Implement waiting for process, CE add command cancelation, rctx many cpus

aux/qemu_amd64.sh

@@ -2,4 +2,4 @@
 
 set -x
 
-qemu-system-x86_64 -M q35 -m 4G -serial stdio -enable-kvm -cdrom mop3.iso -smp 4 $@
+qemu-system-x86_64 -M q35 -m 4G -serial stdio -enable-kvm -cdrom mop3.iso -smp 1 $@

ce/ce.c

@@ -14,6 +14,9 @@
 #include <system.h>
 #include <terminal_cursor.h>
 
+#define CTRL(x)         ((x) - '@')
+#define CPRINTF_BUF_MAX (1024 * 16)
+
 static struct arena arena;
 
 struct strbuf {
@@ -45,8 +48,6 @@ struct context {
   struct strbuf strbuf;
 };
 
-#define CPRINTF_BUF_MAX 4096
-
 void cprintf (struct context* context, const char* fmt, ...) {
   va_list args;
   va_start (args, fmt);
@@ -264,8 +265,26 @@ static int e_pgid;
 
 static bool run = true;
 
-static void putch (char ch) { mail_send (e_pgid, &ch, 1); }
+void putchar_ (char ch) { (void)ch; }
-void putchar_ (char ch) { putch (ch); }
+
+void mprintf (const char* fmt, ...) {
+  va_list args;
+  va_start (args, fmt);
+
+  char* buf = malloc (CPRINTF_BUF_MAX);
+
+  if (buf == NULL) {
+    va_end (args);
+    return;
+  }
+
+  int len = vsnprintf (buf, CPRINTF_BUF_MAX, fmt, args);
+
+  va_end (args);
+
+  mail_send (e_pgid, buf, len);
+  free (buf);
+}
 
 static void tokenize (struct list_node_link** tokens, const char* text) {
   const char* p = text;
@@ -311,7 +330,7 @@ static void tokenize (struct list_node_link** tokens, const char* text) {
       continue;
     }
 
-    printf ("ERROR unknown character '%c'\n", *p);
+    mprintf ("ERROR unknown character '%c'\r\n", *p);
     p++;
   }
 }
@@ -331,7 +350,7 @@ static void parse_and_execute (struct list_node_link* tokens) {
       execute (root, &context);
 
       if (context.strbuf.items != NULL)
-        printf ("%.*s", (int)context.strbuf.count, context.strbuf.items);
+        mprintf ("%.*s", (int)context.strbuf.count, context.strbuf.items);
     }
   }
 }
@@ -350,12 +369,12 @@ static void mkfile (struct context* context, char** file_paths, size_t files_cou
     const char* file_path = file_paths[i];
 
     if (!path_parse (file_path, volume, &path)) {
-      cprintf (context, "ERROR bad path '%s'\n", file_path);
+      cprintf (context, "ERROR bad path '%s'\r\n", file_path);
       continue;
     }
 
     if ((ret = volume_open (volume)) < 0) {
-      cprintf (context, "ERROR could not open volume '%s': %s\n", volume, str_status[-ret]);
+      cprintf (context, "ERROR could not open volume '%s': %s\r\n", volume, str_status[-ret]);
       continue;
     }
 
@@ -375,12 +394,12 @@ static void cat (struct context* context, char** file_paths, size_t files_count)
     const char* file_path = file_paths[i];
 
     if (!path_parse (file_path, volume, &path)) {
-      cprintf (context, "ERROR bad path '%s'\n", file_path);
+      cprintf (context, "ERROR bad path '%s'\r\n", file_path);
       continue;
     }
 
     if ((ret = volume_open (volume)) < 0) {
-      cprintf (context, "ERROR could not open volume '%s': %s\n", volume, str_status[-ret]);
+      cprintf (context, "ERROR could not open volume '%s': %s\r\n", volume, str_status[-ret]);
       continue;
     }
 
