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author | Huang Rui <ray.huang@amd.com> | 2015-08-10 12:19:53 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2015-08-22 14:52:16 +0200 |
commit | f96756746c7909de37db3d03ac5fd5cfb2757f38 (patch) | |
tree | 45032ea51d40f96f21b0e1c534b0c360eb01dee4 /arch/x86/include/asm/mwait.h | |
parent | f0a97af83f6287357dcc100c859ec0066f164f32 (diff) | |
download | linux-stable-f96756746c7909de37db3d03ac5fd5cfb2757f38.tar.gz linux-stable-f96756746c7909de37db3d03ac5fd5cfb2757f38.tar.bz2 linux-stable-f96756746c7909de37db3d03ac5fd5cfb2757f38.zip |
x86/asm: Add MONITORX/MWAITX instruction support
AMD Carrizo processors (Family 15h, Models 60h-6fh) added a new
feature called MWAITX (MWAIT with extensions) as an extension to
MONITOR/MWAIT.
This new instruction controls a configurable timer which causes
the core to exit wait state on timer expiration, in addition to
"normal" MWAIT condition of reading from a monitored VA.
Compared to 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 ==
TSC. The software P0 frequency is the same as the TSC frequency.
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 (SW P0 == TSC)
MONITOR MONITORX
opcode 0f 01 c8 | 0f 01 fa
EAX (logical) address to monitor
ECX #GP if not zero
Max timeout = EBX/(TSC frequency)
Signed-off-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andreas Herrmann <herrmann.der.user@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dirk Brandewie <dirk.j.brandewie@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Li <tony.li@amd.com>
Link: http://lkml.kernel.org/r/1439201994-28067-3-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/mwait.h')
-rw-r--r-- | arch/x86/include/asm/mwait.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h index 653dfa7662e1..c70689b5e5aa 100644 --- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -14,6 +14,9 @@ #define CPUID5_ECX_INTERRUPT_BREAK 0x2 #define MWAIT_ECX_INTERRUPT_BREAK 0x1 +#define MWAITX_ECX_TIMER_ENABLE BIT(1) +#define MWAITX_MAX_LOOPS ((u32)-1) +#define MWAITX_DISABLE_CSTATES 0xf static inline void __monitor(const void *eax, unsigned long ecx, unsigned long edx) @@ -23,6 +26,14 @@ 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 +41,40 @@ static inline void __mwait(unsigned long eax, unsigned long ecx) :: "a" (eax), "c" (ecx)); } +/* + * MWAITX allows for a timer expiration to get the core out a wait state in + * addition to the default MWAIT exit condition of a store appearing at a + * monitored virtual address. + * + * Registers: + * + * MWAITX ECX[1]: enable timer if set + * MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks. The software P0 + * frequency is the same as the TSC frequency. + * + * Below is a comparison between MWAIT and MWAITX on AMD processors: + * + * 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 (P0 clocks) + * + * MONITOR MONITORX + * opcode 0f 01 c8 | 0f 01 fa + * EAX (logical) address to monitor + * ECX #GP if not zero + */ +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(); |