, eq) " %3, [%4]\n"
__futex_atomic_ex_table("%5")
: "+r" (ret), "=&r" (val)
: "r" (oldval), "r" (newval), "r" (uaddr), "Ir" (-EFAULT)
: "cc", "memory");
uaccess_restore(__ua_flags);
*uval = val;
preempt_enable();
return ret;
}
#endif /* !SMP */
static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
{
int oldval = 0, ret, tmp;
if (!access_ok(uaddr, sizeof(u32)))
return -EFAULT;
#ifndef CONFIG_SMP
preempt_disable();
#endif
switch (op) {
case FUTEX_OP_SET:
__futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg);
break;
case FUTEX_OP_ADD:
__futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
break;
case FUTEX_OP_OR:
__futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
break;
case FUTEX_OP_ANDN:
__futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
break;
case FUTEX_OP_XOR:
__futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
break;
default:
ret = -ENOSYS;
}
#ifndef CONFIG_SMP
preempt_enable();
#endif
/*
* Store unconditionally. If ret != 0 the extra store is the least
* of the worries but GCC cannot figure out that __futex_atomic_op()
* is either setting ret to -EFAULT or storing the old value in
* oldval which results in a uninitialized warning at the call site.
*/
*oval = oldval;
return ret;
}
#endif /* __KERNEL__ */
#endif /* _ASM_ARM_FUTEX_H */
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