@@ -396,7 +415,7 @@ static void cat (struct context* context, char** file_paths, size_t files_count)
 
     memset (buffer, 0, desc.size + 1);
     read_file (path, 0, (uint8_t*)buffer, desc.size);
-    cprintf (context, "%s\n", buffer);
+    cprintf (context, "%s\r\n", buffer);
 
   close:
     if (buffer != NULL)
@@ -413,26 +432,26 @@ static void ls (struct context* context, const char* path_string) {
   struct dir_entry entry;
 
   if (!path_parse (path_string, volume, &path)) {
-    cprintf (context, "ERROR bad path '%s'\n", path_string);
+    cprintf (context, "ERROR bad path '%s'\r\n", path_string);
     return;
   }
 
   if ((ret = volume_open (volume)) < 0) {
-    cprintf (context, "ERROR could not open volume '%s': %s\n", volume, str_status[-ret]);
+    cprintf (context, "ERROR could not open volume '%s': %s\r\n", volume, str_status[-ret]);
     return;
   }
 
   describe (path, &desc);
 
   if (desc.type != FS_DIR) {
-    cprintf (context, "ERROR '%s' is not a directory\n", path_string);
+    cprintf (context, "ERROR '%s' is not a directory\r\n", path_string);
     volume_close ();
     return;
   }
 
   size_t entries = desc.size;
-  cprintf (context, "total entries: %zu\n", entries);
+  cprintf (context, "total entries: %zu\r\n", entries);
-  cprintf (context, "\n");
+  cprintf (context, "\r\n");
 
   for (size_t entry_num = 0; entry_num < entries; entry_num++) {
     memset (&desc, 0, sizeof (desc));
@@ -441,7 +460,7 @@ static void ls (struct context* context, const char* path_string) {
     read_dir_entry (path, &entry, entry_num);
     describe (entry.path, &desc);
 
-    cprintf (context, "%c %-40s %-40zu\n", (desc.type == FS_DIR ? 'D' : 'F'), entry.path,
+    cprintf (context, "%c %-40s %-40zu\r\n", (desc.type == FS_DIR ? 'D' : 'F'), entry.path,
              desc.size);
   }
 
@@ -450,17 +469,33 @@ static void ls (struct context* context, const char* path_string) {
 
 static void quit1 (struct context* context) {
   run = false;
-  cprintf (context, "Goodbye!\n");
+  cprintf (context, "Goodbye!\r\n");
 }
 
 static void help (struct context* context) {
-  cprintf (context, "Available commands:\n");
+  cprintf (context, "Available commands:\r\n");
-  cprintf (context, "echo <word1> <word2> <word3> ...\n");
+  cprintf (context, "echo <word1> <word2> <word3> ...\r\n");
-  cprintf (context, "help\n");
+  cprintf (context, "help\r\n");
-  cprintf (context, "cat <file path>\n");
+  cprintf (context, "cat <file path>\r\n");
-  cprintf (context, "ls <directory path>\n");
+  cprintf (context, "ls <directory path>\r\n");
-  cprintf (context, "mkfile <file path>\n");
+  cprintf (context, "mkfile <file path>\r\n");
-  cprintf (context, "quit\n");
+  cprintf (context, "quit\r\n");
+}
+
+static void cmd_cancel_proc (void) {
+  int pid = *(int*)argument_ptr ();
+
+  char ch = 0;
+  for (;;) {
+    mail_receive (&ch, 1);
+
+    if (ch == CTRL ('C'))
+      break;
+  }
+
+  kill (pid);
+
+  quit ();
 }
 
 static void execute_cmd (struct ast_cmd* cmd, struct context* context) {
@@ -477,7 +512,27 @@ static void execute_cmd (struct ast_cmd* cmd, struct context* context) {
   } else if (strcmp (cmd->name, "mkfile") == 0) {
     mkfile (context, cmd->args, cmd->arg_count);
   } else {
-    cprintf (context, "ERROR unknown command '%s'\n", cmd->name);
+    /* cprintf (context, "ERROR unknown command '%s'\r\n", cmd->name); */
+    char volume[VOLUME_MAX];
+    const char* path;
+
+    if (!(path_parse (cmd->name, volume, &path))) {
+      cprintf (context, "ERROR bad path '%s'\r\n", cmd->name);
+      return;
+    }
+
+    int pid = exec (volume, path);
+
+    if (pid < 0) {
+      cprintf (context, "ERROR could not run '%s': %s\r\n", cmd->name, str_status[-pid]);
+      return;
+    }
+
+    int cancel_pid = process_spawn (&cmd_cancel_proc, &pid);
+
+    wait_for_pid (pid);
+
+    kill (cancel_pid);
   }
 }
 
