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#ifndef _ASM_X86_MWAIT_H
#define _ASM_X86_MWAIT_H
#include <linux/sched.h>
#include <asm/spec_ctrl.h>
#include <asm/cpufeature.h>
#include <asm/nospec-branch.h>
#define MWAIT_SUBSTATE_MASK 0xf
#define MWAIT_CSTATE_MASK 0xf
#define MWAIT_SUBSTATE_SIZE 4
#define MWAIT_HINT2CSTATE(hint) (((hint) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK)
#define MWAIT_HINT2SUBSTATE(hint) ((hint) & MWAIT_CSTATE_MASK)
#define CPUID_MWAIT_LEAF 5
#define CPUID5_ECX_EXTENSIONS_SUPPORTED 0x1
#define CPUID5_ECX_INTERRUPT_BREAK 0x2
#define MWAIT_ECX_INTERRUPT_BREAK 0x1
static __always_inline void __monitor(const void *eax, unsigned long ecx,
unsigned long edx)
{
/* "monitor %eax, %ecx, %edx;" */
asm volatile(".byte 0x0f, 0x01, 0xc8;"
:: "a" (eax), "c" (ecx), "d"(edx));
}
static __always_inline void __mwait(unsigned long eax, unsigned long ecx)
{
mds_idle_clear_cpu_buffers();
/* "mwait %eax, %ecx;" */
asm volatile(".byte 0x0f, 0x01, 0xc9;"
:: "a" (eax), "c" (ecx));
}
/*
* This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
* which can obviate IPI to trigger checking of need_resched.
* We execute MONITOR against need_resched and enter optimized wait state
* through MWAIT. Whenever someone changes need_resched, we would be woken
* up from MWAIT (without an IPI).
*
* New with Core Duo processors, MWAIT can take some hints based on CPU
* capability.
*/
static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
{
if (static_cpu_has_bug(X86_BUG_MONITOR) || !current_set_polling_and_test()) {
if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
clflush((void *)¤t_thread_info()->flags);
/*
* IRQs must be disabled here and nmi uses the
* save_paranoid model which always enables ibrs on
* exception entry before any indirect jump can run.
*/
spec_ctrl_ibrs_off();
__monitor((void *)¤t_thread_info()->flags, 0, 0);
if (!need_resched())
__mwait(eax, ecx);
spec_ctrl_ibrs_on();
}
__current_clr_polling();
}
#endif /* _ASM_X86_MWAIT_H */
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