Have Debug memory kind of working again.

Debug exception -> ROM -> RAM -> ROM, then something goes wrong.

8 files changed, 22 insertions, 84 deletions

diff --git a/riscv/debug_module.cc b/riscv/debug_module.cc
index 2cda772..e3eb16b 100644
--- a/riscv/debug_module.cc
+++ b/riscv/debug_module.cc
@@ -5,19 +5,17 @@
 
 #include "debug_rom/debug_rom.h"
 
-debug_module_t::debug_module_t()
-{
-  /* Copy Debug ROM into the page. */
-  memcpy(raw_page + DEBUG_ROM_START - DEBUG_START,
-      debug_rom_raw, debug_rom_raw_len);
-}
-
 bool debug_module_t::load(reg_t addr, size_t len, uint8_t* bytes)
 {
   addr = DEBUG_START + addr;
 
   if (addr >= DEBUG_RAM_START && addr + len <= DEBUG_RAM_END) {
-    memcpy(bytes, raw_page + addr - DEBUG_START, len);
+    memcpy(bytes, debug_ram + addr - DEBUG_RAM_START, len);
+    return true;
+  }
+
+  if (addr >= DEBUG_ROM_START && addr + len <= DEBUG_ROM_END) {
+    memcpy(bytes, debug_rom_raw + addr - DEBUG_ROM_START, len);
     return true;
   }
 
@@ -37,7 +35,7 @@ bool debug_module_t::store(reg_t addr, size_t len, const uint8_t* bytes)
   }
 
   if (addr >= DEBUG_RAM_START && addr + len <= DEBUG_RAM_END) {
-    memcpy(raw_page + addr - DEBUG_START, bytes, len);
+    memcpy(debug_ram + addr - DEBUG_RAM_START, bytes, len);
     return true;
   } else if (len == 4 && addr == DEBUG_CLEARDEBINT) {
     clear_interrupt(bytes[0] | (bytes[1] << 8) |
@@ -52,7 +50,7 @@ bool debug_module_t::store(reg_t addr, size_t len, const uint8_t* bytes)
 
 void debug_module_t::ram_write32(unsigned int index, uint32_t value)
 {
-  char* base = raw_page + DEBUG_RAM_START - DEBUG_START + index * 4;
+  char* base = debug_ram + index * 4;
   base[0] = value & 0xff;
   base[1] = (value >> 8) & 0xff;
   base[2] = (value >> 16) & 0xff;
@@ -63,25 +61,10 @@ uint32_t debug_module_t::ram_read32(unsigned int index)
 {
   // It'd be better for raw_page (and all memory) to be unsigned chars, but mem
   // in sim_t is just chars, so I'm following that convention.
-  unsigned char* base = (unsigned char*)
-    (raw_page + DEBUG_RAM_START - DEBUG_START + index * 4);
+  unsigned char* base = (unsigned char*) (debug_ram + index * 4);
   uint32_t value = ((uint32_t) base[0]) |
     (((uint32_t) base[1]) << 8) |
     (((uint32_t) base[2]) << 16) |
     (((uint32_t) base[3]) << 24);
   return value;
 }
-
-char* debug_module_t::page(reg_t paddr)
-{
-  fprintf(stderr, "dm::page(0x%lx)\n", paddr);
-
-  assert(PGSHIFT == 12);
-
-  if (paddr == (DEBUG_START & PGMASK)) {
-    return raw_page;
-  }
-
-  fprintf(stderr, "ERROR: invalid page to debug module at 0x%lx\n", paddr);
-  return NULL;
-}
diff --git a/riscv/debug_module.h b/riscv/debug_module.h
index 734a2a3..d7c1a87 100644
--- a/riscv/debug_module.h
+++ b/riscv/debug_module.h
@@ -9,11 +9,8 @@
 class debug_module_t : public abstract_device_t
 {
   public:
-    debug_module_t();
-
     bool load(reg_t addr, size_t len, uint8_t* bytes);
     bool store(reg_t addr, size_t len, const uint8_t* bytes);
-    char* page(reg_t paddr);
 
     void ram_write32(unsigned int index, uint32_t value);
     uint32_t ram_read32(unsigned int index);
@@ -33,8 +30,7 @@ class debug_module_t : public abstract_device_t
   private:
     // Track which interrupts from module to debugger are set.
     std::set<uint32_t> interrupt;
-    // TODO: use PGSIZE, which requires solving some circular include dependencies.
-    char raw_page[4096];
+    char debug_ram[DEBUG_RAM_SIZE];
 };
 