@@ -487,12 +542,12 @@ static void execute_redir (struct ast_redir* redir, struct context* context) {
   int ret;
 
   if (!(path_parse (redir->file_path, volume, &path))) {
-    cprintf (context, "ERROR bad path '%s'\n", redir->file_path);
+    cprintf (context, "ERROR bad path '%s'\r\n", redir->file_path);
     return;
   }
 
   if ((ret = volume_open (volume)) < 0) {
-    cprintf (context, "ERROR could not open volume '%s': %s\n", volume, str_status[-ret]);
+    cprintf (context, "ERROR could not open volume '%s': %s\r\n", volume, str_status[-ret]);
     return;
   }
 
@@ -543,7 +598,7 @@ void app_main (void) {
   memset (line_buffer, 0, sizeof (line_buffer));
 
   while (run) {
-    printf (PROMPT);
+    mprintf (PROMPT);
 
     char ch = 0;
     for (;;) {
@@ -554,11 +609,11 @@ void app_main (void) {
 
       if (line_cursor < LINE_BUFFER_MAX) {
         line_buffer[line_cursor++] = ch;
-        printf ("%c", ch);
+        mprintf ("%c", ch);
       }
     }
 
-    printf ("\n");
+    mprintf ("\r\n");
     exec_line (line_buffer);
 
     line_cursor = 0;

include/syscall_defs.h

@@ -25,5 +25,7 @@
 #define SYS_READ_DIR_ENTRY 22
 #define SYS_CREATE_FILE   23
 #define SYS_WRITE_FILE    24
+#define SYS_WAIT_FOR_PID  25
+#define SYS_KILL          26
 
 #endif // _M_SYSCALL_DEFS_H

init/init.c

@@ -6,16 +6,17 @@
 #include <string.h>
 #include <terminal.h>
 
+#define RECV_MAX (1024 * 16)
+
 static int ce_pgid;
 
 void receiver (void) {
   for (;;) {
-    char rcv;
+    char recv[RECV_MAX];
-    mail_receive (&rcv, 1);
+    memset (recv, 0, sizeof (recv));
-    if (rcv == '\n')
+    mail_receive (&recv, sizeof (recv) - 1);
-      terminal_print ("\r\n", 2);
+
-    else
+    terminal_print (recv, strlen (recv));
-      terminal_print (&rcv, 1);
   }
 }
 

kernel/amd64/bootmain.c

@@ -56,8 +56,6 @@ void bootmain (void) {
   devices_init ();
   vfs_init ();
 
-  struct reschedule_ctx rctx = {.cpu = NULL, .reschedule = false};
-
   struct device* ramdisk = device_find ("RD");
   vfs_create_volume ("RD", VFS_TARFS, ramdisk, false);
 

kernel/amd64/intr.c

@@ -5,6 +5,7 @@
 #include <amd64/io.h>
 #include <aux/compiler.h>
 #include <irq/irq.h>
+#include <libk/lengthof.h>
 #include <libk/std.h>
 #include <libk/string.h>
 #include <mm/liballoc.h>
@@ -160,11 +161,19 @@ static void intr_exception (struct saved_regs* regs) {
                regs->rbx);
 
   if (regs->cs == (GDT_UCODE | 0x03)) {
-    struct reschedule_ctx rctx = {.reschedule = false, .cpu = NULL};
+    struct reschedule_ctx rctx = {0};
     proc_kill (thiscpu->proc_current, &rctx);
 
-    if (rctx.reschedule)
+    bool do_thiscpu = false;
-      cpu_request_sched (rctx.cpu);
+    for (size_t i = 0; i < lengthof (rctx.cpus); i++) {
+      if (rctx.cpus[i] != NULL && rctx.cpus[i] != thiscpu)
+        cpu_request_sched (rctx.cpus[i]);
+      else
+        do_thiscpu = true;
+    }
+
+    if (do_thiscpu)
+      cpu_request_sched (thiscpu);
   } else {
     __asm__ volatile ("cli");
     spin ();
@@ -196,11 +205,19 @@ void intr_handler (void* stack_ptr) {
     if (irq == NULL)
       return;
 
