feat(mm): kill user process on access to priv. mem

CMakeLists.txt

@@ -127,6 +127,7 @@ add_custom_target(boot.img
     COMMAND mcopy -i boot.img@@1M ${CMAKE_BINARY_DIR}/user-space-program/stack-test.out ::stack.out
     COMMAND mcopy -i boot.img@@1M ${CMAKE_BINARY_DIR}/user-space-program/init.out ::init.elf
     COMMAND mcopy -i boot.img@@1M ${CMAKE_BINARY_DIR}/user-space-program/sh.out ::sh.elf
+    COMMAND mcopy -i boot.img@@1M ${CMAKE_BINARY_DIR}/user-space-program/priv-test.out ::priv.elf
 )
 
 add_custom_command(OUTPUT run

src/kernel/interrupt.cpp

@@ -21,6 +21,14 @@
 
 static struct IDT_entry IDT[256];
 
+static inline void NORETURN _halt_forever(void)
+{
+    asm_cli();
+    asm_hlt();
+    for (;;)
+        ;
+}
+
 void init_idt()
 {
     asm_cli();
@@ -159,6 +167,16 @@ static inline void _int14_panic(void* eip, void* cr2, struct page_fault_error_co
     assert(false);
 }
 
+static inline void NORETURN _int14_kill_user(void)
+{
+    char buf[256] {};
+    snprintf(buf, 256, "Segmentation Fault (pid%d killed)\n", current_process->pid);
+    kmsg(buf);
+    procs->kill(current_process->pid, -1);
+    schedule();
+    _halt_forever();
+}
+
 // page fault
 extern "C" void int14_handler(int14_data* d)
 {
@@ -169,8 +187,16 @@ extern "C" void int14_handler(int14_data* d)
         mms = kernel_mms;
 
     auto mm_area = mms->find(d->l_addr);
-    if (unlikely(mm_area == mms->end()))
-        _int14_panic(d->v_eip, d->l_addr, d->error_code);
+    if (unlikely(mm_area == mms->end())) {
+        if (d->error_code.user) {
+            // user access of address that does not exist
+            _int14_kill_user();
+        } else {
+            _int14_panic(d->v_eip, d->l_addr, d->error_code);
+        }
+    }
+    if (unlikely(d->error_code.user && mm_area->attr.in.system))
+        _int14_kill_user();
 
     pte_t* pte = to_pte(mms->m_pd, d->l_addr);
     page* page = lto_page(&mm_area, d->l_addr);

user-space-program/CMakeLists.txt

@@ -16,7 +16,8 @@ add_executable(interrupt-test.out interrupt-test.s)
 add_executable(stack-test.out stack-test.s)
 add_executable(init.out init.c)
 add_executable(sh.out sh.c)
+add_executable(priv-test.out priv-test.c)
 
 add_custom_target(user_space_programs
-    DEPENDS hello-world.out interrupt-test.out stack-test.out init.out sh.out
+    DEPENDS hello-world.out interrupt-test.out stack-test.out init.out sh.out priv-test.out
 )

user-space-program/priv-test.c

@@ -0,0 +1,5 @@
+int main(void) {
+    int* ptr = (int*)0x10000;
+    *ptr = 0x114514;
+    return -1;
+}