diff options
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/xen/events.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/arm/include/asm/xen/events.h b/arch/arm/include/asm/xen/events.h index 94b4e9020b02..5c27696de14f 100644 --- a/arch/arm/include/asm/xen/events.h +++ b/arch/arm/include/asm/xen/events.h @@ -15,4 +15,26 @@ static inline int xen_irqs_disabled(struct pt_regs *regs) return raw_irqs_disabled_flags(regs->ARM_cpsr); } +/* + * We cannot use xchg because it does not support 8-byte + * values. However it is safe to use {ldr,dtd}exd directly because all + * platforms which Xen can run on support those instructions. + */ +static inline xen_ulong_t xchg_xen_ulong(xen_ulong_t *ptr, xen_ulong_t val) +{ + xen_ulong_t oldval; + unsigned int tmp; + + wmb(); + asm volatile("@ xchg_xen_ulong\n" + "1: ldrexd %0, %H0, [%3]\n" + " strexd %1, %2, %H2, [%3]\n" + " teq %1, #0\n" + " bne 1b" + : "=&r" (oldval), "=&r" (tmp) + : "r" (val), "r" (ptr) + : "memory", "cc"); + return oldval; +} + #endif /* _ASM_ARM_XEN_EVENTS_H */ |