style fixes

am/arch/x86-qemu/include/am-x86.h

@@ -12,6 +12,7 @@ void lapic_bootap(int cpu, uint32_t address);
 void ioapic_enable(int irq, int cpu);
 void smp_init();
 void cpu_initgdt();
+void cpu_initpte();
 void cpu_setustk(uintptr_t ss0, uintptr_t esp0);
 
 static inline void puts(const char *s) {

am/arch/x86-qemu/src/asye.c

@@ -116,9 +116,10 @@ void irq_handle(struct TrapFrame *tf) {
   _Context *ret_ctx = &ctx;
   if (user_handler) {
     _Context *next = user_handler(ev, &ctx);
-    if (next != NULL) {
-      ret_ctx = next;
+    if (!next) {
+      panic("return to a null context");
     }
+    ret_ctx = next;
   }
 
   // Return to context @ret_ctx
@@ -192,6 +193,10 @@ int _asye_init(_Context*(*handler)(_Event, _Context*)) {
   return 0;
 }
 
+static void panic_on_return() {
+  panic("kernel context returns");
+}
+
 _Context *_kcontext(_Area stack, void (*entry)(void *), void *arg) {
   _Context *ctx = (_Context *)stack.start;
   ctx->eax = ctx->ebx = ctx->ecx = ctx->edx = 0;
@@ -206,7 +211,7 @@ _Context *_kcontext(_Area stack, void (*entry)(void *), void *arg) {
 
   uint32_t **esp = (uint32_t **)&ctx->esp0;
   *(*esp -= 1) = (uint32_t)arg; // argument
-  *(*esp -= 1) = 0; // return address
+  *(*esp -= 1) = (uint32_t)panic_on_return; // return address
   return ctx;
 }
 

am/arch/x86-qemu/src/mpe.c

@@ -58,6 +58,7 @@ static void mp_entry() {
     cpu_initgdt();
     lapic_init();
     ioapic_enable(IRQ_KBD, _cpu());
+    cpu_initpte();
   }
   _atomic_xchg(&ap_boot, 1);
   _entry();

am/arch/x86-qemu/src/pte.c

@@ -16,47 +16,50 @@ static void pgfree(void *ptr) {
   pgfree_usr(ptr);
 }
 
-
-static intptr_t first_proc = 1;
 static PDE *kpt;
 
-static _Area prot_vm_range = {
+static _Area prot_vm_range = { // 1GB protected space
   .start = (void*)0x40000000,
   .end   = (void*)0x80000000,
 };
 static _Area segments[] = {
-    {.start = (void*)0,          .end = (void*)0x10000000},  //   Low memory: kernel data
-    {.start = (void*)0xf0000000, .end = (void*)(0)},         //   High memory: APIC and VGA
+  {.start = (void*)0,          .end = (void*)0x10000000}, // kernel data
+  {.start = (void*)0xf0000000, .end = (void*)(0)},        // system memory
 };
 
-// must be called atomically per-cpu
 int _pte_init(void * (*pgalloc_f)(size_t), void (*pgfree_f)(void *)) {
+  if (_cpu() != 0) {
+    panic("init PTE in non-bootstrap CPU");
+  }
+
   pgalloc_usr = pgalloc_f;
   pgfree_usr = pgfree_f;
 