 #endif
diff --git a/riscv/decode.h b/riscv/decode.h
index 5732a0d..3a8b3a4 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -236,16 +236,16 @@ private:
 #define DCSR_CAUSE_STEPPED      4
 #define DCSR_CAUSE_HALT         5
 
-#define DEBUG_START             0xfffffffffffff000
-#define DEBUG_ROM_START         0xfffffffffffff800       // TODO: 0x800
+#define DEBUG_START             0x100
+#define DEBUG_ROM_START         0x800
 #define DEBUG_ROM_RESUME        (DEBUG_ROM_START + 4)
 #define DEBUG_ROM_END           (DEBUG_ROM_START + debug_rom_raw_len)
-#define DEBUG_RAM_START         0xfffffffffffffc00       // TODO: 0x400
+#define DEBUG_RAM_START         0x400
 #define DEBUG_RAM_SIZE          64
 #define DEBUG_RAM_END           (DEBUG_RAM_START + DEBUG_RAM_SIZE)
-#define DEBUG_END               0xffffffffffffffff
-#define DEBUG_CLEARDEBINT       0xfffffffffffffef8
-#define DEBUG_SETHALTNOT        0xffffffffffffff00
+#define DEBUG_END               0xfff
+#define DEBUG_CLEARDEBINT       0x108
+#define DEBUG_SETHALTNOT        0x100
 #define DEBUG_SIZE              (DEBUG_END - DEBUG_START + 1)
 
 #endif
diff --git a/riscv/devices.cc b/riscv/devices.cc
index e6f5d7d..4e88a1d 100644
--- a/riscv/devices.cc
+++ b/riscv/devices.cc
@@ -7,9 +7,12 @@ void bus_t::add_device(reg_t addr, abstract_device_t* dev)
 
 bool bus_t::load(reg_t addr, size_t len, uint8_t* bytes)
 {
+  fprintf(stderr, "bus load(0x%lx, %ld)\n", addr, len);
   auto it = devices.lower_bound(-addr);
-  if (it == devices.end())
+  if (it == devices.end()) {
+      fprintf(stderr, "  -> false\n");
     return false;
+  }
   return it->second->load(addr - -it->first, len, bytes);
 }
 
@@ -20,11 +23,3 @@ bool bus_t::store(reg_t addr, size_t len, const uint8_t* bytes)
     return false;
   return it->second->store(addr - -it->first, len, bytes);
 }
-
-char* bus_t::page(reg_t paddr)
-{
-  auto it = devices.lower_bound(-paddr);
-  if (it == devices.end())
-    return NULL;
-  return it->second->page(paddr);
-}
diff --git a/riscv/devices.h b/riscv/devices.h
index 8378188..cb3b6d9 100644
--- a/riscv/devices.h
+++ b/riscv/devices.h
@@ -11,9 +11,6 @@ class abstract_device_t {
  public:
   virtual bool load(reg_t addr, size_t len, uint8_t* bytes) = 0;
   virtual bool store(reg_t addr, size_t len, const uint8_t* bytes) = 0;
-  // Return a pointer to the start of the page that addr falls in, or NULL if
-  // there is no IO device at that address.
-  virtual char* page(reg_t addr) { return NULL; }
   virtual ~abstract_device_t() {}
 };
 
