Kernel: Add the clock_gettime syscall, which replaces clock as it can be used for more stuff

kernel/include/sys/Syscall.h

@@ -18,7 +18,7 @@
 #define SYS_execv 12
 #define SYS_fcntl 13
 #define SYS_mprotect 14
-#define SYS_clock 15
+#define SYS_clock_gettime 15
 #define SYS_mkdir 16
 #define SYS_fork 17
 #define SYS_waitpid 18
@@ -34,6 +34,7 @@
 struct stat;
 struct pstat;
 struct luna_dirent;
+struct timespec;
 
 namespace Syscall
 {
@@ -55,7 +56,7 @@ void sys_seek(Context* context, int fd, long offset, int whence);
 void sys_execv(Context* context, const char* pathname, char** argv);
 void sys_fcntl(Context* context, int fd, int command, uintptr_t arg);
 void sys_mprotect(Context* context, void* address, size_t size, int prot);
-void sys_clock(Context* context);
+void sys_clock_gettime(Context* context, int clock_id, struct timespec* tp);
 void sys_mkdir(Context* context, const char* filename, mode_t mode);
 void sys_fork(Context* context);
 void sys_waitpid(Context* context, long pid, int* wstatus, int options);

kernel/src/sys/Syscall.cpp

@@ -26,7 +26,7 @@ void Syscall::entry(Context* context)
     case SYS_execv: sys_execv(context, (const char*)context->rdi, (char**)context->rsi); break;
     case SYS_fcntl: sys_fcntl(context, (int)context->rdi, (int)context->rsi, context->rdx); break;
     case SYS_mprotect: sys_mprotect(context, (void*)context->rdi, context->rsi, (int)context->rdx); break;
-    case SYS_clock: sys_clock(context); break;
+    case SYS_clock_gettime: sys_clock_gettime(context, (int)context->rdi, (struct timespec*)context->rsi); break;
     case SYS_mkdir: sys_mkdir(context, (const char*)context->rdi, (mode_t)context->rsi); break;
     case SYS_fork: sys_fork(context); break;
     case SYS_waitpid: sys_waitpid(context, (long)context->rdi, (int*)context->rsi, (int)context->rdx); break;

kernel/src/sys/clock.cpp

@@ -9,6 +9,62 @@
 
 static uint64_t unix_boot_time;
 
+#define CLOCK_REALTIME 0
+#define CLOCK_MONOTONIC 1
+#define CLOCK_PROCTIME 2
+
+struct timeval
+{
+    time_t tv_sec;
+    suseconds_t tv_usec;
+};
+
+struct timespec
+{
+    time_t tv_sec;
+    long tv_nsec;
+};
+
+static void ms_to_timespec(long ms, struct timespec* tv)
+{
+    tv->tv_sec = ms / 1000;
+    tv->tv_nsec = (ms % 1000) * 1000000;
+}
+
+void sys_clock_gettime(Context* context, int clock, struct timespec* tp)
+{
+    struct timespec* ktp = obtain_user_ref(tp);
+    if (!ktp)
+    {
+        context->rax = -EFAULT; // FIXME: Not sure if clock_gettime can return EFAULT.
+        return;
+    }
+    Task* current_task = Scheduler::current_task();
+    switch (clock)
+    {
+    case CLOCK_REALTIME: {
+        ms_to_timespec(PIT::ms_since_boot, ktp);
+        ktp->tv_sec += unix_boot_time;
+        break;
+    }
+    case CLOCK_MONOTONIC: {
+        ms_to_timespec(PIT::ms_since_boot, ktp);
+        break;
+    }
+    case CLOCK_PROCTIME: {
+        ms_to_timespec(current_task->cpu_time, ktp);
+        break;
+    }
+    default:
+        release_user_ref(ktp);
+        context->rax = -EINVAL;
+        return;
+    }
+    release_user_ref(ktp);
+    context->rax = 0;
+    return;
+}
+
 extern BOOTBOOT bootboot;
 
 void clock_init()