Primitive ability to call kernel code from userspace.

1 files changed, 7 insertions, 81 deletions

diff --git a/src/kern/priv.c b/src/kern/priv.c
index 085de85..3162639 100644
--- a/src/kern/priv.c
+++ b/src/kern/priv.c
@@ -3,87 +3,6 @@
 #include "arch.h"
 #include "kern/log.h"
 
-void handle_svc_call(uint32_t svc_number)
-{
-  klogf("Handle SVC: %p\n", svc_number);
-  for (;;)
-    ;
-}
-
-asm("	.align	2\n"
-    "	.global	on_svc\n"
-    "	.syntax unified\n"
-    "	.fpu softvfp\n"
-    "	.type	on_svc, %function\n"
-    "on_svc:\n"
-    "	tst   lr,#4\n"
-    " ite   eq\n"
-    "	moveq r12,sp\n"
-    "	mrsne r12,psp\n"
-    "	ldr   r12, [r12, #24]\n"
-    "	ldrh  r12, [r12, #-2]\n"
-    "	bics  r12, r12, #0xff00\n"
-    "	push  {r4, lr}\n"
-    "	mov   r0 , r12\n"
-    "	bl    handle_svc_call\n"
-    "	pop   {r4, lr}\n"
-    "	tst   lr, #4\n"
-    " ite   eq\n"
-    "	moveq r12,sp\n"
-    "	mrsne r12,psp\n"
-    "	stm   r12,{r0-r3}\n"
-    "	bx    lr\n");
-
-// void on_svc()  // ISR handler. Override from weak symbol.
-// {
-// asm volatile(
-//     "push {r0-r12, lr}\n\t"
-//     "ldr  r0, [lr, #-4]\n\t"
-//     "bic  r0, r0, #0xff000000\n\t"
-//     );
-
-// TST     LR,#4                   ; Called from Handler Mode?
-// MRSNE   R12,PSP                 ; Yes, use PSP
-// MOVEQ   R12,SP                  ; No, use MSP
-// LDR     R12,[R12,#24]           ; Read Saved PC from Stack
-// LDRH    R12,[R12,#-2]           ; Load Halfword
-// BICS    R12,R12,#0xFF00         ; Extract SVC Number
-// uint32_t reg;
-// asm volatile(
-//     "mov  r12, sp\n\t"
-//     "ldr  r12, [r12,#24]\n\t"
-//     // "ldrh r12,[r12, #-2]\n\t"
-//     // "bics r12, r12, #0xff00\n\t"
-//     "mov  %0, r12\n\t": "=r"(reg));
-
-//   uint32_t base[0];
-//   uint32_t reg;
-//
-//
-//   asm volatile("mov  %0, sp\n\t" : "=r"(reg));
-//   uint32_t* at = (uint32_t*) (reg + 44); /* Does GCC set up 5 stack frame
-//   words? */
-//
-//   klogf("Stack pointer: %p\n", reg);
-//   klogf("Stack pointer +44: %p\n", (reg + 44));
-//   klogf("At_: %p: %p\n\n", 0x80009f6, *(uint32_t*)0x80009f6);
-//   klogf("At: %p: %p\n\n", at, *at);
-//
-//
-//   int i = 0;
-//   for (; i < 20 && &base[i] != (void*)STACK_TOP; ++ i) {
-//     kerr_logf(" (%p) %p\n", &base[i], base[i]);
-//   }
-//
-//   // klogf("TEST %p\n", reg);
-//
-//   for(;;);
-
-// register int svc_number asm ("r0");
-
-// klogf("SVC #: %p\n", svc_number);
-// }
-
 void set_control_register(uint32_t reg)
 {
   asm volatile("msr control, %0" : "=r"(reg) :);
@@ -102,3 +21,10 @@ void enter_user_mode()
       "mov r0, #1\n\t"
       "msr control, r0\n\t");
 }
+
+void jump_to_user_mode()
+{
+  asm volatile(
+      "mov r0, #1\n\t"
+      "msr control, r0\n\t");
+}