[arch][vax] redid the exception code, added timers

The port more or less fully works now, except for actual interrupt
driven io and proper atomics.

Also hit a floating point exception in the string benchmark.

arch/vax/arch.c

@@ -12,6 +12,7 @@
 #include <stdint.h>
 #include <arch/ops.h>
 #include <arch/vax.h>
+#include <kernel/thread.h>
 
 #define LOCAL_TRACE 0
 
@@ -19,8 +20,8 @@
 extern uint8_t boot_stack[1024];
 static uint8_t irq_stack[512] __ALIGNED(4);
 
-static uint32_t SCB[scb_max_index] __ALIGNED(512);
-static struct vax_pcb pcb;
+// defined in assembly
+extern uint32_t SCB[];
 
 extern void vax_undefined_exception(void);
 extern void vax_exception_table(void);
@@ -56,16 +57,19 @@ static void dump_regs(void) {
 
 void arch_early_init(void) {
 
-    // initialize the SCB
-    for (int i = 0; i < scb_max_index; i++) {
-        SCB[i] = ((uint32_t)&vax_exception_table + (i * 16)) | SCB_FLAG_KERNEL_STACK;
+    // initialize any empty slots in the SCB
+    for (int i = 0; i < SCB_MAX_OFFSET / 4; i++) {
+        if (SCB[i] == 0) {
+            SCB[i] = ((uint32_t)&vax_exception_table + (i * 16)) | SCB_FLAG_KERNEL_STACK;
+        }
 
     }
     mtpr((uint32_t)SCB, PR_SCBB);
 
-    // point the pcb base register at an initial, empty PCB.
+    // point the pcb base register at the bootstrap thread's empty pcb.
     // we'll switch from it later when starting the threading system.
-    mtpr((uint32_t)&pcb, PR_PCBB);
+    mtpr((uint32_t)&get_current_thread()->arch.pcb, PR_PCBB);
+    get_current_thread()->arch.pcb.p0lr = (4<<24); // set the AST level to 4
 
     // set the interrupt stack. currently unused, but set it to something safe for now.
     mtpr((uint32_t)irq_stack + sizeof(irq_stack), PR_ISP);

arch/vax/exceptions.S

@@ -6,20 +6,24 @@
  * https://opensource.org/licenses/MIT
  */
 #include <lk/asm.h>
+#include <arch/vax.h>
+
+// a global label, but not typed as a function
+#define GLABEL(x) .globl x; x:
 
 .text
 
 // first level exception vectors must be 4 byte aligned
 .balign 4
-.globl vax_undefined_exception
-vax_undefined_exception:
+GLABEL(vax_undefined_exception)
     halt
 
+// for every possible exception handler, build a veneer routine that pushes
+// the exception number to the stack and branches to a common routine
 .balign 16
-.globl vax_exception_table
-vax_exception_table:
+GLABEL(vax_exception_table)
 .set i, 0
-.rept (0x600/4)
+.rept (SCB_MAX_OFFSET / 4)
 
 pushl   $i
 jbr     interrupt_common
@@ -27,7 +31,43 @@ jbr     interrupt_common
 
 .set i, i + 1
 .endr
+END_DATA(vax_exception_table)
 
-FUNCTION(interrupt_common)
+.align 4
+GLABEL(interrupt_common)
     halt
+END_FUNCTION(interrupt_common)
 
+.align 4
+GLABEL(_vax_mcheck)
+    halt
+END_FUNCTION(_vax_mcheck)
+
+.align 4
+GLABEL(_vax_invkstk)
+    halt
+END_FUNCTION(_vax_invkstk)
+
+.align 4
+GLABEL(_vax_interval_timer)
+    pushr $0xfff
+
+    calls $0,vax_interval_timer
+
+    popr  $0xfff
+    rei
+END_FUNCTION(_vax_interval_timer)
+
+// fill in a pre-computed SCB with a few vectors that we care about
+
+#define SEEK(x) .org (x + SCB)
+#define SCB_VECTOR(offset, funct, stack) SEEK(offset); .long funct + stack
+.section .data
+.balign 4
+DATA(SCB)
+    SCB_VECTOR(4, _vax_mcheck, SCB_FLAG_INT_STACK)
+    SCB_VECTOR(8, _vax_invkstk, SCB_FLAG_INT_STACK)
+    //SCB_VECTOR(40, _vax_syscall, SCB_FLAG_KERNEL_STACK)
+    SCB_VECTOR(0xc0, _vax_interval_timer, SCB_FLAG_KERNEL_STACK)
+    SEEK(SCB_MAX_OFFSET)
+END_DATA(SCB)

arch/vax/include/arch/defines.h

@@ -10,7 +10,7 @@
 #define PAGE_SIZE 512
 #define PAGE_SIZE_SHIFT 9
 
-// XXX is this right?
+// is this right?
 #define CACHE_LINE 32
 
-#define ARCH_DEFAULT_STACK_SIZE 1024
+#define ARCH_DEFAULT_STACK_SIZE 4096

arch/vax/include/arch/vax.h

@@ -7,22 +7,21 @@
  */
 #pragma once
 
-#include <assert.h>
 #include <arch/vax/mtpr.h>
 
-// Indexes (in units of a long word) into the SCB for various vectors
-// that we care about. Many are not used yet, so dont fill all of them.
-enum vax_scb_index {
-    foo = 0,
+// Offsets into the SCB for various vectors  that we care about.
+// Many are not used yet, so dont fill all of them.
 
