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-rw-r--r--src/kern/main.c14
-rw-r--r--src/kern/priv.c14
2 files changed, 13 insertions, 15 deletions
diff --git a/src/kern/main.c b/src/kern/main.c
index 3af8beb..4fddb0a 100644
--- a/src/kern/main.c
+++ b/src/kern/main.c
@@ -35,19 +35,7 @@ void configure_mpu()
int main()
{
configure_mpu();
-
- klogf("Outside of usermode, I can still log stuff using klogf()\n");
-
- enter_user_mode();
-
- logs("Now that I'm in user mode, I have to log stuff using a system call\n");
- logs(
- "because I no longer have direct accss to USART2 and cannot use\n"
- "klogf()\n");
-
-
- for (;;)
- ;
+ jump_to_user_mode();
}
#endif
diff --git a/src/kern/priv.c b/src/kern/priv.c
index 3162639..2c45eca 100644
--- a/src/kern/priv.c
+++ b/src/kern/priv.c
@@ -2,6 +2,7 @@
#include "arch.h"
#include "kern/log.h"
+#include "kern/mem.h"
void set_control_register(uint32_t reg)
{
@@ -24,7 +25,16 @@ void enter_user_mode()
void jump_to_user_mode()
{
+ void* new_stack = kalloc(4096);
+ new_stack += 4096;
+
asm volatile(
- "mov r0, #1\n\t"
- "msr control, r0\n\t");
+ "mov r0, %0\n\t"
+ "msr psp, r0\n\t"
+ "mrs r0, control\n\t"
+ "orrs r0, r0, #3\n\t"
+ "msr control, r0\n\t"
+ "isb\n\t"
+ "dsb\n\t"
+ "b usermode_start\n\t" : : "r"(new_stack));
}