-  if (first_proc) {
-    // first processor, create kernel page table
-
-    kpt = pgalloc();
-    for (int i = 0; i < sizeof(segments) / sizeof(segments[0]); i++) {
-      _Area *seg = &segments[i];
-      for (uint32_t pa = (uint32_t)seg->start; pa != (uint32_t)seg->end; pa += PGSIZE) {
-        PTE *ptab;
-        if (!(kpt[PDX(pa)] & PTE_P)) {
-          ptab = pgalloc();
-          kpt[PDX(pa)] = PTE_P | PTE_W | (uint32_t)ptab;
-        } else {
-          ptab = (PTE*)PTE_ADDR(kpt[PDX(pa)]);
-        }
-        ptab[PTX(pa)] = PTE_P | PTE_W | pa;
+  kpt = pgalloc();
+  for (int i = 0; i < sizeof(segments) / sizeof(segments[0]); i++) {
+    _Area *seg = &segments[i];
+    for (uint32_t pa = (uint32_t)seg->start;
+                  pa != (uint32_t)seg->end;
+                  pa += PGSIZE) {
+      PTE *ptab;
+      if (!(kpt[PDX(pa)] & PTE_P)) {
+        ptab = pgalloc();
+        kpt[PDX(pa)] = PTE_P | PTE_W | (uint32_t)ptab;
+      } else {
+        ptab = (PTE*)PTE_ADDR(kpt[PDX(pa)]);
       }
+      ptab[PTX(pa)] = PTE_P | PTE_W | pa;
     }
+  }
+  cpu_initpte(); // set CR3 and CR0 if kpt is not NULL
+  return 0;
+}
 
+void cpu_initpte() {
+  if (kpt) {
     set_cr3(kpt);
     set_cr0(get_cr0() | CR0_PG);
-    _atomic_xchg(&first_proc, 0);
   }
-  return 0;
 }
 
 int _protect(_Protect *p) {

am/arch/x86-qemu/src/trm.c

@@ -7,7 +7,6 @@ _Area _heap; // the heap memory defined in AM spec
 int main();
 static void memory_init();
 
-
 // the bootloader jumps here,
 // with a (small) bootstrap stack
 void _start() {
@@ -42,15 +41,10 @@ static void memory_init() {
   st = ed = (((uintptr_t)&end) & ~(step - 1)) + step;
   while (1) {
     volatile uint32_t *ptr = (uint32_t*)ed;
-    *ptr = 0x5a5a5a5a; // write
-    if (*ptr == 0x5a5a5a5a) { // then read
-      // if the value check passed, the memory is okay
-      ed += step;
-    } else {
-      // otherwise we hit the end of the physical memory
-      break;
-    }
+    *ptr = 0x5a5a5a5a; // write then read
+    if (*ptr == 0x5a5a5a5a) ed += step; // check passed, memory is okay
+    else break; // hit the end of the physical memory
   }
   _heap.start = (void*)st;
-  _heap.end = (void*)ed;
+  _heap.end   = (void*)ed;
 }

tests/mptest/main.cpp

@@ -3,13 +3,26 @@
 #include <klib.h>
 
 void f() {
-  // printf("%d / %d\n", _cpu(), _ncpu());
   while (1) {
     printf("%d", _cpu());
   }
 }
 
+static uintptr_t start;
+
+static void *alloc(size_t size) {
+  while (start % size != 0) start++;
+  void *ret = (void *)start;
+  start += size;
+  return ret;
+}
+
+static void free(void *ptr) {
+}
+
 int main() {
+  start = (uintptr_t)_heap.start;
+  _pte_init(alloc, free);
   _mpe_init(f);
   assert(0);
   return 0;

tests/mptest/run

@@ -0,0 +1,3 @@
+#!/bin/bash
+make && \
+qemu-system-i386 -smp 4 -serial stdio build/mptest-x86-qemu

tests/vmtest/main.c

@@ -11,7 +11,7 @@ _Context* handler(_Event ev, _Context *ctx) {
       break;
     case _EVENT_IRQ_TIMER:
     case _EVENT_IRQ_IODEV: 
-      printf(".");
+      printf("==== interrupt ===\n");
       break;
     case _EVENT_PAGEFAULT:
       printf("PF: %x %s%s%s\n",
@@ -85,7 +85,7 @@ int main() {
   _Area k = { .start = kstk, .end = kstk + 4096 };
   _Area u = { .start = ptr + pgsz, .end = ptr + pgsz * 2 };
 
-  uctx = _ucontext(&prot, u, k, ptr, NULL);
+  uctx = _ucontext(&prot, u, k, ptr, 0);
   _switch(&prot);
 
   _intr_write(1);