From: Matthias Kruk <m@m10k.eu>
Date: Mon, 4 Nov 2019 02:01:45 +0000 (+0900)
Subject: Change the signature of sys_posixcall() so it can modify the caller's stackframe... 
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=ade6c67b86c389e571dd5c1ce0285cc6b47d7444;p=corax

Change the signature of sys_posixcall() so it can modify the caller's stackframe in the case of sys_fork()
---

diff --git a/kernel/arch/interrupt.c b/kernel/arch/interrupt.c
index c6af750..f109e70 100644
--- a/kernel/arch/interrupt.c
+++ b/kernel/arch/interrupt.c
@@ -29,7 +29,7 @@ void sched_tick(void);
 extern int sys_cxnet(long, long, long, long, long, long, long);
 extern int sys_cxipc(long, long, long);
 #if FEATURE(POSIX)
-extern int sys_posixcall(long, long, long, long, long, long, long);
+extern int sys_posixcall(stack_frame_t*);
 #endif /* FEATURE(POSIX) */
 
 static const char *_exc_name[] = {
@@ -170,7 +170,7 @@ void _sys_handle(stack_frame_t ctx)
 
 #if FEATURE(POSIX)
 	case SYS_VECTOR_POSIX:
-		ret_val = sys_posixcall(ctx.eax, ctx.ebx, ctx.ecx, ctx.edx, ctx.esi, ctx.edi, ctx.ebp);
+		ret_val = sys_posixcall(&ctx);
 		break;
 #endif /* FEATURE(POSIX) */
 
diff --git a/kernel/core/posixcall.c b/kernel/core/posixcall.c
index ffae24d..781c889 100644
--- a/kernel/core/posixcall.c
+++ b/kernel/core/posixcall.c
@@ -5,7 +5,9 @@
 #include <corax/errno.h>
 #include <corax/syscall.h>
 #include <corax/types.h>
+#include <arch.h>
 #include <process.h>
+#include <debug.h>
 
 int sys_exit(int status)
 {
@@ -22,13 +24,27 @@ int sys_exit(int status)
 	return(ret_val);
 }
 
-int sys_fork(void)
+int sys_fork(stack_frame_t *stk)
 {
+	int ret_val;
+	task_t *ct;
+
 	/*
 	 * process_fork() always forks the calling process, so
 	 * it doesn't get told which process to fork
 	 */
-	return(process_fork(0));
+
+	ret_val = process_fork(0);
+
+	/*
+	 * Update the stack frame, since the page directory
+	 * will have changed for one of the processes
+	 */
+	ct = task_get_current();
+
+	stk->cr3 = ct->t_pgdir;
+
+	return(ret_val);
 }
 
 int sys_vfork(void)
@@ -51,31 +67,36 @@ int sys_setsid(void)
 	return(-ENOSYS);
 }
 
-int sys_posixcall(long vec, long arg1, long arg2, long arg3, long arg4, long arg5, long arg6)
+int sys_posixcall(stack_frame_t *stk)
 {
 	int ret_val;
 
 	ret_val = -EFAULT;
 
-	switch(vec) {
+	switch(stk->eax) {
 	case SYS_EXIT:
-		ret_val = sys_exit((int)arg1);
+		ret_val = sys_exit((int)stk->ebx);
 		break;
 
 	case SYS_FORK:
-		ret_val = sys_fork();
+		/* sys_fork() will need to modify the stack frame */
+		ret_val = sys_fork(stk);
 		break;
 
 	case SYS_VFORK:
+		/*
+		 * sys_vfork() spawns a new process within the same address space,
+		 * so it's not necessary for it to modify the stack frame
+		 */
 		ret_val = sys_vfork();
 		break;
 
 	case SYS_WAIT:
-		ret_val = sys_wait((int*)arg1);
+		ret_val = sys_wait((int*)stk->ebx);
 		break;
 
 	case SYS_WAITPID:
-		ret_val = sys_waitpid((pid_t)arg1, (int*)arg2, (int)arg3);
+		ret_val = sys_waitpid((pid_t)stk->ebx, (int*)stk->ecx, (int)stk->edx);
 		break;
 
 	case SYS_WAITID: