internal/cpu, runtime: add CPU feature detection support for AIX

AIX doesn't have HWCAP/HWCAP2 variables like Linux. Therefore, it relies on
getsystemcfg syscall which can provide some information about the CPU.

Change-Id: Ic0dc927e80890d4bf8f0bdfb43fad1e2b890d7a0
Reviewed-on: https://go-review.googlesource.com/c/144959
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>

diff --git a/src/internal/cpu/cpu_ppc64x.go b/src/internal/cpu/cpu_ppc64x.go
index 1e7959b30658b887ab62d4a7bed4605240d71802..880c4e1d01806ac753b288eee022eab226cad1a5 100644 (file)
--- a/src/internal/cpu/cpu_ppc64x.go
+++ b/src/internal/cpu/cpu_ppc64x.go
@@ -11,18 +11,19 @@ const CacheLinePadSize = 128
 // ppc64x doesn't have a 'cpuid' equivalent, so we rely on HWCAP/HWCAP2.
 // These are initialized by archauxv in runtime/os_linux_ppc64x.go.
 // These should not be changed after they are initialized.
+// On aix/ppc64, these values are initialized early in the runtime in runtime/os_aix.go.
 var HWCap uint
 var HWCap2 uint
 
 // HWCAP/HWCAP2 bits. These are exposed by the kernel.
 const (
        // ISA Level
-       _PPC_FEATURE2_ARCH_2_07 = 0x80000000
-       _PPC_FEATURE2_ARCH_3_00 = 0x00800000
+       PPC_FEATURE2_ARCH_2_07 = 0x80000000
+       PPC_FEATURE2_ARCH_3_00 = 0x00800000
 
        // CPU features
-       _PPC_FEATURE2_DARN = 0x00200000
-       _PPC_FEATURE2_SCV  = 0x00100000
+       PPC_FEATURE2_DARN = 0x00200000
+       PPC_FEATURE2_SCV  = 0x00100000
 )
 
 func doinit() {
@@ -36,10 +37,10 @@ func doinit() {
        }
 
        // HWCAP2 feature bits
-       PPC64.IsPOWER8 = isSet(HWCap2, _PPC_FEATURE2_ARCH_2_07)
-       PPC64.IsPOWER9 = isSet(HWCap2, _PPC_FEATURE2_ARCH_3_00)
-       PPC64.HasDARN = isSet(HWCap2, _PPC_FEATURE2_DARN)
-       PPC64.HasSCV = isSet(HWCap2, _PPC_FEATURE2_SCV)
+       PPC64.IsPOWER8 = isSet(HWCap2, PPC_FEATURE2_ARCH_2_07)
+       PPC64.IsPOWER9 = isSet(HWCap2, PPC_FEATURE2_ARCH_3_00)
+       PPC64.HasDARN = isSet(HWCap2, PPC_FEATURE2_DARN)
+       PPC64.HasSCV = isSet(HWCap2, PPC_FEATURE2_SCV)
 }
 
 func isSet(hwc uint, value uint) bool {

diff --git a/src/runtime/os2_aix.go b/src/runtime/os2_aix.go
index 9e26ce23fc457ca1931112556f142892ea10e931..c478d4b0d89b257d0cf833849256b53f8df57f5b 100644 (file)
--- a/src/runtime/os2_aix.go
+++ b/src/runtime/os2_aix.go
@@ -33,6 +33,7 @@ var (
 //go:cgo_import_dynamic libc_close close "libc.a/shr_64.o"
 //go:cgo_import_dynamic libc_exit exit "libc.a/shr_64.o"
 //go:cgo_import_dynamic libc_getpid getpid "libc.a/shr_64.o"
+//go:cgo_import_dynamic libc_getsystemcfg getsystemcfg "libc.a/shr_64.o"
 //go:cgo_import_dynamic libc_kill kill "libc.a/shr_64.o"
 //go:cgo_import_dynamic libc_madvise madvise "libc.a/shr_64.o"
 //go:cgo_import_dynamic libc_malloc malloc "libc.a/shr_64.o"
@@ -69,6 +70,7 @@ var (
 //go:linkname libc_close libc_close
 //go:linkname libc_exit libc_exit
 //go:linkname libc_getpid libc_getpid
+//go:linkname libc_getsystemcfg libc_getsystemcfg
 //go:linkname libc_kill libc_kill
 //go:linkname libc_madvise libc_madvise
 //go:linkname libc_malloc libc_malloc
@@ -107,6 +109,7 @@ var (
        libc_close,
        libc_exit,
        libc_getpid,
+       libc_getsystemcfg,
        libc_kill,
        libc_madvise,
        libc_malloc,
@@ -319,6 +322,12 @@ func sigaltstack(new, old *stackt) {
        }
 }
 
+//go:nosplit
+func getsystemcfg(label uint) uintptr {
+       r, _ := syscall1(&libc_getsystemcfg, uintptr(label))
+       return r
+}
+
 //go:nosplit
 func usleep(us uint32) {
        r, err := syscall1(&libc_usleep, uintptr(us))

diff --git a/src/runtime/os_aix.go b/src/runtime/os_aix.go
index 31590f22d8865a3a64839313a9ddfad2e4523257..141ce3bb119564cba10d242166668d025aeaa7a3 100644 (file)
--- a/src/runtime/os_aix.go
+++ b/src/runtime/os_aix.go
@@ -7,6 +7,7 @@
 package runtime
 
 import (
+       "internal/cpu"
        "unsafe"
 )
 
@@ -93,6 +94,7 @@ func semawakeup(mp *m) {
 func osinit() {
        ncpu = int32(sysconf(__SC_NPROCESSORS_ONLN))
        physPageSize = sysconf(__SC_PAGE_SIZE)
+       setupSystemConf()
 }
 
 // Ms related functions
@@ -260,3 +262,22 @@ func walltime() (sec int64, nsec int32) {
        }
        return ts.tv_sec, int32(ts.tv_nsec)
 }
+
+const (
+       // getsystemcfg constants
+       _SC_IMPL     = 2
+       _IMPL_POWER8 = 0x10000
+       _IMPL_POWER9 = 0x20000
+)
+
+// setupSystemConf retrieves information about the CPU and updates
+// cpu.HWCap variables.
+func setupSystemConf() {
+       impl := getsystemcfg(_SC_IMPL)
+       if impl&_IMPL_POWER8 != 0 {
+               cpu.HWCap2 |= cpu.PPC_FEATURE2_ARCH_2_07
+       }
+       if impl&_IMPL_POWER9 != 0 {
+               cpu.HWCap2 |= cpu.PPC_FEATURE2_ARCH_3_00
+       }
+}