-    struct reschedule_ctx rctx = {.reschedule = false, .cpu = NULL};
+    struct reschedule_ctx rctx = {0};
     irq->func (irq->arg, stack_ptr, &rctx);
 
-    if (rctx.reschedule)
+    bool do_thiscpu = false;
-      cpu_request_sched (rctx.cpu);
+    for (size_t i = 0; i < lengthof (rctx.cpus); i++) {
+      if (rctx.cpus[i] != NULL && rctx.cpus[i] != thiscpu)
+        cpu_request_sched (rctx.cpus[i]);
+      else
+        do_thiscpu = true;
+    }
+
+    if (do_thiscpu)
+      cpu_request_sched (thiscpu);
   }
 }
 

kernel/amd64/proc.c

@@ -109,6 +109,26 @@ struct proc* proc_clone (struct proc* proto, uintptr_t vstack_top, uintptr_t ent
 }
 
 void proc_cleanup (struct proc* proc, struct reschedule_ctx* rctx) {
+  spin_lock (&proc->lock);
+  spin_lock (&proc->done_sq.lock);
+
+  while (proc->done_sq.proc_list != NULL) {
+    struct list_node_link* node = proc->done_sq.proc_list;
+    struct proc_sq_entry* sq_entry = list_entry (node, struct proc_sq_entry, sq_link);
+    struct proc* suspended_proc = sq_entry->proc;
+
+    spin_unlock (&proc->done_sq.lock);
+    spin_unlock (&proc->lock);
+
+    proc_sq_resume (suspended_proc, sq_entry, rctx);
+
+    spin_lock (&proc->lock);
+    spin_lock (&proc->done_sq.lock);
+  }
+
+  spin_unlock (&proc->done_sq.lock);
+  spin_unlock (&proc->lock);
+
   proc_sqs_cleanup (proc);
   proc_mutexes_cleanup (proc, rctx);
 

kernel/amd64/smp.c

@@ -100,10 +100,10 @@ static void smp_bootstrap (struct limine_mp_info* mp_info) {
 
   atomic_fetch_sub (&cpu_counter, 1);
 
-  struct reschedule_ctx rctx = {.cpu = NULL, .reschedule = false};
+  struct reschedule_ctx rctx = {0};
 
   struct proc* spin_proc = proc_from_file (VFS_KERNEL, "RD", "/spin", &rctx);
-  proc_register (spin_proc, thiscpu, NULL);
+  proc_register (spin_proc, thiscpu, &rctx);
 
   spin_lock (&spin_proc->cpu->lock);
   do_sched (spin_proc, &spin_proc->cpu->lock);

kernel/amd64/syscall.c

@@ -3,6 +3,7 @@
 #include <amd64/mm.h>
 #include <amd64/msr-index.h>
 #include <amd64/msr.h>
+#include <libk/lengthof.h>
 #include <libk/list.h>
 #include <libk/string.h>
 #include <mm/liballoc.h>
@@ -37,7 +38,7 @@ uintptr_t syscall_dispatch (void* stack_ptr) {
     return -ST_SYSCALL_NOT_FOUND;
   }
 
-  struct reschedule_ctx rctx = {.reschedule = false, .cpu = NULL};
+  struct reschedule_ctx rctx = {0};
 
   uintptr_t r =
       func (caller, regs, &rctx, regs->rdi, regs->rsi, regs->rdx, regs->r10, regs->r8, regs->r9);
@@ -50,8 +51,16 @@ uintptr_t syscall_dispatch (void* stack_ptr) {
     spin_unlock (&caller->lock);
   }
 
-  if (rctx.reschedule)
+  bool do_thiscpu = false;
-    cpu_request_sched (rctx.cpu);
+  for (size_t i = 0; i < lengthof (rctx.cpus); i++) {
+    if (rctx.cpus[i] != NULL && rctx.cpus[i] != thiscpu)
+      cpu_request_sched (rctx.cpus[i]);
+    else
+      do_thiscpu = true;
+  }
+
+  if (do_thiscpu)
+    cpu_request_sched (thiscpu);
 
   return r;
 }

kernel/proc/mutex.c

@@ -37,6 +37,8 @@ void proc_mutexes_cleanup (struct proc* proc, struct reschedule_ctx* rctx) {
 
       proc_mutex_unlock (proc, &resource->u.mutex, rctx);
     }
+
+    spin_unlock (&resource->lock);
   }
 
   spin_unlock (&proc->procgroup->lock);

kernel/proc/proc.c

@@ -198,10 +198,7 @@ void proc_register (struct proc* proc, struct cpu* register_cpu, struct reschedu
   spin_unlock (&cpu->lock);
   spin_unlock (&proc_tree_lock);
 
