From 7d5a9792e57b4088cce5cc97837eb04016b57a4d Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Thu, 31 Oct 2019 00:49:00 +0100
Subject: Implemented basic syscalls and user mode

Doesn't completely work right now
---
 src/kernel/syscall/syscall.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 src/kernel/syscall/syscall.c

(limited to 'src/kernel/syscall/syscall.c')

diff --git a/src/kernel/syscall/syscall.c b/src/kernel/syscall/syscall.c
new file mode 100644
index 0000000..d1dbd6b
--- /dev/null
+++ b/src/kernel/syscall/syscall.c
@@ -0,0 +1,45 @@
+#include <stdint.h>
+#include <kernel/syscall/syscall.h>
+#include <kernel/interrupts/interrupts.h>
+#include <kernel/graphics/vesa.h>
+#include <kernel/io/io.h>
+
+DEFN_SYSCALL1(vesa_draw_string, 0, const char *);
+
+DEFN_SYSCALL1(vesa_draw_number, 1, int);
+
+DEFN_SYSCALL1(serial_write, 2, const char *);
+
+static void *syscalls[3] = {
+        &vesa_draw_string,
+        &vesa_draw_number,
+        &serial_write,
+};
+uint32_t num_syscalls = 3;
+
+void syscall_handler(struct regs *r) {
+    if (r->eax >= num_syscalls)
+        return;
+
+    void *location = syscalls[r->eax];
+
+    int ret;
+    asm volatile (" \
+     push %1; \
+     push %2; \
+     push %3; \
+     push %4; \
+     push %5; \
+     call *%6; \
+     pop %%ebx; \
+     pop %%ebx; \
+     pop %%ebx; \
+     pop %%ebx; \
+     pop %%ebx; \
+   " : "=a" (ret) : "r" (r->edi), "r" (r->esi), "r" (r->edx), "r" (r->ecx), "r" (r->ebx), "r" (location));
+    r->eax = ret;
+}
+
+void syscalls_install() {
+    irq_install_handler(0x80, &syscall_handler);
+}
-- 
cgit v1.2.3


From 2c7b6e0431d6dfbaf385d30e87e7eb9fd4a0e61d Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Thu, 31 Oct 2019 15:19:12 +0100
Subject: Some user mode improvements

---
 src/kernel/boot.asm          | 29 ++++++++++++++---------------
 src/kernel/gdt/gdt.c         |  2 +-
 src/kernel/graphics/vesa.c   |  2 +-
 src/kernel/kernel.c          |  3 ++-
 src/kernel/syscall/syscall.c |  3 ++-
 src/userspace/main.c         |  6 ++++++
 6 files changed, 26 insertions(+), 19 deletions(-)
 create mode 100644 src/userspace/main.c

(limited to 'src/kernel/syscall/syscall.c')

diff --git a/src/kernel/boot.asm b/src/kernel/boot.asm
index 8f24066..2501ed9 100644
--- a/src/kernel/boot.asm
+++ b/src/kernel/boot.asm
@@ -51,23 +51,22 @@ stublet:
 %include "src/kernel/interact.asm"
 
 global switch_to_user
+extern test_user
 switch_to_user:
-     cli
-     mov ax,0x23
-     mov ds,ax
-     mov es,ax
-     mov fs,ax
-     mov gs,ax
+    sti
+    mov ax, 0x23
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
 
-     mov eax,esp
-     push 0x23
-     push eax
-     pushf
-     pop eax
-     or eax, 0x200
-     push eax
-     push 0x1B
-     iret
+    mov eax, esp
+    push 0x23
+    push eax
+    pushf
+    push 0x1B
+    push test_user
+    iret
 
 ; Store the stack
 SECTION .bss
diff --git a/src/kernel/gdt/gdt.c b/src/kernel/gdt/gdt.c
index b933950..1c69602 100644
--- a/src/kernel/gdt/gdt.c
+++ b/src/kernel/gdt/gdt.c
@@ -97,7 +97,7 @@ void gdt_install() {
 
     // Remove old GDT and install the new changes!
     gdt_flush();
-    tss_flush(); // FAILS
+    tss_flush();
 
     vga_log("Installed Global Descriptor Table", 2);
 }
diff --git a/src/kernel/graphics/vesa.c b/src/kernel/graphics/vesa.c
index 32ca717..858ed95 100644
--- a/src/kernel/graphics/vesa.c
+++ b/src/kernel/graphics/vesa.c
@@ -167,7 +167,7 @@ void set_optimal_resolution() {
             switch_to_vga();
     } else vga_log("Mode detection succeeded", 11);
 
-    timer_wait(500);
+    // timer_wait(500);
 
     vbe_set_mode(highest);
 
diff --git a/src/kernel/kernel.c b/src/kernel/kernel.c
index dd15409..b133a0c 100644
--- a/src/kernel/kernel.c
+++ b/src/kernel/kernel.c
@@ -39,10 +39,11 @@ void kernel_main(struct multiboot *mboot_ptr) {
     initrd_test();
 
     // User mode!
+    info("Switching to user mode...");
     syscalls_install();
     switch_to_user();
 
-    syscall_serial_write("Hello, user world!\n");
+    panic("This should NOT happen!");
 
     // asm volatile  ("div %0" :: "r"(0)); // Exception testing x/0
     loop:
diff --git a/src/kernel/syscall/syscall.c b/src/kernel/syscall/syscall.c
index d1dbd6b..dec3e8e 100644
--- a/src/kernel/syscall/syscall.c
+++ b/src/kernel/syscall/syscall.c
@@ -18,6 +18,7 @@ static void *syscalls[3] = {
 uint32_t num_syscalls = 3;
 
 void syscall_handler(struct regs *r) {
+    serial_write("SYSCALL");
     if (r->eax >= num_syscalls)
         return;
 
@@ -41,5 +42,5 @@ void syscall_handler(struct regs *r) {
 }
 
 void syscalls_install() {
-    irq_install_handler(0x80, &syscall_handler);
+    irq_install_handler(0x80, syscall_handler);
 }
diff --git a/src/userspace/main.c b/src/userspace/main.c
new file mode 100644
index 0000000..d332d8e
--- /dev/null
+++ b/src/userspace/main.c
@@ -0,0 +1,6 @@
+#include <kernel/syscall/syscall.h>
+
+void test_user() {
+    asm volatile ("hlt");
+    syscall_serial_write("Hello, user world!\n");
+}
\ No newline at end of file
-- 
cgit v1.2.3