Made some progress towards working with spike.

I'm writing all the tests so they should just work on real hardware,
too.

2 files changed, 166 insertions, 0 deletions

diff --git a/debug/targets/spike/entry.S b/debug/targets/spike/entry.S
new file mode 100755
index 0000000..ff49cf6
--- /dev/null
+++ b/debug/targets/spike/entry.S
@@ -0,0 +1,131 @@
+#ifndef ENTRY_S
+#define ENTRY_S
+
+#include "encoding.h"
+
+#define STACK_SIZE ((1 << 12) - 128)
+
+#ifdef __riscv64
+# define LREG ld
+# define SREG sd
+# define REGBYTES 8
+#else
+# define LREG lw
+# define SREG sw
+# define REGBYTES 4
+#endif
+
+  .section      .text.entry
+  .globl _start
+_start:
+  j handle_reset
+
+nmi_vector:
+  j nmi_vector
+
+trap_vector:
+  j trap_entry
+
+handle_reset:
+  la t0, trap_entry
+  csrw mtvec, t0
+  csrwi mstatus, 0
+  csrwi mideleg, 0
+  csrwi medeleg, 0
+  csrwi mie, 0
+
+  # initialize global pointer
+  la gp, _gp
+
+  # initialize stack pointer
+  la sp, stack_top
+
+  # perform the rest of initialization in C
+  j _init
+
+trap_entry:
+  addi sp, sp, -32*REGBYTES
+
+  SREG x1, 1*REGBYTES(sp)
+  SREG x2, 2*REGBYTES(sp)
+  SREG x3, 3*REGBYTES(sp)
+  SREG x4, 4*REGBYTES(sp)
+  SREG x5, 5*REGBYTES(sp)
+  SREG x6, 6*REGBYTES(sp)
+  SREG x7, 7*REGBYTES(sp)
+  SREG x8, 8*REGBYTES(sp)
+  SREG x9, 9*REGBYTES(sp)
+  SREG x10, 10*REGBYTES(sp)
+  SREG x11, 11*REGBYTES(sp)
+  SREG x12, 12*REGBYTES(sp)
+  SREG x13, 13*REGBYTES(sp)
+  SREG x14, 14*REGBYTES(sp)
+  SREG x15, 15*REGBYTES(sp)
+  SREG x16, 16*REGBYTES(sp)
+  SREG x17, 17*REGBYTES(sp)
+  SREG x18, 18*REGBYTES(sp)
+  SREG x19, 19*REGBYTES(sp)
+  SREG x20, 20*REGBYTES(sp)
+  SREG x21, 21*REGBYTES(sp)
+  SREG x22, 22*REGBYTES(sp)
+  SREG x23, 23*REGBYTES(sp)
+  SREG x24, 24*REGBYTES(sp)
+  SREG x25, 25*REGBYTES(sp)
+  SREG x26, 26*REGBYTES(sp)
+  SREG x27, 27*REGBYTES(sp)
+  SREG x28, 28*REGBYTES(sp)
+  SREG x29, 29*REGBYTES(sp)
+  SREG x30, 30*REGBYTES(sp)
+  SREG x31, 31*REGBYTES(sp)
+
+  csrr a0, mcause
+  csrr a1, mepc
+  mv a2, sp
+  jal handle_trap
+  csrw mepc, a0
+
+  # Remain in M-mode after mret
+  li t0, MSTATUS_MPP
+  csrs mstatus, t0
+
+  LREG x1, 1*REGBYTES(sp)
+  LREG x2, 2*REGBYTES(sp)
+  LREG x3, 3*REGBYTES(sp)
+  LREG x4, 4*REGBYTES(sp)
+  LREG x5, 5*REGBYTES(sp)
+  LREG x6, 6*REGBYTES(sp)
+  LREG x7, 7*REGBYTES(sp)
+  LREG x8, 8*REGBYTES(sp)
+  LREG x9, 9*REGBYTES(sp)
+  LREG x10, 10*REGBYTES(sp)
+  LREG x11, 11*REGBYTES(sp)
+  LREG x12, 12*REGBYTES(sp)
+  LREG x13, 13*REGBYTES(sp)
+  LREG x14, 14*REGBYTES(sp)
+  LREG x15, 15*REGBYTES(sp)
+  LREG x16, 16*REGBYTES(sp)
+  LREG x17, 17*REGBYTES(sp)
+  LREG x18, 18*REGBYTES(sp)
+  LREG x19, 19*REGBYTES(sp)
+  LREG x20, 20*REGBYTES(sp)
+  LREG x21, 21*REGBYTES(sp)
+  LREG x22, 22*REGBYTES(sp)
+  LREG x23, 23*REGBYTES(sp)
+  LREG x24, 24*REGBYTES(sp)
+  LREG x25, 25*REGBYTES(sp)
+  LREG x26, 26*REGBYTES(sp)
+  LREG x27, 27*REGBYTES(sp)
+  LREG x28, 28*REGBYTES(sp)
+  LREG x29, 29*REGBYTES(sp)
+  LREG x30, 30*REGBYTES(sp)
+  LREG x31, 31*REGBYTES(sp)
+
+  addi sp, sp, 32*REGBYTES
+  mret
+
+  .bss
+  .align 4
+stack_bottom:
+  .skip STACK_SIZE
+stack_top:
+#endif
diff --git a/debug/targets/spike/link.lds b/debug/targets/spike/link.lds
new file mode 100755
index 0000000..029a332
--- /dev/null
+++ b/debug/targets/spike/link.lds
@@ -0,0 +1,35 @@
+OUTPUT_ARCH( "riscv" )
+
+SECTIONS
+{
+  /* Leave some space for pk's data structures, which includes tohost/fromhost
+   * which are special addresses we ought to leave alone.  */
+  . = 0x80010000;
+  .text : 
+  {
+    *(.text.entry)
+    *(.text)
+  }
+
+  /* data segment */
+  .data : { *(.data) }
+
+  .sdata : {
+    _gp = . + 0x800;
+    *(.srodata.cst16) *(.srodata.cst8) *(.srodata.cst4) *(.srodata.cst2)
+    *(.srodata*)
+    *(.sdata .sdata.* .gnu.linkonce.s.*)
+  }
+
+  /* bss segment */
+  .sbss : {
+    *(.sbss .sbss.* .gnu.linkonce.sb.*)
+    *(.scommon)
+  }
+  .bss : { *(.bss) }
+
+  /* End of uninitalized data segement */
+  _end = .;
+  _heap_end = .;
+}
+