-  if (rctx != NULL) {
+  rctx_insert_cpu (rctx, cpu);
-    rctx->reschedule = true;
-    rctx->cpu = cpu;
-  }
 }
 
 /* caller holds cpu->lock */
@@ -225,11 +222,15 @@ static struct proc* proc_find_sched (struct cpu* cpu) {
     struct proc* proc = list_entry (current, struct proc, cpu_run_q_link);
 
     spin_lock (&proc->lock);
-    int state = proc->state;
-    spin_unlock (&proc->lock);
 
-    if (state == PROC_READY)
+    int state = proc->state;
+
+    if (state == PROC_READY) {
+      spin_unlock (&proc->lock);
       return proc;
+    }
+
+    spin_unlock (&proc->lock);
 
     current = current->next ? current->next : cpu->proc_run_q;
   } while (current != start);
@@ -278,7 +279,7 @@ static void proc_reap (struct reschedule_ctx* rctx) {
 
 void proc_sched (void) {
   int s_cycles = atomic_fetch_add (&sched_cycles, 1);
-  struct reschedule_ctx rctx = {.reschedule = false, .cpu = NULL};
+  struct reschedule_ctx rctx = {0};
 
   if (s_cycles % SCHED_REAP_FREQ == 0)
     proc_reap (&rctx);
@@ -321,14 +322,24 @@ void proc_kill (struct proc* proc, struct reschedule_ctx* rctx) {
   spin_unlock (&proc->lock);
   spin_unlock (&cpu->lock);
 
-  rctx->reschedule = true;
+  rctx_insert_cpu (rctx, cpu);
-  rctx->cpu = cpu;
 
   DEBUG ("killed PID %d\n", proc->pid);
 }
 
+void proc_wait_for (struct proc* proc, struct reschedule_ctx* rctx, struct proc* wait_proc) {
+  proc_sq_suspend (proc, &wait_proc->done_sq, NULL, rctx);
+}
+
 static void proc_irq_sched (void* arg, void* regs, struct reschedule_ctx* rctx) {
   (void)arg, (void)regs;
+
+#if defined(__x86_64__)
+  struct saved_regs* sr = regs;
+  if (sr->cs != (GDT_UCODE | 0x3))
+    return;
+#endif
+
   proc_sched ();
 }
 
@@ -338,14 +349,14 @@ void proc_init (void) {
   irq_attach (&proc_irq_sched, NULL, CPU_REQUEST_SCHED);
 #endif
 
-  struct reschedule_ctx rctx = {.cpu = NULL, .reschedule = false};
+  struct reschedule_ctx rctx = {0};
 
   struct proc* spin_proc = proc_from_file (VFS_KERNEL, "RD", "/spin", &rctx);
-  proc_register (spin_proc, thiscpu, NULL);
+  proc_register (spin_proc, thiscpu, &rctx);
 
   struct proc* init = proc_from_file (VFS_KERNEL, "RD", "/init", &rctx);
   init->procgroup->capabilities |= (PROC_CAP_TERMINAL | PROC_CAP_KB);
-  proc_register (init, thiscpu, NULL);
+  proc_register (init, thiscpu, &rctx);
 
   spin_lock (&spin_proc->cpu->lock);
   do_sched (spin_proc, &spin_proc->cpu->lock);

kernel/proc/proc.h

@@ -47,6 +47,7 @@ struct proc {
   void* mail_recv_buffer;
   size_t mail_recv_size;
   char cwv[VOLUME_MAX];
+  struct proc_suspension_q done_sq;
 };
 
 void proc_sched (void);
@@ -68,6 +69,8 @@ int proc_alloc_pid (void);
 
 void proc_pid_alloc_init (void);
 
