kernel/x86_64: compatibility syscall for system_info.cpp.

* define compat_system_info to be used in _user_get_system_info() in
compatibility mode.

Change-Id: Ib917d41a3a87155aee9cb536fd09e7231b232bc8

headers/private/kernel/compat/OS_compat.h

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2018, Haiku Inc. All rights reserved.
+ *
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _KERNEL_COMPAT_OS_H
+#define _KERNEL_COMPAT_OS_H
+
+
+typedef struct {
+	bigtime_t		boot_time;			/* time of boot (usecs since 1/1/1970) */
+
+	uint32			cpu_count;			/* number of cpus */
+
+	uint64			max_pages;			/* total # of accessible pages */
+	uint64			used_pages;			/* # of accessible pages in use */
+	uint64			cached_pages;
+	uint64			block_cache_pages;
+	uint64			ignored_pages;		/* # of ignored/inaccessible pages */
+
+	uint64			needed_memory;
+	uint64			free_memory;
+
+	uint64			max_swap_pages;
+	uint64			free_swap_pages;
+
+	uint32			page_faults;		/* # of page faults */
+
+	uint32			max_sems;
+	uint32			used_sems;
+
+	uint32			max_ports;
+	uint32			used_ports;
+
+	uint32			max_threads;
+	uint32			used_threads;
+
+	uint32			max_teams;
+	uint32			used_teams;
+
+	char			kernel_name[B_FILE_NAME_LENGTH];
+	char			kernel_build_date[B_OS_NAME_LENGTH];
+	char			kernel_build_time[B_OS_NAME_LENGTH];
+
+	int64			kernel_version;
+	uint32			abi;				/* the system API */
+} _PACKED compat_system_info;
+
+
+static_assert(sizeof(compat_system_info) == 0x1c4,
+	"size of compat_system_info mismatch");
+
+
+inline status_t
+copy_ref_var_to_user(system_info &info, system_info* userInfo)
+{
+	if (!IS_USER_ADDRESS(userInfo))
+		return B_BAD_ADDRESS;
+	Thread* thread = thread_get_current_thread();
+	bool compatMode = (thread->flags & THREAD_FLAGS_COMPAT_MODE) != 0;
+	if (compatMode) {
+		compat_system_info compat_info;
+		compat_info.boot_time = info.boot_time;
+		compat_info.cpu_count = info.cpu_count;
+		compat_info.max_pages = info.max_pages;
+		compat_info.used_pages = info.used_pages;
+		compat_info.cached_pages = info.cached_pages;
+		compat_info.block_cache_pages = info.block_cache_pages;
+		compat_info.ignored_pages = info.ignored_pages;
+		compat_info.needed_memory = info.needed_memory;
+		compat_info.free_memory = info.free_memory;
+		compat_info.needed_memory = info.needed_memory;
+		compat_info.max_swap_pages = info.max_swap_pages;
+		compat_info.free_swap_pages = info.free_swap_pages;
+		compat_info.max_sems = info.max_sems;
+		compat_info.used_sems = info.used_sems;
+		compat_info.max_ports = info.max_ports;
+		compat_info.used_ports = info.used_ports;
+		compat_info.max_threads = info.max_threads;
+		compat_info.used_threads = info.used_threads;
+		compat_info.max_teams = info.max_teams;
+		compat_info.used_teams = info.used_teams;
+		strlcpy(compat_info.kernel_name, info.kernel_name, B_FILE_NAME_LENGTH);
+		strlcpy(compat_info.kernel_build_date, info.kernel_build_date,
+			B_OS_NAME_LENGTH);
+		strlcpy(compat_info.kernel_build_time, info.kernel_build_time,
+			B_OS_NAME_LENGTH);
+		compat_info.kernel_version = info.kernel_version;
+		compat_info.abi = info.abi;
+		if (user_memcpy(userInfo, &compat_info, sizeof(compat_info)) < B_OK)
+			return B_BAD_ADDRESS;
+	} else if (user_memcpy(userInfo, &info, sizeof(system_info)) < B_OK)
+		return B_BAD_ADDRESS;
+	return B_OK;
+}
+
+
+#endif // _KERNEL_COMPAT_OS_H

src/system/kernel/system_info.cpp

@@ -31,6 +31,9 @@
 #include <lock.h>
 #include <Notifications.h>
 #include <messaging.h>
+#ifdef _COMPAT_MODE
+#	include <OS_compat.h>
+#endif
 #include <port.h>
 #include <real_time_clock.h>
 #include <sem.h>
@@ -38,6 +41,7 @@
 #include <team.h>
 #include <thread.h>
 #include <util/AutoLock.h>
+#include <util/syscall_args.h>
 #include <vm/vm.h>
 #include <vm/vm_page.h>
 
@@ -545,13 +549,8 @@ _user_get_system_info(system_info* userInfo)
 
 	system_info info;
 	status_t status = get_system_info(&info);
-	if (status == B_OK) {
-		if (user_memcpy(userInfo, &info, sizeof(system_info)) < B_OK)
-			return B_BAD_ADDRESS;
-
-		return B_OK;
-	}
-
+	if (status == B_OK)
+		return copy_ref_var_to_user(info, userInfo);
 	return status;
 }