@@ -21,9 +18,6 @@ class bus_t : public abstract_device_t {
  public:
   bool load(reg_t addr, size_t len, uint8_t* bytes);
   bool store(reg_t addr, size_t len, const uint8_t* bytes);
-  // Return a pointer to the start of the page that addr falls in, or NULL if
-  // there is no IO device at that address.
-  char* page(reg_t paddr);
   void add_device(reg_t addr, abstract_device_t* dev);
 
  private:
diff --git a/riscv/mmu.cc b/riscv/mmu.cc
index 514547c..dee41a9 100644
--- a/riscv/mmu.cc
+++ b/riscv/mmu.cc
@@ -51,28 +51,6 @@ reg_t mmu_t::translate(reg_t addr, access_type type)
   return walk(addr, type, mode > PRV_U, pum) | (addr & (PGSIZE-1));
 }
 
-const char* mmu_t::fill_from_mmio(reg_t vaddr, reg_t paddr)
-{
-  reg_t rv_start = paddr & PGMASK;
-  char* spike_start = proc->sim->mmio_page(rv_start);
-
-  if (!spike_start)
-    return NULL;
-
-  // TODO: refactor with refill_tlb()
-  reg_t idx = (vaddr >> PGSHIFT) % TLB_ENTRIES;
-  reg_t expected_tag = vaddr >> PGSHIFT;
-
-  if (tlb_load_tag[idx] != expected_tag) tlb_load_tag[idx] = -1;
-  if (tlb_store_tag[idx] != expected_tag) tlb_store_tag[idx] = -1;
-  if (tlb_insn_tag[idx] != expected_tag) tlb_insn_tag[idx] = -1;
-
-  tlb_insn_tag[idx] = expected_tag;
-  tlb_data[idx] = spike_start - DEBUG_START;
-
-  return spike_start + (paddr & ~PGMASK);
-}
-
 const uint16_t* mmu_t::fetch_slow_path(reg_t vaddr)
 {
   reg_t paddr = translate(vaddr, FETCH);
diff --git a/riscv/sim.cc b/riscv/sim.cc
index b09e720..4b4eed4 100644
--- a/riscv/sim.cc
+++ b/riscv/sim.cc
@@ -42,6 +42,8 @@ sim_t::sim_t(const char* isa, size_t nprocs, size_t mem_mb, bool halted,
     fprintf(stderr, "warning: only got %lu bytes of target mem (wanted %lu)\n",
             (unsigned long)memsz, (unsigned long)memsz0);
 
+  bus.add_device(DEBUG_START, &debug_module);
+
   debug_mmu = new mmu_t(this, NULL);
 
   for (size_t i = 0; i < procs.size(); i++) {
@@ -52,8 +54,6 @@ sim_t::sim_t(const char* isa, size_t nprocs, size_t mem_mb, bool halted,
 
   rtc.reset(new rtc_t(procs));
   make_config_string();
-
-  bus.add_device(DEBUG_START, &debug_module);
 }
 
 sim_t::~sim_t()
@@ -149,11 +149,6 @@ bool sim_t::mmio_store(reg_t addr, size_t len, const uint8_t* bytes)
   return bus.store(addr, len, bytes);
 }
 
-char* sim_t::mmio_page(reg_t addr)
-{
-  return bus.page(addr);
-}
-
 void sim_t::make_config_string()
 {
   reg_t rtc_addr = EXT_IO_BASE;
diff --git a/riscv/sim.h b/riscv/sim.h
index d3c9a6b..bd42419 100644
--- a/riscv/sim.h
+++ b/riscv/sim.h
@@ -68,9 +68,6 @@ private:
   reg_t mem_to_addr(char* x) { return x - mem + DRAM_BASE; }
   bool mmio_load(reg_t addr, size_t len, uint8_t* bytes);
   bool mmio_store(reg_t addr, size_t len, const uint8_t* bytes);
-  // Return a pointer to the start of the page that addr falls in, or NULL if
-  // there is no IO device at that address.
-  char* mmio_page(reg_t addr);
   void make_config_string();
 
   // presents a prompt for introspection into the simulation