+void proc_wait_for (struct proc* proc, struct reschedule_ctx* rctx, struct proc* wait_proc);
+
 void proc_init (void);
 
 #endif // _KERNEL_PROC_PROC_H

kernel/proc/reschedule.h

@@ -6,8 +6,24 @@
 #include <sys/smp.h>
 
 struct reschedule_ctx {
-  bool reschedule;
+  struct cpu* cpus[CPUS_MAX];
-  struct cpu* cpu;
 };
 
+#define rctx_insert_cpu(rctx, cpu)                                                                 \
+  do {                                                                                             \
+    bool __found = false;                                                                          \
+    for (size_t __i = 0; __i < CPUS_MAX; __i++) {                                                  \
+      if ((rctx)->cpus[__i] == (cpu))                                                              \
+        __found = true;                                                                            \
+    }                                                                                              \
+    if (!__found) {                                                                                \
+      for (size_t __i = 0; __i < CPUS_MAX; __i++) {                                                \
+        if ((rctx)->cpus[__i] == NULL) {                                                           \
+          (rctx)->cpus[__i] = (cpu);                                                               \
+          break;                                                                                   \
+        }                                                                                          \
+      }                                                                                            \
+    }                                                                                              \
+  } while (0)
+
 #endif // _KERNEL_PROC_RESCHEDULE_H

kernel/proc/suspension_q.c

@@ -15,6 +15,7 @@ void proc_sq_suspend (struct proc* proc, struct proc_suspension_q* sq, spin_lock
 
   struct proc_sq_entry* sq_entry = malloc (sizeof (*sq_entry));
   if (!sq_entry) {
+    if (resource_lock != NULL)
       spin_unlock (resource_lock);
     return;
   }
@@ -26,6 +27,7 @@ void proc_sq_suspend (struct proc* proc, struct proc_suspension_q* sq, spin_lock
   spin_lock (&proc->lock);
   spin_lock (&sq->lock);
 
+  if (resource_lock != NULL)
     spin_unlock (resource_lock);
 
   proc->state = PROC_SUSPENDED;
@@ -48,8 +50,7 @@ void proc_sq_suspend (struct proc* proc, struct proc_suspension_q* sq, spin_lock
   spin_unlock (&proc->lock);
   spin_unlock (&cpu->lock);
 
-  rctx->reschedule = true;
+  rctx_insert_cpu (rctx, cpu);
-  rctx->cpu = cpu;
 }
 
 void proc_sq_resume (struct proc* proc, struct proc_sq_entry* sq_entry,
@@ -81,8 +82,7 @@ void proc_sq_resume (struct proc* proc, struct proc_sq_entry* sq_entry,
 
   free (sq_entry);
 
-  rctx->reschedule = true;
+  rctx_insert_cpu (rctx, cpu);
-  rctx->cpu = cpu;
 }
 
 void proc_sqs_cleanup (struct proc* proc) {

kernel/syscall/syscall.c

@@ -105,12 +105,17 @@ DEFINE_SYSCALL (sys_clone) {
 }
 
 /* void* argument_ptr (void) */
-DEFINE_SYSCALL (sys_argument_ptr) { return proc->uvaddr_argument; }
+DEFINE_SYSCALL (sys_argument_ptr) {
+  spin_lock (&proc->lock);
+  uintptr_t p = proc->uvaddr_argument;
+  spin_unlock (&proc->lock);
+
+  return p;
+}
 
 /* int sched (void) */
 DEFINE_SYSCALL (sys_sched) {
-  rctx->reschedule = true;
+  rctx_insert_cpu (rctx, thiscpu);
-  rctx->cpu = thiscpu;
   return SYSRESULT (ST_OK);
 }
 
@@ -121,7 +126,11 @@ DEFINE_SYSCALL (sys_mutex_create) {
   if (mutex_resource == NULL)
     return SYSRESULT (-ST_OOM_ERROR);
 
-  return SYSRESULT (mutex_resource->rid);
+  spin_lock (&mutex_resource->lock);
+  int rid = mutex_resource->rid;
+  spin_unlock (&mutex_resource->lock);
+
+  return SYSRESULT (rid);
 }
 
