Add privilege level information to processes and tasks

diff --git a/kernel/arch/process.c b/kernel/arch/process.c
index 552abbcea674aa164be9780e5aa189753d2ff227..f3716a17160c673609726f10c48d946bcd2f9ca5 100644 (file)
--- a/kernel/arch/process.c
+++ b/kernel/arch/process.c
@@ -8,7 +8,8 @@
 
 struct process {
        struct pagedir *p_pgdir;
-       struct task *p_tasks;
+       struct task    *p_tasks;
+       u32_t          p_privl;
 };
 
 void foo(void)
@@ -20,7 +21,7 @@ void foo(void)
 
 extern int _pg_dir_vpxlate(pg_dir_t*, u32_t, u32_t*);
 
-int process_create(process_t **dst)
+int process_create(process_t **dst, u32_t ppl)
 {
        int ret_val;
        process_t *proc;
@@ -50,8 +51,10 @@ int process_create(process_t **dst)
                        goto cleanup;
                }
 
+               proc->p_privl = ppl;
+
                task_prepare(proc->p_tasks, (u32_t)pdbr, (u32_t)foo,
-                                        (u32_t)kstack, (u32_t)ustack + PAGE_SIZE, 3);
+                                        (u32_t)kstack, (u32_t)ustack + PAGE_SIZE, ppl);
 
                proc->p_tasks->t_sp = (u32_t)(CONFIG_KERNEL_STACK_BASE +
                                                                          ((u32_t)proc->p_tasks->t_sp - (u32_t)kstack));

diff --git a/kernel/arch/task.S b/kernel/arch/task.S
index b78b2af169a78fb3d6681c267c860efd63bb618b..f69c1bf5067cc7d96b337bd7a46b484028f6d6bc 100644 (file)
--- a/kernel/arch/task.S
+++ b/kernel/arch/task.S
@@ -27,6 +27,7 @@
 #define OFFSET_ESP0   0
 #define OFFSET_CR3    4
 #define OFFSET_KSTACK 8
+#define OFFSET_PRIVL  12
 
 .extern _cpu
 
@@ -52,6 +53,10 @@ task_prepare:
        movl    8(%esp), %eax
        movl    %eax, OFFSET_CR3(%edi)
 
+       /* store privilege level in task structure */
+       movl    24(%esp), %eax
+       movl    %eax, OFFSET_PRIVL(%edi)
+
        /* calculate stack start (since it grows down) */
        movl    16(%esp), %eax
        addl    $CONFIG_KERNEL_STACK_SIZE, %eax
@@ -168,18 +173,24 @@ task_switch:
        movl    %ecx, CPU_ESP0(%eax)
        movl    $KERNEL_DATA, CPU_SS0(%eax)
 
+       /* set CS according to the task's privilege level */
+       movl    OFFSET_PRIVL(%edi), %ecx
+       shll    $4, %ecx
+       addl    $8, %ecx
+       orl             OFFSET_PRIVL(%edi), %ecx
+       movl    %ecx, CPU_CS(%eax)
+
        /*
-        * We need to figure out the task's privilege level and
-        * set the segment registers accordingly
+        * Set the data segment selectors (this assumes a privilege
+        * level's DS descriptor follows the CS descriptor)
         */
-       /*
-       movl    $USER_CODE, CPU_CS(%eax)
-       movl    $USER_DATA, CPU_DS(%eax)
-       movl    $USER_DATA, CPU_ES(%eax)
-       movl    $USER_DATA, CPU_FS(%eax)
-       movl    $USER_DATA, CPU_GS(%eax)
-       movl    $USER_DATA, CPU_SS(%eax)
-       */
+       addl    $8, %ecx
+       movl    %ecx, CPU_DS(%eax)
+       movl    %ecx, CPU_ES(%eax)
+       movl    %ecx, CPU_FS(%eax)
+       movl    %ecx, CPU_GS(%eax)
+       movl    %ecx, CPU_SS(%eax)
+
        movl    OFFSET_CR3(%edi), %ecx
 
        /* check if we can avoid writing to cr3, which would clear the TLB */

diff --git a/kernel/include/arch.h b/kernel/include/arch.h
index 43064fd566178ae3f45c3d3fe9a8db6c050bee76..7503a2b5f873366a8e2e82555b1b638c95a05cab 100644 (file)
--- a/kernel/include/arch.h
+++ b/kernel/include/arch.h
@@ -27,6 +27,7 @@ struct task {
        u32_t t_sp;
        u32_t t_pgdir;
        void *t_kstack;
+       u32_t t_privl;
 } __attribute__((packed));
 
 int     cpu_get_id(void);
@@ -35,7 +36,7 @@ u64_t   cpu_timestamp(void);
 
 u32_t   cpu_set_pstate(int pstate);
 
-int     process_create(process_t**);
+int     process_create(process_t**, u32_t);
 
 int     task_prepare(struct task*, u32_t cr3, u32_t eip, u32_t esp0, u32_t esp, u32_t priv);
 int     task_switch(struct task*);