More fork() work

That doesn't mean it works.
Why doesn't it work??

Oh well...

apps/Makefile

@@ -11,7 +11,6 @@ CFLAGS := -Wall -Wextra -Werror -Os
 $(APPS_BIN)/%: $(APPS_SRC)/%.c
 	@mkdir -p $(@D)
 	$(CC) $(CFLAGS) -o $@ $^
-	$(STRIP) $@
 
 build: $(REAL_APPS)
 

apps/src/init.c

@@ -141,9 +141,13 @@ int main()
 
     fclose(new_stderr);
 
-    execv("/bin/sym", NULL);
-
-    perror("execv"); // If we're here, execv failed
-
-    return 1;
+    pid_t child = fork();
+    if (child == 0)
+    {
+        msleep(500);
+        printf("I am the child, who is my parent?\n");
+    }
+    else { printf("My child is %ld!", child); }
+
+    return 0;
 }

kernel/src/sys/exec.cpp

@@ -32,16 +32,23 @@ void sys_fork(Context* context) // FIXME: Even though both processes's address s
 
     size_t stack_bytes = get_top_of_stack(parent->allocated_stack, TASK_PAGES_IN_STACK) - parent->regs.rsp;
 
-    child->regs.rsp -= stack_bytes;
+    child->regs.rsp = get_top_of_stack(child->allocated_stack, TASK_PAGES_IN_STACK) - stack_bytes;
 
     memcpy((void*)child->regs.rsp, (void*)parent->regs.rsp, stack_bytes);
 
+    child->regs.rsp += sizeof(uintptr_t) * 2; // I don't know why this is...
+
     child->address_space = parent->address_space.clone();
 
     child->regs.rax = 0;
     context->rax = child->id;
 
-    kinfoln("fork(): forked parent %d into child %d", parent->id, child->id);
+    child->state = child->Running;
+
+    kinfoln("fork(): parent RIP %lx, child RIP %lx, parent RSP %lx, child RSP %lx", parent->regs.rip, child->regs.rip,
+            parent->regs.rsp, child->regs.rsp);
+
+    kinfoln("fork(): forked parent %ld into child %ld", parent->id, child->id);
 
     return;
 }

kernel/src/trace/StackTracer.cpp

@@ -1,5 +1,6 @@
 #include "trace/StackTracer.h"
 #include "memory/Memory.h"
+#include "memory/VMM.h"
 #include "std/stdio.h"
 #include "trace/Resolve.h"
 
@@ -20,6 +21,11 @@ typedef struct stackframe
 
 void StackTracer::trace()
 {
+    if (!VMM::is_using_kernel_address_space())
+    {
+        VMM::switch_back_to_kernel_address_space();
+        VMM::apply_address_space();
+    }
     stackframe* frame = (stackframe*)m_base_pointer;
     while (frame && frame->instruction)
     {
@@ -27,6 +33,7 @@ void StackTracer::trace()
         get_symbol_name(frame->instruction, symbol_name, sizeof(symbol_name));
         printf("%lx: %s\n", frame->instruction, symbol_name);
         frame = frame->next;
+        if (VMM::get_physical((uint64_t)frame) == (uint64_t)-1) return;
     }
 }
 

libs/libc/include/luna/syscall.h

@@ -17,6 +17,7 @@
 #define SYS_fcntl 13
 #define SYS_mprotect 14
 #define SYS_clock 15
+#define SYS_fork 16
 
 #ifndef __want_syscalls
 #ifdef __cplusplus

libs/libc/include/unistd.h

@@ -22,7 +22,8 @@ extern "C"
     int execve(const char*, char* const[], char* const[]);
     /* Not implemented. */
     int execvp(const char*, char* const[]);
-    /* Not implemented. */
+
+    /* Creates an identical copy of the current process and returns its process ID. */
     pid_t fork(void);
 
     /* Terminates the program with the status code status. */

libs/libc/src/unistd.cpp

@@ -19,9 +19,10 @@ extern "C"
     {
         NOT_IMPLEMENTED("execvp");
     }
+
     pid_t fork(void)
     {
-        NOT_IMPLEMENTED("fork");
+        return syscall(SYS_fork);
     }
 
     long syscall(long number, ...)
@@ -34,6 +35,7 @@ extern "C"
         {
         case SYS_clock:
         case SYS_yield:
+        case SYS_fork:
         case SYS_gettid: result = __luna_syscall0(number); break;
         case SYS_exit:
         case SYS_close: