gnu: add sched_getcpu()

on x86_64 implemented with rdtscp or rdpid, generically with a syscall.

Change-Id: I8f776848bf35575abec8a8c612c4a25d8550daea
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6866
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

headers/compatibility/gnu/sched.h

@@ -0,0 +1,29 @@
+/*
+* Copyright 2023 Haiku, Inc. All Rights Reserved.
+* Distributed under the terms of the MIT License.
+*/
+#ifndef _GNU_SCHED_H_
+#define _GNU_SCHED_H_
+
+
+#include_next <sched.h>
+
+
+#ifdef _GNU_SOURCE
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int sched_getcpu(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif
+
+
+#endif  /* _GNU_SCHED_H_ */

headers/private/kernel/thread.h

@@ -159,6 +159,7 @@ status_t _user_receive_data(thread_id *_sender, void *buffer, size_t buffer_size
 thread_id _user_find_thread(const char *name);
 status_t _user_get_thread_info(thread_id id, thread_info *info);
 status_t _user_get_next_thread_info(team_id team, int32 *cookie, thread_info *info);
+int _user_get_cpu();
 
 status_t _user_block_thread(uint32 flags, bigtime_t timeout);
 status_t _user_unblock_thread(thread_id thread, status_t status);

headers/private/system/syscalls.h

@@ -196,6 +196,7 @@ extern status_t		_kern_get_team_usage_info(team_id team, int32 who,
 						team_usage_info *info, size_t size);
 extern status_t		_kern_get_extended_team_info(team_id teamID, uint32 flags,
 						void* buffer, size_t size, size_t* _sizeNeeded);
+extern int			_kern_get_cpu();
 
 extern status_t		_kern_start_watching_system(int32 object, uint32 flags,
 						port_id port, int32 token);

src/libs/gnu/Jamfile

@@ -10,10 +10,16 @@ SubDirC++Flags [ FDefines _GNU_SOURCE=1 ] ;
 local architectureObject ;
 for architectureObject in [ MultiArchSubDirSetup ] {
 	on $(architectureObject) {
+		UsePrivateSystemHeaders ;
+		if $(TARGET_ARCH) = x86_64 {
+			SubDirC++Flags -mrdpid ;
+		}
+
 		SharedLibrary [ MultiArchDefaultGristFiles libgnu.so ] :
 			crypt.cpp
 			memmem.c
 			qsort.c
+			sched_getcpu.cpp
 			xattr.cpp
 			;
 	}

src/libs/gnu/sched_getcpu.cpp

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2023, Jérôme Duval, jerome.duval@gmail.com. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include <sched.h>
+
+#include <syscalls.h>
+
+#ifdef __x86_64__
+
+#include <pthread.h>
+
+#include <x86intrin.h>
+
+#define IA32_FEATURE_RDPID			(1 << 22) // RDPID Instruction
+#define IA32_FEATURE_AMD_EXT_RDTSCP		(1 << 27) // rdtscp instruction
+
+
+typedef int (*sched_cpu_func)();
+static pthread_once_t sSchedCpuInitOnce = PTHREAD_ONCE_INIT;
+static sched_cpu_func sSchedCpuFunc = NULL;
+
+
+static int
+__sched_cpu_syscall()
+{
+	return _kern_get_cpu();
+}
+
+
+static int
+__sched_cpu_rdtscp()
+{
+	uint32_t aux;
+	__rdtscp(&aux);
+	return aux;
+}
+
+
+static int
+__sched_cpu_rdpid()
+{
+	return _rdpid_u32();
+}
+
+
+static void
+initSchedCpuFunc()
+{
+	cpuid_info cpuInfo;
+	get_cpuid(&cpuInfo, 0, 0);
+	if (cpuInfo.eax_0.max_eax >= 0x7) {
+		get_cpuid(&cpuInfo, 0x7, 0);
+		if ((cpuInfo.regs.ecx & IA32_FEATURE_RDPID) != 0) {
+			sSchedCpuFunc = __sched_cpu_rdpid;
+			return;
+		}
+	}
+	get_cpuid(&cpuInfo, 0x80000000, 0);
+	if (cpuInfo.eax_0.max_eax >= 0x80000001) {
+		get_cpuid(&cpuInfo, 0x80000001, 0);
+		if ((cpuInfo.regs.edx & IA32_FEATURE_AMD_EXT_RDTSCP)!= 0) {
+			sSchedCpuFunc = __sched_cpu_rdtscp;
+			return;
+		}
+	}
+	sSchedCpuFunc = __sched_cpu_syscall;
+}
+
+
+int
+sched_getcpu()
+{
+	if (sSchedCpuFunc == NULL) {
+		pthread_once(&sSchedCpuInitOnce, &initSchedCpuFunc);
+	}
+	return sSchedCpuFunc();
+}
+
+
+#else
+int
+sched_getcpu()
+{
+	return _kern_get_cpu();
+}
+#endif
+

src/system/kernel/thread.cpp

@@ -3915,3 +3915,11 @@ _user_setrlimit(int resource, const struct rlimit *userResourceLimit)
 
 	return common_setrlimit(resource, &resourceLimit);
 }
+
+
+int
+_user_get_cpu()
+{
+	Thread* thread = thread_get_current_thread();
+	return thread->cpu->cpu_num;
+}

src/tests/libs/gnu/Jamfile

@@ -0,0 +1,8 @@
+SubDir HAIKU_TOP src tests libs gnu ;
+
+UseHeaders [ FDirName $(HAIKU_TOP) headers compatibility gnu ] : true ;
+SubDirC++Flags [ FDefines _GNU_SOURCE=1 ] ;
+
+SimpleTest sched_getcpu_test : sched_getcpu_test.cpp : libgnu.so ;
+
+

src/tests/libs/gnu/sched_getcpu_test.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2023, Jérôme Duval, jerome.duval@gmail.com. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include <sched.h>
+#include <stdio.h>
+
+
+int
+main(int argc, char** argv)
+{
+	int cpu = sched_getcpu();
+	printf("cpu: %d\n", cpu);
+	return 0;
+}
+