On Wed, 2014-11-12 at 19:25 -0800, Andy Lutomirski wrote:
On 11/11/2014 10:43 AM, Ross Zwisler wrote:
Add support for the new pcommit instruction. This instruction was announced in the document "Intel Architecture Instruction Set Extensions Programming Reference" with reference number 319433-022.
https://software.intel.com/sites/default/files/managed/0d/53/319433-022.pdf
Signed-off-by: Ross Zwisler ross.zwisler@linux.intel.com Cc: H Peter Anvin h.peter.anvin@intel.com Cc: Ingo Molnar mingo@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: David Airlie airlied@linux.ie Cc: dri-devel@lists.freedesktop.org Cc: x86@kernel.org
arch/x86/include/asm/cpufeature.h | 1 + arch/x86/include/asm/special_insns.h | 6 ++++++ 2 files changed, 7 insertions(+)
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 0bb1335..b3e6b89 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -225,6 +225,7 @@ #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_PCOMMIT ( 9*32+22) /* PCOMMIT instruction */ #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 */ diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index e820c08..1709a2e 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -199,6 +199,12 @@ static inline void clflushopt(volatile void *__p) "+m" (*(volatile char __force *)__p)); }
+static inline void pcommit(void) +{
- alternative(ASM_NOP4, ".byte 0x66, 0x0f, 0xae, 0xf8",
X86_FEATURE_PCOMMIT);+}
Should this patch add the feature bit and cpuinfo entry to go with it?
--Andy
I think this patch does everything we need? The text for cpuinfo is auto-generated in arch/x86/kernel/cpu/capflags.c from the flags defined in arch/x86/include/asm/cpufeature.h, I think. Here's what I get in cpuinfo on my system with a faked-out CPUID saying that clwb and pcommit are present:
$ grep 'flags' /proc/cpuinfo flags : fpu <snip> erms pcommit clflushopt clwb xsaveopt
The X86_FEATURE_CLWB and X86_FEATURE_PCOMMIT flags are being set up according to what's in CPUID, and the proper alternatives are being triggered. I stuck some debug code in the alternatives code to see what was being patched in the presence and absence of each of the flags.
Is there something else I'm missing?
Thanks, - Ross