-    scb_adaptor_base_index = 0x100/4,
+#define SCB_ADAPTER_BASE        (0x100)
+#define SCB_DEVICE_BASE         (0x200)
+#define SCB_MAX_OFFSET          (0x600) // according to the 1987 vax arch manual
 
-    scb_device_base_index = 0x200/4,
-    scb_max_index = 0x600/4
-};
+#define SCB_FLAG_KERNEL_STACK   (0b00)
+#define SCB_FLAG_INT_STACK      (0b01)
 
-#define SCB_FLAG_KERNEL_STACK (0b00)
-#define SCB_FLAG_INT_STACK    (0b01)
+#ifndef __ASSEMBLER__
+
+#include <assert.h>
 
 struct vax_pcb {
     uint32_t ksp;
@@ -39,4 +38,5 @@ struct vax_pcb {
 };
 
 static_assert(sizeof(struct vax_pcb) == 96);
+#endif // __ASSEMBLER__
 

arch/vax/include/arch/vax/mtpr.h

@@ -27,8 +27,7 @@
 
  /* All bugs are subject to removal without further notice */
 
-#ifndef _VAX_MTPR_H_
-#define _VAX_MTPR_H_
+#pragma once
 
 /******************************************************************************
 
@@ -159,7 +158,7 @@
 #define AST_NO    4
 #define AST_OK    3
 
-#ifndef _LOCORE
+#ifndef __ASSEMBLER__
 
 typedef unsigned int register_t;
 
@@ -183,6 +182,4 @@ mfpr(int reg)
         : "g" (reg));
     return __val;
 }
-#endif  /* _LOCORE */
-
-#endif /* _VAX_MTPR_H_ */
+#endif  /* __ASSEMBLY__ */

arch/vax/thread.c

@@ -14,7 +14,7 @@
 #include <kernel/thread.h>
 #include <arch/vax.h>
 
-#define LOCAL_TRACE 1
+#define LOCAL_TRACE 0
 
 struct thread *_current_thread;
 

platform/vax/console.c

@@ -82,4 +82,6 @@ void platform_early_console_init(void) {
     }
 }
 
+void platform_console_init(void) {
+}
 

platform/vax/init.c

@@ -40,14 +40,10 @@ void platform_early_init(void) {
     printf("VAX: sid %#x\n", sid);
     printf("VAX: cputype %#x\n", vax_cputype);
     printf("VAX: boardtype %#x\n", vax_boardtype);
+
+    platform_early_timer_init();
 }
 
-// stubbed out time
-static lk_time_t t = 0;
-lk_time_t current_time() {
-    return ++t;
-}
-
-lk_bigtime_t current_time_hires() {
-    return (++t) * 1000;
+void platform_init(void) {
+    platform_console_init();
 }

platform/vax/platform_p.h

@@ -15,3 +15,5 @@ extern uint32_t vax_cputype;
 extern uint32_t vax_boardtype;
 
 void platform_early_console_init(void);
+void platform_console_init(void);
+void platform_early_timer_init(void);

platform/vax/timer.c

@@ -7,12 +7,58 @@
  */
 #include <lk/debug.h>
 #include <lk/err.h>
+#include <lk/trace.h>
+#include <kernel/thread.h>
 #include <platform.h>
 #include <platform/timer.h>
+#include <arch/vax.h>
+
+static uint32_t ticks;
+static platform_timer_callback cb;
+static void *cb_arg;
 
 // stubbed out timer
 status_t platform_set_periodic_timer(platform_timer_callback callback, void *arg, lk_time_t interval) {
+    // for the moment, assume the kernel is asking for 10ms
+    DEBUG_ASSERT(interval == 10);
+
+    cb = callback;
+    cb_arg = arg;
+
     return NO_ERROR;
-    PANIC_UNIMPLEMENTED;
+}
+
+// fires once every 10ms
+void vax_interval_timer(void) {
+    ticks++;
+
+    enum handler_return ret = cb(cb_arg, current_time());
+    if (ret == INT_RESCHEDULE) {
+        thread_preempt();
+    }
+}
+
+void platform_early_timer_init(void) {
+    // we can only assume there is a single 10ms interval timer available,
+    // but go ahead and configure it using the full register interface, since it
+    // wont hurt.
+
+    // load the next count register with -10000 usecs
+    mtpr(-10000, PR_NICR);
+
+    // start the timer and clear any old state
+    // clear error, clear interrupt, enable interrupt, load count, run
+    mtpr((1<<31) | (1<<7) | (1<<6) | (1<<4) | (1<<0), PR_ICCS);
+}
+
+void platform_timer_init(void) {
+}
+
+lk_time_t current_time() {
+    return ticks * 10;
+}
+
+lk_bigtime_t current_time_hires() {
+    return ticks * 10000;
 }
 

top/include/lk/asm.h

@@ -12,3 +12,7 @@
 
 #define LOCAL_FUNCTION(x) .type x,STT_FUNC; x:
 #define LOCAL_DATA(x) .type x,STT_OBJECT; x:
+
+#define END_FUNCTION(x) .size x, . - x
+#define END_DATA(x) .size x, . - x
+