On Thu, Jun 11, 2015 at 10:14:10PM +0800, Huang Rui wrote:
> On AMD Carrizo processors (Family 15h, Model 60h-6fh), there is a new
> feature called MWAITT (Mwait with a timer) as an extension of
> Monitor/Mwait.
>
> MWAITT, another name is MWAITX (MWAIT with extensions), has a configurable
> timer that causes MWAITX to exit on expiration.
>
> Compared with MONITOR/MWAIT, there are minor differences in opcode and
> input parameters.
>
> MWAITX ECX[1]: enable timer if set
> MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks
>
> MWAIT MWAITX
> opcode 0f 01 c9 | 0f 01 fb
> ECX[0] value of RFLAGS.IF seen by instruction
> ECX[1] unused/#GP if set | enable timer if set
> ECX[31:2] unused/#GP if set
> EAX unused (reserve for hint)
> EBX[31:0] unused | max wait time (loops)
>
> MONITOR MONITORX
> opcode 0f 01 c8 | 0f 01 fa
> EAX (logical) address to monitor
> ECX #GP if not zero
>
> The software P0 frequency is the same as the TSC frequency.
>
> Max timeout = EBX/(TSC frequency)
As suggested last time, please put the description of MWAITX over
__mwaitx() in the code as comments below. See below.
> Signed-off-by: Huang Rui <ray.hu...@amd.com>
> ---
> arch/x86/include/asm/cpufeature.h | 1 +
> arch/x86/include/asm/mwait.h | 16 ++++++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/arch/x86/include/asm/cpufeature.h
> b/arch/x86/include/asm/cpufeature.h
> index 3d6606f..3ef1f6e 100644
> --- a/arch/x86/include/asm/cpufeature.h
> +++ b/arch/x86/include/asm/cpufeature.h
> @@ -176,6 +176,7 @@
> #define X86_FEATURE_PERFCTR_NB ( 6*32+24) /* NB performance counter
> extensions */
> #define X86_FEATURE_BPEXT (6*32+26) /* data breakpoint extension */
> #define X86_FEATURE_PERFCTR_L2 ( 6*32+28) /* L2 performance counter
> extensions */
> +#define X86_FEATURE_MWAITT ( 6*32+29) /* Mwait extension (MonitorX/MwaitX)
> */
>
> /*
> * Auxiliary flags: Linux defined - For features scattered in various
> diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
> index 653dfa7..ece8048 100644
> --- a/arch/x86/include/asm/mwait.h
> +++ b/arch/x86/include/asm/mwait.h
> @@ -23,6 +23,14 @@ static inline void __monitor(const void *eax, unsigned
> long ecx,
> :: "a" (eax), "c" (ecx), "d"(edx));
> }
>
> +static inline void __monitorx(const void *eax, unsigned long ecx,
> + unsigned long edx)
> +{
> + /* "monitorx %eax, %ecx, %edx;" */
> + asm volatile(".byte 0x0f, 0x01, 0xfa;"
> + :: "a" (eax), "c" (ecx), "d"(edx));
> +}
> +
> static inline void __mwait(unsigned long eax, unsigned long ecx)
> {
> /* "mwait %eax, %ecx;" */
> @@ -30,6 +38,14 @@ static inline void __mwait(unsigned long eax, unsigned
> long ecx)
> :: "a" (eax), "c" (ecx));
> }
<Add comment here!>
> +static inline void __mwaitx(unsigned long eax, unsigned long ebx,
> + unsigned long ecx)
> +{
> + /* "mwaitx %eax, %ebx, %ecx;" */
> + asm volatile(".byte 0x0f, 0x01, 0xfb;"
> + :: "a" (eax), "b" (ebx), "c" (ecx));
> +}
> +
> static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
> {
> trace_hardirqs_on();
> --
> 1.9.1
>
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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