 /* int mutex_delete (int mutex_rid) */
@@ -425,7 +434,18 @@ DEFINE_SYSCALL (sys_get_procgroup) {
   if (target_proc == NULL)
     return SYSRESULT (-ST_NOT_FOUND);
 
-  return SYSRESULT (target_proc->procgroup->pgid);
+  spin_lock (&target_proc->lock);
+
+  if (target_proc->state == PROC_DEAD) {
+    spin_unlock (&target_proc->lock);
+    return SYSRESULT (-ST_NOT_FOUND);
+  }
+
+  int pgid = target_proc->procgroup->pgid;
+
+  spin_unlock (&target_proc->lock);
+
+  return SYSRESULT (pgid);
 }
 
 /* int read_dir_entry (char* path, struct dir_entry* entry, size_t entry_num) */
@@ -516,7 +536,60 @@ DEFINE_SYSCALL (sys_write_file) {
 }
 
 /* int get_exec_pid (void) */
-DEFINE_SYSCALL (sys_get_exec_pid) { return SYSRESULT (proc->exec_pid); }
+DEFINE_SYSCALL (sys_get_exec_pid) {
+  spin_lock (&proc->lock);
+  int exec_pid = proc->exec_pid;
+  spin_unlock (&proc->lock);
+
+  return SYSRESULT (exec_pid);
+}
+
+/* wait_for_pid (int pid) */
+DEFINE_SYSCALL (sys_wait_for_pid) {
+  int pid = (int)a1;
+
+  struct proc* wait_proc = proc_find_pid (pid);
+
+  if (wait_proc == NULL)
+    return SYSRESULT (-ST_NOT_FOUND);
+
+  spin_lock (&wait_proc->lock);
+
+  if (wait_proc->state == PROC_DEAD) {
+    spin_unlock (&wait_proc->lock);
+    return SYSRESULT (-ST_NOT_FOUND);
+  }
+
+  spin_unlock (&wait_proc->lock);
+
+  proc_wait_for (proc, rctx, wait_proc);
+
+  return SYSRESULT (ST_OK);
+}
+
+/* int kill (int pid) */
+
+DEFINE_SYSCALL (sys_kill) {
+  int pid = (int)a1;
+
+  struct proc* target_proc = proc_find_pid (pid);
+
+  if (target_proc == NULL)
+    return SYSRESULT (-ST_NOT_FOUND);
+
+  spin_lock (&target_proc->lock);
+
+  if (target_proc->state == PROC_DEAD) {
+    spin_unlock (&target_proc->lock);
+    return SYSRESULT (-ST_NOT_FOUND);
+  }
+
+  spin_unlock (&target_proc->lock);
+
+  proc_kill (target_proc, rctx);
+
+  return ST_OK;
+}
 
 static syscall_handler_func_t handler_table[] = {
     [SYS_QUIT] = &sys_quit,
@@ -543,6 +616,8 @@ static syscall_handler_func_t handler_table[] = {
     [SYS_READ_DIR_ENTRY] = &sys_read_dir_entry,
     [SYS_CREATE_FILE] = &sys_create_file,
     [SYS_WRITE_FILE] = &sys_write_file,
+    [SYS_WAIT_FOR_PID] = &sys_wait_for_pid,
+    [SYS_KILL] = &sys_kill,
 };
 
 syscall_handler_func_t syscall_find_handler (int syscall_num) {

libsystem/system.c

@@ -74,3 +74,7 @@ int create_file (const char* path) { return (int)do_syscall (SYS_CREATE_FILE, pa
 int write_file (const char* path, size_t off, uint8_t* buffer, size_t size) {
   return (int)do_syscall (SYS_WRITE_FILE, path, off, buffer, size);
 }
+
+int wait_for_pid (int pid) { return (int)do_syscall (SYS_WAIT_FOR_PID, pid); }
+
+int kill (int pid) { return (int)do_syscall (SYS_KILL, pid); }

libsystem/system.h

@@ -87,4 +87,10 @@ int create_file (const char* path);
 /* write to a file */
 int write_file (const char* path, size_t off, uint8_t* buffer, size_t size);
 
+/* wait for process */
+int wait_for_pid (int pid);
+
+/* Kill process */
+int kill (int pid);
+
 #endif // _LIBMSL_M_SYSTEM_H