timer scheduling works!

P-Gu · Feb 27, 2022 · 9958ca2 · 9958ca2
1 parent 18a0646
commit 9958ca2
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Showing 4 changed files with 33 additions and 27 deletions.
diff --git a/earth/cpu_intr.c b/earth/cpu_intr.c
@@ -27,8 +27,9 @@ int intr_init() {
 }
 
 static void trap_entry() {
- int mcause;
+ int mcause, mepc;
  __asm__ volatile("csrr %0, mcause" : "=r"(mcause));
+ __asm__ volatile("csrr %0, mepc" : "=r"(mepc));
 
  int id = mcause & METAL_MCAUSE_IDMASK;
  if (mcause & METAL_MCAUSE_INTR) {
@@ -39,9 +40,19 @@ static void trap_entry() {
  } else {
  if (excp_handler != NULL)
  excp_handler(id);
- else
- FATAL("Got exception %d but handler not registered", id);
+ else {
+ if (id == 2 && mepc == 0) {
+ /* This might be a bug of the CPU */
+ INFO("Got spurious exception %d (mepc=%x)", id, mepc);
+ __asm__ volatile("csrw mepc, %0" ::"r"(VADDR_START));
+ return;
+ } else {
+ FATAL("Got exception %d (mepc=%x) but handler not registered", id, mepc); 
+ }
+ }
  }
+
+ __asm__ volatile("csrw mepc, %0" ::"r"(mepc));
 }
 
 int intr_register(handler_t _handler) {

diff --git a/grass/process.c b/grass/process.c
@@ -54,8 +54,17 @@ void ctx_entry() {
  ctx_switch(&tmp, proc_set[proc_curr_idx].sp);
 }
 
+
+static void proc_entry() __attribute__((interrupt, aligned(128)));
+static void proc_entry() {
+ __asm__ volatile("csrw mepc, %0" ::"r"(VADDR_START));
+}
+
 static void proc_yield() {
- if (earth->disk_busy()) {
+ int mepc;
+ __asm__ volatile("csrr %0, mepc" : "=r"(mepc));
+
+ if (earth->disk_busy() || mepc < VADDR_START) {
  timer_reset();
  return;
  }
@@ -79,32 +88,18 @@ static void proc_yield() {
  int next_pid = PID(proc_next_idx);
  int next_status = proc_set[proc_next_idx].status;
 
+ /* HIGHLIGHT("Switch from process %d", curr_pid); */
  earth->mmu_switch(next_pid);
  proc_set_running(next_pid);
  proc_set_runnable(curr_pid);
  proc_curr_idx = proc_next_idx;
- timer_reset();
 
  if (next_status == PROC_READY) {
- INFO("0x80000000: %.8x", *(int*)VADDR_START);
- INFO("0x80000004: %.8x", *(int*)(VADDR_START + 4));
- INFO("0x80000008: %.8x", *(int*)(VADDR_START + 8));
- INFO("0x8000000c: %.8x", *(int*)(VADDR_START + 12));
- INFO("0x80000010: %.8x", *(int*)(VADDR_START + 16));
- INFO("0x80000014: %.8x", *(int*)(VADDR_START + 20));
- INFO("0x80000018: %.8x", *(int*)(VADDR_START + 24));
- INFO("0x8000001c: %.8x", *(int*)(VADDR_START + 28));
- INFO("0x80000020: %.8x", *(int*)(VADDR_START + 32));
- INFO("0x80000024: %.8x", *(int*)(VADDR_START + 36));
- INFO("0x80000028: %.8x", *(int*)(VADDR_START + 40));
- INFO("0x8000002c: %.8x", *(int*)(VADDR_START + 44));
- INFO("saved stack pointer: %.8x", proc_set[0].sp);
- INFO("earth log: %.8x", earth->log);
- INFO("earth log info: %.8x", earth->log.log_info);
- __asm__ volatile("csrw mepc, %0" ::"r"(VADDR_START));
- __asm__ volatile("mret");
+ timer_reset();
+ proc_entry();
+ FATAL("proc_entry should never return");
  } else if (next_status == PROC_RUNNABLE) {
- INFO("here2");
+ timer_reset();
  void* tmp;
  ctx_switch(&tmp, proc_set[proc_curr_idx].sp);
  }

diff --git a/shared/ctx.S b/shared/ctx.S
@@ -11,7 +11,6 @@
  .global ctx_switch
 ctx_switch:
  addi sp,sp,-64
- sw ra,0(sp) /* save return address */
  sw s0,4(sp) /* save callee-saved registers */
  sw s1,8(sp)
  sw s2,12(sp)
@@ -24,9 +23,9 @@ ctx_switch:
  sw s9,40(sp)
  sw s10,44(sp)
  sw s11,48(sp)
+ sw ra,52(sp) /* save return address */
  sw sp,0(a0) /* save the current stack pointer */
  mv sp,a1 /* switch the stack */
- lw ra,0(sp) /* restore return address */
  lw s0,4(sp) /* restore callee-saved registers */
  lw s1,8(sp)
  lw s2,12(sp)
@@ -39,12 +38,12 @@ ctx_switch:
  lw s9,40(sp)
  lw s10,44(sp)
  lw s11,48(sp)
+ lw ra,52(sp) /* restore return address */
  addi sp,sp,64
  ret
 
 ctx_start:
  addi sp,sp,-64
- sw ra,0(sp) /* save return address */
  sw s0,4(sp) /* save callee-saved registers */
  sw s1,8(sp)
  sw s2,12(sp)
@@ -57,6 +56,7 @@ ctx_start:
  sw s9,40(sp)
  sw s10,44(sp)
  sw s11,48(sp)
+ sw ra,52(sp) /* save return address */
  sw sp,0(a0) /* save the current stack pointer */
  mv sp,a1 /* switch the stack */
  jal ctx_entry /* call ctx_entry() */
diff --git a/shared/include/egos.h b/shared/include/egos.h
@@ -4,7 +4,7 @@
 
 #define INTR_ID_TMR 7
 #define INTR_ID_SOFT 3
-#define QUANTUM_NCYCLES 500
+#define QUANTUM_NCYCLES 5000
 
 #define F_INUSE 0x1
 #define F_READ 0x2