x86: Add support for the clflushopt instruction
Add support for the new clflushopt instruction. This instruction was
announced in the document "Intel Architecture Instruction Set Extensions
Programming Reference" with Ref # 319433-018.
http://download-software.intel.com/sites/default/files/managed/50/1a/319433-018.pdf
[ hpa: changed the feature flag to simply X86_FEATURE_CLFLUSHOPT - if
that is what we want to report in /proc/cpuinfo anyway... ]
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Link: http://lkml.kernel.org/r/1393441612-19729-2-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 5f12968..bc507d7 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -221,6 +221,7 @@
#define X86_FEATURE_RDSEED (9*32+18) /* The RDSEED instruction */
#define X86_FEATURE_ADX (9*32+19) /* The ADCX and ADOX instructions */
#define X86_FEATURE_SMAP (9*32+20) /* Supervisor Mode Access Prevention */
+#define X86_FEATURE_CLFLUSHOPT (9*32+23) /* CLFLUSHOPT instruction */
#define X86_FEATURE_AVX512PF (9*32+26) /* AVX-512 Prefetch */
#define X86_FEATURE_AVX512ER (9*32+27) /* AVX-512 Exponential and Reciprocal */
#define X86_FEATURE_AVX512CD (9*32+28) /* AVX-512 Conflict Detection */
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 645cad2..e820c08 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -191,6 +191,14 @@
asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
}
+static inline void clflushopt(volatile void *__p)
+{
+ alternative_io(".byte " __stringify(NOP_DS_PREFIX) "; clflush %P0",
+ ".byte 0x66; clflush %P0",
+ X86_FEATURE_CLFLUSHOPT,
+ "+m" (*(volatile char __force *)__p));
+}
+
#define nop() asm volatile ("nop")