arch: add cpu probing

For now, just a check to see if we have SSE4.2.

Signed-off-by: Sage Weil <[email protected]>

src/Makefile.am

@@ -1504,6 +1504,8 @@ crush_files = \
 # this list ommits the ceph_ver.c file
 libcommon_files = \
 	./ceph_ver.c \
+	arch/probe.cc \
+	arch/intel.c \
 	auth/AuthAuthorizeHandler.cc \
 	auth/AuthClientHandler.cc \
 	auth/AuthSessionHandler.cc \
@@ -1746,6 +1748,8 @@ python_PYTHON = pybind/rados.py \
 # that autotools doesn't magically identify.
 noinst_HEADERS = \
 	rados_sync.h \
+	arch/probe.h \
+	arch/intel.h \
 	auth/cephx/CephxAuthorizeHandler.h\
 	auth/cephx/CephxKeyServer.h\
 	auth/cephx/CephxProtocol.h\

src/arch/intel.c

@@ -0,0 +1,46 @@
+#include "arch/probe.h"
+
+/* flags we export */
+int ceph_arch_intel_sse42 = 0;
+
+
+/* this probably isn't specific enough for x86_64?  fix me someday */
+#ifdef __LP64__
+
+/* intel cpu? */
+static void do_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
+                     unsigned int *edx)
+{
+        int id = *eax;
+
+        asm("movl %4, %%eax;"
+            "cpuid;"
+            "movl %%eax, %0;"
+            "movl %%ebx, %1;"
+            "movl %%ecx, %2;"
+            "movl %%edx, %3;"
+                : "=r" (*eax), "=r" (*ebx), "=r" (*ecx), "=r" (*edx)
+                : "r" (id)
+                : "eax", "ebx", "ecx", "edx");
+}
+
+int ceph_arch_intel_probe(void)
+{
+	/* i know how to check this on x86_64... */
+	unsigned int eax = 1, ebx, ecx, edx;
+	do_cpuid(&eax, &ebx, &ecx, &edx);
+	if ((ecx & (1 << 20)) != 0) {
+		ceph_arch_intel_sse42 = 1;
+	}
+	return 0;
+}
+
+#else // __LP64__
+
+int ceph_arch_intel_probe(void)
+{
+	/* no features */
+	return 0;
+}
+
+#endif // __LP64__

src/arch/intel.h

@@ -0,0 +1,16 @@
+#ifndef CEPH_ARCH_INTEL_H
+#define CEPH_ARCH_INTEL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int ceph_arch_intel_sse42;  /* true if we have sse 4.2 features */
+
+extern int ceph_arch_intel_probe(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/arch/probe.cc

@@ -0,0 +1,20 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "arch/probe.h"
+
+#include "arch/intel.h"
+
+int ceph_arch_probe(void)
+{
+  if (ceph_arch_probed)
+    return 1;
+
+  ceph_arch_intel_probe();
+
+  ceph_arch_probed = 1;
+  return 1;
+}
+
+// do this once using the magic of c++.
+int ceph_arch_probed = ceph_arch_probe();

src/arch/probe.h

@@ -0,0 +1,16 @@
+#ifndef CEPH_ARCH_PROBE_H
+#define CEPH_ARCH_PROBE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int ceph_arch_probed;  /* non-zero if we've probed features */
+
+extern int ceph_arch_probe(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif