Implement draft of new calling convention

Here is the new syscall ABI:

  syscall number in a7
  args in a0 - a6
  return value in a0

Here is the integer register map:

  x0  -> x0
  x1  -> ra
  x2  -> sp
  x3  -> tp
  x4  -> gp
  x5  -> t0
  x6  -> t1
  x7  -> t2
  x8  -> s0
  x9  -> s1
  x10 -> a0
  x11 -> a1
  x12 -> a2
  x13 -> a3
  x14 -> a4
  x15 -> a5
  x16 -> a6
  x17 -> a7
  x18 -> s2
  x19 -> s3
  x20 -> s4
  x21 -> s5
  x22 -> s6
  x23 -> s7
  x24 -> s8
  x25 -> s9
  x26 -> s10
  x27 -> s11
  x28 -> t3
  x29 -> t4
  x30 -> t5
  x31 -> t6

5 files changed, 12 insertions, 14 deletions

diff --git a/pk/console.c b/pk/console.c
index 7e17210..4828d3f 100644
--- a/pk/console.c
+++ b/pk/console.c
@@ -113,10 +113,10 @@ void sprintk(char* out, const char* s, ...)
 void dump_tf(trapframe_t* tf)
 {
   static const char* regnames[] = {
-    "z ", "ra", "s0", "s1", "s2", "s3", "s4", "s5",
-    "s6", "s7", "s8", "s9", "sA", "sB", "sp", "tp",
-    "v0", "v1", "a0", "a1", "a2", "a3", "a4", "a5",
-    "a6", "a7", "t0", "t1", "t2", "t3", "t4", "t5"
+    "z ", "ra", "sp", "gp", "tp", "t0",  "t1",  "t2",
+    "s0", "s1", "a0", "a1", "a2", "a3",  "a4",  "a5",
+    "a6", "a7", "s2", "s3", "s4", "s5",  "s6",  "s7",
+    "s8", "s9", "sA", "sB", "t3", "t4",  "t5",  "t6"
   };
 
   tf->gpr[0] = 0;
diff --git a/pk/entry.S b/pk/entry.S
index ad3213c..e5faa24 100644
--- a/pk/entry.S
+++ b/pk/entry.S
@@ -117,18 +117,17 @@ pop_tf:  # write the trap frame onto the stack
   .global  trap_entry
 trap_entry:
   csrw  sup0, x1
-  csrw  sup1, x2
+  csrw  sup1, sp
 
   # when coming from kernel, continue below its stack
   csrr  x1, status
   and   x1, x1, SR_PS
-  add   x2, sp, -320
+  add   sp, sp, -320
   bnez  x1, 1f
-  la    x2, stack_top-320
+  la    sp, stack_top-320
 
 1:save_tf
-  move  sp,x2
-  move  a0,x2
+  move  a0,sp
   j     handle_trap
 
   .bss
diff --git a/pk/fp_asm.S b/pk/fp_asm.S
index a247952..5e00c6c 100644
--- a/pk/fp_asm.S
+++ b/pk/fp_asm.S
@@ -4,8 +4,6 @@
 	.globl	get_fp_state
 get_fp_state:
 
-	frsr	v0
-
 	fsd		f0 ,  0(a0)
 	fsd		f1 ,  8(a0)
 	fsd		f2 , 16(a0)
@@ -39,6 +37,7 @@ get_fp_state:
 	fsd		f30,240(a0)
 	fsd		f31,248(a0)
 
+	frsr	a0
 	ret
 
 	.globl	put_fp_state
diff --git a/pk/handlers.c b/pk/handlers.c
index 2d5356a..2b5bf22 100644
--- a/pk/handlers.c
+++ b/pk/handlers.c
@@ -112,8 +112,8 @@ void handle_fault_store(trapframe_t* tf)
 
 static void handle_syscall(trapframe_t* tf)
 {
-  tf->gpr[16] = do_syscall(tf->gpr[18], tf->gpr[19], tf->gpr[20], tf->gpr[21],
-                           tf->gpr[22], tf->gpr[23], tf->gpr[16]);
+  tf->gpr[10] = do_syscall(tf->gpr[10], tf->gpr[11], tf->gpr[12], tf->gpr[13],
+                           tf->gpr[14], tf->gpr[15], tf->gpr[17]);
   tf->epc += 4;
 }
 
diff --git a/pk/init.c b/pk/init.c
index 53a014f..db74e70 100644
--- a/pk/init.c
+++ b/pk/init.c
@@ -25,7 +25,7 @@ void init_tf(trapframe_t* tf, long pc, long sp, int user64)
   tf->sr = (read_csr(status) & (SR_IM | SR_S64 | SR_VM)) | SR_S | SR_PEI;
   if(user64)
     tf->sr |= SR_U64;
-  tf->gpr[14] = sp;
+  tf->gpr[2] = sp;
   tf->epc = pc;
 }